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REPORT
THIRD MEETING
BRITISH ASSOCIATION
FOR THE
ADVANCEMENT OF SCIENCE;
HELD AT CAMBRIDGE IN 1833.
LONDON:
JOHN MURRAY, ALBEMARLE STREET.
1834.
LONDON:
PRINTED BY RICHARD TAYLOR,
RED LION COURT, FLEET STREET.
PREFACE,
a et
'T'HE Transactions of the British Association consist of
three parts ; first, of Reports on the State of Science drawn
up at the instance of the Association ; secondly, of Miscel-
laneous Communications to the Meetings; and thirdly, of
Recommendations by the Committees, having for their ob-
jects to mark out certain points for scientific inquiry.
It is proper to remark, that some of the Reports here
printed are to be considered in the light of first parts of
the intended survey of the sciences reviewed in them, the
continuation being postponed to a future Meeting. Thus,
the Report on Hydraulics, by Mr. G. RENNIE, will be
completed in a second part, to be presented to the Meeting
at Edinburgh ; the Report on the mathematical theory of
the same science, by the Rev. Mr. Cuauuis, which is
here restricted to problems on the common theory of Fluids,
will be further extended to the theories which have recently
been advanced respecting the internal constitution of Fluids
and the state of their caloric, to account for certain phzeno-
mena of their equilibrium and motion ; and the Report on
Analytical Science, by the Rev. Mr. Peacock, which in the
present volume includes Algebra, and the application of
Algebra to Geometry, is intended to be hereafter concluded
by a review of the Differential and Integral Calculus and the
theory of Series. In like manner, to the Report on Botany,
by Dr. Linpuey, which embraces only the physiological
part of the science, that which Mr. BentHam has under-
taken on the State and Progress of Systematic Botany will
be supplemental ; and to the present Report, by Dr. CHARLES
Henry, on one branch of Animal Physiology, a more
general review of the progress of that science will be added
by the Rev. Dr. Cuark. — /
_ With respect to the next part of the Transactions, which
includes the communications made to the Sections, two
a 2
iv PREFACE.
rules have been adopted ; the first is, to print no oral com-
munications unless furnished or revised by the Author him-
self. In the former volume this rule was slightly deviated
from, for the purpose of showing in what manner the
Meetings were conducted. But however valuable a part of
the proceedings of the Meetings the verbal communications
and discussions may be, it is evidently impossible to publish
a safe and satisfactory report of them from any minutes
which can be taken. The second ruleis, not to print any
of the miscellaneous communications at length ; but eitker
abstracts of them, or notices* only, the object of the rule
being to keep the Transactions within the bounds which
the Association has prescribed to itself, and to prevent any
interference with the publications of other societies. In
the present volume, there is one paper printed at lengtht,
which contains the results of certain experiments instituted
expressly at the request of the Association.
The Recommendations of various subjects for scientific
inquiry agreed upon at Cambridge have been here incor-
porated with those adopted at former Meetings, and the
Suggestions which are contained in the Reports on the state
of science, published in the present and preceding volume,
have likewise been added; so as to present a general view of
the desiderata in science to which attention has been invited.
To this part of the volume are also appended those direc-
tions for the use of observers which have proceeded from
Committees appointed to promote particular investigations.
To the Transactions is prefixed a brief outline of the
General Proceedings of the Cambridge Meeting, a fuller Re-
port of them having been rendered unnecessary by the ac-
count which has already issued from the University press.
The observations, however, delivered by the Rev. Mr. WuE-
WELL on the state of science as it is exhibited in the first
volume of the Reports of the Association, not having been
before published, are printed at length.
* The notices of Communications will be found in the general account of the
Proceedings of the Sections, p. 353.
+ ‘* Experiments on the Quantity of Rain which falls at different Heights in
the Atmosphere.”
eon x
CONTENTS
ProcEEDINGS OF THE MEETING .-...- +e sees reer certs eters
TRANSACTIONS.
Report on the State of Knowledge respecting Mineral Veins. By
Joun Taytor, F.R.S., Treasurer of the Geological Society and
of the British Association for the Advancement of Science,. &c.
On the Principal Questions at present debated in the Philosophy
of Botany. By Joun Linviey, Ph. D:, F.R.S., Professor of
Botany in the University of London ..........+--++++++++-
Report on the Physiology of the Nervous System. By WriiiiAm
Caries Henry, M.D., Physician to the Manchester Royal In-
Report on the present State of our Knowledge respecting the
Strength of Materials. By Peter Bartow, F.R.S., Corr. Memb.
Inst. France, &c. &C. 2... ee ee ees
Report on the State of our Knowledge respecting the Magnetism
of the Earth. By S. Hunver Curisriz, M.A., F.R.S., M.C.P.S.,
Corr. Memb. Philom. Soc. Paris, Hon. Memb. Yorkshire Phil.
Soc.; of the Royal Military Academy ; and Member of Trinity
College Cambridge ..... 1... +0. eee e tere ere e eee r
Report on the present State of the Analytical Theory of Hydro-
statics and Hydrodynamics. By the Rev. J. Cuautis, late Fel-
low of Trinity College Cambridge... ........---+---- ee eee
Report on the Progress and present State of our Knowledge of
Hydraulics as a Branch of Engineering. By Grorcz RENNIE,
AAS AER ORT gible TENG. ooh ot cca eae a eae ee
Report on the recent Progress and present State of certain Branches
of Analysis. By Grorce Peacock, M.A., F.R.S., F.G.S.,
F.Z.S., F.R.A.S., F.C.P.S., Fellow and Tutor of Trinity Col-
lege Cambridge ...... 2.2.02. eee eee eee rete e eens
TRANSACTIONS OF THE SECTIONS.
_ I, Maruemarics anD Puysics.
Professor CErstep on the Compressibility of Water............
W.R. Hamuzron on some Results of the View of a Characteristic
Function in Optics ..........0 02s eee eee ee eee
The Rey. H. Luoyp on Conical Refraction ..........-.-- 056:
27
59
93
131
153
185
vi CONTENTS.
Page.
Sir Jounn F. W. Herscuet on the Absorption of Light by coloured
Media, viewed in connexion with the undulatory Theory .... 373
The Rey. Bapen Powe tt on the Dispersive Powers of the Media
of the Eye, in connexion with its Achromatism ............ 374
R. Porrer, Jun., on the power of Glass of Antimony to reflect
i anne core mbar nec) Samim cens cs 377
on a Phenomenon in the Interference of Light
Hitherto! WOCdeSeribed.\).j4c00 = «fois: lm oler-uays = eheeeetehate tena eh een 378
Sir Joun F. W. Herscuex’s Explanation of the Principle and Con-
atroction of the Actinometer ....:. 9) ..1cjehitis : 101s bias pant 379
M. Me ttonr’s Account of some recent Experiments on Radiant Rs
1 SVE RRR Ae ai hr ae ARENT CID Cisio din Dalodig ico ae 381
Joun ParpEavux on Thermo-Electricity ..2..0................ 384
W. Syow Harris on some new Phenomena of Electrical Attrac-
Fiemme. area Aeterna fs). This Se WG die ea coe ies Been dee 386
The Rev. Joun G. MacVicar on Electricity ................ 390
The Rev. J. Powrr’s Inquiry into the Cause of Endosmose and
HS XOSMOSE ea jers s haPAE HE elses Ee cpatege vere wept eke os Seen 391
Micuart Farapay on Electro-chemical Decomposition ........ 393
Dr. Turner's Experiments on Atomic Weights .............. 399
Prof. Jounnsron’s Notice of a Method of analysing Carbonaceous
URS Se SC eg ig ha Na BY se ange hale Sate ae 400
R. Porrzr, Jun. A Communication respecting an Arch of the
paninigtes ESQEC ANI 5. 22015 ).15. 0 2 rele BE hss, UE IE a ee 401
Joun Puruiipes’s Report of Experiments on the Quantities of Rain
falling at different Elevations above the Surface of the Ground at
Woes oe Hah cusliva wits Andie cet aes Bi eae eee 401
II. Partosoruicat Instruments AnD Mecuanicat Arts.
The Rev. Wm. Scorzssy on a peculiar Source of Error in Experi-
ments: Wea the Dipping Needle... 23.42 0.01.07 2. eee 412
The Rev. W. H. Mizzer on the Construction of anew Barometer 414
W. L. Wuarron on a Barometer with an enlarged Scale ...... 414
W.S. Harris on the Construction of a new Wheel Barometer .. 414
J. Newman on a new Method of constructing a Portable Barometer 417
The Rev. James Cummine on an Instrument for measuring the
total heating Effect of the Sun’s Rays for a giveu time ...... 418
———— on some Electro-magnetic Instruments 418
Anprew Ure on the Thermostat, or Heat-governor .......... 419
Tuomas Davison on a Reflecting Telescope ................ 420
W.L. Wuarton on a Steam-engine for pumping Water ...... 421
E. J. Denv on the Application of a glass Balance-spring to Chro-
MRODACLETS 2). 2.2, 21: hcp een Re eee Macnee eer le cholo rainy tole ke Tele 421
E. Hopexinson on the Effect of Impact on Beams...... Bo te al 421
——————. on the direct tensile Strength of Cast Iron ...... 423
J. I. Hawxrys’s Investigation of the Principle of Mr. Saxton’s loco-
mouve diftercntial Pulley, be.') > 2a OPE Oe, 424
Joun Tayior’s Account of the Depths of Mines.............. 427
J; Owen on Naval Architecture awit see ae GEOL S 8 Es 430
CONTENTS. vil
Page.
III. Naturat Historny—Anatomy—Puysio.uoey.
Professor AGarpu on the originary Structure of the Flower, and
the mutual Dependency of its Parts ................,..... 433
Professor DausEny’s Notice of Researches on the Action of Light
CEDARS GET Sipe I pia ih iS arti 8 1 Bi ol Cag 436
Watrer Apam on some symmetrical Relations of the Bones of the
(SS ACT lig ie OR Ra Riemer be Nig A 2 ie 437
R. Haran on some new species of Fossil Saurians found in Ame-
CR ee en epee RMS ae oniciol Sects Se SRE ol eco ac ease eRe ml Sees as 440
The Rev. L. Jenyns’s Remarks on Genera and Subgenera, &c. .. 440
J. Macartney on some parts of the Natural History of the Com-
DKS WBE G ites ee ae an Ms PNR oA oO A ao a 44]
J. Buackwa.t’s Observations relative to the Structure and Func-
SUMS ARNE SSPUCLELS eet a hrs) elle nis Sor pee ie siete ee olen ooo ook ees 444
W. Yarrect on the Reproduction of the Eel ................ 446
C. Wittcox on the Naturalization in England of the Mytilus cre-
natus, a native of India, and the Bate dal Heros, a native
6) aN ietee | ee ae el Racal “bce ae er aims ete ica ng AA ac Neri Ae Soe 448
J. Macartney’s Abstract of Observations on the Structure and
Functions of the Nervous System ........................ 449
H. Carurte’s Abstract of Observations on the Motions and Sounds
Bierce Lcantere Tes i erase sean lo eins coh a eee Gehan 454
H. Earze on the Mechanism and Physiology of the Urethra .... 460
Burt on the Nomenclature of Clouds .................. 460
G. H. Frexpine on the peculiar Atmospherical Phenomena as ob-
served at Hull during April and May 1833, in relation to the
Pm mCUICE Ol MIUCH AAS 2th 0ns Gate. Se. Bae RL ee 461
IV. History or Science.
Francis Baity’s short Account of some MS. Letters (addressed
to Mr. Abraham Sharp, relative to the Publication of Mr. Flam-
steed’s Historia Celestis,) laid on the table for the inspection of
the Members of the Association................ 0.00 eeeeee 462
Recommendations of the British Association for the Advancement
2 ha ER AR, 5 Ae ae ey Ey i 4 fale ARE neh ns eas 467
Recommendations of the Committees cat 4 \ fe gE RP, beh Oe aR 469
Sap RETRGR ERA 2) SoG) 9. eee ys Ret ee en) Se OPN ae ey ogee, bate 484
Prospectus of the Objects and Plan of the Statistical Society of
CUS gees bo a0 ier, Sneath ain ena Se eR OU DR 492
Objects and Rules of the Association’. °. o) 005.8000. 2 eee ee 497
|G LS ee Se 2 file a ROR Ca COR UG aise AN afc clee Er 501
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SINNOOOV SMAYASVAWL
THIRD REPORT.
PROCEEDINGS OF THE MERTING.
1833.
THE third Meeting of the British Association commenced its
sittings at Cambridge on Monday, the 24th of June, 1833. It
was attended by more than nine hundred Members, and. was
honoured with the presence of several foreign philosophers.
The extent of accommodation provided by the University, and
by the societies of which it consists, corresponded with the
magnitude of the Meeting. The public schools, with two
adjoining halls, were allotted to the use of the Sections and
Committees, and the Senate-house was appropriated to the
reception of the general assemblies; a large proportion of the
visitors were lodged within the walls of the Colleges, and the
great halls of the two principal foundations were opened in
hospitality to a concourse of guests collected from all parts by
a common interest in scientific pursuits.
GENERAL MEETING.
On Monday evening, at eight o’clock, the Members assem-
bled in the Senate-house: and a public discussion took place
on the phenomena and theory of the Aurora Borealis.
On Tuesday, at 1 p.m. a General Meeting was held in
the Senate-house ; the President of the preceding year, (the
Rey. Dr. Buckland,) resigned his office. In the course of
his speech*, he congratulated the Meeting on the proof af-
forded by the Report recently published, that the Association
was pursuing a course of peculiar utility to science, whilst at the
_ * A fuller account of the speeches delivered at the Meeting will be found
/ annexed to the lithographed signatures, &c., published at Cambridge.
3. b
x THIRD REPORT—18338.
same time it had fully redeemed its pledge of not interfering with
the province of other Scientific Societies.
The President (the Rev. Professor Sedgwick,) stated, in his
opening speech, that it was the desire of the Vice-Chancellor
and the Heads of Colleges that everything should be done on
the present occasion to emulate, as far as circumstances per-
mitted, the splendid reception which had been given to the
Association by the sister University of Oxford. He dwelt on
the advantages which such a Meeting brought with it to the
places in which it was held, by inducing scientific foreigners to
visit them, and expressed the delight with which he hailed such
visits, as an omen that the great barriers which for a length
of time had served man for man, had now been broken
down. He described the character of the Reports which
the Association has published ; and added that he attached so
much value to these expositions of the state of science, that
he had requested one of the Secretaries, (the Rev. William
Whewell,) to present to the Meeting a fuller analysis of their
contents. ‘The President concluded his speech with the fol-
lowing gratifying announcement: ‘ There is a philosopher,” he
said, ‘‘ sitting among us whose hair is blanched by time, but
possessing an intellect stillin its healthiest vigour,—a man whose
whole life has been devoted to the cause of truth,—my vener-
able friend Dr. Dalton. Without any powerful apparatus for
making philosophical’ experiments, with an apparatus, indeed,
which many might think almost contemptible, and with very
limited external means for employing his great natural powers,
he has gone straight forward in his distinguished course, and
obtained for himself in those branches of knowledge which he
has cultivated, a name not perhaps equalled by that of any
other living philosopher in the world. From the hour he came
from his mother’s womb the God of nature laid his hand upon
him, and ordained him for the ministration of high philosophy.
But his natural talents, great as they are, and his almost
intuitive skill in tracing the relations of material phenomena,
would have been of comparatively little value to himself and to
society, had there not been superadded to them a beautiful
moral simplicity and singleness of heart, which made him go
on steadily in the way he saw before him, without turning to
the right hand or to the left, and taught him to do homage to
no authority before that of truth. Fixing his eye on the most
extensive views of science, he has been not only a successful
experimenter, but a philosopher of the highest order; his
experiments have never had an insulated character, but have
been always made as contributions towards some important
PROCEEDINGS OF THE MEETING. Xi
end, as among the steps towards some lofty generalization.
And with a most happy prescience of the points to which the
rays of scattered observations were converging, he has more
than once seen light while to other eyes all was yet in darkness ;
out of seeming confusion has elicited order; and has thus
reached the high distinction of being one of the greatest legis-
lators of chemical science.
“It is my delightful privilege this day to announce (on the
authority of a Minister of the Crown who sits near me,*) that
His Majesty, King William the Fourth, wishing to manifest
his attachment to science, and his regard for a character like
that of Dr. Dalton, has graciously conferred on him, out of
the funds of the Civil List, a substantial mark of his royal
favour.”
The Rev. Wint1amM WHEWELL, being called upon by the
President, delivered the following address :—
The British Association for the Advancement of Science
meets at present under different circumstances from those
which accompanied its former Meetings. The publication of
the volume containing the Reports applied for by the Meeting
at York, in 1831, and read before the Meeting at Oxford last
year, must affect its proceedings during our sittings on the
present occasion ; and thus we are now to ‘ook for the operation
of one part of the machinery which its founders have endea-
voured to put in action. Entertaining the views which sug-
gested to them the scheme and plan of the Association, they
must needs hope that such an event as this publication will
exercise a beneficial influence upon its future career.
“This hope is derived, they trust, from no visionary or
presumptuous notions of what institutions and associations can
effect. Let none suppose that we ascribe to assembled num-
bers and conjoined labours extravagant powers and privileges
in the promotion of science ;—that we believe in the omnipo-
tence of a parliament of the scientific world. We know that
the progress of discovery can no more be suddenly accelerated
by a word of command uttered by a multitude, than by a
single voice. ‘There is, as was long ago said, no royal road to
_ knowledge—no possibility of shortening the way, because he
who wishes to travel along it is the most powerful one; and
just as little is there any mode of making it shorter, because
they who press forward are many. We must all start from
our actual position, and we cannot accelerate our advance by
* The Right Honourable T. Spring Rice.
b2
xii : THIRD REPORT—1833.
any method of giving to each man his mile of the march. Yet
something we may do: we may take care that those who come
ready and willing for the road, shall start from the proper
point and in the proper direction ;—shall not scramble over
broken ground, when there is a causeway parallel to their
path, nor set off confidently from an advanced point when the
first steps of the road are still doubtful ;—shall not waste their
powers in struggling forwards where movement is not progress,
and shall have pointed out to them all glimmerings of light,
through the dense and deep screen which divides us from the
next bright region of philosophical truth. We cannot create,
we cannot even direct, the powers of discovery; but we may
perhaps aid them to direct themselves; we may perhaps
enable them to feel how many of us are ready to admire their
success, and willing, so far as it is possible for intellects of a
common pitch, to minister to their exertions.
‘< Tt was conceived that an exposition of the recent progress,
the present condition, the most pressing requirements of the
principal branches of science at the present moment, might
answer some of the purposes I have attempted to describe.
Several such expositions have accordingly been presented to
the Association by persons selected for the task, most of them
eminent for their own contributions to the department which
they lad to review ; and these are now accessible to Members
of the Association and to the public. It appears to be suitable
to the design of this body, and likely to further its aims, that
some one should endeavour to point out the bearing which the
statements thus brought before it may and ought to have upon
its future proceedings, and especially upon the labours of the
Meeting now begun. I am well persuaded that if the President
had taken this office upon himself, the striking and important
views which it may naturally suggest would have been pre-
sented in a manner worthy of the occasion: he has been
influenced by various causes to wish to devolve it upon me, and
I have considered that I should show my respect for the Asso-
ciation better by attempting the task, however imperfectly,
than by pleading my inferior fitness for it.
‘* The particular questions which require consideration, and
the researches which most require prosecution, in the sciences
to which the Reports now before you refer, will be offered to
the notice of the Sections of the Association which the subjects
respectively concern, at their separate sittings. It is conceived
that the most obvious and promising chance of removing
deficiencies and solving difficulties in each subject, is to be
found in drawing to them the notice of persons who have paid
s
PROCEEDINGS OF THE MEETING. xiii
a continued and especial attention to the subject. The con-
sideration of these points will therefore properly form a part
of the business of the Sectional Meetings ; and all Members of
the Association, according to their own peculiar pursuits
and means, will thus have the opportunity of supplying any
wanting knowledge, and of throwing light upon any existing
perplexity.
‘** But besides this special examination of the suggestions
which your Reports contain, there are some more general
reflexions to which they naturally give rise, which may perhaps
be properly brought forward upon this first General Assembly
of the present Meeting; and which, if they are well founded,
may preside over and influence the aims and exertions of many
of us, both during our present discussions and in our future
attempts to further the ends of science.
** There is here neither time nor occasion for any but the
most rapid survey of the subjects to which your Reports refer,
in the point of view in which the Reports place them before
you. Astronomy, which stands first on the list, is not only
the queen of sciences, but, in a stricter sense of the term, the
only perfect science ;—the only branch of human knowledge
in which particulars are completely subjugated to generals,
effects to causes ;—in which the long observation of the past
has been, by human reason, twined into a chain which binds
in its links the remotest events of the future ;—in which we
are able fully and clearly to interpret Nature’s oracles, so that
by that which we have tried we receive a prophecy of that
which is untried. The rules of all our leading facts have
been made out by observations of which the science began
with the earliest dawn of ‘history; the grand law of causation
by which they are all bound together has been enunciated for
150 years; and we have in this case an example of a science
in that elevated state of flourishing maturity, in which all that
remains is to determine with the extreme of accuracy the con-
sequences of its rules by the profoundest combinations of
mathematics, the magnitude of its data by the minutest scru-
pulousness of observation; in which, further, its claims are so
fully acknowledged, that the public wealth of every nation pre-
tending to civilization, the most consummate productions of
labour and skill, and the loftiest and most powerful intellects
which appear among men, are gladly and emulously assigned
to the task of adding to its completeness. In this condition of
the science, it will readily be understood that Professor Airy,
your Reporter upon it, has had to mark his desiderata, in no
cases but those where some further developement of calcula-
xiv THIRD REPORT—1880.
tion, some further delicacy of observation, some further accu-
mulation of exact facts, are requisite ; though in every branch
of the subject the labour of calculation, the delicacy of obser-
vation, and the accumulation of exact facts, have already gone
so far that the mere statement of what has been done can
hardly be made credible or conceivable to a person unfamiliar
with the study.
*< One article, indeed, in his list of recommendations to future
labourers, read at the last Meeting of the Association, may ap-
pear capable of being accomplished by more limited labour than
the rest,—the determination of the mass of Jupiter by obser-
vations of the elongations of his satellites. And undoubtedly,
many persons were surprised when they found that on this, so
obvious a subject of interest, no measures had been obtained
since those which Pound took at the request of Newton. Yet
in this case, if an accuracy and certainty worthy of the present
condition of Astronomy were to be aimed at, the requisite ob-
servations could not be few nor the calculation easy, when it
is considered in how complex a manner the satellites disturb
each other’s motions. But the Meeting will learn with pleasure
that the task which he thus pointed out to others, he has him-
self in the intervening time executed in the most complete
manner. He has weighed the mass of Jupiter in the way he
thus recommended ; and it may show the wonderful perfection
of such astronomical measures to state, that he has proved with
certainty, that this mass is more than 322 and less than 323
times the mass of the terrestrial globe on which we stand.
** Such is Astronomy: but in proceeding to other sciences, ’
our condition and our task are of a far different kind. Instead
of developing our theories, we have to establish them ; instead
of determining our data and rules with the last accuracy, we
have to obtain first approximations to them. This, indeed,
may be asserted of the next subject on the list, though that
is, in its principles, a branch of Physical Astronomy ; for that
alone of all the branches of Physical Astronomy had been al-
most or altogether neglected by men of science. I speak of
the science of the Tides. Mr. Lubbock terminated his Report
on this subject, by lamenting in Laplace’s words this unmerited
neglect. He himself in England, and Laplace in France, were
indeed the only mathematicians who had applied themselves
to do some portion of what was to be done with respect to this
subject. Since our Meeting last year, Mr. Dessiou has, under
Mr. Lubbock’s direction, compared the tides of London, Sheer-
ness, Portsmouth, Plymouth, Brest, and St. Helena; and the
comparison has brought to light very remarkable agreements.
PROCEEDINGS OF THE MEETING. xv
in the law which regulates the time of high water, agreements
both with each other and with theory; and has at the same
time brought into view some anomalies which will give a strong
impulse to the curiosity with which we shall examine the re-
cords of future observations at some of these places and at
many others. I may perhaps here take the liberty of mention-
ing my own attempts since our last Meeting, to contribute
something bearing on this department. It appeared to me that
our knowledge of one particular branch of this subject, the
motion of the tide-wave in all parts of the ocean, was in such a
condition, that by collecting and arranging our existing mate-
rials, we should probably be enabled to precure abundant and
valuable additions to them. This, therefore, I attempted to
do; and I have embodied the result of this attempt in an
‘ Essay towards a First Approximation to a Map of Cotidal
Lines,’ which is now just printed in the Philosophical Transac-
tions of the Royal Society. If the time of the Meeting allows,
I would willingly place before you the views at which we have
now arrived, and the direction of our labours which these
suggest.
*‘ In'the case of the science of Tides, we have no doubt about
the general theory to which the phenomena are to be referred,
the law of universal gravitation; though we still desiderate a
clear application of the theory to the details. Im another sub-
ject which comes under our review, the science of Light, the
prominent point of interest is the selection of the general
theory. Sir David Brewster, the author of our Report on this
subject, has spoken of ‘the two rival theories of light,’ which
are, as you are aware, that which makes light to consist in
material particles emitted by a luminous body, and that which
makes it to consist in undulations propagated through a sta-
tionary ether. The rivalry of these theories, so far as they
can now be said to be rivals, has been by no means barren of
interest and instruction during the year which is just elapsed.
The discussions on the undulatory theory in our scientific
journals have been animated, and cannot, I think, be considered
as having left the subject where they found it. The claims of
the undulatory theory, it will be recollected, do not depend
only on its explaining the facts which it was originally intended
to explain; but on this;—that the suppositions adopted in
order to account for one set of facts, fall in most wonderfully
with the suppositions requisite to explain a class of facts en-
tirely different ; in the same manner as in the doctrine of gra-
vitation, the law of force which is derived from the revolutions
of the planets in their orbits, accounts for the apparently re-
XVi THIRD REPORT—1839.
mote facts of the precession of the equinoxes and the tides.
To all this there is nothing corresponding in the history of the
theory of emission; and no one, I think, well acquainted with
the subject, would now assert, that if this latter theory had
been as much cultivated as the other, it might have had a simi-
lar brilliant fortune in these respects.
‘“‘ But if the undulatory theory be true, there must be solu-
tions to all the apparent difficulties and contradictions which
may occur in particular cases ; and moreover the doctrine will
probably gain general acceptance, in proportion as these solu-
tions are propounded and understood, and as prophecies of
untried results are delivered and fulfilled. In the way of such
prophecies few things have been more remarkable than the
prediction, that under particular circumstances a ray of light
must be refracted into a conical pencil, deduced from the theory
by Professor Hamilton of Dublin, and afterwards verified ex-
perimentally by Professor Lloyd. In the way of special diffi-
culties, Mr. Potter proposed an ingenious experiment which
appeared to him inconsistent with the theory. Professor Airy,
from a mathematical examination of this case, asserted that the
facts, which are indeed difficult to observe, must be somewhat
different from what they appeared to Mr. Potter; and having
myself been present at Professor Airy’s experiments, I can
venture to say, that the appearances agree exactly with the
results which he has deduced from the theory. Another gen-
tleman, Mr. Barton, proposed other difficulties founded upon
the calculation of certain experiments of Biot and Newton;
and Professor Powell of Oxford has pointed out that the data
so referred to cannot safely be made the basis of such calcula-
tions, for mathematical reasons. There is indeed here, also,
one question of fact concerning an experiment stated in New-
ton’s Optics: In a part of the image of an aperture where
Newton’s statement places a dark line, in which Mr. Barton has
followed him, Professors Airy, Powell, and others, have been
able to see only a bright space, as the theory would require.
Probably the experiments giving the two different results have
not been made under precisely the same circumstances; and
the admirers of Newton are the persons who will least of all
consider his immoveable fame as exposed to any shock by these
discussions.
“Perhaps, while the undulationist will conceive that his
opinions have gained no small accession of evidence by this ex-
emplification of what they will account for, those who think the
advocates of the theory have advanced its claims too far, will
be in some degree conciliated by having a distinct acknow-
PROCEEDINGS OF THE MEETING. xvii
ledgement, as during these discussions they have had, of what
it does not pretend to explain. The whole doctrine of the
absorption of light is at present out of the pale of its calcula-
tions ; and if the theory is ever extended to these phenomena,
it must be by supplementary suppositions concerning the ether
and its undulations, of which we have at present not the slight-
est conception.
«There are various of the Physical subjects to which your
Reports refer, which it is less necessary to notice in a general
sketch like the present. The recent discoveries in Thermo-
electricity, of which Professor Cumming has presented you
with a review, and the investigations concerning Radiant Heat
which have been arranged and stated by Professor Powell, are
subjects of great interest and promise ; and they are gradually
advancing, by the accumulation of facts bound together by
subordinate rules, into that condition in which we may hope to
see them subjugated to general and philosophical theories.
But with regard to this prospect, the subjects I have mentioned
are only the fragments of sciences, on which we cannot hope
to theorize successfully except by considering them with refer-
ence to their whole ; —Thermo-electricity with reference to the
whole doctrine of electricity ; Radiant Heat with reference to
the whole doctrine of heat.
“If the subjects just mentioned be but parts of sciences,
there is another on which you have a Report before you, which,
though treated as one science, is in reality a collection of several
sciences, each of great extent. I speak of Meteorology, which
is reported on by Professor Forbes. ‘There is perhaps no por-
tion of human knowledge more capable of being advanced by
our conjoined exertions than this: some of the requisite ob-
servations demand practice and skill; but others are easily
made, when the observer is once imbued with sound elemen-
tary notions; and in all departments of the subject little can
be done without a great accumulation of facts and a patient in-
quiry after their rules. Some such contributions we may look
for at our present Meeting. Professor Forbes has spoken of
the possibility of constructing maps of the sky by which we
may trace the daily and hourly condition of the atmosphere
over large tracts of the earth. If, indeed, we could make a
stratigraphical analysis of the aerial shell of the earth, as the
geologist has done of its solid crust, this would be a vast step
for Meteorology. This, however, must needs be a difficult task :
in addition to the complexity of these superincumbent masses,
time enters here as a new element of variety: the strata of the
geologist continue fixed and permanent: those of the meteoro-
XVlii THIRD REPORT—1833.
logist change from one moment to another. Another difficulty
is this; that while we want to determine what takes place in
the whole depth of the aerial ocean, our observations are neces-
sarily made almost solely at its bottom. Our access to the
heights of the atmosphere is more limited, in comparison with
what we wish to observe, than our access to the depths of the
earth.
_ © Geology, indeed, is a most signal and animating instance of
what may be effected by continued labours governed by common
views. Mr. Conybeare’s Report upon this science gives you
a view of what has been done in it during the last twenty years;
and his ‘ Section of Europe from the North of Scotland to the
Adriatic,’ which is annexed to the Report, conveys the general
views with regard to the structure of Central Europe, at which
geologists have now arrived. To point out any more recent
additions to its progress or its prospects is an undertaking
more suitable to the geologists by profession, than to the pre-
sent sketch. And all who take an interest in the subject will
rejoice that the constitution and practice of the Geological So-
ciety very happily provide, by the annual addresses of its Pre-
sidents, against any arrear in the incorporation of fresh acquisi-
tions with its accumulated treasures.
**'The science of Mineralogy, on which I had the honour of
offering a Report to the Association, was formerly looked upon
as a subordinate portion of Geology. It may, however, now be
most usefully considered as a science co-ordinate and closely
allied with Chemistry, and the most important questions for
examination in the one science belong almost equally to the
other. Mr. Johnston, in his Report on Chemical Science, has,
as the subject required, dwelt upon the questions of isomor-
phism and plesiomorphism, which I had noticed as of great im-
portance to Mineralogy. Dr. Turner and Prof. Miller, who at
the last Meeting undertook to inquire into this subject, have
examined a number of cases, and obtained some valuable facts ;
but the progress of our knowledge here necessarily requires
time, since the most delicate chemical analysis and the exact
measurement of 30 or 40 crystals are wanted for the satisfac-
tory establishment of the properties of each species *. In Che-
* Perhaps I shall not have a more favourable occasion than the present of
correcting astatement in my Report, which is not perfectly accurate, on a point
which has been a subject of controversy between Sir David Brewster and Mr.
Brooke. I have noticed (p. 338.) the sulphato-tricarbonate of lead of Mr.
Brooke, as a mineral which at first appeared to contradict Sir David Brewster’s
general law of the connexion of crystalline form with optical structure, in as
much as it appeared to be of the rhombohedral system, and was found to have
PROCEEDINGS OF THE MEETING. xix
mistry, besides the great subject of isomorphism to which I
have referred, there are some other yet undecided questions,
as for instance those concerning the existence and relations
of the sulpho-salts and chloro-salts; and these are not small
points, for they affect the whole aspect of chemical theory, and
thus show us how erroneously we should judge, if we were to
consider this science as otherwise than in its infancy.
“In every science, Notation and Nomenclature are questions
subordinate to calculation and theory. The Notation of Cry-
stallography is such as to answer the purposes of calculation,
whether we take that of Mohs, Weiss, or Nauman. It appears
very desirable that the Notation of Chemistry also should be so
constructed as to answer the same purpose. Dr. Turner in the
last edition of his Chemistry, and Mr. Johnston in his Report,
have used a notation which has this advantage, which that
commonly employed by the continental Chemists does not
possess.
**T have elsewhere stated to the Association how little hope
there appears at present to be of purifying and systematizing
our mineralogical nomenclature. The changes of theory in
Chemistry to which I have already referred, must necessarily
superinduce a change of its nomenclature, in the same manner
in which the existing nomenclature was introduced by the pre-
valent theory ; and the new views have in fact been connected
with such a change by those who have propounded them. It
will be for the Chemical Section of the Association to consider
how far these questions of Nomenclature and Notation can be
discussed with advantage at the present Meeting.
‘‘'The Reports presented at the last Meeting had a reference,
for the most part, to physical rather than physiological science.
The latter department of human knowledge will be more pro-.
minently the subject of some of the Reports which are to come
before us on the present occasion. There is, however, one of
two axes of double refraction ; and which was afterwards found to confirm the
law, the apparently rhombohedral forms being found by Mv. Haidinger to be
not simple but compound. It seems, however, that the solution of the difficulty
(for no one now will doubt that it has a solution,) is somewhat different. There
appear to have been included under this name two different kinds of crystals
belonging to different systems of crystallization. Some which Mr. Brooke found
to be rhombohedral, Sir David Brewster found to have a single optical axis
with no trace of composition; others were prismatic with two axes; and thus
Mr. Brooke’s original determinations were probably correct. The high reputa-
tion of the parties in this controversy does not need this explanation; but pro-
bably those who look with pleasure atthe manner in which the apparent excep-
tions to laws of nature gradually disappear, may not think a moment or two lost
in placing the matter on its proper footing.
Xe THIRD REPORT—1833.
last year’s Reports which refers to one of the widest questions
of Physiology; that of Dr. Prichard on the History of the
Human Species, and its subdivision into races. The other
lines of research which tend in the same direction will probably
be brought before the Association in successive years, and thus
give us a view of the extent of knowledge which is accessible
to us on this subject.
«In addition to these particular notices of the aspect under
which various sciences present themselves to us as resulting
from the Reports of last years, there is a reflexion which may
I think be collected from the general consideration of these
sciences, and which is important to us, since it bears upon the
manner in which science is to be promoted by combined labour
such as that which it is a main object of this Association to
stimulate and organize. The reflexion to which I refer is
this ;—that a combination of theory with facts, of general views
with experimental industry, is requisite, even in subordinate
contributors to science. It has of late been common to assert
that facts alone are valuable in science ; that theory, so far as
it is valuable, is contained in the facts; and, so far as it is not
contained in the facts, can merely mislead and preoccupy men.
But this antithesis between theory and facts has probably in
its turn contributed to delude and perplex ; to make men’s ob-
servations and speculations useless and fruitless. For it is only
through some view or other of the connexion and relation of
facts, that we know what circumstances we ought to notice and
record; and every labourer in the field of science, however
humble, must direct his labours by some theoretical views,
original or adopted. Or if the word theory be unconquerably
obnoxious, as to some it appears to be, it will probably still be
conceded, that it is the rules of facts, as well as facts themselves,
with which it is our business to acquaint ourselves. That the
recollection of this may not be useless, we may collect from the
contrast which Professor Airy in his Report has drawn between
the astronomers of our own and of other countries. ‘In En-
gland,” he says, (p. 184,) ‘‘ an observer conceives that he has
done everything when he has made an observation.” ‘‘ In
foreign observatories,” he adds, ‘‘ the exhibition of results and
the comparison of results with theory, are considered as de-
serving more of an astronomer’s attention, and demanding
greater exercise of his intellect, than the mere observation of a
body on the wire of a telescope.” We may, indeed, perceive
in some measure the reason which has led to the neglect of
theory with us. For a long period astronomical theory was
greatly a-head of observation, and this deficiency was mainly:
PROCEEDINGS OF THE MEETING. Xxi
supplied by the perseverance and accuracy of English ob-
servers. It was natural that the value and reputation which
our observations thus acquired for the time, should lead us to
think too disrespectfully, in comparison, of the other depart-
ments of the science. Nor is the lesson thus taught us con-
fined to Astronomy ; for, though we may not be able in other
respects to compare our facts with the results of a vast and yet
certain theory, we ought never to forget that facts can only
become portions of knowledge as they become classed and con-
nected ; that they can only constitute truth when they are in-
cluded in general propositions. Without some attention to this
consideration, we may notice daily the changes of the winds
and skies, and make a journal of the weather, which shall have
no more value than a journal of our dreams would have ; but
if we can once obtain fixed measures of what we notice, and
connect our measures by probable or certain rules, it is no
longer a vacant employment to gaze at the clouds, or an un-
profitable stringing together of expletives to remark on the
weather ; the caprices of the atmosphere become steady dispo-
sitions, and we are on the road to meteorological science.
‘It may be added—as a further reason why no observer
should be content without arranging his observations, in what-
ever part of Physics, and without endeavouring at least to
classify and connect them—that when this is not done at first,
it will most likely never be done. The circumstances of the
observation can hardly ever be properly understood or inter-
preted by others; the suggestions which the observations
themselves supply, for change of plan or details, cannot in any
other way be properly appreciated and acted on. And even
the mere multitude of unanalysed observations may drive future
students of the subject into a despair of rendering them useful.
Among the other desiderata in Astronomy which Professor
Airy mentions, he observes, ‘‘ Bradley’s observations of stars,”
made in 1750, “‘ were nearly useless till Bessel undertook to re-
duce them” in 1818. “In like manner Bradley’s and Mas-
kelyne’s observations of the sun are still nearly useless,” and
they and many more must continue so till they are reduced.
This could not have happened if they had been reduced and
compared with theory at the time ; and it cannot but grieve us
to see so much skill, labour and zeal thus wasted. The per-
petual reference or attempt to refer observations, however nu-
merous, to the most probable known rules, can alone obviate
similar evils.
_ “It may appear to many, that by thus recommending theory
we incur the danger of encouraging theoretical speculations
XXil THIRD REPORT—183535.
to the detriment of observation. To do this would be indeed
to render an ill service to science: but we conceive that our
purpose cannot so far be misunderstood. Without here at-
tempting any nice or technical distinctions between theory and
hypothesis, it may be sufficient to observe that all deductions
from theory for any other pupose than that of comparison with
observation are frivolous and useless exercises of ingenuity, so
far as the interests of physical science are concerned. Specu-
lators, if of active and inventive minds, wi// form theories
whether we wish it or no. ‘These theories may be useful or
may be otherwise—we have examples of both results. If the
theories merely stimulate the examination of facts, and are
modified as and when the facts suggest modification, they may be
erroneous, but they will still be beneficial ;—they may die, but
they will not have lived in vain. If, on the other hand, our
theory be supposed to have a truth of a superior kind to the
facts; to be certain independently of its exemplification in par-
ticular cases ;—if, when exceptions to our propositions occur,
instead of modifying the theory, we explain away the facts,—
our theory then becomes our tyrant, and all who work under
its bidding do the work of slaves, they themselves deriving no
benefit from the result of their labours. For the sake of ex-
ample we may point out the Geological Society as a body which,
labouring in the former spirit, has ennobled and enriched itself
by its exertions: if any body of men should employ themselves
in the way last described, they must soon expend the small
stock of @ priori plausibility with which they must of course
begin the world.
** To exemplify the distinction for a moment longer, let it be
recollected that we have at the present time two rival theories
of the history of the earth which prevail in the minds of geo-
logists ;—one, which asserts that the changes of which we trace
the evidence in the earth’s materials have been produced by
causes such as are still acting at the surface ; another, which
considers that the elevation of mountain chains and the transi-
tion from the organized world of one formation to that of the
next, have been produced by events which, compared with the
present course of things, may be called catastrophes and con-
vulsions. Who does not see that all that those theories have
hitherto done, has been, to lead geologists to study more ex-
actly the laws of permanence and of change in the existing
organic and inorganic world, on the one hand; and on the
other, the relations of mountain chains to each other, and to
the phenomena which their strata present?) And who doubts,
that, as the amount of the full evidence may finally be, (which
PROCEEDINGS OF THE MEETING. xxiii
may, indeed, perhaps require many generations to accumulate,)
geologists will give their assent to the one or the other of these
views, or to some intermediate opinion to which both may
gradually converge?
“On the other hand—to take an example from a science with
which I have had a professional concern—the theory that ery-
stalline bodies are composed of ultimate molecules which have
a definite and constant geometrical form, may properly and
philosophically be adopted, so far as we can, by means of it,
reduce to rules the actually occurring secondary faces of such
substances. But if we assume the doctrine of such an atomic
composition, and then form imaginary arrangements of these
atoms, and enunciate these as explanations of dimorphism,
or plesiomorphism, or any other apparent exception to the
general principle, we proceed, as appears to me, unphilosophi-
cally. Let us collect and classify the facts of dimorphism and
plesiomorphism, and see what rules they follow, and we may
then hope to discern whether our atomic theory of crystalline
molecules is tenable, and what modifications of it these cases,
uncontemplated in its original formation, now demand.
“T will not now attempt to draw forth other lessons which
the Report of last year may supply for our future guidance ;
although such offer themselves, and will undoubtedly affect
the spirit of our proceedings during this Meeting. But there
is a reflexion belonging to what I may call the morals of science,
which seems to me to lie on the face of this Report, and which
I cannot prevail upon myself to pass over. In looking steadily
at the past history and present state of physical knowledge, we
cannot, I think, avoid being struck with this thought,—How
little is done and how much remains to do ;—and again, not-
withstanding this, how much we owe to the great philosophers
who have preceded us. It is sometimes advanced as a charge
against the studies of modern science, that they give men an
overweening opinion of their own acquirements, of the supe-
riority of the present generation, and of the intellectual power
and progress of man ;—that they make men confident and con-
temptuous, vain and proud. That they never do this, would
be much to say of these or of any other studies ; but, assuredly,
those must read the history of science with strange preposses-
sions who find in it an aliment for such feelings. What is the
picture which we have had presented to us? Among all the
attempts of man to systematize and complete his knowledge,
there is one'science, Astronomy, in which he may be considered
to have been successful; he has there attained a general and
certain theory: for this success, the labour of the most highly.
XXIV THIRD REPORT—1835.
gifted portion of the species for 5000 years has been requisite.
There is another science, Optics, in which we are, perhaps, in
the act of obtaining the same success, with regard to a part of
the phenomena. But all the rest of the prospect is compara-
tively darkness and chaos; limited rules, imperfectly known,
imperfectly verified, connected by no known cause, are all that
we can discern. Even in those sciences which are considered
as having been most successful, as Chemistry, every few years
changes the aspect under which the theory presents the facts
to our minds, while no theory, as yet, has advanced beyond the
mere horn-book of calculation. What is there here of which
man can be proud, or from which he can find reason to be pre-
sumptuous? And evenif the Discoverers to whom these sciences
owe such progress as they have made—the great men of the
present and the past—if THEY might be elate and confident
in the exercises of their intellectual powers, who are we, that
we should ape their mental attitudes ?—we, who can but with
pain and effort keep a firm hold of the views which they have
disclosed? But it has not been so; they, the really great in
the world of intellect, have never had their characters marked
with admiration of themselves and contempt of others. Their
genuine nobility has ever been superior to those ignoble and
low-born tempers. Their views of their own powers and achieve-
ments have been sober and modest, because they have ever felt
how near their predecessors had advanced to what they had
done, and what patience and labour their own small progress
had cost. Knowledge, like wealth, is not likely to make us
proud or vain, except when it comes suddenly and unlearned ;
and in such a case, it is little to be hoped that we shall use
well, or increase, our ill-understood possession.
“« Perhaps some of the appearance of overweening estimation
of ourselves and our generation which has been charged against
science, has arisen from the natural exultation which men feel
at witnessing the successes of art. I need not here dwell upon
the distinction of science and art; of knowledge, and the ap-
plication of knowledge to the uses of life; of theory and
practice. In the success of the mechanical arts there is much
that we look at with an admiration mingled with some feeling
of triumph; and this feeling is here natural and blameless.
For what is all such art but a struggle,—a perpetual conflict
with the inertness of matter and its unfitness for our purposes?
And when, in this conflict, we gain some point, it is impossible
we should not feel some of the exultation of victory. In all
stages of civilization this temper prevails: from the naked in-
habitant of the islands of the ocean, who by means of a piece
PROCEEDINGS OF THE MEETING. XXV
of board glides through the furious and apparently deadly line
of breakers, to the traveller who starts along a rail-road with
a rapidity that dazzles the eye, this triumphant joy in suc-
cessful art is universally felt. But we shall have no difficulty
in distinguishing this feeling from the calm pleasure which we
receive from the contemplation of truth. And when we con-
sider how small an advance of speculative science is implied in
each successful step of art, we shall be in no danger of im-
bibing, from the mere high spirits produced by difficulty over-
come, any extravagant estimate of what man has done or can
ir any perverse conception of the true scale of his aims and
opes.
te Still, it would little become us here to be unjust to prac-
tical science. Practice has always been the origin and stimulus
of theory: Art has ever been the mother of Science; the
comely and busy mother of a daughter of a far loftier and
serener beauty. And so it is likely still to be: there are no
subjects in which we may look more hopefully to an advance in
sound theoretical views, than those in which the demands of
practice make men willing to experiment on an expensive scale,
with keenness and perseverance; and reward every addition
of our knowledge with an addition to our power. And even
they—for undoubtedly there are many such—who require no
such bribe as an inducement to their own exertions, may still
be glad that such a fund should exist, as a means of engaging
and recompensing subordinate labourers.
**T will not detain you longer by endeavouring to follow
more into detail the application of these observations to the
proceedings of the General and Sectional Meetings during the
present week. But I may remark that some subjects, circum-
stanced exactly as I have described, will be brought under
your notice by the Reports which we have reason to hope for
on the present occasion. Thus, the state of our knowledge of
the laws of the motion of fluids is universally important, since
the motion of boats of all kinds, hydraulic machinery, the tides,
the flowing of rivers, all depend upon it. Mr. Stevenson and
Mr. Rennie have undertaken to give us an account of different
branches of this subject as connected with practice ; and: Mr.
Challis will report to us on the present state of the analytical
theory. In like manner the subject of the strength of materials,
which the multiplied uses of iron, stone and wood, make so inter-
esting, will be brought. before you by Mr. Barlow. These were
two of the portions of mechanics the earliest speculated upon,
and in them the latest speculators have as yet advanced little
beyond the views of the earliest. PS
c
XXV1 THIRD REPORT—1833.
**I mention these as specimens only of the points to which
we may more particularly direct our attention. I will only
observe, in addition, that if some studies, as for instance those
of Natural History and Physiology, appear hitherto to have
occupied less space in our proceedings than their importance
and interest might justly demand, this has occurred because
the Reports on other subjects appeared more easy to obtain in
the first instance ; and the balance will I trust be restored at
the present Meeting. I need not add anything further on this
subject. Among an assembly of persons such as are now met
in this place, there can be no doubt that the most important
and profound questions of science in its existing state will be
those which will most naturally occur in our assemblies and
discussions. It merely remains for me to congratulate the As-
sociation upon the circumstances under which it is assembled ;
and to express my persuasion that all of us, acting under the
elevating and yet sobering thought of being engaged in the
great cause of the advancement of true science, and cherishing
the views and feelings which such a situation inspires, shall
derive satisfaction and benefit from the occasions of the present
week.” ;
Mr. Whewell having concluded his Address, the Meeting
adjourned, after electing by a general vote the candidates who
had been approved by the Council and by the General Com-
mittee.
At eight p.m., the Members having reassembled in the Senate-
house, Mr. Taylor read a Report on the state of our know-
ledge respecting Mineral Veins, which was followed by a general
discussion on the nature and origin of veins.
On Wednesday at one P.m., the Chairmen of the Sections hay-
ing read the minutes of their proceedings to the Meeting, the
Rey. G. Peacock delivered a brief abstract of his Report on
the state of the Theory of Algebra. Professor Lindley read a
Report on the state of Physiological Botany; and Mr. G. Ren-
nie on the state of Practical Hydraulics. Auditors were ap-
pointed to examine the accounts. :
On Thursday, at one p.m., the auditors reported the state
of the accounts. The Chairmen of the Sections read the mi-
nutes of their proceedings. Professor Christie read a Report
on the porsent state of our knowledge respecting the Magnetism
of the Earth. A summary of the contents of a Report on the
state of knowledge as to the Strength of Materials, by Pro:
PROCEEDINGS OF THE MEETING. XXVil
fessor Barlow, was given, in the absence of the Author, by the
Rev. W. Whevwell.
In the evening, Mr. Whewell delivered a Lecture in the
Senate-louse, on the manner in which observations of the Tide
may be usefully made to serve as a groundwork for general
views; either by observing the time of high water at different
places on the same day, in order to determine the motion of
the summit of the tide-wave; or by continuing the observations
for a considerable time, and comparing them with the moon’s
transit to obtain the semi-menstrual inequality. He observed,
that it appears from Mr. Lubbock’s recent researches on the
subject, that the tides of Portsmouth and Brest agree very —
closely in the law of this inequality, and that the tides of Ply-
mouth and London also agree; but that there is an anomaly
which cannot at present be explained in the comparison of Brest
with Plymouth. Professor Farish explained to the Meeting
the advantages which he conceived would be derived from ap-
plying the power of steam to carriages on undulating roads in
preference to level rail-ways.
On Friday, at one p.m., the Chairmen of the Sections havin
read the minutes of their proceedings, the Rey. J. Challis made
a Report on the progress of the Theory of Fluids. The Pre-
sident stated the appropriation* to certain scientific objects of
a portion of the funds of the Association to the amount of
6007. Mr. Babbage, at the President’s request, explained his
views respecting the advantages which would accrue to science
from such a collection of numerical facts as he had formerly
recommended under the title of ‘Constants of Nature and
Art.” The President announced, that it had been resolved
by the General Committee, that the Meeting of 1834 should
take place at Edinburgh in the early part of the month of Sep-
tember ; he read the names of the Officers and Members of the
‘Council appointed for the ensuing year. .
The thanks of the Meeting were then voted to the Vice-
Chancellor and the other authorities of the University, to the
retiring Officers and Members of the Council, to the President,
the Secretaries for Cambridge, the Local Committee of Manage-
ment, and the General Secretary. ae
_ The President, in his concluding Address to the Meeting,
explained an irregularity which had occurred in the formation
of anew Section. In addition to the five Sections into which
the Meeting had been divided by the authority of the General
* Fora particular account of these appropriations, see p. Xxxvi. _
c2
XXvill THIRD REPORT— 1833.
Committee, he stated that another had come into operation, the
object of which was to promote statistical inquiries. It had
originated with some distinguished philosophers, but could not
be regarded as a legitimate branch of the Association till it had
received the recognition of the governing body ; there could be
little doubt, however, that the new Section would obtain the
sanction of the General Committee, with some limitation per-
haps of the specific objects of inquiry. On this subject he
made the following observations :—
* Some remarks may be expected from me in reference to the
objects of this Section, as several Members may perhaps think
them ill fitted to a Society formed only for the promotion of
natural science. ‘To set, as far as I am able, these doubts at
rest, I will explain what I understand by science, and what I
think the proper objects of the Association. By science, then,
I understand the consideration of all subjects, whether of a pure
or mixed nature, capable of being reduced to measurement and
calculation. All things comprehended under the categories of
space, time and number properly belong to our investigations ;
and all phenomena capable of being brought under the sem-
blance of a law are legitimate objects of our inquiries. But there
are many important subjects of human contemplation which come
under none of these heads, being separated from them by new
elements ; for they bear upon the passions, affections and feel-
ings of our moral nature. Most important parts of our nature
such elements indeed are; and God forbid that I should call
upon any man to extinguish them; but they enter not amon
the objects of the Association. The sciences of morals me
politics are elevated far above the speculations of our philosophy.
Can, then, statistical inquiries be made compatible with our
objects, and taken into the bosom of our Society? I think
they unquestionably may, so far as they have to do with matters
of fact, with mere abstractions, and with numerical results.
Considered in that light they give what may be called the raw
material to political economy and political philosophy ; and by
their help the lasting foundations of those sciences may be per-
haps ultimately laid. These inquiries are, however, it is import-
ant to observe, most intimately connected with moral pheno-
mena and economical speculations,—they touch the mainsprings
of passion and feeling,—they blend themselves with the generali-
zations of political science; but when we enter on these higher
generalizations, that moment they are dissevered from the ob-
jects of the Association, and must be abandoned by it, if it
means not to desert the secure ground which it has now taken.
“Should any one affirm (what, indeed, no one is prepared
PROCEEDINGS OF THE MEETING. xxix
to deny,) that all truth has one common essence, and should
he then go on to ask why truths of different degrees should be
thus dissevered from each other, the reply would not be dif-
ficult. In physical truth, whatever may be our difference of
opinion, there is an ultimate appeal to experiment and ob-
servation, against which passion and prejudice have not a
single plea to urge. But in moral and political reasoning, we
have ever to do with questions, in which the waywardness of
man’s will and the turbulence of man’s passions are among the
strongest elements. The consequence it is not for me to tell.
Look around you, and you will then see the whole framework
of society put in movement bythe worst passions of our na-
ture; you will see love turned into hate, deliberation into dis-
cord, and men, instead of mitigating the evils which are about
them, tearing and mangling each other, and deforming the
moral aspect of the world. And let not the Members of the
Association indulge a fancy, that they are themselves exempt
from the common evils of humanity. There is that within us,
which, if put into a flame, may consume our whole fabric,—
may produce an explosion, capable at once of destroying all
the principles by which we are held together, and of dissi-
pating our body in the air. Our Meetings have been essen-
tially harmonious, only because we have kept within our proper
boundaries, confined ourselves to the laws of nature, and
steered clear of all questions in the decision of which bad
passions could have any play. But if we transgress our pro-
per boundaries, go into provinces not belonging to us, and open
a door of communication with the dreary wild of politics, that
instant will the foul Damon of discord find his way into our
Eden of Philosophy.
‘*In every condition of society there is some bright spot on
which the eye loves to rest. In the turbulent republics of
ancient Greece, where men seemed in an almost ceaseless war-
fare of mind andbody, they had their seasons of solemnity, when
hostile nations made a truce with their bitter feelings, as-
sembled together, for a time, in harmony, and joined in a great
festival; which, however differing from what we now see in
its magnitude and forms of celebration, was consecrated, like
our present Meeting, to the honour of national genius. What-
ever have been the bitter feelings which have so often disgraced
the civil history of mankind, I dare to hope that they will never
find their resting-place within the threshold where this Associa-
tion meets; that peace and good will, though banished from
every other corner of the land, will ever find an honoured seat
amongst us; and that the congregated philosophers of the
empire, throwing aside bad passion and party animosity, will,
XXX THIRD REPORT—1833.
year by year, come to their philosophical Olympia, to witness
a noble ceremonial, to meet in a pacific combat, and share in the
glorious privilege of pushing on the triumphal car of Truth.
“ The last duty I have to perform this morning would be a
painful one indeed, were our Assembly to be broken up into
elements which were not again to be reunited. ‘The Association
is not, however, dissolved ; its meeting is only adjourned to an-
other year; and it has been a matter of great joy to me to an-
_nounce to you, that the Committee has elected for your next
President a distinguished soldier and philosopher; and that it
will be your privilege to reassemble in one of the fairest capitals
of the world,—in a city which has nursed a race of literary and
philosophic giants,—in a land filled with natural beauties, and
wedded to the imagination and the memory by a thousand en-
dearing associations.
‘** There is a solemnity in parting words, which may, I think,
justify me (especially after what has been so well said this morn-
ing by the Marquis of Northampton,) in passing the limits I
have so far carefully prescribed to myself, and in treading for a
moment on more hallowed ground. In the first place, I would
entreat you to remember that you ought above all things to re-
joice in the moral influence of an Association like the present.
Facts, which are the first objects of our pursuit, are of compa-
atively small value till they are combined together so as to
lead to some philosophic inference. Physical experiments, con-
sidered merely by themselves, and apart from the rest of nature,
are no better than stones lying scattered on the ground, which
require to be chiselled and cemented before they can be made
into a building fit for the habitation of man. The true value
of an experiment is, that itis subordinate to some law,—that it
is a step toward the knowledge of some general truth. Without,
at least, a glimmering of such truth, physical knowledge has no
true nobility. But there is in the intellect of man an appetency
for the discovery of general truth, and by this appetency, in
subordination to the capacities of his mind, has he been led on to
the discovery of general laws; and thus has his soul been fitted
to reflect back upon the world a portion of the counsels of his
Creator. If I have said that physical phenomena, unless con-
nected with the ideas of order and of law, are of little worth,
I may further say, that an intellectual grasp of material laws of
the highest order has no moral worth, except it be combined
with another movement of the mind, raising it to the perception
of an intelligent First Cause. It is by help of this last movement
that nature’s language is comprehended ; that her laws become
pregnant with meaning; that material phenomena are instinct
with life; that all moral and material changes become linked
PROCEEDINGS OF THE MEETING. Xxxi
together ; and that Truth, under whatever forms she may pre-
sent herself, seems to have but one essential substance. ‘
‘I have before spoken of the distinctions between moral and
physical science; and I need not repeat what I have said, unless
it be once more solemnly to adjure you not to leave the straight
path by which you are advancing,—not todesert the cause for
which. you have so well combined together. But let no one
misunderstand my meaning. If I have said that bad passions
mingle themselves with moral and political sciences, and that
the conclusions of these sciences are made obscure from the
want of our comprehending all the elements with which we
have to deal, I have only spoken the truth ; but still I hold that
moral and political science is of a higher order than the physical.
The latter has sometimes, in the estimation of man, been placed
on a higher level than it deserves, only from the circumstance of
its being so well defined, and grounded in the evidence of ex-
periments appealing to the senses. Its progress is marked by
indices the eye can follow; and the boundaries of its conquests
are traced by landmarks which stand high in the horizon of
man’s history. But with all these accompaniments, the moral _
and political sciences entirely swallow up the physical in impor-
tance. For what are they but an interpretation of the governing
laws of intellectual nature, having a relation in time present to
the social happiness of millions, and bearing in their end on the
destinies of immortal beings ?
“Gentlemen, if I look forward with delight to our meeting
again at Edinburgh, it is a delight chastised by a far different
feeling, to which, had not these been parting words, I should
not have ventured to give an utterance. It is not possible
we should all again meet together. Some of those whose
voices have been lifted up during this great Meeting, whose
eyes have brightened at the presence of their friends, and
whose hearts have beat high during the intellectual commu-
nion of the week, before another year may not be numbered
with the living. Nay, by that law of nature to which every
living man must in his turn yield obedience, it is certain that
before another festival, the cold hand of death will rest on the
head of some who are present in this assembly. If a thought
like this gives a tone of grave solemnity to words of parting, it
surely ought to teach us, during our common rejoicings at the
triumphal progress of science, a personal lesson of deep humility.
By the laws of nature, before we can meet again, many of those
bright faces which during the past week I have seen around me
may be laid low, for the hand of death may have been upon
them; but wherever we reassemble, God grant that all our
attainments in science may tend to our moral improvement}- and
XXXil THIRD REPORT—1833.
may we all meet at last in the presence of that Almighty Being,
whose will is the rule of all law, and whose bosom is the centre
of all power!”
SECTIONAL MEETINGS.
The Sections assembled daily at eleven a.m., and occasion-
ally also at half-past eight p.m., at their respective places of
meeting, in the Schools, the Astronomical Lecture-room, and
the Hall of Caius College. On Saturday, the Section of Na-
tural History made an excursion to the Fens.
Abstracts of most of the Communications which were made
to the Sections will be found in a subsequent part of the
volume.
In addition to the communications of which abstracts are
there given, notices of the following transactions appear on the
minutes :—
M. Quetelet described the observations which he had made
on Falling Stars. It was suggested that such observations
might be available in certain cases for determining differences
of longitude.
Mr. Potter communicated some calculations of the height
of the Aurora Borealis, seen on the 21st of March 1833,
Mr. Hopkins gave an abstract of a paper on the Vibration
of Air in Cylindrical Tubes of definite length.
Dr. Ritchie made some remarks on the Sensibility of the
Eye, and the errors to which it is subject.
Mr. Barton gave a view of his opinions on the Propagation
of Heat in solid bodies.
A letter was received from Mr. Frend regarding certain
points in the Theory of the Tides.
The Rev. W. Scoresby described a Celestial Compass invent-
ed by Col. Graydon.
Mr. R. Murphy read some remarks on the utility of observ-
ing the Magnetic Dip in Mines.
M. Quetelet gave an account of some observations made by
himself and M. Necker de Saussure, which corroborate the
statements of M. Kuppfer, respecting the inequality of magne-
tic intensity at the top and the base of mountains.
Professor Christie stated his views relative to the cause of
the Magnetism of the Earth.
Mr. A. Trevelyan read a paper on certain Vibrations of
Heated Metals.
Mr. Brunel exhibited and explained a Model in illustration
of his method of constructing Bridges without centering.
PROCEEDINGS OF THE MEETING. XXXill
A notice of some experiments relative to Isomorphism, by
Dr. Turner and Professor Miller, was read.
Dr. Daubeny made a communication on the Gases given off
from the surfaces of the water in certain thermal springs.
The Rev. W. V. Harcourt exhibited specimens of Metal taken
out of the crevices at the bottom of a mould in which a large
bronze figure had been cast by Mr. Chantrey; together with
fragments of the Bronze employed in the casting, from which
the former specimens differed considerably in colour, frangi-
bility, &c.
Mr. Lowe gave an account of various chemical products
found in the retorts and flues of Gas Works.
Mr. Pearsall made a communication on the bleaching powers
of Oxygen.
Mr. J. Taylor described the character of the Ecton Mine,
and the occurrence of the copper ore in connected cavities
which had been explored to a depth of 225 fathoms without
reaching the termination of them.
Dr. Buckland described. the manner in which fibrous Lime-
stone occurs in the Isle of Purbeck and other situations.
_ Mr. Murchison stated, and illustrated by Maps and Sections,
the principal results of his inquiries into the sedimentary de-
osits which occupy the western parts of Shropshire and Here-
fordshire, and are prolonged in a S.W. direction through the
counties of Radnor, Brecknock, and Caermarthen, and the in-
trusive igneous rocks which occur in certain parts of the di-
strict. He mentioned the occurrence of freshwater Limestone
in a detached Coal-field of Shropshire. :
Professor Sedgwick described the leading features in the
Geology of North Wales, the lines of elevation, the relation of
the trap rocks to the slate system, the cleavage of the slate ;
pointed out the relations of this tract to that examined by Mr-
Murchison; and drew a general parallel between the slate
formations of Wales and Cumberland.
Mr. J. Taylor having read to the Section the concluding
part of his Report on Veins, in the discussion which followed,
M. Dufrénoy entered into a consideration of some phenomena of
the igneous rocks of Britanny and Central France, viewed with
reference to the connexion between them and the metalliferous
veins of those districts, and remarked on the occurrence in
Central France of mineral veins, only in the narrow zone at the
junction of the unstratified and stratified rocks. He also made
some remarks on the association of dolomite and gypsum, with
the igneous rocks of the Alps and the Pyrenees.
Professor Sedgwick gave a general account of the Red Sand=
stones connected with the Coal-measures of Scotland, and the
XXXIV THIRD REPORT—1833.
Isle of Arran, with the view of showing that they are perfectly
distinct from the similar rocks connected with the Magnesian
‘Limestone. 2 :
Mr. Hartop exhibited a Map and Sections to illustrate the
series of Coal Strata in South Yorkshire, and their direction and
varying dip in the valley of the Dun, and to the north and south
of that river; described the characters of the strata, and the in-
fluence of certain great dislocations on the quality of the coal.
_. Mr. Greenough exhibited a Map of Western Europe, on
which the relative levels of land and water were represented by
means of colours, instead of engraving. Mr. Greenough was
requested to permit a map on this plan to be published.
The Rev. J. Hailstone communicated some notices relating
to Mineral Veins. :
Sections of the Well in the Dock Yard at Portsmouth, and
of the Well in the Victualling Yard at Weevil, were communi-
cated by the Rev. Mr. Leggat and Mr. Blackburn, on the part
of the Portsmouth Philosophical Society; and a letter from
Mr. Goodrich, explanatary of the Sections, was read.
Mr. Mantell exhibited a perfect Femur of the Iguanodon,
and explained its distinctive anatomical characters.
Mr. W. C. Trevelyan exhibited specimens of Coprolites,
and remains of Fishes, from the Edinburgh Coal-field.
- Mr. Fox exhibited specimens of Fishes from the Magnesian
Limestone and Marl-slate of Durham. i
Mr. Gray made some remarks on the occurrence of Water
in the Valves of Bivalve Shells, and exhibited a specimen of
Spondylus varius, in which water was contained in both the
valves.
Mr. Ogilby gave an account of his views respecting the
classification of Ruminating Quadrupeds, which he proposed to
found upon the presence or absence of horns on the female sex;
the peculiar form of the upper lip; and the presence or absence
of the subocular and submaxillary glands. He showed the ap-
plication of these views to the division of hollow-horned rumi-
nating animals without horns in the female sex, which he dis-
tributed into five new genera.
The Rey. W. Scoresby communicated some observations on
the adaptation of the Structure of the Cetacea to their habits
of life and residence in the Ocean; and suggested the use
which might be made of the peculiar forms of the Whalebone
in their classification.
Lieutenant Colonel Sykes exhibited a specimen of the Short-
tailed Manis, and communicated some observations on its mode
of progression. !
Mr. Brayley communicated a memoir on the laws regulating
PROCEEDINGS OF THE MEETING. XXXV
the distribution of the powers of producing Light and Heat
among Animals.
Mr. H. Strickland made some remarks on the Vipera Chersea,
showing its specific difference from the common Viper.
The subject of the use of the Pith in Plants, was discussed
by Professor Burnett, Professor Henslow, Mr. Curtis, and Mr.
Gray.
Dr. Roupell exhibited some Drawings representing the
effects of irritant Poisons upon the living membrane of the in-
testinal canal of Men and Animals.
Mr. Fisher communicated some observations on the physical
condition of the Brain during sleep.
Mr. Brooke made some remarks on the physiology of the
Eye and the Ear.
Dr. Marshall Hall gave an abstract of his views respectmg
the reflex function of the Medulla oblongata and Medulla spi-
nalis.
COMMITTEES.
~ ‘The General Committee met daily at ten a.m., and at other
hours by adjournment, in the Hall of Trinity Hall. The Com-
mittees of Sciences met as soon after ten as the business of the
General Committee permitted, in the rooms of their respective
Sections. The General Committee made the necessary arrange-
ments for the conduct of the Meeting; formed the Sectional
Committees of Sciences; determined the place and time of the
next Meeting ; appointed the new Officers and Council; and
passed the following Resolutions :—
- 1. That thethanks of the Association be given to the Societies
and Institutions from which it has received invitations,—in Bris-
tol, Birmingham, Liverpool, Newcastle and Edinburgh.
2. That Members of the Association whose subscription shall
have been due for two years, and who shall not pay it on proper
notice, shall cease to be Members, power being left to the Com-
mittee or Council to reinstate them on reasonable grounds
within one year, on payment of their arrears.
- 3. That the number of Deputies which provincial Institutions
shall be entitled to send to the Meetings as Members of the
General Committee, shall be two from each Institution.
4, That the following instructions be given to each of the Com-
mittees of Sciences:—-- .-——- tAdait
__To’select those points of science, which, on a review of the
former Recommendations of the Committees, or those contained
XXXVi THIRD REPORT—1833,
in the Reports published by the Association, or from sugges-
tions made at the present Meeting, they may think most fit to
be advanced by an application of the funds of the Society,
either in compensation for labour, or in defraying the expense
of apparatus, or otherwise. The Committee are requested to
confine their selections to definite as well as important objects ;
to state their reasons for the selection, and where they may
think proper, to designate individuals to undertake the desired
investigations ; they are to transmit their Recommendations
through their Secretaries to the General Committee.
The Committees of Sciences having complied with these in-
structions, the following Resolutions were passed by the General
Committee:
1. That a sum not exceeding 2001. be devoted to the dis-
cussion of observations of the Tides, and the formation of Tide
Tables, under the superintendence of Mr. Baily, Mr. Lubbock,
Rev. G. Peacock, and Rev. W. Whewell.
2. That a sum not exceeding 50/. be appropriated to the
construction of a Telescopic Lens, or Lenses, out of Rock Salt,
under the direction of Sir David Brewster.
3. That Dr. Dalton and Dr. Prout be requested to ae
experiments onthe specific gravities of Oxygen, Hydrogen, and
Carbonic Acid; and that a sum not exceeding 50/. be appropri-
ated to defray the expense of any apparatus which may be re-
quired.
4, That a series of experiments on the effects of long con-
tinued Heat be instituted at some iron furnace, or in any other
suitable situation; and that a sum not exceeding 50/. be placed
at the disposal of a Sub-Committee, consisting of Professor
Daubeny, Rev. W. V. Harcourt, Professor Sedgwick, and Pro-
fessor Turner, to meet any expense which may be incurred *.
5. That measurements should be made, and the necessary
data procured, to determine the question of the permanence or
change of the relative Level of Sea and Land on the coasts of
Great Britain and Ireland; and that for this purpose a sum
not exceeding 100/. be placed at the disposal of a Sub-Com-
mittee, consisting of Mr. Greenough, Mr. Lubbock, Mr. G.
Rennie, Professor Sedgwick, Mr. Stevenson, and Rev. W.
Whewell ;—the measurements to be so executed, as to furnish
the means of reference in future times, not only as to the re-
lative levels of the land and sea, but also as to waste or exten-
sion of the land.
* These experiments have been instituted by Mr. Harcourt, in Yorkshire, at
the Low Moor Iron Works, the property of Messrs. Hird and Co., and at the
Elsecar Furnace, belonging to Earl Fitzwilliam.
PROCEEDINGS OF THE MEETING. XXXvik
6. That the effects of Poisons on the Animal Economy should
be investigated and illustrated by graphic representations ; and
that a sum not exceeding 25/. be appropriated for this object.
Dr. Roupell, and Dr. Hodgkin were requested to undertake
this investigation.
7. That the sensibilities of the Nerves of the Brain should
be investigated ; and that a sum not exceeding 25/. should be
appropriated to this object. Dr. Marshall Hall and Mr. S. D.
Broughton were requested to undertake these experiments.
8. That a sum not exceeding 100/. be appropriated towards
the execution of the plan proposed by Professor Babbage, for
collecting and arranging the Constants of Nature and Art*.
_ 9. That arepresentation be submitted to Government on the
part of the British Association, stating that it would tend greatly
to the advancement of astronomy, and the art of navigation, if the
observations of the sun, moon and planets, made by Bradley,
Maskelyne and Pond, were reduced ; and that.a deputation} be
appointed to wait upon the Lords of the Treasuzy with a re-
quest, that public provision may be made for the accomplish-
ment of this great national object.
Proposals for the formation of a Statistical Section were ap-
proved. Itwas resolved, that the inquiries of this Section should
be restricted to those classes of facts relating to communities of
men which are capable of being expressed by numbers, and
which promise, when sufficiently multiplied, to indicate general
laws.
A Committee of Statistical Science was formed t+. The Re-
commendations § of the several Committees of Science were re-
vised and approved.
_ TRUSTEES OF THE ASSOCIATION.
Charles Babbage, F.R.S. Lucasian Professor of Mathe-
matics, Cambridge.
R. I. Murchison, F.R.S. V.P.G.S. &c.
_ John Taylor, F.R.S. Treas. G.S. &c.
_ * For an abstract of Mr. Babbage’s plan, see the Appendix. ;
+ The deputation consisted of Professor Airy, Mr. Baily, Mr. D. Gilbert and
Sir John Herschel. The application wasimmediately complied with by the Go-
vernment.
. } For an account of the proceedings of this Committee, see the Appendix.
§ These Recommendations will be found marked with an asterisk in the col-
leguon of Recommendations and Suggestions printed in the latter part of .the
volume, ;
XXXVIli THIRD REPORT—1833.
. OFFICERS.
President.— Rev. Adam Sedgwick, F.R.S. G.S. and Wood-
wardian Professor of Geology, Cambridge.
Vice-Presidents.—G. B. ‘Airy, F.G.S. Plumian Pyoteddex of
Astronomy, Cambridge. John aDolecee D.C.L. F.R.S. Instit.
Reg. Sc. Paris. Corresp.
President elect.—Lieut. Gen. Sir T. M. Brisbane, K.C.B.
F.R.S. L. & E. President of the Royal Soc. Edinb. Inst.
Reg. Sc. Paris. Corresp.
Vice-Presidents elect.—Sir David Brewster, K.G.H. LL.D.
F.R.S. L. & E. Rey. J. Robinson, D.D. Antconeaner Royal
at Armagh.
Treasurer.—Jobn Taylor, F.R.S. Treas. G. S.
General Secretary.—Rev. W. V. Harcourt, F.R.S. G.S.
Assistant Secretary.—John Phillips, F.R.S. G.S. Professor
of Geology in King’s College, London.
Secretaries for Oxford.—Charles Daubeny, M.D. F.R.S.
L.S. Professor of Botany. Rev. B. Powell, F.R.S. Savilian
Professor of Geometry.
Secretaries for Cambridge.—Rev. J. 8S. Henslow, F.L.S.
G.S. Professor of Botany. Rev. W. Whewell, F.R.S. &c.°
Secretaries for Edinburgh.—John Robison, Sec. R.S.E.
James D. Forbes, F.R.S. L. & E. F.G.S. Professor of Natural
Philosophy.
Secretary for Dublin.—Rev. Thomas Luby.
COUNCIL.
- Rev. W. Buckland, D.D. F.R.S. Professor of Geol. and Min;
Oxford. W. Clift, F.R.S. Rev. T. Chalmers, D.D. Professor of
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kin, M. D. London. W. R. Hamilton, Astronomer Royal
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don. J. S. Traill, M.D. W. Yarrell, F.L.S. &c... Ex officio
members,—The Prasees and Officers of the Association. _
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PROCEEDINGS OF THE MEETING. XKXI1X
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Murchison, F.R.S. V.P.G.S. < Ww
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G.S. : >. RM
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xl THIRD REPORT—1833.
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TRANSACTIONS.
Report on the State of Knowledge respecting Mineral Veins.
- By Joun Taytor, F.R.S., Treasurer of the Geological So-
ciety and of the British Association for the Advancement of
Science, Fc. Fe.
I HAVE found it very difficult to execute the task proposed to
me in a manner Satisfactory to myself, as we have at this time
no digested account of the views entertained by geologists of
the present day upon this interesting subject. The most per-
fect treatise is that of Werner, which deserves much attention
for the observation of facts which it displays; but as it was
written to propound a theory, and as that theory depended
upon views of the structure of the crust of the earth which
modern geology has at least thrown much doubt upon, so his
work cannot be taken as an outline of our present state of
knowledge.
Since his time but little has been attempted respecting vein
formations; and the subject has been, I think, rather neglected
by geologists, who have advanced other branches of the science
with extraordinary skill, industry and success. Detached pa-
pers have, indeed, appeared by English authors, among which
that on the veins of Cornwall, by Mr. Joseph Carne, holds a
distinguished place.
As some proof that the subject of veins has not been much
attended to, I would remark, that in the Second Series of the
Transactions of the Geological Society of London, consisting
now of the first and second volumes complete, and two Parts of
the third volume, no paper expressly on veins is to be found.
In the First Series there are two papers, one by the late Mr.
W. Phillips, giving an outline of facts more generally observed
with respect to veins in Cornwall, from observations made
principally in the year 1800. Another is by Dr. Berger, on
the physical structure of Devon and Cornwall, from observa-
tions made in 1809. The writeradopts the Wernerian theory,
and mentions cases which he thinks confirmatory of its truth.
In the four volumes of the Transactions of the Royal Geo-
ert: Society of Cornwall, we shall find this subject more
: B
2 ' THIRD REPORT—1833.
attended to, and there are several communications relating to
it: among the authors are Dr. Boase, Mr. Carne, Dr. Davey,
Mr. R. W. Fox, and Mr. John Hawkins. One of the papers
by Mr. Carne is that to which I have before alluded.
One of the most recent works by foreign writers is that of
the late M. Schmidt of Siegen. He was an experienced prac-
tical miner, and wrote chiefly with a view to his art, describing
the various derangements in mineral veins, and tracing the best
rules to be observed in pursuing researches in difficult circum-
stances. He adopts the Wernerian theory of formations, and
refers to the author of it as the great master of the subject.
Though no general theory has of late been produced in re-
gular form, yet with the great attention that has been given to
geology by so many eminent men, an extended field of observa-
tion has taken place, leading to a very general change of opi-
nion on most important points; many conjectures respecting the
formation of veins have sprung up, and which, when the facts
are more investigated, and they shall have been recorded and
classified, may form the groundwork for a more enlarged and
rational theory, by which their phenomena and structure may
be explained, and the causes of their formation, the manner of
filling up, and the circumstances of the varied derangements
and dislocations, may be traced and be better understood.
The subject is of threefold importance: first, as it relates to
science, wherein a better knowledge of veins generally must
very materially contribute to sound investigations as to the
structure of the rocks that inclose them: secondly, as it is much
owing to the pursuit of the minerals which are deposited in veins
that we have acquired and may yet extend our knowledge of
geology in general: thirdly, in relation to the question some-
times proposed as to the usefulness of geological science, the
most ready answer may be given, if it be considered that this
inquiry will relate to subjects of practical utility, in which man-
kind are universally and largely interested.
Before I proceed to any account of the opinions as to the
formation of veins, I would offer some definition descriptive of
their character and structure, that in proceeding with our sub-
ject we may clearly understand what is meant to be treated on.
Werner lays it down, ‘‘ That veins are particular mineral re-
positories, of a flat or tabular shape, which in general traverse
the strata of mountains, and are filled with mineral matter dif-
fering more or less from the nature of the rocks in which they
oceur.
_ “Veins cross the strata, and have a direction different from
theirs. Other mineral repositories, such as particular strata or
$$
rr
REPORT ON MINERAL VEINS. _ 3
beds, of whatever thickness they occur, have, on the contrary,
a similar direction with the strata of the rock, and instead of
crossing, run parallel with them: this forms the characteristic
difference.”
. Playfair says: ‘‘ Veins are of various kinds, and may in ge-
neral be defined, separations in the continuity of a rock, of a
determinate width, but extending indefinitely in length and
depth, and filled with mineral substances different from the
rock itself. The mineral veins, strictly so called, are those filled
with sparry or crystallized substances, and containing the me-
tallic ores.”
Mr. Carne says: “ By a true vein I understand the mineral
contents of a vertical or inclined fissure, nearly straight, and
of indefinite length and depth. 'These contents are generally,
but not always, different from the strata or the rocks which the
vein intersects. ‘Irue veins have regular walls, and sometimes
a thin layer of clay between the wall and the vein; small
branches are also frequently found to diverge from them on
both sides.”
Mr. Carne mentiens other veins, which he distinguishes from
the true ones as being shorter, crooked, and irregular in size ;
he considers these to have formed in a different manner: but
this will be discussed hereafter.
These definitions seem to me to be sufficient for our pur-
pose; but it may be advantageous here to introduce some
further description of circumstances connected with veins, and
to explain the terms’ usually employed to describe them.
\ Being tabular masses, generally of no great width, any one
will, whether vertical or inclined, present at its intersection
with the surface a line nearly straight: this may be from north
to south, or from east to west, or in any intermediate course.
This is usually called the direction; by miners frequently the
run of the vein, or the course of the vein, and is denoted by the
points of the compass it may cross.
The length, as Werner states, is indefinite, it being doubtful
whether any vein has been pursued to a perfect termination.
The tabular mass, again, may be either vertical to the plane
of the earth’s surface, or may deviate from this position by in-
clining to one side or the other of the perpendicular. ‘This
deviation is called the inclination of the vein; by the Cornish
miners the underlie. It is measured by the angle made with
the perpendicular; and as the dip will be to one side of the
direction, the latter being known, the other is easily expressed.
The depth to which veins descend into the earth is unknown,
as well as the length, and for the same reason.
BR
4 THIRD REPORT—1833.
The only dimension we can ascertain is that across from oné
side to the other of the tabular mass, and is measured from one
wall to the other, which is the term used in England for the
cheeks or sides presented by the inclosing rock. This dimen-
sion is called the width, or frequently the size of the vein.
The width varies considerably in the same vein. In Europe
a vein containing ore is considered to be a wide one if it ex-
ceeds five or six feet. In Mexico the width of veins is gene-
rally greater.
In metalliferous veins the deposits of ore are extremely irre-
gular, forming masses of very diversified form and extent, and
are separated from each other by intervening masses of vein-
stone or matrix, either entirely devoid of ore, or more or less
mixed with it. It is rare to find a vein entirely filled with ore
in any part.
In this respect they differ from most beds, where, as in those
of coal, the whole is a uniform mass.
The layer of clay, which, as Mr. Carne says, is frequent in
such veins, will deserve particular notice when we consider
their general structure and the theories of their formation:
this is called Saal-bande by the Germans, and jflookan by the
Cornish miners.
The clearest idea of a vein will be obtained by imagining a
crack or fissure in the rocks, running in nearly a straight line,
extending to great and unknown length and depth, and filled
with various substances.
I do not intend by this description to convey any theoretic
opinion as to the manner in which such fissures may have been
formed, or as to the mode of their being furnished with their
present contents. These are subjects on which the greatest
diversity of opinion has existed in former times, and this diver-
sity is continued to the present period. It is the main business
of this Report to state these opinions, and to describe our pre-
sent state of knowledge of this difficult subject. I feel great
distrust of my power to do it justice; but I am encouraged by
the idea that a feeble sketch may induce abler hands to pursue
the design, and throw more and more light upon this interesting
branch of geology.
It would be of little use to go into details of the conjectures
of ancient authors, or into the mysteries with which this sub-
ject was enveloped in the age of alchemy.
The earliest writer who is worthy to be consulted is Agricola
(whose proper name was Bauer): he resided in the Saxon Erz-
gebirge, and died in the middle of the sixteenth century.. He
has been called the father of mineralogy, and of the science of
REPORT ON MINERAL VEINS. 5
mining. He had the rare merit of emerging from the mists and
clouds of an absurd school of philosophy, which had till then
obscured the objects which it pretended to illustrate; and he
first subjected them to inquiries prompted by sound reason and
just views of nature.
His writings were numerous, and’in such pure Latin that
they are said to be entitled to a place among the classics. He
treats of veins in a work called Bermannus, but more particularly
in the third book of his great work De Re Metallica.
Agricola being held to be the first who has written anything
certain onthe formation of veins, and his theory of the manner
of their being filled up having, with some modifications, been
for a long period generally received, and in part even adopted.
by Werner, I shall commence from his time the notice of the
opinions promulgated by various writers antecedent to Werner
and Hutton.
Some have maintained, That veins and their branchings are
to be considered as the branches and twigs of an immense trunk
which exists in the interior of the globe :
That from the bowels of the earth metallic particles issued
forth in the form of vapours and exhalations through the rents,
in the same manner as sap rises and circulates in vegetables.
This speculation was proposed by Von Oppel, captain-ge-
neral of the Saxon mines, who wrote in 1749. He was a skilful
miner and an accurate observer; and it is singular that this opi-
nion is not consistent with most that he has elsewhere said on
the subject, which generally rather agreed with the views which
were adopted by Werner and others.
- Henkel, who wrote in the early part of the seventeenth cen-
tury, and who has been held to be the father of mineralogical
chemistry, first attributed the formation of the contents of veins
to peculiar exhalations: he supposed the basis of each metal
and mineral to have existed in the substance of the rock, and
to have been developed by a peculiar process of nature.
Becher about the same time supported very similar views.
Stahl, who commented upon the writings of Becher, had ad-
vanced a somewhat similar opinion; but he afterwards rejected
this theory, and considered veins, as well as the substances of
which they are composed, as having been formed at the same
time with the earth itself.
~ Zimmerman, chief commissioner of mines in Saxony, who
died in 1747, had an idea that the variety of minerals contained
in veins had been produced by a transformation of the sub-
stance of the rock.
_ Charpentier, in 1778, supported nearly similar opinions, and
6 THIRD REPORT—1833.
combated strenuously against the theory which considers veins
to have been rents that were afterwards filled up by different
mineral substances.
This is the theory, however, which, from the time of Agricola
to the present day, has been most generally received, namely,
that veins were fissures which have been since filled up by de-
grees with mineral matters.
The causes of such fissures, and the mode of their contents
being deposited, have been variously stated, and have given rise
to much conjecture; and allowing for these differences, the main
proposition has been supported by many writers. Among these
I would name Agricola; Balthazar Roésler, an eminent miner of
Freyberg, who died in 1673; Hoffman, a commissioner of mines
at the same place, in 1746; Von Oppel, before mentioned, who,
though he had indulged in other speculations, distinctly lays
down in his Introduction to Subterranean Geometry, (Dres-
den, 1749,) that veins were formerly fissures, open in their su-
perior part, and that they traverse and intersect the strata.
Bergman entertained opinions very similar, which were also
supported by Delius, an author on mining, of considerable ce-
lebrity, who wrote about 1770.
Gerhard, in his Essay on the History of the Mineral King-
dom, (Berlin, 1781,) gives a collection of interesting facts con-
cerning veins, and considers them to have originally been rents,
which were afterwards filled up with mineral substances.
To this list may be added Lasius, in his Observations on the
Mountains of the Hartz,in 1787; and Linnzus is stated ‘‘to have
wondered at the nature of that force which split the rocks into
those cracks; and adds, that probably the cause is very familiar,
—that they were formed moist, and cracked in drying *.”
In England we have testimony to the same opinion from
Dr. Pryce, who wrote his Mineralogia Cornubiensis in 1778,
He says, ‘‘ When solid bodies were separated from fluid, certain
cracks, chinks and fissures in various directions were formed,
and as the matter of each stratum became more compact and
dense by the desertion of moisture, each stratum within itself
had its fissures likewise, which, for the most part, being in-
fluenced by peculiar distinct laws, were either perpendicular,
oblique,” &c.
He afterwards adds, that those very fissures are the wombs
or receptacles of all metals, and most minerals. He assigns the
derangements of veins to the effect of fracture by violence, and
quotes subsidence as one of the probable causes of such dislo-
cations. He says there can be no doubt that many alterations
* Hill.
REPORT ON MINERAL VEINS. 7
have happened to various parts of the earth before, at, and
after the Flood, from inundations, earthquakes, and the dis-
solvent powers of subterranean fire and water, which variety of
causes and circumstances must infallibly have produced many
irregularities in the disposition and situation of circumjacent
strata and lodes*.
He describes twelve kinds of lodes or veins in Cornwall,
naming them from their chief contents. But the most remark~-
able observation of Dr. Pryce is respecting the relative age of
veins, of which he seems to have given the first intimation.
Werner, long after, states this as a discovery of his own, and
as an essential part of his theory. His translator, however,
(Dr. Anderson,) does Pryce justice, and remarks that his ob-
servations must have been unknown to Werner, who showed
much anxiety in all cases to confer on every writer the merit
which was due to him.
Dr. Anderson quotes the passage as one of much importance.
‘‘ Because the cross gossans or cross flookans run through
all veins of opposite directions, without the least interruption
from them, but, on the contrary, do apparently disjoint and
dislocate all of them, it seems reasonable to conclude, that the
east and west veins were antecedent to cross veins, and that
some great event, long after the Creation, occasioned those
transverse clefts and openings. But how or when this should
come to pass, we cannot presume to form any adequate idea.”
Kirwan supports the doctrine that some veins were originally
open, as appears from the rounded stones and petrifactions
found in them. Thus, in the granitic mountain of Pangel in
Silesia there is a-vein filled with globular basalt. So also in
veins of wacken, in Joachimstahl in Bohemia, trees and their
branches have been found.
But he deems it improbable that all veins were originally
open to day, and filled from above. He inclines to the theory
of veins being filled by the percolation of solutions of the me-
tals and earths.
Having now taken a cursory view of the opinions held before
Werner published his Theory of Veins, and seen something of
the state of knowledge relating to this subject, we may bear
in mind the materials which he had to work with, and take
into account his well-known views as to the origin of rocks from
aqueous deposition, and we shall comprehend the system which
he developed, with respect to veins, in the only work, I believe,
which proceeded from his own hand, and which was published
* ‘Lode’ is the term used in Cornwall for a metalliferous vein.
+ Mineralogia Cornubiensis, p. 101. .
8 THIRD REPORT—1833.
at Freyberg in 1791. Werner adopts, in the first place, the
proposition that the spaces now occupied by veins were origi-
nally rents formed in the substance of rocks, and states that
this is not a new opinion.
He claims the merit of having ascertained in a more positive
manner the causes which have produced these rents, and of
having brought forward better proofs of it than had formerly
been done.
He admits that rents may be produced by many different
causes, but he assigns the greater part to subsidence. He lays
it down, that when the mass of materials of which the rocks
were formed by precipitation in the humid way, and which was
at first soft and moveable, began to sink and dry, fissures must
of necessity have been formed, chiefly in those places where
mountain chains and high land existed. He adds, that rents
and fissures are still forming from time to time in mountains
which haye a close resemblance to those spaces now occupied
by veins, and that this happens in rainy seasons and from
earthquakes.
He adduces as a proof of his assertions, that veins, in respect
of their form, situation and position, bear a strong resemblance
to rents and fissures which are formed in rocks and in the
earth; that is to say, both have the same tabular figure, and
the deviations which they make from their general direction
are few in number and very inconsiderable; and he remarks,
that all the veins of a mining district, more particularly when
they are of the same formation, have a similar direction, which
shows them to have been produced by the same general cause.
But what Werner claimed as altogether new, and what he
challenges as his own particular discovery is,
1. To have determined and described in a more particular
manner the internal structure of veins, as well as the formation
of the different substances of which they are composed, and to
have settled the relative age of each.
2. To have given the most accurate observations and most
perfect knowledge of the meetings and intersections of veins,
and to have made these observations subservient to the deter-
mining their relative ages.
3. 'To haye determined the different vein formations, parti-
cularly metalliferous veins, as well as their age.
4, ‘To have been the first who entertained the idea that the
spaces which veins occupy were filled by precipitations from
the solutions, which at the same time formed by other precipi-
tations the beds of mountains, and to haye furnished proofs of
this: and,
REPORT ON MINERAL VEINS. 9
5. To have determined the essential differences that are
found between the structure of veins and that of beds.
Werner illustrates his propositions by many observations,
which his intimate acquaintance with the extensive mining di-
stricts in which he was engaged gave him the power of observin
and recording ; and it must be conceded, at least, that his state-
ment of facts, and his arrangement of them, give him a manifest
superiority over most writers upon this subject. Every one
who has had opportunity to see much of these storehouses of
nature will be struck with the accuracy of most of his descrip-
tions, whether they admit the theory by which they are ex-
plained, or not.
He allows that the enrichment of veins, or their being filled
with ores or metals, may have taken place by,
1, a. A particular filling up from above.
6. By particular internal canals.
ec. By infiltration across the mass of the vein.
2. A metallic vein may be increased by the junction of a new
metalliferous vein.
3, Though rarely, the richness of a vein may be the effect of
an elective attraction or affinity of the neighbouring rock.
The mode assigned by Werner for the formation of the
spaces now occupied by veins is still further demonstrated, in
his opinion, by the relation which veins have to one another ; as,
_ Their intersecting one another.
Their shifting one another.
Their splitting one another into branches.
Their joining and accompanying one another.
Their cutting off one another.
All these peculiarities, he remarks, are produced by the ef-
fects of a new fissure upon one that is older.
Subsidence having been the cause of fissures he thinks is
proved by the difference in the level in the parts of the same
stratum or bed in which a vein is inclosed; and this throwing
up or down, as the miners term it, bears a proportion to the
size of the vein.
The interior structure of many veins is quoted to show that
the fissures had been originally open, and which had been af-
terwards filled by degrees.
Such veins are composed of beds, arranged in a direction pa-
rallel to their sides; their crystallizations are supposed to show
these beds to have been deposited successively on each other,
and that those next the walls have been first formed. A cir-
cumstance much relied on, also, is the existence of rolled masses
or water-borne stones, fragments of the adjacent rock, some-
10 THIRD REPORT—1833.
times forming a breccia, remains or impressions of organic bo-
dies, coal and rock salt substances of recent formation, and other
matters, which should appear to have come in from above.
This theory obtained considerable attention, and was very
generally adopted from the time of its being made known; and
it has, I believe, many adherents at this day, particularly among
miners or those who have much opportunity of actual observa-
tion.
Hutton’s Theory of the Earth was published afterwards, in
1795; and as his views regarding the operations employed in
the formation of the structure of the rocks differed entirely
from those who assigned to them an aqueous origin, so it will
readily be supposed that he would promulgate a new explana-
tion of the formation of veins.
According to Playfair, this theory embraced the following
propositions :— :
It allowed that veins are of a formation subsequent to the
hardening and consolidation of the strata which they traverse,
and that the crystallized and sparry structure of the substances
contained in them shows that these substances must have con-
creted from a fluid state.
It assumes that this fluidity was simple like that of fusion by
heat, and not compound like that of solution in a menstruum.
It is inferred that this is so from the acknowledged insolu-
bility of the substances that fill the veins in any one menstruum,
and from the total disappearance of the solvent, if there was
any, it being argued that nothing but heat could have escaped
from the cavities.
It is further maintained, that as the metals generally appear
in veins in the form of sulphurets, the combination to which
their composition is owing could only have taken place by the
action of heat. And, further, that metals being also found na~-
tive, to suppose that they could have been precipitated pure
and uncombined from any menstruum, is to trespass against all
analogy, and to maintain a physical impossibility.
It is therefore inferred, that the materials which fill the mi-
neral veins were melted by heat, and forcibly injected in that
state into the clefts and fissures of the strata.
The fissures must have arisen, not merely from the shrinking
of the strata while they acquired hardness and solidity, but
from the violence done to them when they were heaved up and
elevated in the manner which the theory has laid down.
Slips or heaves of veins, and of the strata inclosing them,
are to be explained from the same violence which has been
exerted.
ee
REPORT ON MINERAL VEINS. 11
It is admitted as interesting to remark, that in the midst. of
the signs of disturbance which prevail in the bowels of the
earth, there reigns a.certain symmetry and order, which indi-
cates a force of incredible magnitude, but slow and gradual in
its effects.
Further, that as a long period was required for the elevation
of the strata, the rents made in them are not all of the same
date, nor the veins all of the same formation. Tair ie | OTe ives fa whe syne! igile abies enact i %
t. # pele: te fet ety Sevee Ra slices
ve 4
On the Principal Questions at present debated in the Philoso-
phy of Botany. By Joun Linvtey, Ph. D., F.RS., §c.,
Professor of Botany in the University of London.
Ir we compare the state of Botany at the end of the last cen-
tury with its present condition, we shall find that it has become
so changed as scarcely to be recognised for the same science.
Improvements in the construction of the microscope, the disco-
veries in vegetable chemistry, the exchange of artificial methods
of arrangement for an extended and universal contemplation of
natural affinities, the reduction of all classes of phanomena to
general principles, and, above all things, the adoption of the
philosophical views of Gothe, together with the recognition of
an universal unity of design throughout the vegetable world,
are undoubtedly the principal causes to which this change is
to be ascribed.
As the general nature of recent discoveries, and a sufficient-
ly definite notion of the present state of botanical science, may
be collected from the introductory works which have appeared
in this country within the last three years, it is presumed that
the object of the British Association will be attained if the
present Report is confined to the most interesting only of those
subjects upon which botanists have been recently occupied,
and to an indication of the points to which it is more particularly
desirable that inquiries should now be directed. I have also
excluded everything that relates to mere systematic botany, in
the hope that some one will take that subject as the basis of a
separate Report.
Elementary Organs.—This country has, till lately, been re-
markably barren of discoveries in vegetable anatomy, since the
time of Grew, who was one of the fathers of that branch of
science. Whatever progress has been made in the determina-
tion of the exact nature of those minute organs, by the united
powers of which the functions of vegetation are sustained, it
has been chiefly in foreign countries that it has taken place:
the names of Mirbel, Moldenhauer, Kieser, Link and Amici,
stand alone during the period when their works were published ;
and it has only been within a very few years that those of
Brown, Valentine, Griffith and Slack have entered into com-
petition with the anatomists of Germany and France.
By the researches of these and other patient inquirers, we
28 THIRD REPORT—18383.
have already reduced our knowledge of the exact internal struc-
ture of plants to a state of very considerable precision; although
it must be confessed that vegetable anatomy is still the field
where the greatest discoveries may be expected.
It is now generally agreed that the old opinions, that the tis-
sue of plants is either a membrane doubled together in endless
folds, or a congeries of cavities formed in solidifiable mucus
by the extrication of gaseous matter, are equally erroneous,
and that it really consists of distinct sacs or cells, pressed to-
gether and adhering to each other by the sides where they are
in contact.
It is considered that this is proved by the following circum-
stances. 1. By the action of some powerful solvent, such as
nitric acid, the cells may be artificially separated from each
other. 2. In parts which become succulent, the cells separate
spontaneously, as in the receptacle of the strawberry, the berry
of the privet, &c. 3. When the parts are young, their tissue
may be easily separated by pressure in water. 4. It is con-
formable to what has been observed in the growth of plants.
Amici found that the new tubes of Chara appear like young buds
from the points or axille of pre-existing tubes ; an observation
that has been confirmed by Mr. Henry Slack*. It has been
distinctly proved by M. Mirbel +, that the same thing occurs in
the case of Marchantia polymorpha. 'That learned botanist, in
the course of his inquiries into the structure of this remarkable
plant, may be said to have been present at the birth of its cel-
lular tissue; and he found that in all cases one tube or utricle
generated another, so that sometimes the young masses of tis-
sue had the appearance of knotted or branched cords. He satis-
fied himself, by a beautifully connected series of observations,
that new parts are not formed by the adhesion of vesicles origi-
nally distinct, as many have asserted, but by the generative
power of one first utricle, which engenders others endowed with
the same property.
It appears that when first formed the sacs are completely
closed up, so that there is no communication between the one
and the other, excepting through the highly permeable mem-
brane of which they are composed. This, indeed, is not con-
formable to the observations of those who have described and
represented pores or passages of considerable magnitude pierced
in the sides of the sacs; but it has been satisfactorily shown by
Dutrochet, that the spaces supposed by such observers to be
* Transactions of the Society of Arts, vol. xlix.
+ “Recherches Anatomiques et Physiologiques sur le Marchantia polymor-
pha,” in Nouv. Ann. du Muséum, vol. i. p. 98.
—
REPORT ON THE PHILOSOPHY OF BOTANY. 29
pores are nothing more than grains of amylaceous matter stick-
ing to the sides of the sacs; for he found that by immersing the
latter in hot nitric acid, the supposed pores became opake, and
by afterwards moistening them with a weak solution of caustic
potash, they recovered their transparency: we also find that
the supposed pores are readily detached from the sides of the
sacs to which they adhere; and I think it may be added, that
our microscopes are now alone sufficient to show what they are.
The question as to the perceptible porosity of vegetable tis-
sue may therefore be considered, I think, disposed of as a
general fact; for the objection that Dr. Mohl has taken to this
explanation *,—namely, that in a transverse section we ought to
find such grains projecting from the sides of the cells like little
eminences,—cannot surely be entitled to much weight, if we op-
pose to this negative observation the positive evidence already
mentioned, and especially if we consider that it is next to im-
possible for the keenest knife to make a section of such delicate
parts without carrying away such particles upon its edge. There
are, nevertheless, cases in which the point is still open to in-
vestigation.
Thus Mirbel, in his second memoir on the Marchaniia j,
positively declares that the curious cells which line the anther
of the common gourd, are continuous membranes till just be-
fore the expansion of the flower, when they very suddenly en-
large, and their sides divide into the narrow ribands or threads
which give their name to what we call fibrous cells. In this,
and the multitudes of similar cases with which Purkinje has
made us acquainted, there can be no doubt that the sides of
the cells consist ultimately of nothing but openwork; but still
it seems certain that during the principal part of their existence
they were completely closed up.
It is also probable that in other cases the sides of the cells
or vessels ultimately give way and slit; but this rending seems
to be a phenomenon attendant upon the cessation of the ordi-
nary functions of tissue, and independent of their original con-
struction.
In coniferous plants the wood is in a great measure com-
posed of closed tubes, tapering to each end, the sides of which
are marked with circles, containing a smaller circle in their cen-
tre. These-circles have long been considered undoubted pores,
and it does not appear possible to prove them otherwise by any
of the tests already mentioned.
* Ueber die Poren des Pflanzen-Zellgewebes, p. 11. Tubingen, 1828.
t Archives de Botanique, vol. i.
30 THIRD REPORT—1833.
I have endeavoured to show * that they are glands of a pecu-
liar figure, which stick to the sides of the tubes; and I have
ascertained that the large round holes that are certainly found
in coniferous tissue are caused by the dropping or rubbing off
of such supposed glands. But a very different opinion is en-
tertained by Dr. Mohl}, whose observations have been con-
firmed by Dr. Unger{. In the opinion of the former of these
botanists the supposed glands of coniferous tissue are circular
spaces where the membrane of the tube becomes abruptly ex-
tremely thin; and it is said that transverse slices of coniferous
wood, made at an angle of forty-five degrees, demonstrate the
fact. Dr. Mohl is also of opinion, as has been already said,
that the porous appearances above mentioned, and ascribed to
the adhesion of amylaceous matter to the sides, are of a similar
nature.
It has been shown by Mr. Griffiths, that in the kind of tissue
called the dotted duct, the suspicion of Du Petit Thouars that
this form of tissue is composed of short cylindrical cells placed
end to end, and opening into each other, is correct; their com-
munication, however, is not by means of an organic perfo-
ration, but is produced by the absorption and rupture of the
ends which come in contact. Mr. Slack has also stated,
in a very good paper upon Vegetable Tissue§, that in other
cases the vessels of plants open into each other where they
come in contact; as, for example, at the conical extremities,
where ducts join each other ; but he represents this to be owing
to the obliteration of their membrane at that point; the internal
fibre, of which they are in part composed, remaining like a
‘grating stretched across the opening where the enveloping
membrane has disappeared.
In a short paper, published in the Journal of the Royal In-
stitution in December 1831, I have endeavoured to show that
membrane and fibre are to be considered the organic elements
of vegetable tissue, contrary to the more usual opinion that
membrane only is its basis: this was attempted to be proved,
not only by the fact that the simple cells of the testa of Mau-
randia, &c., are apparently formed by a fibre twisted spirally
in the inside of their membrane, but also by the elastic spires I
had discovered on the outside of the seed of Collomia, in which
it is plain that no membrane whatever is generated.
* Introduction to Botany, p. 16. t. 2. f. 7.
+ Ueber die Poren des Pflanzen-Zeligewebes.
{ Botanische Zeitung, October 7, 1832.
§ Transactions of the Society of Arts, vol. xlix.
|
REPORT ON THE PHILOSOPHY OF BOTANY. 31
It would, however, appear from the researches of Mirbel*,
that the presence of a twisted fibre within a cell is not always
the cause of the spiral or fibrous character so common in tissue.
He finds, as has been already stated, that the cells that line
the anther of a gourd are at first membranous and closed, and
that they continue in this state till just before the bursting of the
anther, when they suddenly divide in such a way as to assume
the appearance of delicate threads, curved in almost elliptical
rings, which adhere to the shell of the anther by one end; these
rings are placed parallel with each other in each cell, to which
they give an appearance like that of a little gallery with two
rows of pilasters, the connecting arches of which remain after
the destruction of the roof and walls. He also watched the
development of the curious bodies called elaters in the Mar-
chantia, which he describes to the following effect. At first
they are long slender tubes, pointed at each end; at a subse-
quent stage their walls thicken, and become less transparent,
and are marked all round through their entire length with two
parallel, very close, spiral streaks ; later still the tubes enlarge,
and their streaks become slits, which divide the walls all round,
from one end to the other, into two filaments; and, finally, the
circumvolutions of the filaments separate, assume the appear-
ance of a corkscrew, acquire a rust colour, and the elater is
complete. These elaters he considers organically identical with
the spiral vessel, and hence he concludes that every description
of vessel is a cell, differing from ordinary cells in being larger.
Upon the general accuracy’of these observations I am dis-
-posed to place great confidence; and I would even add, that the
theory of pierced or open cellular tissue being produced by
the spontaneous rending of its membrane, is apparently con-
nected with an observation of my own‘, that in some plants
simple vegetable membrane will tear more readily in one direc-
tion than another. It is nevertheless to be observed, that the
theory of fibre being one of the organic elements of tissue does
not seem to have occurred to the experienced physiologist to
whose observations I am referring, and that some of the ap-
pearances he mentions at a stage preceding transformation are
very like those of the development of an internal fibre.
The opinion of the organic identity of all the forms of tissue
has also been maintained by Mr. Slack, in the paper already
referred to, and by Dr. Mohl, in his memoir on the comparative
anatomy of the stem of Cyeadee, Conifere, and Tree Ferns.
* Archives de Botanique, vol. i.
+ Introduction to Botany, p. 2.
32 THIRD REPORT—1833.
The latter considers that the dotted tubes of Cycadee un-
doubtedly pass directly into the vessels called by the Germans
vasa scalariformia; but my own observations do not confirm
this statement. :
Circulation Whether or not plants have a circulation ana-
logous to that of animals, is a topic that was more open to con-
jecture at a time when the real structure of the former was un-
nown, than it can be at the present day. Knowing, as we
now do, that a tree is more analogous to a Polype than toa
simple animal; that it is a congeries of vital systems, acting
indeed in concert, but to a great degree independent of each
other, and that it has myriads of seats of life, we cannot expect
that in such productions anything absolutely similar to the mo-
tion of the blood of animals from and to one common point
should be found. The idea of circulation existing in plants
must therefore be abandoned; but that a motion of some kind
is constantly going on in their fluids was sufliciently proved by
the well-known facts of the flow of the sap, the bleeding of the
vine, the immense loss plants sustain by evaporation, and by
similar phenomena. ‘The motion was for the first time beheld
by Amici, the Professor at Modena, who discovered it in the
Chara. He found that in this plant the cylindrical cells of the
stem are filled with fluid, in which are suspended grains of
green matter of irregular form and size. ‘These grains were
distinctly seen to ascend one side of each tube, and descend the
other, after the manner of a jack-chain, and to be continually
in action, in the same manner, as long as the cell retained its
life; the motion of the grains was evidently due to the ascend-
ing and descending current in the fluid contained within the
tube-like cell. It could not be ascertained that any kind of
communication existed between the cells, but each was seen to
have a motion of its own.
The observations of Amici have been verified in this country
chiefly upon species of Nitella ; and from the investigations of
Mr. Solly, Mr. Varley, and Mr. Slack*, the nature of the phz-
nomenon has been determined with considerable precision.
Among other things, it has been ascertained that in Nétella
the currents have always a certain relation to the axis of growth,
the ascending current uniformly passing along the side of the
cell most remote from the axis, and the descending current
along the side next the axis.
Similar motions have been seen in several other plants. In
the cells of Hydrocharis Morsus-Rane the fluid has been ob-
* Transactions of the Society of Arts, vol. xlix.
REPORT ON THE PHILOSOPHY OF BOTANY. 30
served to move round and round their sides in a rotatory man-
ner, which, however, has not been seen to follow any particular
law. In the joints of the hairs of Tradescantia virginica
several currents of a similar nature exist; and in the hair of
the corolla of a species of Pentstemon, Mr. Slack has observed
several currents taking various directions, some continuing to
the summit of the hair, whilst others turn and descend in va-
rious places, two currents frequently uniting in one channel.
It may hence, possibly, be assumed that in the cells of plants,
when filled with fluid, there is a very general rotatory move-
ment, which is confined to each particular cell. ‘This, it is ob-
vious, can form no part of the general circulation of the system,
which must often occur with great rapidity, and which must
take place from the roots to the extremities. The rotatory
motion may perhaps be considered a sort of motion of di-
gestion, and connected with the chemical changes which matter
undergoes in the cells from the united action of light, heat,
and air.
What has been supposed to be a discovery of the universal
motion of sap has been made by Professor Schultz of Berlin,
who remarked two torrents, one of which was progressive, and
the other retrogressive, in what he calls the vital vessels (ap-
parently the woody fibre) in the veins of Chelidoniwm majus,
and in the stipule of Ficus elastica.
His observations have been repeated by a Commission of the
Tnstitute, composed of MM. Mirbel and Cassini, who have
reported* that they have also seen the motion described by
Professor Schultz; and I have myself witnessed it as is repre-
sented by those observers. But it appears probable, from se-
veral circumstances, that the motion that has been seen has
either been owing merely to the vessels in which it was re-
marked having been cut through, and emptying themselves of
their contents, as Mr. Slack has suggested, or else was nothing
but the common rotatory motion imperfectly observed.
Structure of the Axis.—From the period when M. Desfon-
taines first demonstrated the existence of two totally distinct
modes of increase in the diameter of the stems of plants, it has
been received as a certain fact that monocotyledonous plants
increase by addition to the centre of their stem, and dicotyle-
donous by addition to the circumference. Nothing has yet
arisen to throw any doubt upon the exactness of this notion in
wegard to dicotyledonous plants; but Dr. Hugo Mohl has
endeavoured to show} that monocotyledonous stems are not
* Annales des Sciences, vol. xxii. p. 89.
; + Mohl, “De Palmarum Structura,” in Martius’s Genera et Species Palmarum.
Ovv. D
34 THIRD REPORT—1833.
formed in the manner that has been supposed. According to
him, the new matter from which the wood results is not a mere
addition of new matter to the centre, but consists of bundles
of wood, which, originating at the base of the leaves, take first
a direction towards the centre, and then a course outwards
towards the circumference, forming a curve; so that the stem
of a Palm is, in fact, a mass of woody arcs intersecting each
other, and having their extremities next the circumference of
the trunk. I regret that I have not been able to consult Dr.
von Martius’s splendid work on Palms since this Report was
commenced, and that I am therefore unable to state upon what
evidence Dr. Mohl has rested his theory.
The same writer has stated* that Cycadee—that singular
tribe, which is placed, as it were, on the boundary line between
cellular and vascular plants,—are not in a great measure desti-
tute of vessels as is commonly supposed, but, on the contrary,
are composed exclusively of spiral vessels and their modifica-
tions, without any mixture of woody fibre. I have already ad-
verted to this hypothesis in speaking of the same author's state-
ment, that the dotted tubes of Cycadee are a slight modi-
fication of vasa scalariformia. Dr. Mohl is also of opinion
that Cycadee are not exogenous in their mode of growth, as
seems to be indicated by their appearance when cut, and by
their dicotyledonous embryo, but that they are more like
Palms in their manner of forming their wood, which is essen-
tially endogenous. He asserts that the stem of Cycadee, in
regard to its anatomical condition, must be considered inter-
mediate between that of Tree Ferns and Conifere, just as their
leaves and fructification undoubtedly are. He states that in
Cycadee a body of wood is gradually formed of the fibres con-
nected with the central and terminal bud; that so long as this
original wood is soft, and capable of giving way to the fibres
that are continually passing downwards, no second cylinder of
wood is formed; but in time the original wood becomes hard-
ened, and then the new fibres find their way outward and down-
ward, collecting into a second cylinder on the outside of the
original wood. It is obvious that this explanation is not so sa-
tisfactory as could be desired; for, in the first place, such a
distinction between Cycadee and Exogene as that which Dr.
Mohl states to exist, is verbal rather than real, since he admits
that the second cylinder of wood is formed externally to the
first; and secondly, it is obvious that if that structure which is
represented in the 21st plate of the third volume of the Hortus
* Ueber den Bau des Cycadeen Stammes und sein Verhaltniss xu den Stamm
der Coniferen und Baumfarrn. 4to. Munich, 1882.
REPORT ON THE PHILOSOPHY OF BOTANY. 35
Malabaricus be correct, where the stem of Cycas circinalis is
shown to have several concentric zones, precisely as in other
exogenous trees, it must follow that Dr. Mohl’s explanation
would be still more inadmissible; accordingly, this author dis-
credits the fact of the stem of Cycas cércinalis haying numer-
ous concentric zones. It is, however, certain, from the speci-
mens brought to England by Dr. Wallich, that the structure
of this Cycas is really such as is shown in the Hortus Malaba-
ricus. It is nevertheless extremely well worth further inquiry
whether there is not some important but as yet undiscovered
peculiarity in the mode of forming their stem by Cycade@; for
it must be confessed that growth by a single terminal bud,
after the manner of Palms, is not what we should expect to
meet with in exegenous trees.
Professor Schultz of Berlin has indicated* the existence of a
group of plants, the structure of whose stems he considers at
variance with all the forms at present recognised; and to this
group he refers Cycadee : but the assemblage of orders which
he collects under what he calls the same plan of growth is so
extremely incongruous as to lead to no other conclusion than
that subordinate modifications of internal structure are of no
general importance, but are merely indicative of individual pe-
culiarities.
Dr. Mohl further states, that Cryptogamic plants of the
highest degree of organization, such as Ferns, Lycopodiacea,
Marsileacee, and Mosses, in ail which a distinct axis is found,
have a mode of growth neither exogenous nor endogenous, but
altogether of a peculiar nature. In these plants, when once
the lower part of the stem is formed it becomes incapable of
any further alteration, but hardens, and the stem continues to
grow only by its point, which lengthens merely by the progres-
sive development of the parts already formed, without sending
downwards any fibrous or woody bundles, as both in exoge-
nous and endogenous plants.
M. Lestiboudois, the Professor of Botany at Lille, distin-
guishes Monecotyledons from Dicotyledons, upon principles
different from those generally adnfitted. According to this
writer, dicotyledonous trees have two systems, one, the central,
consisting of the medullary sheath and the wood; the other,
the cortical, composing the bark. These two systems increase
separately, so that in Dicotyledons there are two surfaces of
increase, that of the central system, which adds to its outside,
and that of the cortical system, which adds to its inside: but
* Naturliches System des Pflanxenreichs nach seiner inneren Organization.
8vo. Berlin, 1832.
D2
1853.
36 THIRD REPORT
in the stem of Monocotyledons there is only one surface of in-
crease, namely, that on the inside; and hence he concludes
that such plants have only a cortical system, and consist of
bark alone. It must be obvious that there are too many ana-
tomical objections to this theory to render it deserving of any
other than this incidental notice *.
The cause of the formation of wood has always been a sub-
ject upon which physiologists have been unable to agree; and
if the opinions held by the writers of the last century have been
disproved, it cannot be added that those of the present day are
by any means settled. It is now, indeed, admitted on all hands
that wood is a deposit in some way eee ie with the action
of leaves ; for it has been proved beyond all question that the
quantity of wood that is formed is in direct proportion to the
number of leaves that are evolved, and to their healthy action,
and that where no leaves are formed, neither is wood deposited.
But it is a subject of dispute whether wood is actually or-
ganized matter generated by the leaves, and sent downwards
by them, or whether it is a mere secretion, which is deposited
in the course of its descent from the leaves to the roots. The
former opinion has been maintained in different forms by De
la Hire, Darwin, Du Petit Thouars, Poiteau, and myself, and
would perhaps have been more generally adopted if it had not
been too much mixed up with hypothetical statements, to the
reception of which there are in the opinion of many persons
strong objections. For example, it has been asserted that the
wood of trees is an aggregation of the roots of myriads of buds
in a state of action, and that consequently a tree is an asso-
ciation of individuals having a peculiar organic adhesion and
a common system of growth, but each its own individual life.
To this view it is no doubt very easy to raise objections, some
of which it may be difficult, in the present state of our know-
ledge, to answer; and therefore it is better for the moment to
leave this part of the proposition out of consideration, and to
confine it to the simple statement that wood is organized matter,
generated by the leaves, and sent downwards by them. In
support of this it is argued? Ist, That an anatomical examination
of a plant shows that the woody systems of the leaf and stem
are continuous: 2ndly, That this is not only the fact in exogenous
plants, but in all endogenous and cellular plants that have
been examined ; so that it may be considered a universal law:
3rdly, That in the early spring, and for some time after plants be-
gin to grow, the woody matter is actually to be seen and traced
5 a) U - . .
* Achille Richard, Nouveaux Elémens de la Botanique, 5me edit. p. 119. _
Y
ee ee eee
REPORT ON THE PHILOSOPHY OF BOTANY. 37
descending in parallel tubes from the origin of the leaves, and
from no other place: 4thly, That in all cases where obstacles
are presented to the descent of such tubes, they turn aside, and
afterwards resume their parallelism when the obstacle has been
_ passed by: 5thly, That in endogenous plants, such as Palms, and
in some exogenous trees, such as Lignum Vite, they cross and
interlace each other in a manner which can only be accounted
for by their passing downwards, the one over the other, as the
leaves are developed: and, finally, That the perfect organization
of the wood is incompatible with a mere deposit of secreted
matter. To all which the following evidence has been added
by M. Achille Richard. He states* that he saw in the pos-
session of Du Petit Thouars a branch of Robinia Pseudacacia,
on which Robinia hispida had been grafted. The stock had
died, but the scion had continued to grow, and had emitted
from its base a sort of plaster, formed of very distinct fibres,
which surrounded the extremity of the branch to some distance,
and formed a sort of sheath; thus demonstrating incontestibly
that fibres do descend from the base of the scion, to overlay
the stock.
To this several objections have been taken, the most im-
portant of which are the following. If wood were really or-
ganized matter, emanating from the leaves, it must necessarily
happen that in grafted plants the stock ought in time to acquire
the nature of the scion, because its wood would be formed en-
tirely by the addition of new matter, said to be furnished by
the leaves of the scion; so far, however, is this from being the
fact, that it is well known that in the oldest grafted trees there
is no action whatever exercised by the scion upon the stock,
but that, on the contrary, a distinct line of organic demarcation
separates the wood of the one from the other, and the shoots
emitted from the stock by wood said to have been generated
by the leaves of the scion, are in all respects of the nature of
the stock. Again,—if a ring of bark from a red-wooded tree
is made to grow in the room of a similar ring of bark of a white-
wooded tree, as it easily may be made, the trunk will increase
in diameter, but all the wood beneath the ring of red bark will
be red, although it must have originated in the leaves of the
tree which produces white wood. It is further urged, that in
grafted plants the scion often overgrows the stock, increasing
much the more rapidly in diameter, or that the reverse takes
place, as when the Pavia lutea is grafted upon the common
Horse-chestnut,—and that these circumstances are inconsistent
i
* Nouveaux Elémens de la Botanique, Sme edit. p. 105.
on
38 THIRD REPORT—18335.
with the supposition that the wood is organic matter engendered
by leaves. ‘To these statements there is nothing to object as
mere facts, for they are true; but they certainly do not warrant
the conclusions that have been drawn from them. One most
important point is overlooked by those who employ these argu-
ments, namely, that in all plants there are two distinct simul-
taneous systems of growth, the cellular and the fibro-vascular,
of which the former is horizontal, and the latter vertical. The
cellular gives origin to the pith, the medullary rays, and the
principal part of the cortical integument ; the fibro-vascular, to
the wood and a portion of the bark; so that the axis of a plant
may be not inaptly compared to a piece of linen, the cellular
system being the woof, the fibro-vascular the warp. It has alse
been proved by Mr. Knight* and M. De Candolle + that buds
are exclusively generated by the cellular system, while roots are
evolved from the fibro-vascular system. Now if these facts are
rightly considered, they will be found to offer an obvious expla-
nation of the phenomena produced by those botanists who think
that wood cannot be matter generated in an organic state by the
leaves. ‘The character of wood is chiefly owing to the colour;
quantity, size, and distortions of the medullary rays, which be-
long to the horizontal system; it is for this reason that there is
so distinct a line drawn between the wood of the graft and
stock, for the horizontal systems of each are constantly pressing
together with nearly equal force, and uniting as the trunk in-
creases in diameter. As buds from which new branches elon-
gate are generated by cellular tissue, they also belong to the
horizontal system; and hence it is that the stock will always
produce branches like itself, notwithstanding the long super-
position of new wood which has been taking place in it from
the scion.
The case of a ring of red bark always forming red wood be-
neath it, is precisely of the same nature. After the new bark
has adhered to the mouths of the medullary rays of the stock,
and so identified itself with the horizontal system, it is gradually
pushed outwards by the descent of woody matter from above
through it: but in giving way it is constantly generating red
matter from its horizontal system, through which the wood de-
scends, which thus acquires a colour that does not properly
belong to it. With regard to the instances of grafts over-
growing their stock, or vice versd, it is obvious that these are
susceptible of explanation upon the same principle. If the hori-
zontal system of both stock and scion has an equal power of
* Philosophical Transactions, 1805, p. 257.
+ Physiologie Végétale, p. 158.
REPORT ON THE PHILOSOPHY OF BOTANY. 39
lateral extension, the diameter-of each will remain the same;
but if one grows more rapidly than the other, the diameters
will necessarily be different: where the scion has a horizontal
system that develops more rapidly than that of the stock, the
latter will be the smaller, and vice versd. It iss however, to be
observed, that in these cases plants are altogether in a morbid
state, and will not live for any considerable time.
Those who object to the theory of wood being generated by
the action of leaves, either suppose—Ist, that liber is developed
by alburnum, and wood by liber; or, 2ndly, that ‘the woody and
cortical layers originate laterally from the cambium furnished
by preexisting layers, and nourished by the descending sap*.”
The first of these opinions appears to be that of M. ‘Turpiny,
as far as can be collected from a long memoir upon the grafting
of plants and animals; but I must fairly confess that 1 am not
sure I have rightly understood his meaning, so much are his
facts mixed up with gratuitous hypothesis and obscure specu-
lations upon the action of what he calls globuline. The second
is the opinion commonly entertained in France, and adopted
by M. De Candolle in his latest published work.
The objections to the views of M. Turpin need hardly be
stated in a Report like this, where conciseness is so much an
object. Those which especially bear upon the view taken by
M. De Candolle are, that his theory is not applicable to all
parts of the vegetable kingdom, but to exogenous plants only;
that it is inconceivable how the highly organized parallel tubes)
of the wood, which can be traced anatomically from the leayes,
and which are formed with great rapidity, can be a lateral de-
posit from the liber and alburnum; that they are manifestly
formed long before it can be supposed that the leaves have
commenced their office of elaborating the descending sap; and,
finally, that endogenous and cryptogamic plants, in which there
is no secretion of cambium, nevertheless have wood.
Such is the state of this subject at the time I am writing. To
use the words of M. De Candolle, ‘‘' The whole question may
be reduced to this,—Either there descend from the top of a tree
the rudiments of fibres, which are nourished and developed by
the juices springing laterally from the body of wood and bark,
or new layers are developed by preexisting layers, which are
nourished by the descending juices formed in the leaves {.”
As this is one of the most curious points remaining to be
settled among botanists, and as it is still as much open to dis-
* De Candolle, Physiologie Végétale, p. 165.
+ See Annales des Sciences, vols. xxiv. and xxv., particularly vol. xxv. p. 43.
}De Candolle, Physiologie Végétale, p. 157.
40 THIRD REPORT—1833.
cussion as ever, I have dwelt upon it at an unusual length, in
the hope that some Member of the British Association may
have leisure to prosecute the inquiry. Perhaps there is no
mode of proceeding to elucidate it which would be more likely
to lead to positive results, than a very careful anatomical exami-
nation of the progressive development of the Mangel Wurzel
root, beginning with the dormant embryo, and concluding with
the perfectly formed plant.
Arrangement of Leaves.—It has for a long time been thought
that the various modes in which leaves, and the organs which
are the result of them, are arranged upon a stem might be re-
duced to the spiral, and that all deviations from this law of
arrangement are to be considered as caused by the breaking of
spires into verticilli. In the Pine Apple, for instance, the Pine
Cone, the Screw Pine, and many other plants, the spiral arrange-
ment of the leaves is so obvious that it cannot be overlooked ;
in trees with alternate leaves this same order of arrangement
may be discovered if a line is drawn from the base of one leaf
to that of another, always following the same direction; even
in verticillate plants we not unfrequently see that the whorls
are dislocated by the preternatural elongation of their axis, and
then become converted into a spire; and the same phenome-
non is of common occurrence among the verticilli of leaves in
»the form of calyx, corolla, stamens, and carpella, which com-
pose the flower. This will be the more distinctly apparent if we
Weonsider that, as M. Adolphe Brongniart has shown*, what we
¢e horls in a flower often are not so, strictly speaking, but
only a series of parts placed in close approximation, and at dif-
ferent heights, wpon the short branch that forms their axis.
Dr. Alexander Braun has endeavoured} to prove mathema-
tically that the spiral arrangement of the parts of plants is not
only universal, but subject to laws of a very precise nature.
His memoir is of considerable length, and would be wholly un-
intelligible without the plates that illustrate it. It is therefore
only possible on this occasion to mention the results. Setting
out with a contemplation of the manner in which the scales of
a Pine Cone are placed, to which a long and ingenious method
of analysis was applied, he found that several different series of
spires are discoverable, between which there invariably exist
peculiar arithmetical relations, which are the expression of the
various combinations of a certain number of elements disposed
in aregular manner. All these spires depend upon the posi-
* Annales des Sciences, vol. xxiii. p. 226.
+ Vergleichende Untersuchung tiber die Ordnung der Schuppen an den Tan-
nenzxapfen. Ito. 1830,
.
REPORT ON THE PHILOSOPHY OF BOTANY. Al
tion of a fundamental series, from which the others are devia-
tions. The nature of the fundamental series is expressed by a
fraction, of which the numerator indicates the whole number
of turns required to complete one spire, and the denominator
the number of scales or parts which constitute it: thus 4 in-
dicates that eight turns are made round the axis before any
seale or part is exactly vertical to that which was first formed,
and the number of scales or parts that intervene before this
coincidence takes place is twenty-one.
It does not appear that this inquiry has as yet led to any
practical application, although one might have expected that
as the natural affinities of plants are determined, in a great de-
gree, by the accordance that is observable in the relative posi-
tion of their parts, the spires of which those parts are composed
might have had something in common which would be suscep-
tible of being expressed by numbers. If any practical applica-
tion can be made of Dr. Braun’s fractions, it seems likely to be
confined to the distinction of species. His observations seem,
however, to have established the truth of the doctrine that, be-
ginning with the cotyledons, the whole of the appendages of
the axis of plants,—leaves, calyx, corolla, stamens, and car-
pella,—form an uninterrupted spire, governed by laws which
are almost constant. - a
Structure of Leaves.—The leaves of plants have been found”
by M. Adolphe Brongniart to be not merely expansions of_
the cellular integument of stems, traversed by veins originating”
in the woody system, but to be organs in which the int ,
parenchyma is arranged with beautiful uniformity, in the man-
ner most conducive to the end of exposure to light and air, and
of elaboration, for which the leaves are chiefly destined. In
their usual structure leaves have been found by this observer
either to consist of two principal layers,—of which the upper,
- into which the ascending sap is first introduced, is formed of
compact cells, more or less perpendicular to the plane of the cu-
ticle, and the under, into which the returning sap is propelled,
is formed of very lax cavernous tissue, more or less parallel with
the cuticle of the lower surface,—or else of two layers perpen-
dicular to the cuticle, with a central parallel stratum.
The observations of Drs. Mohl and Meyen generally confirm
this; but at the same time the latter instances several cases in
which the texture of the leaf has been found to be nearly the
same throughout.
Dutrochet* states, in addition, that the interior of the leaf
* Annales des Sciences, vol. xxv. p. 245.
42 THIRD REPORT—1833.
is divided completely by a number of partitions caused by the
ribs and principal veins, so that the air cavities have not actually
a free communication in every direction through the parenchy-
ma, but are to a certain extent cut off from each other. This
is conformable to what M. Mirbel has described in Marchantia,
who finds the leafy expansions of that plant separated by par-
titions into chambers, between which he is of opinion that
there is no other communication than what results from the per-
meability of the tissue *. j
The statement of M. Adolphe Brongniart, that all leaves in-
tended to exist in the air are furnished with a distinct cuticle
on their two faces, while those which are developed under
water have no cuticle at all, has not been disproved, unless in
the case of Marchantia}, whose under surface can scarcely be
said to have a distinct cuticle; but this plant, which can only
exist in humid shady places, is*perhaps rather a proof of the
accuracy of the theory of M. Brongniart than an exception
to it.
That the stomata in all cases open into internal cavities in
the leaf, where the tissue is extremely lax and cavernous, ap-
pears also extremely probable, It was especially found to be
the case by M. Mirbel in his so often quoted remarks upon
Marchantia.
With regard to the stomata themselves, no one appears yet
to have confirmed the observation of Dr. Brown}, that their
“apparent orifice is closed up bya membrane. On the contrary,
the observations of M. Mirbel on Marchaniia, if they are to
be taken as illustrative of the usual structure of those singular
organs, go to establish the accuracy of the common opinion
that the stomata are apertures in the cuticle. That most skil-
ful physiologist, while watching the development of Marchantia,
remarked the very birth of the stomata, which he describes as
taking place thus:—The appearance of a little pit in the middle
of four or five cells placed in a ring is a certain indication of
the beginning of a stoma. The pit evidently increases by the
enlargement and separation of the surrounding cells. If the
nascent stoma consists of five cells, of which one is surrounded
by four others, then the central one is destroyed; but if it con-
sists of three or four cells adjusted so as to form a disk, then
the stoma is caused by the separation of their sides in the cen-
tre, by which means a sort of star is created. It is true that
* “Recherches Anatomiques et Physiologiques sur le Marchantia polymor-
pha,” in Nouveaux Annales du Muséum, vol. i. p. 7.
+ Ibid. p. 93.
} Suppl. primum Prédromi Flore Nove Hollandia, p. 3.
REPORT ON THE PHILOSOPHY OF BOTANY. 43
the stomata of Marchantia are in some respects different from
what are found upon flowering plants; yet I think we can hardly
doubt that the plan upon which they are all formed is essen-
tially the same.
Dutrochet also confirms * the statement of Amici, that the
stomata are perforations; for he finds that when leaves are de-
prived of their air by the air-pump, it is chiefly on the under
side, where the greatest number of stomata is found, that little
air bubbles make their appearance; and that itis through the
stomata that water rushes into the cavernous parenchyma to
supply the loss occasioned by the abstraction of air.
Anther, §¢c.—Some curious remarks upon the nature of the
tissue that lines the cells of the anther have been published by
Dr. John E. Purkinje, Professor of Medicine at Breslau. His
researches are chiefly directed to the determination of the na-
ture of the tissue that is in immediate contact with the pollen;
and he has demonstrated in an elaborate Essay}, that the opi-
nion emitted by Mirbel in 1808}, that the cause of the dehis-
cence of the anther is its lining, consisting of cellular tissue cut
into slits and eminently hygrometrical, is substantially true.
He shows that this lining is composed of cellular tissue chiefly
of the fibrous kind, which forms an infinite multitude of little
spriiigs, that when dry contract and pull back the valves of the
anthers by a powerful accumulation of forces which are indivi-
dually scarcely appreciable: so that the opening of the anther
is not a mere act of chance, but the admirably contrived result
of the maturity of the pollen,—an epoch at which the surround-
ing tissue is necessarily exhausted of its fluid by the force of
endosmosis exercised by each particular grain of pollen.
That this exhaustion of the circumambient tissue by the en-
dosmosis of the pollen is not a mere hypothesis, has been
shown by Mirbel in a continuation of the beautiful memoir I
have already so often referred to§. He finds that, on the one
hand, a great abundance of fluid is directed into the utricles,
in which the pollen is developed a little before the maturity of
the latter, and that by a dislocation of those utricles the pollen
loses all organic connexion with the lining of the anther; and
that, on the other hand, these utricles are dried up, lacerated,
and disorganized, at the time when the pollen has acquired its
full development.
* Aninales des Sciences, vol. x¥V. p. 247.
+ De Cellulis Antherarum fibrosis. 4to. Wratislavie, 1830.
¢ “Observations sur un Systéme d’Anatomie Comparée de. Végétaux, fondés
sur l’'Organization de la Fleur,” in A¢émoires de l'Institut, 1808, p. 331.
§ “Complément des Observations sur le Marchantia polymorpha,” in dr-
chives de Botanique, vol. i.
4A THIRD REPORT—1833.
The Origin of the Pollen, connected as it intimately is with
the singular phenomena of vegetable sexuality, has naturally
been of late an object of some inquiry. To the important dis-
coveries of the younger Brongniart and of Dr. Robert Brown,
M. Mirbel has added some observations*, detailed with that
admirable clearness and precision which give so great a value
to all his writings, and which are the more interesting as they
serve to explain what was before obscure, and to correct what
appears to have been either inaccurately or imperfectly de-
cribed. ‘This he has been enabled to do by beginning his in-
quiry at the very earliest period when the organization of the
anther can be discovered: his subject was the common Gourd.
At a very early time the whole tissue of the anther is of the
most perfect uniformity, consisting of cellules, the transverse
section of which represents nearly regular hexagons and penta-
gons. In every cell, without even excepting those which com-
pose the superficies of the anther, are found little loose bodies,
so exceedingly minute that a magnifying power of 500 or 600
diameters is scarcely sufficient to examine them: they may be
compared to transparent, nearly colourless vesicles, more or
less round, and of unequal size. At a stage but little more ad-
vanced, you may observe on each side of the medial line of a
transverse section of a lobe of an anther, a collection of cellules
rather larger than the remainder: it will afterwards be seen
that it is here that the pollen is engendered; such cells are
therefore called pollen-cells.. Ina bud, a line and a half or two
lines in diameter, some remarkable alterations were found to
have taken place; the pollen-cells had enlarged and their gra-
nules had so much increased in number, that they nearly filled
the cells in opake masses. ‘These granules and pollen-cells
formed together a greyish mass, connected with the rest of the
tissue by the intervention of a cellular membrane, which, not-
withstanding its organic continuity with the surrounding parts,
is at once distinguishable; for while the cells of the surrounding
parts elongate parallel to the plane of the surface, and to the
plane of the base of the anther, those of the cellular membrane
elongate from the centre to the circumference. In more ad-
vanced anthers, the sides of the pollen-cells, from being thin
and dry, had changed to a perceptible thickness, and their sub-
stance, gorged with fluid, resembled a colourless jelly. When
the buds were three or four lines long, an unexpected phzno-
menon presented itself. At first the thick and succulent walls
of each pollen-cell dilated so as to leave an empty space between
the inner face and the granules, not one of which separated
* “Complement des Observations,” Sc., as above quoted.
REPORT ON THE PHILOSOPHY OF BOTANY. 45
from the general mass, which showed that some power kept
them united. Shortly after, four appendages, like knife-blades,
developed at equal distances upon the inner face of the cell,
and gradually projected their edges towards the centre, till at
last they divided the granular mass into four little triangular
bodies; when the appendages had completely united at their
edges, they divided the cavity of the pollen-cells into four di-
stinct boxes, which then began to rounden, and finally became
little spherical masses. Each of these was the rudiment of a
grain of pollen, subsequently acquired a membranous integu-
ment, hardened, became yellow, and thus arrived at maturity.
What is perhaps most important in these observations is the
demonstration of the original organic continuity of all the parts
of the anther, against the statement of M. Adolphe Brongniart,
and also against what appears to be the opinion of Dr. Brown,
as far as can be collected from the manner in which he speaks
of the evolution of the pollen in Tradescantia virginica*.
Although it is not directly shown by these observations whe-
ther the perfect grain of pollen has one or two integuments,—a
question that may still be said to be unsettled,—it nevertheless
appears from other instances that M. Mirbel admits the exist-
ence of an outer not distensible coat, and of an inner highly
extensible lining. A curious paper upon this point+ has been
published by a Saxon botanist named Fritzsche. By means of:
a mixture of two parts by weight of concentrated sulphuric
acid, and five parts of water, he found that the grains of pollen
can be rendered so transparent as to reveal their internal struc-
ture, and that the whole process of the emission of the pollen-
tubes can be distinctly traced. He describes the universal pre-
sence of two coatings to the grains of pollen; and he also finds
that the pollen contains a quantity of oily particles in addition
to the moving corpuscles,—a fact which has also been noticed
by Dr. Brown.
Although the generalizations in this work are less satisfactory
than could be desired, it must nevertheless be considered a
most valuable collection of facts, and as containing the best
arrangement that has as yet appeared of the various forms un-
der which the pollen is seen.
Fertilization. —'The road which some years since was so
happily opened by Amici to the discovery of the exact manner
in which vegetable fertilization takes effect, is every day be-
coming more and more direct. The doubts of those who could
not discern the tubes that are projected into the style by the
* Observations upon Orchidez and Asclepiadee, p. 21.
+ Beitrtige zur Kenntniss des Pollen. 4to. Berlin, 1833.
46 THIRD REPORT—1833.
pollen, have been removed; the important demonstration by
Dr. Brown of the universal presence of a passage through the
integuments of the ovulum at the point of the nucleus has been
extended and confirmed by M. Mirbel in a paper of the high-
est interest *; the fact that it is at the point of the nucleus (where
this passage exists,) that the nascent embryo makes it appear-
ance, is now undisputed; the passage of the contents of the
pollen down the pollen-tubes, and the curious discovery of a
power of motion in the granules that are thus emitted, are also
recognised: it now only remains to be proved that the pollen-
tubes come in contact with the nucleus, and the whole secret of
fertilization is revealed. A few remarkable contributions to
this part of the subject have lately been made.
Some plants have the passage or foramen in their ovulum so
remote from any part through which the pollen-tubes can be
supposed to convey their influence, as to have thrown consider-
able difficulty in the way of the supposition that actual contact
between the point of the nucleus and the fertilizing tissue is
indispensable.
The manner in which, notwithstanding the apparent difficulty
of such contact taking place, this happens in Statice Armeria,
was long since made out by Dr. Brown, in whose possession I
several years ago saw drawings illustrating this phenomenon ;
it has since been explained by M. Mirbel. Another case, pre-
senting similar apparent difficulties, occurs in Helianthemum.
In plants of that genus the foramen is at that end of the ovulum
which is most remote from the hilum; and although the ovula
themselves are elevated upon cords much longer than are usually
met with, yet there are no obvious means of their coming in con-
tact with any part through which the matter projected into the
pollen-tubes can be supposed to descend. It has, however,
been ascertained by M. Adolphe Brongniart+, that at the time
when the stigma is covered with pollen, and fertilization has
taken effect, there is a bundle of threads, originating from the
base of the style, which hang down in the cavity of the ovarium,
and, floating there, are abundantly sufficient to convey the in-
fluence of the pollen to the points of the nuclei. So again in
Asclepiadee. In this tribe, from the peculiar conformation of
the parts, and from the grains of pollen being all shut up in a
sort of bag, out of which there seemed to be no escape, it was
supposed that this tribe must at least form an exception to the
general rule. But before the month of November 1828}, the
* Nouvelles Recherches sur la Structure de U Ovule Végétal et sur ses Déve-
loppements. ‘Also Additions aux ‘Nouvelles Recherches,’ §c.
+ Annales des Sciences, vol. xxiv. p. 123. t Linnea, vol. iv. p. 94.
———— —
REPORT ON THE PHILOSOPHY OF BOTANY. 47
celebrated Prussian traveller and botanist Ehrenberg had dis-
covered that the grains of pollen of Asclepiadee acquire a sort
of tails which are all directed to a suture of their sac on the side
next the stigma, and which at the period of fertilization are
lengthened and emitted; but he did not discover that these
tails are only formed subsequently to the commencement of a
new vital action connected with fertilization, and he thought
that they were of a different nature from the pollen-tubes of
other plants; he particularly observed in Asclepias syriaca
that the tails become exceedingly long and hang down.
In 1831 the subject was resumed by Dr. Brown* in this
country, and by M. Adolphe Brongniart + in France, at times so
nearly identical, that it really seems to me impossible to say
with which the discovery about to be mentioned originated : it
will therefore be only justice if the Essays referred to are spoken
of collectively instead of separately. ‘These two distinguished
botanists ascertained that the production of tails by the grains
of pollen was a phenomenon connected with the action of ferti-
lization; they confirmed the existence of the suture described
by Ehrenberg ; they found that the true stigma of Asclepia-
dee is at the lower part of the discoid head of the style, and
so placed as to be within reach of the suture through which the
pollen-tubes or tails are emitted; they remarked that the latter
insinuate themselves below the head of the style, and follow its
surface until they reached the stigma, into the tissue of which
they buried themselves so perceptibly that they were enabled to
trace them, occasionally, almost into the cavity of the ovarium;
and thus they established the highly important fact, that this
family, which was thought to be one of those in which it was
impossible to suppose that fertilization takes place by actual
contact between the pollen and the stigma, offers the most
beautiful of all examples of the exactness of the theory, that it
is at least owing to the projection of pollen-tubes into the sub-
stance of the stigma. In the more essential parts these two
observers are agreed: they, however, differ in some of the de-
tails; as, for instance, in the texture of the part of the style
which I have here called stigma, and into which the pollen-
tubes are introduced. M. Brongniart both describes and figures
it as much more lax than the contiguous tissue, while on the
other hand Dr. Brown declares that he has in no case been able
‘to observe “the slightest appearance of secretion, or any dif-
* Observations on the Organs and Mode of Fecundation of Orchidew and
Asclepiadez. London, October 1831.
+ Annalesides Sciences for October and November 1831 ; from observations
made in July, August and September of that year.
oOo
48 THIRD REPORT—18338.
ferences whatever in texture between that part and the general
surface of the stigma” (meaning what I have described as the
discoid head of the style): but this is not the place for entering
into the discussion of these subordinate points.
Orchidee are another tribe in which similar difficulties have
been found in reconciling structure with the necessity of con-
tact between the pollen and stigma in order to effect impregna-
tion. Indeed it seems in these plants as if every possible pre-
caution had been taken by nature to prevent such contact.
Nevertheless it is represented by M. Adolphe Brongniart, in a
paper read before the Academy of Sciences of Paris in July
1831 *, that contact is as necessary in these plants as in others,
and that in the emission of pollen-tubes they do not differ from
other plants. These statements have been followed up by Dr.
Brownj, in en elaborate Essay upon the subject, in which the
results that are arrived at by our learned countryman are es-
sentially to the same effect. To these there is at present no-
thing equally positive to oppose; but as the indirect observa-
tions of Mr. Bauer}, and the general structure of the order, are
very much at variance with the probability of actual contact
being necessary, and especially as Dr. Brown is obliged to have
_ recourse to the supposition that the pollen of many of these
plants must be actually carried by insects from the boxes in
which it is naturally locked up,—it must be considered, I think,
that the mode of fertilization in Orchidec is still far from being
determined. I must particularly remark that the very proble-
matical agency of insects, to which Dr. Brown has recourse in
order to make out his case, seems to be singularly at variance
with his supposition§ that the insect forms, which in Ophrys
are so striking, and which he finds resemble the insects of the
countries in which the plants are found, are intended rather to
repel than to attract. It may be true, as Dr. Brown observes,
that there is less necessity for the agency of insects in such
flowers as the European Ophryde@; but what other means
than the assistance of insects can be supposed to extricate the
pollen from the cells in the insect flowers of such plants as
Renanthera Arachnites, the whole genus Oncidium, Tetramicra
rigida, several species of Epidendrum, Cymbidium tenuifolium,
Vanda peduncularis, and a host of others ?
* Annales des Sciences, vol. xxiv. p. 113.
+ Observations upon the Organs and Mode of Fecundation of Orchidex and
Asclepiadez.
t Illustrations of the Genera and Species of Orchideous Plants. Part II.
“‘ Fructification,” tabb. 5. 12. 13. 14.
§ “ Proceedings of the Linnean Society,”’ June 5, 1832, as given in the Lon-
don and Edinburgh Philosophical Magaxine and Journal.
’
REPORT ON THE PHILOSOPHY OF BOTANY. 49
Origin of Organs.—There is no part of vegetable physiology
so obscure as that which relates to the origin of organs. We
find a degree of simplicity that is perfectly astonishing in the
fundamental structure of the whole vegetable kingdom; we
are able to prove by rigorous demonstration that every one of
the appendages of the axis is a modification of a leaf, to which
there is a constant tendency to revert; we see that in some cases
a part which usually performs one function assumes another,
as in the Alstrémerias, whose leaves by a twist of their petiole
turn their under surface upwards: but we are entirely ignorant
of the causes to which these changes are owing. An impor-
tant step in elucidating the subject has been lately taken by
M. Mirbel, in his memoir upon the structure of Marchantia po-
lymorpha. The young bulbs by which this plant is multiplied
are originally so homogeneous in structure, that there is no
apparent character in their organization to show which of their
faces is destined to become the upper surface, and which the
under. For the purpose of ascertaining whether there existed
any natural but invisible predisposition in the two faces to un-
dergo the changes which subsequently become so apparent,
and by means of which their respective functions are performed,
or whether the tendency is given by some cause posterior to
their first creation, the following experiments were instituted.
Five bulbs were sown upon powdered sandstone, and it was
found that the face which touched the sandstone produced
roots, and the opposite face formed stomata. It was, however,
possible that, the five bulbs might have all accidentally fallen
upon the face which was predisposed to emit roots; other
experiments of the same kind were therefore tried, first with
eighty and afterwards with hundreds of little bulbs,—and._ the
result was the same as with the five. This proved that either
face was originally adapted for producing either roots or sto-
mata, and that the tendency was determined merely by the po-
sition in which the surfaces were placed. The next point to
ascertain was, whether the tendency once given could be after-
wards altered; some little bulbs, that had been growing for
twenty-four hours only, had emitted roots; they were turned, ~
so that the upper surface touched the soil, and the under was
exposed to light. : In twenty-four hours more the two faces
had both produced roots; that which had originally been the
under surface went on pushing out new roots; that which had
originally been the upper surface had also produced roots:
but in a few days the sides of the young plants began to rise
from the soil, became erect, turned over, and finally recovered
1833. E Ba
50 THIRD REPORT—1833.
in this way their original position, and the face which had ori-
ginally been the uppermost, immediately became covered with
stomata. It, therefore, appears that the impulse once given,
the predisposition to assume particular appearances or func-
tions is absolutely fixed, and will not change in the ordinary
course of nature. ‘This is a fact of very high interest for
those who are occupied in researches into the causes of what is
called vegetable metamorphosis, an expression which has been
justly criticised as giving a false idea of the subject to which
it relates. :
_ Morphology.—When those who first seized upon the im-
portant but neglected facts out of which the modern theory of
morphology has been constructed, asserted that all the appen-
dages of the axis of a plant are metamorphosed leaves, more
was certainly stated than fhe evidence would justify; for we
cannot say that an organ is a metamorphosed leaf, which in
point of fact has never been a leaf. What was meant, and that
which is supported by the most conclusive evidence, is, that
every appendage of the axis, whether leaf, bractea, sepal, petal,
stamen, cr pistillum, is originally constructed of the same ele-
ments, arranged upon a common plan, and varying in their
manner of development, not on account of any original differ-
ence in structure, but on account of special and local predis-
posing causes: of this the leaf is taken as the type, because it
is the organ which is most usually the result of the develop-
ment of those elements,—is that to which the other organs
generally revert, when from any accidental disturbing cause
they do not assume the appearance to which they were originally
predisposed,—and, moreover, is that in which we have the most
complete state of organization.
This is not a place for the discussion of the details upon
which the theory of morphology is founded; it is sufficient to
state that it has become the basis of all philosophical views of
structure, and an inseparable part of the science of botany. Its
practical importance will be elucidated by the following circum-
stance. Fourteen or fifteen years ago I was led to take a
view of the structure of Reseda very difterent from that usually
assigned to the genus; and when a few years afterwards that
view was published, it attracted a good deal of attention, and
gained some converts among the botanists of Germany and
France. It was afterwards objected to by Dr. Brown upon
several grounds; but I am not aware that they were considered
sufficiently valid to produce any change in the opinions of those
who had adopted my hypothesis. Lately, however, Professor
REPORT ON THE PHILOSOPHY OF BOTANY. 51
Henslow has satisfactorily proved*, in part by the aid of a
monstrosity in the common Mignonette, and in part by a severe
application of morphological rules, that my hypothesis must
necessarily be false ; and I am glad to have this opportunity of
expressing my full concurrence in his opinion.
It has long been known that the ligulate and tubular corollas
of Composite are anatomically almost identical, and that their
difference consists only in the five petals of the tubular corolla
all separating regularly for a short distance from their apex,
while the five petals of the ligulate corolla adhere up to their
very points, except on the side next the axis of inflorescence,
where two of them are altogether distinct except at their base.
M. Leopold von Buch explains this circumstance in the follow-
ing manner. He states that these ligulate corollas when unex-
panded bear at their point a little, white, and very viscid body
or gland, which is a peculiar secretion that dries up when it
comes in contact with the atmosphere. The adhesion of this
gland is too powerful to be overcome by the force of the style
and stamens pressing against it from within. The corollas, which
are gradually curved outwards by the growth of those in the
centre of the inflorescence, at the same time bend down the
style, which consequently presses up against the line of union
of the two petals nearest the axis: although the style cannot
overcome the adhesion of the viscid gland at the point of the
corolla, it is able in time to destroy the union of the two inte-
rior petals, which finally give way and allow the stamens and
style toescape. As soon as this takes place, the corolla can no
longer remain erect, but falls back towards the circumference
of the capitulum, and thus contributes to the radiating character
of this sort of inflorescence. When the viscid body is either
not at all, or very imperfectly produced at the point of the co-
rolla, as sometimes happens in the genus Hieracium, especially
HZ. bifurcum, tubular corollas are produced instead of ligulate
ones.
The ovulum is the organ where the greatest difficulty has
occurred in reducing the structure to anything analogous to
that of other parts. It is true that Du Petit Thouars regarded
it as analogous to aleaf bud; but his view appears to have been
purely hypothetical, for I am not aware that he had any distinct
evidence of the fact. Some years ago M. Turpin, in showing
the great similarity that exists between the convolute bractez
of certain Marcgraviacee and the exterior envelope of the
ovulum, took the first step towards proving that the hypothesis
* Transactions of the Philosophical Society of Cambridge, vol. v. Part I.
EZ
52 THIRD REPORT—1833.
of Du Petit Thouars was susceptible of demonstration ; it was’
more distinctly shown by the interesting discovery of Professor
Henslow, that the leaves of Malaxis paludosa had on their
margins what no doubt must be considered buds, but what in
structure are an intermediate state between buds and ovula;
and it has been recently asserted by Engelmann’*, still, how-
ever, without the production of any proof, that “ovula are buds
of,a higher kind, their integuments leaves, and their funiculus
the axis, all which, in cases of retrograde metamorphosis, are in
fact converted into stem and green leaves.” The nearest ap-
proach to a demonstration that has yet been afforded of ovula
being buds is in a valuable paper by Professor Henslow, just
printed inthe Transactions of the Philosophical Society of Cam-
bridge}, in which it is shown that in the Mignonette the ovula
are in fact transformed occasionally into leaves, either solitary
or rolled together round an axis, of which the nucleus is the
termination. ;
M. Dumortier has endeavoured to prove t that the embryo
itself is essentially the same as a single internodium of the stem
with its vital point or rudimentary bud attached to it. Although
the author’s demonstration is a failure, and his paper a series
of confused and illogical reasoning, yet there can be little doubt
that the hypothesis itself is a close approximation to the truth.
Dr. George Engelmann has recently attempted § to classify
the aberrations from normal structure, which throw so much
light upon the real origin and nature of the organs of plants.
He has collected a very considerable number of cases under
the following heads. 1. Retrograde metamorphosis (Regressus),
when organs assume the state of some of those on the outside
of them, as when carpella change to stamens or petals, hypo-
gynous scales to stamens, stamens to pétals or sepals, sepals to
ordinary leaves, irregular structure to regular, and the like.
2. Foliaceous metamorphosis (Virescentia), when all the parts
of a flower assume more or less completely the state of leaves.
3. Disunion (Disjunctio), when the parts that usually cohere
are separated, as the carpella of a syncarpous pistillum, the
filaments of monadelphous stamens, the petals of a monopeta-
lous corolla, &c. 4. Dislocation (Apostasis); in this case the
whorls of the flower are broken up by the extension of the .
axis. 5. Viviparousness (Diaphysis), when the axis is not only
elongated, but continues to grow and form new parts, as in those
* De Antholysi Prodromus, p. 61. + vol. v. Part I.
{ Nova Acta Academie Nature Curiosorum, vol. xvi. p. 245,
§ De Antholysi Prodromus.
REPORT ON THE PHILOSOPHY OF BOTANY. 53
instances where one flower grows from within another. And
finally, 6. Proliferousness (Ecblastesis), when buds are deve-
loped in the axille of the floral organs, so as to convert a sim-
ple flower into a mass of inflorescence. A very considerable
number of instances are adduced in illustration of these divi-
sions, and the work will be found highly useful as.a collection
of curious or important facts.
- The doctrines of morphology, and the evidence in support
of them, may now be considered so far settled as to require but
little further illustration for the present. This is, however,
only true of flowering plants: in the whole division of flower-
less plants there has been scarcely any attempt to discover the
analogy of organs, and to reduce their structure to a correspond-
ing state of identification. 1 some time since* endeavoured to
excite attention to this subject, by hazarding some speculations
which had at least the merit of novelty to recommend them ;
but I cannot discover that any one has since turned his atten-
tion to the inquiry, although it must be confessed that the com-
parative anatomy of flowerless plants is among the most inter-
esting topics still remaining for discussion, and that it is rather
discreditable to Cryptogamic botanists that the elucidation of
so very curious a matter should be postponed to the compara-
tively unimportant business of distinguishing or dividing genera
and species.
Gradual Development.—The theory of the gradual deve-
lopment of the highest class of organic bodies, in consequence
of a combination and complication of the phenomena attendant
upon the development of the lowest classes, has acquired so
great a degree of probability among animals, that it has become
a question of no small interest whether traces of the same, or a
similar law, cannot be found among plants. In an inquiry of
such a nature, it seems obvious that attention should in the first
instance be directed to a search after positive and incontestable
facts, and that mere hypotheses should in the beginning be to-
tally rejected. The only circumstances that occur to me as
bearing directly upon this point are the following. It has been
ascertained by M. Mirbel, in his memoir on the Marchantia,
that the sporule of that very simple plant is a single vesicle,
which, when it begins to grow, produces other vesicles on its
surface, which go on propagating in the same manner, every
new vesicle engendering others; and that different modifica-
tions of this process produce the different parts that the per-
fect plant finally develops.
* Outlines of the First Principles of Botany, p. 533, &c. Introduction to the
Natural System of Botany, p. 313, &c. ,
54 THIRD REPORT—1830.
The same principle of growth appears to obtain in Conferve,
and probably is found in other vegetables of the lowest grade.
This is analogous to what takes place in the formation of the
embryo of Vasculares. In the opinion of Dr. Brown and of
Mirbel, the first rudiment of a plant far more complicated than.
Marchantia, consists also of a vesicle, but suspended by a
thread to the summit of the cavity of the ovulum; and the dif-
ference between the one case and the other is, that while in the
Marchaniia the original vesicle, “‘ as soon as it is formed, pos-
sesses all the conditions requisite for developing a complete
plant on the surface of the soil; on the other hand, that of
flowering plants must, on pain of death, commence its deve-
lopment in the interior of the ovulum, and cannot continue it.
further until it has produced the rudiments of root, stem, and
cotyledons *.
Beyond this I do not think that any attempt has been made
to elucidate the question.
Trritability.—Dyr. Dutrochet has published} the result of
some experiments with the air-pump upon the pneumatic system
of plants. Independently of confirming the fact, already gene-
rally known, of plants having the means of containing a large
quantity of air, he arrived at the unexpected result, that the
sleep of plants and their irritability are certainly dependent upon
the presence of air within them. A sensitive plant, left in the
vacuum of an air-pump for eighteen hours, indicated no sign
whatever of the accustomed collapse of its leaflets on the ap-
proach of night, nor when it was restored to the air could it be.
stimulated by the smartest shocks; but in time it recovered its
irritability. When flowers that usually close at night were
placed in a vacuum while expanded, they would not close; and
when flowers already closed. were placed in the same situation,
they would not unfold at the return of morning; whence Dr.
Dutrochet infers that the internal air of plants is indispensably
necessary to the exercise of their alternate motions of sleeping
and waking, and in general to the existence of the faculty they
possess of indicating by their movements the influence of ex-
ternal exciting causes.
Action of Coloured Light.—Professor Morren, of Ghent, has
mentioned { the result of some experiments upon the action of
the coloured rays upon germination; and he has found that
while those rays in which the illuminating power is the most
feeble were, as might have been expected, the most favourable
to germination, their power of decomposing carbonic acid, and
* Archives de Botanique, vol.i. + Annales des Sciences, vol. xxv. p. 243.
{ Annales des Sciences, vol. xxvii. p. 201.
~
REPORT ON THE PHILOSOPHY OF BOTANY. 55
producing a green deposit in the parenchyma, is in proportion
to their illuminating property; that no decomposed rays effect
this so rapidly as white light; and that the yellow ray possesses
the greening power in the highest degree, the orange in a very
slight degree, and violet, red and purple not at all.
Colours.—Nothing can be named in the whole range of bo-
tany upon which information is so much wanted as the cause of
the various colours of plants. It was, indeed, long since sus-
pected by Lamarck that the autumnal colouring of leaves and
’ fruits was a morbid condition of those parts; and it has subse-
quently been ascertained that all colours are owing to the pre-
sence of a substance, called ehromule by De Candolle, which
fills the parenchyma, assuming different tints. Green has also
been clearly made out to be connected with exposure to light,
and has been considered to be in all probability owing to the
deposition of the carbon left upon the decomposition of car-
bonic acid. Some botanists have also observed the connexion
of red colour with acidity ; but still we had scarcely any positive
knowledge of the cause of the production of any colour except
green, till M. Macaire of Geneva* remarked, that just before
leaves begin to change colour in the autumn, they cease parting
with oxygen in the day, although they go on absorbing it at
night; whence he concluded that their chromule is oxygenated,
by which a yellow colour is first caused, and then a red,—for he
found that in all cases a change to red is preceded by a change
to yellow. He also ascertained that the chromule of the red
bractez and calyx of Salvia splendens is chemically the same
as that of autumnal leaves. Coupling this with the fact that
petals do not part with oxygen, it would seem as if their colour,
if yellow or red, may also be owing to a kind of oxygenation.
But according to M. Theodore de Saussure}, coloured fruits
part with their oxygen; so that, if this be true, red and yellow
cannot always be ascribed to such a cause. M. De Candollet
has some excellent observations upon this subject in his recent
admirable digest of the laws of vegetable physiology ; in which
he concludes, from the inquiries hitherto instituted, that all co-
lours depend upon the degree of oxygenation. When oxygen
is in excess, the colour seems to tend to yellow or red; and
when it is deficient, or when the chromule is more carbonized,
which is the same thing, it has a tendency to blue. Local ad-
ditions of alkaline matters are also called in aid of an explanation
of the various shades of colour that flowers and fruits present.
* Mémoires de la Société Physique de Généve, vol. iv. p. 50.
+ Ibid. vol. i. p. 284. » + Physiologie Végétale, p. 906.
56 THIRD REPORT—1833.
Dr. Dutrochet is of opinion* that the whitish spots we some-
times see in leaves, and the paler tint that generally character-
izes the under side of the same organs, are owing to the presence
of air beneath the cuticle. He finds that the arrow-head shaped
blotch on the upper side of the leaf of Trifolium pratense, and
the whitish spots on Pulmonaria officinalis, disappear when the
leaves are plunged in water beneath the exhausted receiver of
the air-pump, and that the lower surface of leaves acquires the
same depth of colour as the upper under similar circumstances.
This he ascribes to the air naturally found in the leaves being
abstracted, and its place supplied with water; a conclusion
which agrees with what might be inferred from the anatomical
structure of the parts in question.
Excretions.—It has long been known that some plants are
incapable of growing, or at least of remaining in a healthy state,
in soil in which the same species has previously been cultivated.
For instance, a new apple orchard cannot be made to succeed
on the site of an old apple orchard, unless some years inter-
vene between the destruction of the one and the planting of
the other: in gardens, no quantity of manure will enable one
kind of fruit-tree to flourish on a spot from which another tree
of the same species has been recently removed ; and all farmers
practically evince, by the rotation of their crops, their expe-
rience of the existence of this law.
Exhaustion of the soil is evidently not the cause of this, for
abundant manuring will not supersede the necessity of the usual
rotation. The celebrated Duhamel long ago remarked, that the
Elm parts by its roots with an unctuous dark-coloured substance ;
and, according to De Candolle, both Humboldt and Plenck
suspected that some poisonous matter is secreted by roots;
but it is to M. Macaire, who at the instance of the first of these
three botanists undertook to inquire experimentally into the
subject, that we owe the discovery of the suspicion above al-
luded to being well founded. He ascertained} that all plants
part with a kind of fecal matter by their roots, that the nature
of such excretions varies with species or large natural orders:
in Cichoracee and Papaveracee he found that the matter was
analogous to opium, and in Leguminose to gum; in Graminee
it consists of alkaline and earthy alkalies and carbonates, and
in Euphorbiacee of an acrid gum-resinous substance. These
excretions are evidently thrown off by the roots on account of
their presence in the system being deleterious ; and it was found
by experiment, that plants artificially poisoned parted with the
* Annales des Sciences, vol. xxv. p. 246.
¢ De Candolle, Physiologie Végétale, p. 249.
REPORT ON THE PHILOSOPHY OF BOTANY. 57
poisonous matter by their roots. For instance, a plant of Mer-
curialis had its roots divided into two parcels, of which one was
immersed in the neck of a bottle filled with a weak solution of
acetate of lead, and the other parcel was plunged into the neck
of a corresponding bottle filled with pure water. In afew days
the pure water had become sensibly impregnated with acetate
of lead. ‘This, coupled with the well known fact that plants,
although they generate poisonous secretions, yet cannot absorb
them by their roots without death, as, for instance, is the case
with Atropa Belladonna, seems to prove that the necessity of
the rotation of crops is more dependent upon the soil being
poisoned than upon its being exhausted.
‘This is a part of vegetable physiology of vast importance to
an agricultural country like England, and may possibly cause
a total revolution in our system of husbandry.
All that M. Macaire can be said as yet to have done, is to
have discovered the fact and to have pointed out certain strong
examples of it; but if the discovery is to be converted toa
practically useful purpose, we require positive information upon
the following points :—
1. The nature of the fecal excretions of every plant culti-
vated by the farmer.
2. The nature of the same excretions of the common weeds
of agriculture.
3. The degree in which such excretions are poisonous to the
plants that yield them, or to others.
4. The most ready means of decomposing those excretions
by manures or other means. ‘
It would be superfluous to point out what the application
would be of such information as this; but I cannot forbear ex-
pressing a hope that a question upon which so many deep inter-
ests are involved may be among the first to occupy the atten-
tion of the chemists of the British Association.
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[ 59 J
Report on the Physiology of the Nervous System. By Wit-
-uiam Cuartes Henry, M.D., Physician to the Manchester
Royal Infirmary.
Introduction—Tux science of Physiology has for its object to
ascertain, to analyse, and to classify the qualities and actions
which are peculiar to living bodies. 'These vital properties re-
side exclusively in organized matter, which is characterized by
a molecular arrangement, not producible by ordinary physical
attractions and laws. Matter thus organized consists essen-
tially of solids, so disposed into an irregular network. of laminz
and filaments, as to leave spaces occupied by fluids of various
natures. ‘Texture’ or ‘tissue’ is the anatomical term by which
such assemblages are distinguished. Of these the cellular, or
tela cellulosa, is most elementary, being the sole constituent of
several, and a partial component of all tissues and. systems.
Thus the membranes and vessels consist entirely of condensed
cellular substance ; and even muscle and nerve are resolvable,
by microscopic analysis, into globules deposited in attenuated
cellular element. ,
But though the phenomena, which are designated as vital,
are never found apart from organization, and have even by
some naturalists been regarded as identical with it, yet in the
order of succession vital actions seem necessarily to stand to
organized structures in the relation of antecedents; for the
production of even the most rudimentary forms and textures
implies the previous operation of combining tendencies or ‘ vital
affinities’. ‘The origin and early development of these vital
tendencies, and of organized structures, are beyond the pale of
exact or even of approximative knowledge. But it is matter of
certainty, that life is the product only of life; that every new
plant or animal proceeds from some pre-existent being of the
same form and character; and thus that the image of the great
Epicurean poet, ‘‘ Quasi cursores vitai lampada tradunt,” pos-
sesses a compass and force of illustration which, as a supporter
of the doctrine of fortuitous production, he could not have him-
self contemplated.
The popular notions respecting life are obscure and indeter-
minate; nor are the opinions even of philosophers characterized
by much greater distinctness or mutual accordance. Like other
complex terms, ‘life’ can obviously be defined only by an enume-
60 THIRD REPORT—1833.
ration of the phenomena which it associates. This enumera-
tion will comprehend a greater or a smaller number of particu-
lars, according to the station in the scale of living beings which
is occupied by the object of survey. In its simplest manifesta-
tion, the principle of life may be resolved into the functions of
nutrition, secretion and absorption. It consists, according to
Cuvier, of the faculty possessed by certain combinations of
matter, of existing for a certain time and under a determinate
form, by-attracting unceasingly into their composition a part of
surrounding substances, and by restoring portions of their own
substance to the elements. ‘This definition comprehends all
the essential phenomena of vegetable life. Nutritive matter is
drawn from the soil by the spreading fibres of the root, through
the instrumentality of spongioles or minute turgid bodies at
their extremities, which act, according to Dutrochet, by a power
which he has called ‘endosmosis.’ The same agency raises the
nutrient fluid through the lymphatic tubes to the leaves, where
it seems to undergo a kind of respiratory process, and becomes
fit for assimilation. These changes, and the subsequent pro-
pulsion of the sap to the different parts and textures, plainly
indicate independent fibrillary movements, which are repre-
sented in animal life by what Bichat has termed ‘the pheno-
mena of organic contractility’. ‘The power residing in each
part of detecting in the circulating fluid, and of appropriating,
matters fitted to renovate its specific structure, is designated in
the same system by the term ‘organic sensibility’.
Ascending from the vegetable to the animal kingdom, the
term ‘life’ advances greatly in comprehensiveness. ‘The exist-
ence of a plant is limited to that portion of space in which acci-
dent or design has inserted its germ; while animals are for
the most part gifted with the faculties of changing their place,
and of receiving from the external world various impressions.
Along with the general nutritive functions, the higher attri-
butes of locomotion and sensation are therefore comprised in
the extended compass of meaning which the term ‘life’ acquires
with the prefix ‘animal’. The nutritive functions, too,emerging
from their original simplicity, are accomplished by a more com-
plex mechanism, and by agencies further removed from those
which govern the inanimate world.
Locomotion is effected either by means of a contractile tissue,
or of distinct muscular fibres. ‘These fibres have been said to
consist of globules resembling, and equal in magnitude to, those
of the blood, disposed in lines, in the elementary cellulosity, which
by an extension of the analogy is compared to serum. But the
latest microscopical observations of Dr. Hodgkin are opposed
REPORT ON THE PHYSIOLOGY OF THE NERVOUS SYSTEM. 61
to this globular constitution of the contractile fibre. ‘‘ Innu-
merable very minute but clear and fine parallel lines or strie
may be distinctly perceived, transversely marking the fibrillz.”
Irritability, or the faculty of contracting on the application of a
stimulant, is a property inherent in the living fibre. It is an
essential element of all vital operations, except of those which
have their seat in the nervous system, such as sensation, voli-
tion, the intellectual.states, and moral affections. All the phe-
nomena of life, in the higher animals, may then be ultimately
resolved into the single or combined action of these two ele-
mentary properties,—irritability and nervous influence, each
residing in its appropriate texture and system.
These preliminary remarks are designed to unfold the prin-
ciples to be followed in classifying the vital functions. In ge-
neral or comparative physiology, a strictly scientific arrangement
would contemplate first the phenomena of the most elementary
life, and would successively trace the more perfect development
of those simple actions and their gradual transition into more
complex processes, as well as the new functions, superadded
in the ascending scale of endowment. But such a mode of
classification is wholly inapplicable to the particular physiology
of man and of the more perfect animals, viewed by itself and
without reference to inferior orders of beings; for the nutri-
tive functions of this class, which correspond with the elemen-
tary actions of the simplest vegetable life, are effected by a
complex system of vessels and surfaces, deriving their vital
powers from contractile fibres, and controlled, if not wholly
governed, by nervous influence. It is then manifest, that in
the higher physiology the general laws of contractility and ‘in-
nervation’ must precede the description of the several functions,
which all depend on their single or united agency. The parti-
cular functions will afterwards be classed, as they stand in more
immediate relation to one or other of the two essential princi-
ples of life.
In the present state of physiological knowledge, it is impos-
sible to determine absolutely, and without an opening to con-
troversy, whether the functions of muscle or those of nerve are
entitled to precedency. If each were equally independent of
the other in the performance of their several offices, the question
of priority would resolve itself into one of simple convenience.
The actions of the nervous system, if contemplated for the short
interval of time during which they are capable of persisting
without renovation of tissue, are entirely independent of the
contractile fibre. But it is certain that the cooperation of
nerve is required in most, if not in all, the actions of the mus-
62 THIRD REPORT—1833.
cular system. Thus the voluntary muscles in all their natural
and sympathetic contractions receive the stimulant impulse of
volition through the medium of nerve; and though the mode,
in which the motive impression is communicated to the invo-
luntary muscles, is still matter of controversy, there seems suffi-
cient evidence * to sanction the conclusion that nerve is in this
case also the channel of transmission ;—“ that the immediate
antecedent of the contraction of the muscular fibre is univer-
sally a change in the ultimate nervous filament distributed to
that fibre.” If this be correct, the physiological history of
muscle’cannot be rendered complete without reference to that
of nerve.
In the higher manifestations of life, nervous matter is in-
vested with the most eminently vital attributes. It is the ex-
clusive seat of the various modes of sensation, and of all the
intellectual operations; or, rather, it is the point of transition,
where the physical conditions of the organs, which are induced
by external objects, pass into states of mind, becoming per-
ceptions; and where the mental act of volition first impresses
a change on living matter. These two offices of conducting
motive impressions from the central seat of the will to the mus-
cles, and of propagating sensations from the surface of the body
and the external organs of sense to the sensorium commune,
have been of late years shown to reside in distinct portions of
nervous substance.
The honour of this discovery, doubtless the most important
accession to physiological knowledge since the time of Harvey,
belongs exclusively to Sir Charles Bell. It constitutes, more-
over, only a part of the new truths, which his researches have
unveiled, regarding the general laws of nervous action, and the
offices of individual nerves. His successive experiments on
function, guided always by strong anatomical analogies in struc-
ture, in origin, or in distribution, have led to the entire remo-
delling of nervous physiology, and to the formation of a system
of arrangement, based on essential affinities and on parity of
intimate composition, instead of on apparent sequence or prox-
imity of origin. Among the continental anatomists, MM. Ma-
gendie and Flourens have contributed most largely to our
knowledge of this part of physiology; the former by repeating
and confirming the experiments of Bell, as well as by various
original inquiries; the latter by his important researches into
the vital offices of the brain and its appendages. Much light,
_ * See “A Critical and Experimental Enquiry into the Relations subsisting
between Nerve and Muscle,” in the 37th vol. of the Edinburgh Medical and
Surgical Journal.
REPORT ON THE PHYSIOLOGY OF THE NERVOUS SYSTEM. 63
too, has been thrown on the functions of several of the ence-
phalic nerves, and especially of those supplying the face and
its connected cavities, by Mr. Herbert Mayo, who has analysed
their anatomical composition, and pursued their course with
singular precision, and has thus been enabled to correct some
errors of detail in the system of Sir Charles Bell.
Nervous System.—In man, and in other vertebrated animals,
the nervous system consists of the cerebrum, cerebellum, me-
dulla oblongata, medulla spinalis, and of the encephalic, spinal,
and ganglionic nerves. It seems most natural to observe this
order of anatomical sequence in recording what is known of
nervous functions. .
Cerebrum, or Brain-proper.—The physiology of the brain
has received of late years very considerable accessions, and its
vital offices, viewed as an entire organ, have now probably been
ascertained with sufficient precision. Some portion of this newly
acquired knowledge has been gathered from experiments on
living animals, but the greater and more valuable part has
flowed from the study of comparative development. In this
latter field of inquiry, 'Tiedemann’s elaborate history of the pro-
gressive evolution of the human brain during the period of
foetal existence, with reference to the comparative structure of
that organ in the lower animals, merits an early and detailed
notice. It had been discovered by Harvey, that the foetus in
the human species, as well as in inferior animals, is not a pre-
cise facsimile of the adult, but that it commences from a form
infinitely more simple, and passes through several successive
stages of organization before reaching its perfect development.
In the circulatory system, these changes have been minutely
observed and faithfully recorded*. ‘Tiedemann has traced a
similar progression in the brain and nervous system, and has
moreover established an exact parallel between the temporary
states of the foetal brain in the periods of advancing gestation,
and the permanent development of that organ at successive
points of the animal scale. The first part of his work is simply
descriptive of the nervous system of the embryo at each suc-
cessive month of foetal life. It constitutes the anatomical ground-
work upon which are raised the general laws of cerebral forma-
tion, and the higher philosophy of the science. In the second
part, Tiedemann has established, by examples drawn from all
the grand divisions of the animal kingdom, the universality of
the law of formation, as traced in the nervous system of the
* See an excellent Essay on the Development of the Vascular System in the
Feetus of Vertebrated Animals, by Dr. Allen Thomson.
64 THIRD REPORT—1833.
human foetus, and the existence of one and the same funda-
mental type in the brain of man and of the inferior animals.
The facts which have been unfolded by the industry of Tiede-
mann, besides leading to the universal law of nervous develop-
ment, throw important light upon nervous function: for it is
. observed that the successive increments of nervous matter, and
especially of brain, mark successive advances in the scale of
being ; and, in general, that the development of the higher in-
stincts and faculties keeps pace with that of brain. Thus, in
the zoophyta, and in all living beings destitute of nerves, no-
thing that resembles an instinct or voluntary act is discovera-
ble. In fishes the hemispheres of the brain are small, and.
marked with few furrows or eminences. In birds they are
much more voluminous, more raised and vaulted than in rep-
tiles; yet no convolutions or anfractuosities can be perceived
on any point of their surface, nor are they divided into lobes.
The brain of the mammalia approaches by successive steps to
that of man. That of the rodentia is at the lowest point of
organization. ‘Thus the hemispheres in the mouse, rat, and
squirrel are smooth and without convolutions. In the carnivo-
rous and ruminating tribes, the hemispheres are much larger
and marked by numerous convolutions. In the ape tribe the
brain is still more capacious and more convex; it covers the
cerebellum, and is divided into anterior, middle, and posterior
lobes. It is in. man that the brain attains its greatest magni-
tude and most elaborate organization. Sommerring has proved
that the volume of the brain, referred to that of the spinal mar-
row as a standard of comparison, is greater in man than in any
other animal.
Various attempts have been made of late years, chiefly
by the French physiologists, to ascertain the functions of the
brain by actual experiment. It will appear from a detailed
survey of their labours, that little more than a few general
facts respecting the function of its /arger masses and great na-
tural divisions have flowed from this mode of research. The
offices of the smaller parts of cerebral substance cannot with
any certainty be derived from the phenomena that have been
hitherto observed to follow the removal of those parts, since
the most practised vivisectors have obtained conflicting results.
Nor is it difficult, after having performed or witnessed such
experiments, to point out many unavoidable sources of fallacy.
In operations on living animals, and especially on so delicate
an organ as the brain, it is scarcely possible for the most skilful
manipulator to preserve exact anatomical boundaries, to restrain
hemorrhage, or prevent the extension to contiguous parts, of
REPORT ON THE PHYSIOLOGY OF THE NERVOUS SYSTEM. 65
the morbid actions consequent upon such serious injuries, and
to distinguish the secondary and varying phenomena, induced
‘by the pressure of extravasated blood, or the spread of an in-
flammatory process, from those which are essential and pri-
mary. The ablation of small and completely insulated portions
of brain must, then, be classed among the “ agenda” of experi-
mental physiology.
The most decisive researches, that have been hitherto insti-
tuted on the functions of the brain, are those of M. Flourens.
His mode of operating was to remove cautiously successive thin
slices of cerebral matter, and to note the corresponding changes
of function. He commenced with the hemispheres of the brain,
which he found might be thus cut away, including the corpora
striata and thalami optici, without apparently occasioning any
pain to the animal, and without exciting convulsive motions.
Entire removal of the cerebrum induces a state resembling coma;
the animal appears plunged in a profound sleep, being wholly
lost to external impressions, and incapable of originating mo-
tion; it is deprived, too, according to Flourens, of every mode
of sensation. Hence the cerebrum is inferred to be the organ in
which reside the faculties of perception, volition and memory.
Though not itself sensible, in the ordinary acceptation of the
word,—that is, capable, on contact or injury, of propagating sen-
sation,—yet it is the point where impressions made on the ex-
ternal organs of sense become objects of perception. This ab-
sence of general sensibility observed in the brain has also been
experimentally demonstrated in the nerves dedicated to the func-
tions of sight, of smell and of hearing, and constitutes, perhaps,
one of the most remarkable phenomena that have been disclosed
by interrogating living nature. Flourens appears, however, to
have failed in proving that ali the sensations demand for their
perception the integrity of the brain. He has himself stated
that an animal deprived of that organ, when violently struck,
‘‘ has the air of awakening from sleep,” and that if pushed for-
wards, it continues to advance after the impelling force must
have been wholly expended. Cuvier has therefore concluded,
in his Report to the Academy of Sciences upon M. Flourens’
paper, that the cerebral lobes are the receptacle in which the
impressions made on the organs of sight and hearing only, be-
come perceptible by the animal, and that probably there too
all the sensations assume.a distinct form, and leave durable im-
pressions,—that the lobes are, in short, the abode of memory.
The lobes, too, would seem to be the part in which those mo-
tions which flow from spontaneous acts of the mind haye their
i But a power of effecting regular and combined move~
. F
66 THIRD REPORT—1833.
ments, on external stimulation, evidently survives the destruc-
tion of the cerebral hemispheres.
A very elaborate series of experiments on the functions of
the brain in general, and especially on those of its anterior por-
tion, have been since performed by M. Bouillaud*. That ob-
server concurs with Flourens in viewing the cerebral lobes as
the seat of the remembrance of those sensations which are fur-
nished to us by sight and hearing, as well as of all the intel-
lectual operations to which these sensations may be subjected,
such as comparison, judgment and reasoning. But he proves
that the ordinary tactual sensibility does not require for its
manifestation the presence of the brain. For animals entirely
deprived of brain were awakened by being struck, and gave
evident indications of suffering when exposed to any cause of
physical pain. Bouillaud observes, too, that the iris continues
obedient to the stimulus of light, after ablation of the hemi-
spheres, and on this ground calls in question the loss of vision
asserted by Flourens. Nor are the lobes (he contends,) the
only receptacle of intelligence, of instincts and of volition: for
to admit this proposition of Flourens would be to grant that an
animal which retains the power of locomotion, which makes
every effort to escape from irritation, which preserves its appro-
priate attitude, and executes the same movements after as be-
fore mutilation, may perform all those actions without the agency
of the will or of instinct. Another doctrine of Flourens, which
has been experimentally refuted by Bouillaud, is, “that the
cerebral lobes concur as a whole in the full and entire exercise
of their functions; that when one sense is lost, all are lost;
when one faculty disappears, all disappear;” in short, that a
certain amount of cerebral matter may be cut away without ap-
parent injury, but that when this limit is passed, all voluntary
acts and all perceptions perish simultaneously. Bouillaud, on
the contrary, has described several experiments which show
that animals, from whom the anterior or frontal part of the brain
had been removed, preserved sight and hearing, though de-
prived of the knowledge of external objects, and of the power
of seeking their food.
The second part of M. Bouillaud’s researches is entirely de-
voted to the functions of the anterior lobes of the brain. These
were either removed by the scalpel, or destroyed by the actual
cautery, in dogs, rabbits and pigeons. Animals thus mutilated
feel, see, hear and smell; are easily alarmed, and execute a
number of voluntary acts, but cease to recognise the persons
* Magendie, Journal de Physiologie, tom. x. p. 36.
REPORT ON THE PHYSIOLOGY OF THE NERVOUS sysTEM. 67
or objects which surround them. They no longer seek food,
or perform any action announcing a combination of ideas. Thus
the most docile and intelligent dogs lost all power of compre-
hending signs or words which were before familiar to them,
became indifferent to menaces or caresses, were no longer
amenable to authority, and retained no remembrance of places,
of things, or of persons. They saw distinctly food presented
to them, but had ceased to associate with its external qualities
all perception of its relations to themselves as an object of de-
sire. The anterior or frontal part of the brain is hence inferred
to be the seat of several intellectual faculties. Its removal oc-
casions a state resembling idiotism, characterized by loss of the
power of discriminating external objects, which, however, co-
exists with the faculties of sensation.
It will be unnecessary to describe fully in this place the ex-
periments of Professor Rolando of Turin, performed in 1809, and
published in Magendie’s Journal, tom. iii., 1823, since the more
important of his facts have reference, not to the brain-proper,
but to the cerebellum. His paper certainly contains some cu-
rious anticipations of phenomena, since more accurately ob-
served by Flourens and Magendie; yet as regards the brain,
properly so called, his results are vague and inconclusive.
Accident, rather than a well matured design, seems to have
directed what parts of the brain he should remove; and from
having comprehended in the same injury totally distinct anato-
mical divisions, he has rendered it impossible to arrive at the
precise function of any one part. Thus we are told that injury
of the thalami optici and tubercula quadrigemina in a dog was
followed by violent muscular contractions. Now all subsequent
experimenters agree, that irritation of the thalami is incapable
of inducing convulsive motions ; and Flourens has proved that
this property has its beginning in the tubercula,—an important
fact, which Rolando, with a little more precision in anatomical
manipulation, could scarcely have failed to discover.
Magendie has described* some curious experiments on the
corpora striata, which, though closely analogous in their results
to those on the cerebellum, have their proper place in this
section. Removal of one corpus striatum was followed by no
remarkable change; but when both had been cut away, the
animal rushed violently forwards, never deviating from a recti-
linear course, and striking against any objects in its way. In his
lecture of February 7, 1828, Magendie, in the presence of his
class, removed both corpora striata from a rabbit. The animal
* Journal de Physiologie, tom. iii. p. 376.
F2
68 THIRD REPORT—1833.
attempted to rush forwards, and, if restrained, appeared rest=
less, continuing in the attitude of incipient progression. One
thalamus opticus was then cut away from the same animal. The
direction of its motion was immediately changed from a straight
to a curved line. It continued for some time to run round in
circles, turning towards the injured side. When the other
thalamus was removed, the animal ceased its motions and re-
mained perfectly tranquil, with the head inclined backwards.
These experiments, it may be observed, furnish no support to
the opinions of MM. Foville and Pinel Grandchamps, who have
assigned the anterior lobes and corpora striata as the parts
presiding over the movements of the inferior extremities, and
the posterior lobes and thalami as regulating the superior.
Cerebellum.—It may be regarded as nearly established by
modern researches, that the cerebellum is more or less directly
connected with the function of locomotion. The precise nature
and extent of its control over the actions of the voluntary
muscles are, however, far from being clearly determined. In
the higher animals, the mental act of volition probably has its
commencing point, as productive of a physical change, in the
brain-proper; though it must be confessed that some of the
experiments of Flourens, and all of those of Bouillaud, indicate
the persistence of many instinctive, and even of some automatic
motions, after destruction of the brain. But there does appear
sufficient evidence to prove that those volitions which have
motion as their effect, whatever be their origin, whether in the
cerebrum, cerebellum, or medulla oblongata*, require for their
accomplishment the cooperation of the cerebellum. This evi-
dence has been mainly supplied by the same inquirers whose
researches on the cerebrum have been already analysed.
In the order of time, though not of importance, the experi-
ments of Professor Rolando stand foremost. Injuries of the
cerebellum, he observed, were always followed by diminished
motive power; and this partial loss of power was always in
direct proportion to the amount of injury. 4 bd2s => ° Case 4, my x bdss = E.
12 Pw 2 ew
Roem Pt BS ane
1 lI? w 5 lw
es balea ag eS are
Hence, again, from the column marked E in the following
Table, the deflection a given load will produce in any case may be
computed ; or, the deflection being fixed, the dimension of the
beam may be found. Some authors, instead of this measure of
- 102 THIRD REPORT—1833.
3
elasticity, deduce it immediately from the formula 3b dzs : aa 5 = E,
substituting for w the height in inches of a column of the ma-
terial, having the section of the beam for its base, which is equal
to the weight w, and this is then denominated the modulus of
elasticity. It is useful in showing the relation between the
weight and elasticity of different materials, and is accordingly
introduced into the following Table.
The above formule embrace all those cases most commonly
employed in practice. There are, of course, other strains con-
nected with this inquiry, as in the case of torsion in the axles
and shafts of wheels, mills, &c., the tension of bars in suspen-
sion bridges, and those arising from internal pressure in cylin-
ders, as in guns, water-pipes, hydraulic presses, &c.; but these
fall rather under the head of the resolution of forces than that
of direct strength. It may just be observed, that the equation
due to the latter strain is .
t(c —n) =nR,
where ¢ is the thickness of metal in inches, c the cohesive power
in pounds of a square inch rod of the given material, » the
pressure on a square inch of the fluid in pounds, and R the in-
terior radius of the cylinder in inches. Our column marked C
will apply to this case, but here again not more than one third
the tabular value can be depended upon in practice.
ha oe
ee
REPORT ON THE STRENGTH OF MATERIALS. 103
Table of the Mean Strength and Elasticity of various Materials, as
deduced from the most accurate Experiments.
Cc. lw
Mean S=a@ Bw
E=—333
strength of | Constants 6d33 | Modulus of Remarks,
sta- | cohesionon | for trans- | Constants | Elasticity.
+ |aninch sec-| verse for deflec-
strains. tions.
1800 | 4609000) 3739000\of English growth.
2026 6580000) 4988000 ditto.
1560 | 5417000) 4457000 ditto.
Birch, Common 700 1900 | 6570000} 5406000 ditto.
, American Black} 750 1500 | 5700000} 3388000) American.
2650 |10512000| 5878000)|Berbice.
2500 | 7437000) 4759000\ditto.
11000 1550 | 6350000} 5378000
11000 1730 | 6420000} 6268000
5780 1030 | 2803000) 3007000/English.
Fir, New England ... 12000 1100 | 5967000) 6249000
—, Riga 750} 12600 1130 | 5314000) 4080000
1140 | 3400000) 2797000)\Scotland.
2700 |10620000) 6118000|Berbice.
1120 | 4200000) 4480000
3400 767000) 4649000) America, South.
Mahogany
Norway Spars 1470 | 5830000) 5789000
: from} 70 1200 | 3490000) 2872000) \ Results very va
Oak, English { to...| 900 2260 | 700000047020000 \ riable.
—.,, African 2000 | 9500000)55830000
iati 1380 | 3880000) 2257000
1760 | 8590000) 5674000
1450 | 4760000) 3607000
2200 | 6760000) 6488000|East Indies.
1630 | 5000000) 4364000
1340 | 7360000) 6423000
2460 | 9660000) 7417000|East Indies.
2700 |10620000) 5826000|Berbice.
8100 69120000) 5530006 :
Mean of Englis
9000 eis 6770000) ( and Foreign.
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[ 105 ]
Report on the State of our Knowledge respecting the Magnetism
of the Earth. By S. Hunter Curistiz, Esq., M.A., FBS.
M.C.P.S., Corr. Memb. Philom. Soc. Paris, Hon. Memb.
Yorkshire Phil. Soc.; of the Royal Military Academy ; and
Member of Trinity College, Cambridge.
Hap the discovery of the loadstone’s directive power been made
by a philosopher who at the same time pointed out its import-
ance to the purposes of navigation, we might expect that his
name would have been handed down to posterity as one of the
greatest benefactors of mankind. The discovery was, however,
most likely made by one so engaged in maritime enterprise that,
in his eyes, this application constituted its whole value; and it
is not improbable that, being for some time kept secret, it may
have been the principal cause of the success of many enterprises
attributed to the superior skill and bravery of the leaders. The
knowledge of this property of the magnet, though gradually
diffused, would long be guarded with jealousy by those who
justly viewed it as of the highest advantage in their predatory
or commercial excursions; and this is, perhaps, the cause of the
obscurity in which the subject is veiled. If the discovery is
European, there is no people, from the character of their early
enterprises, and, I may add, from the nature of the rocks of
their country, more likely to have made it than the early Nor-
wegians; and as there is reason for believing that they were
acquainted with the directive property of the loadstone at least
half a century earlier than its use is supposed to have been
known in other parts of Europe, it may be but justice to allow
them the honour of having been the discoverers. Whether the
discovery was made in Asia or in Europe, in the North or in
the South, I am not, however, now called upon to decide, but
to point out the consequences which have followed that disco-
very by unveiling gradually phenomena, though less striking,
yet equally interesting, and some even more difficult of expla-
nation.
These phenomena are, the variation of the magnetic needle,
with its annual and diurnal changes; the dip of the needle; and
the intensity of the magnetic force of the earth; which are, how-
ever, all comprised under two heads,—The Direction and the
Intensity of the terrestrial magnetic force.
106 THIRD REPORT—1833.
I. The Direction of the Terrestrial Magnetic Force.
1. The Variation of the Needle.—For some centuries after
the directive property of the loadstone was discovered, it was
generally supposed that the needle pointed correctly towards
the pole of the heavens. It has however been said, on the
authority of a letter by Peter Adsiger, that the variation of
the needle was known as early as 1269; and if we fully admit
the authenticity of this letter, we must allow that the writer
was at that date not only aware of the fact, but that he had
observed the extent of the deviation of the needle from the
meridian*. It is possible that such an observation as this
may have been made at this early period by an individual de-
voting his time to the examination of magnetical phenomena;
* This curious and highly interesting letter, dated the 8th of August 1269,
is contained in a volume of manuscripts in the Library of the University of
Leyden, and we are indebted to Cavallo for having published extracts from it.
The variation is thus referred to: “Take notice that the magnet (stone), as well
as the needle that has been touched (rubbed) by it, does not point exactly to
the poles; but that part of it which is reckoned to point to the south declines a
little to the west, and that part which looks towards the north inclines as much
to the east. The exact, quantity of this declination I have found, after numer-
ous experiments, to be five degrees. However, this declination is no obstacle
to our guidance, because we make the needle itself decline from the true south
by nearly one point and an half towards the west. A point, then, contains five
degrees.” (Letter of Peter Adsiger, Cavallo On Magnetism, London 1800, p. 317.)
It is certainly extraordinary, if so clear an account of the deviation of the needle
from the meridian as this, was communicated to any one by the person who had
himself observed that deviation, that for more than two centuries afterwards we
should have no record of a second observation of the fact. This alone would
throw doubt on the authenticity of the letter, and the estimate given of the
variation may appear to confirm these doubts; for, according to the period of
change which best agrees with the observations during more than two hundred
years, the variation, if observed, would have been found to be westerly instead
of easterly in 1269. It may however be urged, that as the whole period of
change has not yet elapsed since observations were made, we are not in pos-
session of a sufficient number of facts to authorize us to draw conclusions re-
specting the variation at such an early date; and also, that if the letter be spu-
rious, or the original date have been altered to that which it bears, this or the
fabrication can only have been for the purpose of founding claims in consequence
of the contents of this letter; and as no such claims have been advanced, there
appears no motive either for fabrication or alteration. In a preceding part of
the letter the author gives methods for finding the poles of a loadstone; and
certainly the direction of the axis could not be determined to within five degrees
by either of these; so that, as regards the loadstone, we may, I think, conclude
that the author did not make the observation. As a matter of curious history
connected with magnetism, it is desirable that either the authenticity of this
letter should be clearly established, or reasons given for doubting it, by those
who have an opportunity of consulting the original.
REPORT ON THE MAGNETISM OF THE EARTH. 107
and as it is probable that for some time subsequent to the dis-
covery of the directive property of the needle the deviation in
Europe was not of sufficient magnitude to have been easily de-
tected by means of the rude instruments then in use, it may
very likely be owing to this circumstance that we have not
earlier records of the variation*. 'That Columbus, the most
scientific navigator of his age, when he commenced his career
of discovery, and undertook to show the western route to India,
was not aware of it, is clear, since the discovery during his first
voyage has been attributed to him. However, although Co-
lumbus may have noticed that the needle did not in every situa-
tion point due north, and Adsiger, long before him, may even
have rudely obtained the amount of its deviation, the first ob- |
servations of the variation on which any reliance can be placed
appear to have been made about the middle of the sixteenth
century, and shortly afterwards it was well known that the va-
riation is not the same in all places f.
2. Change in the Direction of the Needle-——When it was
first determined by observation, about 1541, that the needle
did not point to the pole of the earth, it was found that this vari-
ation from the meridian, at Paris, was about 7° or 8° towards
the east. In 1550 it was observed 8° or 9° east; and in
1580, 114° east. Norman appears to have been the first who
observed the variation with any degree of accuracy in Lon-
don. He states that he observed it to be 11° 15’ east t, but he
was not aware that it does not remain constant in the same
place§. In 1580, Burough found the variation at Limehouse
to be 113° or 114° east||, and his observations appear to be
* * Another reason why the variation was not earlier observed may be that the
natural magnet was first used for the purposes of navigation, and its directive
line was that which pointed to the pole star. As it was therefore considered
that the natural magnet indicated the direction of the meridian, and it was
found that a needle touched by it had the directive power, when the needle was
introduced it was assumed that this also pointed in the meridian.
+ The New Attractive, by Robert Norman, chap. ix. London 1596.
t Ibid. No date is given for this observation ; but from the circumstance of
Burough referring to Norman’s book in the preface to his Discourse of the Va-
riation of the Compasse, dated 1581, (the copy of this to which I have access
was printed in 1596, but the Bodleian Library contains one printed in 1581,)
it would appear that there must have been an earlier edition of Norman’s book
than that of 1596, and that his observations must have been made before 1581.
Bond, Philosophical Transactions, vol. viii. p. 6066, gives 1576 as the date of
Norman’s observations.
§ “ And although this variation of the needle be found in travaile to be divers
and changeable, yet at anie land or fixed place assigned, it remaineth alwaies
one, still permanent and abiding.” New Attractive, chap. ix.
|| The mean of his observations, which do not differ 20', is 11° 19! east.
108 THIRD REPORT—1833.
entitled to much confidence ; but he was of the same opinion
as Norman with respect to the constancy of the variation*.
Gunter, in 1612, found the variation in London to be 5° 36/
east; and Gellibrand, in 1633, observed it 4° 4’ east. Dr. Wal-
lis considers Gellibrand to have been the discoverer of “ the
variation of the variation};” but if Gunter had any confidence
in his own observations and those of Burough, he must have
been aware of the change in the variation. In 1630, Petit
found the variation at Paris to be 44° east, but suspected, at
the time, that the earlier observations there had been incorrect;
and it was not until 1660, when he found the variation to be
only 10’ east, that he was satisfied of the change of the varia-
tion. About ten years later, Azaut, at Rome, where the va-
riation had been observed 8° east, found it to be more than 2°
west; and Hevelius, who at Dantzick in 1642 had found it to
be 3° 5/ west, now found it to be 7° 20! west.
3. Diurnal Change in the Variation.—This was discovered
in 1722 by Graham, to whose talents and mechanical skill
science is so deeply indebted. He found that with several
needles, on the construction of which much care had been be-
stowed, the variation was not always the same; and at length
determined that the variation was different at different hours
in the day, the greatest westerly variation occurring between
noon and four hours after, and the least about six or seven
o'clock in the eveningt. Wargentin at Stockholm in 1750,
and Canton in London from 1756 to 1759, more particularly
observed this phenomenon; and the latter determined that
the time of minimum westerly variation in London was between
eight and nine in the morning, and the time of maximum be-
tween one and two in the afternoon. Canton likewise deter-
mined in 1759, that the daily variation was different at different
times in the year, the maximum change occurring about the end
of June, and the minimum in December §. Cassini, during more
than five years and a half, namely, from May 1783 to January
1789, carefully observed, at particular hours, the direction of a
needle suspended in the Observatory at Paris; and although
he does not correctly state the course of the daily variation,
overlooking altogether the second maximum west, and the pro-
gress of the needle towards the east in the early part of the
* © For considering it remayneth alwaies constant without alteration in every
severall place, there is hope it may be reduced into method and rule.” Dis-
course, chap. x.
+ Philosophical Transactions, 1701, vol. xxii. p. 1036.
¢ Lbid. 1724, vol. xxxiii. p. 96.
§ Ibid. 1759, vol. xli. p. 398.
REPORT ON THE MAGNETISM OF THE EARTH. 109
morning*, yet his observations and reniarks are of great value
as pointing out the annual oscillations of the needle}. Since
this, the diurnal variation has been very generally observed,
but by no one with greater care and perseverance than by the
late Colonel Beaufoy f.
In order to determine whether the course of the diurnal va-
riation is influenced by the elevation of the place of observation,
the zealous and indefatigable De Saussure undertook a series
of observations on the Col du Géant, nearly 11,300 feet above
the level of the sea. This series, after incurring much personal
inconvenience and even risk in that region of snow and of storms,
he completed; and he has compared the results with observa-
tions which he made immediately before and after at Chamouni
and Geneva. From this comparison it appears that the course
of the diurnal variation was nearly the same on one of the
highest mountains, in a deep and narrow valley at its foot, and
in the middle of a plain or of a large valley. The times of the
maxima, east and west, are in each case nearly those previously
determined by Canton, these maxima occurring rather later on
the Col du Géant than at the other stations. Excluding in all
cases the results where extraordinary causes appear to have
operated, the extent of the diurnal variation at Chamouni ex-
ceeds that at Geneva and also that on the Col, the two latter
being very nearly the same. The observations, however, are,
as Saussure very justly remarks, much too limited to give cor-
rect means §.
5. The Dip of the Magnetic Needle.—Norman having found
with different needles, and with one in particular on the con-
struction of which he had bestowed much pains, that although
perfectly balanced on the centre previously to being touched
by the magnet, after this operation the north end always de-
clined below the horizon, devised an instrument by which he
* Journal de Physique, Mai 1792, tom. xl. p. 345. + Ibid. p. 348.
+ Many of the results of Colonel Beaufoy’s observations are published in the
Edinburgh Philosophical Journal, vols. i. ii. iii. iv. and vii.
§ Saussure, Voyages dans les Alpes, tom. iv. p. 302 au p. 312. As Saussure
does not give the mean results, I insert them here.
Time of absolute mmaximum./Time of second maximum.!py tent - Elevation
| diurnal | above the
East. West. East. West. | change.| — sea.
hom ee nn one Ree
Geneva ...... 7 56 a.m.| 1 09 P.m.\6 26 p.m.\11 17 p.m.J15 42}) 1305
Chamouni ...| 7 34 1 41 7 44 10 46 17 06| 34538
Col du Géant| 8 09 2 00 5 51 10 17 15 43} 11274
110° THIRD REPORT—1833.
could determine the inclination of the needle to the plane of the
horizon*. The figure given of the instrument is sufficiently
rude, but the principles of its construction, as stated by Nor-
man, are correct. With this instrument he found the inclina-
tion of the needle to the horizon in London to be about 71° 50’,
but gives no date to the observation, though Bond assigns 1576
as the time}. Although in a theoretical point of view it would
be desirable to have so early a record of the dip, particularly as
subsequent observations lead us to suppose that the dip attained
its maximum after this time, yet, considering the uncertainty
attending such observations, even with the present improved
instruments, we cannot place much confidence in this result,
however we may rely upon the author having used every pre-
caution in his power to ensure accuracy. Having determined
the dip of the needle in London, Norman states that this de-
clining of the needle will be found to be different at different
places on the earth}, though he does not take a correct view
of the subject, for he considers that the needle will always be
directed towards a fixed point.
5. Variation of the Dip.—Subsequent observations by Bond,
Graham, Cavendish, and Gilpin, and the more recent ones in
our own time, have shown that the inclination of the needle to
the horizon at the same place, like the angle which it makes
with the meridian, is subject to change; but the diurnal oscil-
lations of the direction are of too minute a character to have
been ascertained with the imperfect instruments which we
possess.
This is an outline of the phenomena hitherto observed, de-
pending upon the direction of the forces acting upon the needle.
Various attempts have been made to account for those obser-
vable at fixed points on the earth’s surface at different periods,
and also to connect those depending on the different positions
of the places of observation, but hitherto with only very partial
success. It is not my intention to enter into a detailed history
of these attempts, but I may briefly notice some of the most
remarkable.
To Gilbert we are indebted not only for the first clear views
of the principles of magnetism, but of their application to the
phznomenon of the directive power of the needle; and indeed
we may say that, with the exception of the recent discoveries,
all that has been done since, in magnetism, has for its foundation
the principles which he established by experiment§. He con-
* New Attractive, chap. iii. iv.
+ Philosophical Transactions, 1673, vol. viii. p. 6066.
t New Attractive, chap. vii. § Gilbert, De Magnete, §c. Lond. 1600.
REPORT ON THE MAGNETISM OF THE EARTH. 111
sidered that the earth acts upon a magnetized bar, and upon
iron, like a magnet, the directive power of the needle being due
to the action of magnetism of a contrary kind to that at the
end of the needle directed towards the pole of the earth. He
applied the term “pole” to the ends of the needle directed
towards the poles of the earth, according to the view he had
taken of terrestrial magnetism, designating the end pointing
towards the north, as the south pole of the needle, and that point-
ing towards the south, as its north pole*. It is to be regretted
that some English philosophers, guided by less correct views,
have since his time applied these terms in the reverse sense,
which occasionally introduces some ambiguity, though now they
are used in this country, as on the Continent, in the sense ori-
ginally given to them by Gilbert. )
In 1668 Bond published a Table of computed variations in
London, for every year, from that time to the year 1716+. The
variations in this Table agree nearly with those afterwards ob-
served for about twenty-five years, beyond which time they
differ very widely; and I only notice this Table as the first em-
pirical attempt at the solution of a problem which is, as yet,
unsolved. Bond afterwards proposed to account for the change
in the variation and dip of the needle by the motion of two
magnetic poles about the poles of the earth. He professed not
only to give the period of this motion, but to be able to point
out its cause, and even proposed to determine the longitude
by means of the dip{. He, however, did not make public either
his methods or his views; but with regard to the longitude, it
is probable they were the same as those afterwards adopted by
Churchman.
Halley considered that the direction of the needle at different
places on the earth’s surface might be explained on the suppo-
sition that the earth had four magnetic poles§, and that the
change in the direction at the same place was due to the motion
of two of these poles about the axis of the earth, the other two
being fixed. He does not enter into any calculations to show
the accordance of the phenomena with such an hypothesis, but
conjectures that the period of revolution of these poles is about
700 years ||. :
Since this time, calculations have been made by various au-
thors, both on the hypothesis of two magnetic poles and on
that of four, with the view of comparing the results of these
. * Gilbert, De Magnete, §c., lib. i. cap. iv.
+ Philosophical Transactions, 1668, vol. iii. p. 789.
t Ibid. 1673, vol. viii. p. 6065. § Ibid. 1683, vol. xiii. p. 208.
|| Zbid. 1692, vol. xvii. p. 563.
112 THIRD REPORT—1833.
hypotheses with actual observation. ‘The most recent attempt
of this kind is that by Professor Hansteen. He adopts Halley's
hypothesis of four magnetical poles, but considers that they all
revolve, and in different periods, the northern poles from west
to east, and the southern ones from east to west. The results
calculated on this hypothesis agree pretty nearly with the ob-
servations with which they are compared; but as considerable
uncertainty attends magnetical observations, excepting those
of the variation made at fixed observatories, and especially the
early ones of the dip and variation, on which the periods of the
poles and their intensities must so much depend, it would cer-
tainly be premature to say that such an hypothesis satisfactorily
explains the phenomena of terrestrial magnetism. If we admit
that the progressive changes which take place in the direction
of the needle are due to the rotation of these poles, we must
look to the oscillations of the same poles for the cause of the
diurnal oscillation of the needle. Any hypothesis which by
means of two or more magnetic poles will thus connect the
phenomena of magnetism, is of great advantage, however un-
able we may be to give a reason for the particular positions of
the poles, or for their revolution. Hansteen refers these to
the agency of the sun and moon.
Without assigning any cause either for the direction of the
needle, or for the progressive change of that direction, attempts
have been made to account for its diurnal oscillations. But
before taking a review of these, it is necessary that I should
state more particularly the precise nature of the phenomenon.
This I cannot do better than by referring to the results de-
duced from Canton’s observations*. From these it appears
that in London, during the twenty-four hours, a double oscilla-
tion of the needle takes place, the absolute maximum west
happening about half-past one in the afternoon, and the abso-
lute maximum east, that is, the minimum west, about nine in
the morning; besides which there was another maximum east
about nine in the evening, and a maximum west near midnight
or very early in the morning, the two latter maxima being small
compared with the absolute maxima. Colonel Beaufoy’s very
extensive series of observations, made when the variation was
between 24° and 25° west, (Canton’s having. been made when
it was 19°,) give nearly the same results, the absolute maxima
happening somewhat earlier, and the second maxima west
about eleven in the evening.
Canton explained the westerly motion of the needle in the
* Philosophical Transactions, 1759, p. 398, and 1827, pp. 333, 334,
REPORT ON THE MAGNETISM OF THE EARTH. 113
latter part of the morning, and the subsequent easterly motion,
by supposing that the heat of the sun acted upon the northern
parts of the earth as upon a magnet, by weakening their in-
fluence, but offered no explanation of the morning easterly mo-
tion of the needle.
Oersted’s discovery of the influence of the closed voltaic
circuit upon the magnetic needle, and the consequent discoveries
of Davy, Ampére and Arago, immediately led to the considera-
tion, whether all the phenomena of terrestrial magnetism were
not due to electric currents; and the discovery of Seebeck, that
electric currents are excited when metals having different
owers of conducting heat are in contact,—which discovery
with but few holds the rank to which it is eminently entitled,—
pointed to a probable source for the existence of such currents.
At the conclusion of a highly interesting paper on the develop-
ment of electro-magnetism by heat, Professor Cumming re-
marks that ‘‘magnetism, and that to a considerable extent, it
appears, is excited by the unequal distribution of heat amongst
metallic, and possibly amongst other bodies. Is it improbable
that the diurnal variation of the needle, which follows the
course of the sun, and therefore seems to depend upon heat,
may result from the metals, and other substances which com-
pose the surface of the earth, being unequally heated, and con-
sequently suffering a change in their magnetic influence?” And
in the second part of a paper, detailing some thermo-magnetical
experiments, read before the Royal Society of Edinburgh,
Dr. Traill considers “that the disturbance of the equilibrium
of the temperature of our planet, by the continual action of the
sun’s rays on its intertropical regions, and of the polar ices,
must convert the earth into a vast thermo-magnetic apparatus: ”
and “that the disturbance of the equilibrium of temperature,
even in stony strata, may elicit some degree of magnetism*.”
Previous to this, I had adopted the opinion that temperature,
_ if not the only cause, is the principal one of the daily variation.
It did not, however, appear to me, that any of the experiments
hitherto made bore directly on the subject, since the metals
producing electric currents by their unequal conduction of heat
were only in contact at particular parts, and in no case had
such currents been excited by different metals having their
surfaces symmetrically united throughout. I in consequence
instituted a series of experiments with two metals so united,
and found that electric currents were still excited on the
* Transactions of the Philosophieal Society of Cambridge, vol. ii. p. 64.
+ Philosophieal Transactions, 1823, p. 392.
1833. I
114 ; THIRD REPORT—1838.
application of heat, the phenomena corresponding to magneti¢
polarization in a particular direction with reference to the place
of greatest heat*. From these experiments I drew the con-
clusion that one part of the earth, with the atmosphere, being
more heated than another, two magnetic poles, or rather elec-
tric currents producing effects referrible to such poles, would _
be formed on each side of the equator, poles of different names
being opposed to each other on the contrary sides of the equa-
tor; and that different points in the earth’s equator becoming
successively those of greatest heat, these poles would be carried
round the axis of the earth, and would necessarily cause a de-
viation in the horizontal needle +. On comparing experimentally
the effects that would result from the revolution of such poles
with the diurnal deviations at London, as observed by Canton
and Beaufoy, also with those observed by Lieut. Hood at Fort
Enterprise, and finally with the late Captain Foster’s at Port
Bowen, I found a close agreement in all cases in the general
character of the phenomena, and that the times of the maxima
east and west did not differ greatly in the several cases. The
double oscillation of the needle, to which I have referred in
Canton’s and Beaufoy’s observations, clearly resulted from this
view of the subject. Some of the experiments to which I have
referred showed that when heat was applied to a globe, the
electric currents excited were such, that on contrary sides of
the equator the deviations of the end of the needle of the
same name as the latitude were at the same time always in the
same direction, either both towards east or both towards west.
No observations having at that time been made on the diurnal
variation of the needle in a high southern latitude, I considered
“that the agreement of the theoretical results with such ob-
servations would be almost decisive of the correctness of the
theory.” Captain Foster’s observations at Cape Horn, South
Shetland, and the Cape of Good Hope, show most decidedly
that in the southern hemisphere the diurnal deviations of the
south end of the needle correspond very precisely with those of
the north end in the northern hemisphere ; and most fully bear
me out in the view which I had taken. These valuable obser-
vations have been placed in my hands by His Royal Highness
the President, and the Council of the Royal Society, and I in-
tend, when I have sufficient leisure, rigidly to compare them,
and likewise those to which I have already referred in the
northern hemisphere, with the diurnal deviations that would
Traniactions, 1827, pp. 321, 326.
} Ibid. pp. 827, 328.
* “Theory of the Diurnal Variation of the Magnetic Needle,” Philosophical
REPORT ON THE MAGNETISM OF THE EARTH. 115
result at the corresponding places on the earth’s surface, on
the supposition that such electric currents as I have supposed
are excited on contrary sides of the equator, in consequence of
different parts on the earth’s surface becoming successively the
places of greatest heat, during its revolution upon its axis.
Should there be found in these results that accordance which I
have reason to expect, there will, I think, be no doubt that the
diurnal deviation of the needle is due to electric currents excited
by the heat of the sun.
I have already adverted to the hypotheses of two or more
poles, by means of which attempts have been made to explain
the phenomena of terrestrial magnetism, and I may now re-
mark, that if we admit the existence of such poles, we must be
careful not to consider the magnetic meridians as great circles:
they are unquestionably curves of double curvature. Nor must
we consider these poles to be, like the poles of a magnet, cen-
tres of force not far removed from the surface. If such centres
of force exist for the whole surface of the earth, the experi-
mental determinations of the magnetic force at different places,
to which I shall shortly advert, at least show that they cannot
be far removed from the centre of figure.
In the delineation of magnetic charts, more attention has
hitherto been paid to the Halleyan lines, or lines of equal varia-
tion, than to any others; and I am not disposed to undervalue
charts where such lines alone are exhibited : to the navigator they
are of the greatest value; but they throw little light on the phe-
nomena in general. Ifthe meridians were correctly represented,
they would at least indicate clearly their points of convergence, if
such in all cases exist ; but the lines that would be most likely to
guide us to a true theory of terrestrial magnetism, are the nor-
mals to the direction of the needle. | If, as is highly probable,
the direction of the needle is due to electric currents circulating
either in the interior or near the surface of the earth, these
normals would represent the intersection of the planes of the
currents with the surface of the earth ; and, by their delineation,
we should have exhibited in one view the course of the currents
and the physical features by which that course may be modified,
so that any striking correspondences which may exist, would
_ be immediately seized, and lead to important conclusions.
Changes of temperature I consider to be the principal cause of
the diurnal changes in the direction of the needle: and if any
connexion exist between these electric currents and climate,
we are to expect that the curvature of these normal lines will
be influenced by the forms, the extent and direction of the con-
tinents or seas over which they pass, and also by the height,
I
116 THIRD REPORT—1838.
direction and extent of chains of mountains, and probably by
their geological structure.
‘These normal lines may, to a certain extent, agree with the
lines of equal dip, which have already been delineated upon
some charts. In Churchman’s charts they are represented in
the positions they would have on Euler’s hypothesis of the earth
haying two magnetic poles. The only use, however, of such
hypothetical representations is, that by comparison with actual
observation they become tests of the correctness of the theory,.
or they may point out the modifications which it requires, in
order that it may accord with observation. In Professor Hans-
teen’s chart the lines of equal dip are projected from observa-
tions reduced to the year 1780. Considering how very deficient
we are, even now, in correct observations of the dip, I should
not be disposed to place much reliance upon the accuracy of
these lines, particularly where they cross great extents of sea
affording no poiuts of land necessary for observations of the dip.
Of these lines of equal dip the most important is the magnetic:
equator, or that line on the earth at which the dipping needle
would be horizontal. The observations giving this result can
of course be but few, and are therefore very inadequate for the
correct representation of this line. In order to obviate this’
difficulty, M. Morlet made use of all observations not very re-
mote from the equator, determining the distance of that line
from the place of observation by means of the law, that the
tangent of the magnetic latitude is half the tangent of the dip,
which is derived from the hypothesis of two magnetic poles near
to. the centre of the earth. By this means the position of the
equator was determined throughout its whole extent; and a
surprising agreement was found between the determinations of
each point by means of different observations, which shows
that, within certain limits near the equator, the hypothesis very
correctly represents the observations. ‘This line exhibits in-
flections in its course which have been attributed, and probably
with justice, to the physical constitution of the surface in their
vicinity *. It has been considered also that a general resem=
blance exists between the isothermal lines and the lines of equal
dip on the surface of the earth +. .
All the lines to which I have here referred have been hitherto
represented on a plane, either on the stereographical, the glo-
bular, or Mercator’s projection. Mr. Barlow has, however,
very lately represented the lines of equal variation on a globe,
from a great mass of the most recent documents connected with
* Biot, Traité de Physique.
+ Hansteen, Edinburgh Philosophical Journal, vol. iii. p. 127.
REPORT ON THE MAGNETISM OF THE EARTH. 117
the variation, furnished to him by the Admiralty, the East India
Company, and from other sources. If to the lines of equal .va-
riation were added the magnetic meridians and their normals,
the isodynamic lines, with those of equal dip, such a globe would
form the most complete representation of facts connected with
terrestrial magnetism that has ever been exhibited, and might
indicate relations which have hitherto been overlooked.
Having discovered that a peculiar polarity is imparted to iron
by the simple act of rotation, I was led to consider whether the
principal phenomenon of terrestrial magnetism is not, ina great
measure, due to its rotation. ‘The subsequent discovery by
Arago, that analogous effects take place during the rotation of
all metals, and Faraday’s more recent discovery, that electrical
currents are not only excited during the motion of metals, but
that such currents are transmitted by them, render such an
opinion not improbable. It is, however, to be remarked, that,
in all these cases, motion alone is not the cause of the effects
produced ; but that these effects are due to electricity induced
in the body by its motion in the neighbourhood of a magnetized
body. If, then, electrical currents are excited in the earth in
consequence of its rotation, we must look to some body exterior
to the earth for the inducing cause. ‘The magnetic influence
attributed by Morichini and Mrs. Somerville to the violet ray,
and the effect which I found to be produced on a magnetized
needle when vibrated in sunshine, and which appeared not to
admit of explanation without attributing such influence to the
sun’s rays, might appear to point to the sun as the inducing
body. ‘The experiments, however, of Morichini and Mrs. So-
merville, have not succeeded on repetition ; and in a recent re-
petition of my own experiments, in a vacuum, by Mr. Snow
Harris, the effects which I observed were not detected. I had
found that the effects produced on an unmagnetized steel needle
differed from those produced. on a similar needle when magnet-
ized, and therefore considered that the idea of these effects
being independent of magnetism was precluded ; but Mr. Har-
ris’s results may possibly be considered to indicate that they
were due solely to currents of air excited by the sun’s rays.
These circumstances render it doubtful whether the sun’s rays
possess any magnetic influence independent of their heating
power; but besides this, supposing such influence to exist, if
electric currents were induced in the earth during its rotation,
they would be nearly at right angles to the equator, and would
therefore cause a magnetized needle to place itself nearly per-
pendicular to the meridians, or parallel to the equator.
Although it would therefore appear that: the rotation of the
118 " THIRD REPORT—1833.
earth is not the cause of its magnetism, yet it is highly pro-
bable, from Mr. Faraday’s experiments*, that, magnetism ex-
isting in the earth independently of it, electrical currents may
be produced, not only by the earth’s rotation, but by the motion
of the waters on its surface, and even by that of the atmosphere;
so that the direction and intensity of the magnetic forces would
be modified by the influence of these currents.
This subject is at present involved in obscurity: still, consi-
dering how many have been the discoveries made within a few
years,—all bearing more or less directly upon it, though none
afford a complete explanation of the phanomena,—it does not
appear unreasonable to expect that we are not far removed from
a point where a few steps shall place us beyond the mist in which
we are now enveloped.
Mr. Fox, having observed effects attributable to the electri-
city of metalliferous veins, appears disposed to refer some of
the phenomena of terrestrial magnetism to electrical cur-
rents existing in these veins}; but although we should not be
warranted in denying the existence of these currents, indepen-
dently of the wires made use of in Mr. Fox’s experiments, or
even their influence on the needle, yet I think we should be
cautious in drawing conclusions from these experiments f.
Il. Intensity of the Terrestrial Magnetie Foree.
I have as yet said little on the intensity of the terrestrial mag-
netic forces. Graham, after having discovered the daily varia-
tion of the needle, suspected that the force which urges it varies
not only in direction, but also in intensity. He made a great
variety of observations with a dipping needle, but drew no ge-
neral conclusion from his results. Indeed, with the instruments
then in use, he was not likely to determine that which has al-
most escaped detection with instruments of more accurate con-
struction, for the diurnal variation of the whole magnetic force
may perhaps still be considered doubtful. Later observations,
particularly those of Professor Hansteen, have shown that the
time of vibration of a horizontal needle varies during the day,
from which it was inferred that the horizontal force also varies.
Professor Hansteen, by this means, found that the horizontal
intensity of terrestrial magnetism has a diurnal variation, de-
* Philosophical Transactions, 1832, p. 176. + Ibid. 1830, -p 407.
+ Mr. Henwood informs me that he has repeated the experiments of Mr.
Fox in from forty to fifty places not before experimented on, and that he pro~
poses greatly extending them. As far as he can yet see, he considers that his
results go to confirm Mr. Fox’s deductions,—I suppose with regard to the elec-
tricity of metalliferous veins.
REPORT ON THE MAGNETISM OF THE EARTH. 119
creasing, at Christiana, until ten or eleven o'clock in the morn-
ing, when it attains its minimum, and then increases until four
or five o'clock after noon, when it appeared to reach its maxi-
mum*. By observing, at different times of the day, the direc-
tion of a horizontal needle thrown nearly at right angles to the
meridian, by the action of two powerful magnets, placed in the
meridian, passing through its centre, after correcting the ob-
servations for the effect of changes of temperature on the in-
tensity of the force of the magnets, I found that at Woolwich
the terrestrial horizontal intensity decreased until 10° 30™ a.m.,
when it reached its minimum, and increasing from that time,
attained its maximum about 75 30" p.m.}. ‘This agreement, in
results obtained by totally independent methods, removes all
doubt respecting the diurnal variation of the horizontal force.
The difference in the time of the maximum in the two cases
may be accounted for, independently of the difference in the
variation at the two places of observation, by the circumstance
that no correction for the effect of temperature on the time of
vibration is made in Professor Hansteen’s observation. As no
such correction had hitherto been made, it must have been con-
sidered that differences in the temperature at which observations ©
were made had little influence on the intensity of the vibrating
heedle ; but in the communication containing these observations,
I pointed out the necessity of such a correction{; and since
then, in deducing the terrestrial intensity from the times of vi-
* Edinburgh Philusophical Journal, vol. iv. p. 297.
+ Philosophical Transactions, 1825, pp.50 & 57. An inconvenience attending
the method which I employed is, that the observations require a correction for
temperature which is not very readily applied, as will be seen by referring to my
paper ; but this might in a great measure be obviated, by rendering the tempera-
ture of the magnets employed always the same previous to observation. If, how-
ever, in order to retain the needle in its position nearly at right angles to the me-
ridian, torsion were applied instead of the repulsive forces of magnets, the correc-
tion for temperature would be nearly reduced to that due to the effects produced.
on the intensity of the needle itself by changes of temperature. But even this
method is not without objection; for the sensibility of the needle depending
upon the number of circles of torsion requisite to bring it into the proper posi-
tion, if a wire were employed, unless very long, its elasticity would be impaired
by more than two or three turns; and it is doubtful whether a filament of glass
of moderate length would bear more than this without fracture. I had pro-
posed to the late Captain Foster, previous to his last voyage, that he should de-
termine the horizontal intensity at different stations, and also its diurnal changes
by this method, and had a balance of torsion constructed for him for the purpose ;
but as the instrument is extremely troublesome in its adjustments, I consider
that the many other observations which he had to make did not allow him time
for the extensive use of this instrument which he had proposed. It is, however,
very desirable that it should be ascertained how far this method is applicable.
{Philosophical Transactions, 1825.
«
120 THIRD REPORT—18383.
bration of a needle, it has been customary to apply a correction
for differences in the temperatures at which the observations
may have been made.
‘The horizontal intensity varying during the day, it becomes
a question whether this arises from a change alone in the direc-
tion of the force, or whether this change of direction is not
accompanied by a change in the intensity of the whole force.
In a communication to the Philosophical Society of Cambridge *,
I suggested that deviations, from whatever cause, in the direc-
tion of the horizontal needle, were referrible to the deviations
which, under the same circumstances, would take place in the
direction of the dipping needle. Adopting these views, Captain
Foster infers, from observations made by him at Port Bowen,
on the corresponding times of vibration of a dipping needle,
supported on its axis and suspended horizontally, that the diur-
nal change in the horizontal intensity is due principally, if not
wholly, to a small change in the amount of the dip. ‘The observa-
tions, however, do not indicate that the force in. the direction of
the dip is constant. Captain Foster's observations at Spitzber-
gen7} show, more decidedly, the diurnal variation of this force:
there, its maximum intensity appears to have occurred at about
3" 36™ a.m., and the minimum at 2" 47™ p.M. ; its greatest change
amounting to 5 of its mean value. The maximum horizontal
intensity appears to have occurred a little after noon, and the
minimum nearly an hour after midnight; but there is consider-
able irregularity in the changes which it undergoes. It would,
however, appear, from these observations, that the variations in
the absolute intensity were in opposition to those in the hori-
zontal resolved part of it; so that the principal cause of the
latter variations must have been a change in the dip itself.
Captain Foster considers “ that the times of the day when these
changes are the greatest and least, point clearly to the sun as
the primary agent in the production of them; and that this
agency is such as to produce a constant inflection of the pole
towards the sun during the twenty-four hours.” ‘This is in per-
fect accordance with the conclusions I had previously drawn
from the experiments on which I founded the theory of the di-
urnal variation of the needle {, as I had shown that if the diur-
nal variation of the needle arise from the cause which I have
assigned for it, the dip ought to be a maximum, in northern la-
titudes, nearly when the sun is on the south magnetic meridian,
and a minimum when it has passed it about 130°.
* Transactions of the Philosophical Sogiety of Cambridge, 1820.
+ Philosophical Transactions, 1828. t Ibid, 1827, pp. 345, 349.
REPORT ON THE MAGNETISM OF THE EARTH. 121
_, Humboldt was the first who determined that the intensity of
the whole magnetic force is different at different positions on
the earth’s surface. Having made observations on the times of
vibration of the same dipping needle, at various stations in the
vicinity of the equator, and approaching to the northern pole,
he found that the intensity of the terrestrial force decreases in
approaching the equator; but no precise law, according to which
the intensity depends upon the distance from the equator, can
be determined from these observations. _Numberless observa-
tions have since been made in both hemispheres, with every
precaution to ensure accuracy in the results, but they do not in
general accord with the theoretical formule with which they
have been compared. « .
“On the hypothesis of two magnetic poles not far removed
from the centre of the earth, if 3 represent the dip, 4 the mag-
netic latitude of the place of observation, I the intensity of the
force in the direction of the dip, and m a constant, then
weer m
~ (4. — 3 sin? 3)’
tan’ = 2 tan A;
and therefore,
I= * V (3 sin? A + 1);
or ifz is the angular distance from the magnetic pole, or the
complement of the latitude,
I= Zw (Bcos?é + 1).
By comparing his own observations with the first of these
formulz, Captain Sabine came to the conclusion that they were
“‘ decisive against the supposed relation of the force to the ob-
served dip, and equally so against any other relation whatso-
ever, in which the respective phenomena might be supposed to
vary in correspondence with each other.” Comparing them,
however, with the last formula, he concludes that “ the accord-
ance of the experimental results with the general law proposed
for their representation, cannot be contemplated as otherwise
than most striking and remarkable.” How the same set of
observations should be in remarkable accordance with the one
formula and at variance with the other, when these formule are
‘dependent on each other, it is difficult to conceive; but the
conclusion drawn by Captain Sabine from his observations, at
least shows the danger of relying upon any single set of obser-
vations as confirmatory or subversive of theoretical views. I
122 THIRD REPORT—1839.
have not yet compared with these results of theory the numer-
ous observations made by Captain Foster, both in the northern
and in the southern hemispheres ; but it is my intention to do
this as soon as I can determine what correction ought to be
made for the differences of temperature at the several stations:
I do not, however, anticipate any very close accordance.
In Captain Sabine’s observations, the observed intensities,
compared with those deduced from the preceding formule, are
in excess near the equator, and in defect near the pole; and it
is not improbable that, as Mr. Barlow has suggested, this in-
crease of magnetic action near the equator above that which
the theory gives, is due to the higher temperature in the equa-
torial regions *. I am, however, disposed.to assign even a more
powerful influence than this to difference of temperature ; for I
think it very possible, and indeed not improbable, that this may
be the primary cause of the polarity of the earth, although its
influence may be much modified by other circumstances. At
the conclusion of the paper on the diurnal variation}, to which
I have already referred, I have suggested an experiment which
I think might throw much light on this subject. I have pro-
osed that a large copper sphere, of uniform thickness, should
be filled with bismuth, the two metals being in perfect contact
throughout, and that experiments should be made with it simi-
lar to those which I had made with one of smaller dimensions,
but from which I was unable to obtain any very definite results,
in consequence of the want of uniformity in the thickness of the
copper and in the contact of the two metals. On heating the
equator of such a sphere, the parts round the poles being cooled
by caps of ice—which might not unaptly represent the polar ices,
—we may expect that currents of electricity would be excited ;
in which case the direction of those currents would decide whe-
ther the experiment were illustrative of the principal phenome-
non of terrestrial magnetism, or not. Should these currents of
electricity be in the direction of the meridians,—which is impro-
bable, since in this case opposing currents would meet at the
poles, and there would be no means of discharge for them,—I
think we might then conclude that the magnetism of the earth
cannot be due to the difference in the temperature of its polar
and equatorial regions; but if, on the contrary, the currents
should be in a direction parallel to the equator,—in which case
their action upon a magnetized needle would be to urge it in
the direction of the meridians,—I should then say that, in order
to account for the terrestrial magnetic forces, and the diurnal
* Edinburgh New Philosophical Journal, July 1827.
+ Philosophical Transactions, 1827, p. 354.
REPORT ON THE MAGNETISM OF THE EARTH. 123
changes in their direction and intensity, it would only be re-
quired to show, that electrical phenomena may be excited, in
such bodies as the earth and the atmosphere, by a disturbance
in their temperature when in contact. As I consider that if
such an experiment were carefully made it must give conclusive
results, I would strongly suggest to the Council of the British
Association the importance of having it made.
It has been a question whether the intensity of terrestrial
magnetism is the same at the surface of the sea and at heights
above that surface to which we can attain. MM. Gay-Lussac
and Biot, in their aérostatic ascent, could detect no difference
at the height of 4000 metres*. Saussure had, however, con-
cluded, from the observations which he made at Geneva, Cha-
mouni, and on the Col du Géant, that the intensity was consi-
derably less at the latter station than at either of the former,
the difference in the levels being in the one case about 10,000
feet, in the other about 7800+.
M. Kupffer t also considers that his observations in the vi-
cinity of Elbours, in which the difference of elevation of his two
stations was 4500 feet, show clearly that the horizontal intensity
decreases as we ascend above the surface; and he accounts for
this decrease not having been observed by MM. Biot and Gay-
* Biot, Traité de Physique.
+ Voyages dans les Alpes, tom. iv. p. 313.—I take for granted that, admit-
ting the accuracy of Saussure’s observations, they warranted the conclusions
he drew from them ; but some unaccountable errors must have crept in, either in
transcribing or in printing them; for not only the means which he deduces do not
result from the observations, but the numbers which he employs contradict his
conclusions. I transcribe the passage from the only edition I can consult, pub-
lished at Neufchatel, 1796. ‘“ A‘ Généve ces vingt oscillations employerent
5m 2°; 4m 50°; 5m; 4m 40®; dont la moyenne étoit 5™ 0*4; le thermometre
étant 46 dégrés. A‘ Chamouni 5™ 33"; 5" 34°; moyenne 5" 33°*:5; thermometre
12 dég. Au Col du Géant 5™ 30°3; 5™30°5 ; 5™31°-4; 5™ 34*-6, moyenne
5™ 32°-45; thermometre 12:4 dégrés.”’
_ “Or les forces magnétiques sont, inversement comme les quarrés des tems.
Mais, 4 Généve, le tems étoit 5™ 0*-4 ou 300°.4, dont le quarré = 111155°56 ;
a Chamouni 5™ 33°-5 = 333%-5, dont le quarré = 111223. Au Géant 5m
32°45 = 332*-45, dont le quarré = 11523-0025; d’ou il suivroit que la plus
grande force étoit dans la plaine, et la plus petite sur la plus haute montagne,
a peu pres d’une cinquieme: observation bien importante, si elle étoit confirmée
par des expériences répétées, et faites 4 la méme température.”
The means of the above observations are 4™ 53° = 293°, 5™ 33°-5 = 333*-5,
and 5™ 31*-7 = 331°-7; and the squares of these numbers are 85849, 111222°25,
110024:89. So that, according to this, the force was greatest at Geneva, and
least. at Chamouni. Taking Saussure’s numbers, 300*-4, 333°-5, 332°-45, their
Squares are 90240:16, 111222-25, 110523-0025; so that still the general con-
clusions are the same.
} Voyage dans les Environs du Mont Elbronz. Rapport fait @ U Académie
Impériale des Sciences de St. Petersbourg, p. 88.
124 THIRD REPORT—18338.
Lussac, by its having been counteracted by the increase of in-
tensity, arising from the diminution of temperature. Mr. Hen-
wood informs me that he has made corresponding observations,
consisting of two series, each of 3900 vibrations at each place;
on Cairn Brea Hill, 710 feet above the level of the sea; at the
surface of Dolcoath mine, 570 feet above the sea; and at a depth
of 1320 feet beneath the surface in Dolcoath mine, or 950 feet
below the level of the sea; and that, after clearing the results
from the effects of temperature, the differences are so minute
that he cannot yet venture to say he has detected any difference
in the magnetic intensity at these stations. If, notwithstanding
these results, we are to admit the correctness of M. Kupffer’s
conclusions, I think we must infer that the diminution of hori-
zontal intensity at his higher station was due to an increase in
the dip, which element would not probably be so much affected
by a change of elevation in a comparatively level country, like
Cornwall, as on the flank of such a mountain mass as Elbours.
Before dismissing the subject of the terrestrial intensity, I
should mention that attempts have been made to delineate on
charts the course of isodynamic lines. Professor Hansteen has
published a chart in which this is done for the year 1824... Of
all observations, however, requisite for graphic exhibitions con-
nected with terrestrial magnetism, those on the authority of
which such lines must be drawn are fewest in number and least
satisfactory in their results; we should, therefore, be very cau-
tious in drawing conclusions from such delineations.
Hitherto I have only referred to such changes in the direction
of the magnetic force, and in its intensity, as appear to depend
upon general causes; but, besides these, sudden and sometimes
considerable irregular changes occur. ‘These have very gene-
rally been attributed to the influence of the aurora borealis,
whether visible or not at the place of observation; and I think
it not improbable that some may be due to a peculiar electrical
state of the atmosphere, independent of that meteor. ‘The in-
fluence of the aurora borealis on the magnetic needle has, how-
ever, been denied by some, principally because, during the
occurrence of that meteor at Port Bowen, Captain Foster did
not observe peculiar changes in the direction of the needle, al-
though, from his proximity to the magnetic pole, the diurnal
change sometimes amounted to 4° or 5°; and, under such cir-
cumstances, it was considered that these changes ought to have
been particularly conspicuous. In a paper inserted in the se-
cond volume of the Journal of the Royal Institution, 1 have,
however, shown that Captain Foster’s Port Bowen observations
do not warrant the conclusions which have been drawn from
REPORT ON THE MAGNETISM OF THE EARTH. 125
them, and have pointed out circumstances which may, in this
ease, have rendered the effect of the aurora upon the horizon-
tal needle less sensible than might have been expected. ‘That
changes in the direction and intensity of the terrestrial forces
are simultaneous with the aurora borealis I feel no doubt, for I
have seen the changes in the direction of the needle to accord
so perfectly with the occurrence of this meteor, and to such an
extent, that in my mind the connexion of the phenomena be-.
came unquestionable*. As, however, the magnetic influence
of the aurora borealis has been doubted, I shall here point out
the manner in which I consider the effects may be best ob-
served.
If the magnetic forces brought into action during an aurora
are in the direction of the magnetic meridian, they will affect a
dipping needle adjusted to the plane of that meridian, but the
direction of an horizontal needle will remain unchanged: on
the other hand, if the resultant of these forces makes an angle
with the meridian, the direction of the horizontal needle will be
changed, but the dipping needle may not be affected. In order
to determine correctly the magnetic influence of the aurora by
means of an horizontal needle, it is therefore necessary not only
to have regard to those forces which influence its direction, but
likewise to those which affect the horizontal intensity. The
effects of the former are the objects of direct observation, but
those of the latter are not'so immediately observable. As, du-
ring an aurora, the intensity may vary at every imstant,—and it is
these changes which are to be detected,—the method of deter-
mining the intensity by the time of vibration of the needle can-
not here be applied, and other means must be adopted. The
best method «appears to me to be that which I employed for
determining the diurnal variation of the horizontal intensity,
the needle being retained nearly at right angles to the meridian
by the repulsive force of a magnet, or by the torsion of a fine
wire or thread of glass. For the purpose, then, of detecting
in all cases the magnetic influence of the aurora, I consider that
two horizontal needles should be employed; one, adjusted in
the meridian, for determining the changes which may take place
in the direction of the horizontal force, and the other at right
angles to the meridian, to determine the changes in the inten-
sity of that force, arising principally from new forces in the
plane of the meridian, and which would affect the direction of
the dipping needle alone. Both these needles should be deli-
* For the observations to which I here particularly refer, see the Journal of
the Royal Institution, yol. ii. p. 272. ‘
126 THIRD REPORT—1833.
eately suspended, either by very fine wire, or by untwisted
fibres of silk. In order to render the changes in the direction
of the needle in the meridian more sensible, its directive force
should be diminished by means of two magnets north and south
of it, and having their axes in the meridian. These magnets
should- be made to approach the needle until it points about
30° on either side of the meridian, and they should be so ad-
justed that the forces acting upon the needle will retain it zn
equilibrio with its marked end at about 30° to the east and 30°
to the west of north, and also at south. The needle is to be
left with its marked end pointing south, for the purpose of ob-
serving the changes occurring in its direction. If magnets are
employed to retain the second needle nearly at right angles to
the meridian, they should be made to approach its centre until
the points of equilibrium are at about 80° east, 80° west and
south, the observations being made with the needle at 80° east
or 80° west. An objection to this method of adjusting this
needle by means of magnets, and to which I have already re-
ferred in a note, is that any change in their temperature will
have a very sensible effect on the direction of the needle in this
position; and should such change take place during the ob-
servations, corrections must be applied to the results before
any accurate conclusions can be drawn from them. As, how-
ever, an aurora is not generally of long continuance, any change
in the temperature of the magnets during the observations is
much more easily guarded against than where the observations
have to be continued during successive days and at different
seasons of the year. I have before remarked that this incon-
venience will be, in a great measure, obviated by employing the
torsion of a fine wire, or a very fine filament of glass, to retain
the needle at about 80° from the meridian. In this case, the
ratio of the force of torsion to the terrestrial force acting upon
the needle having been determined, a measure will be obtained
of the changes which take place in the intensity of the terres-
trial force during the occurrence of an aurora. It is very de-
sirable that it should be ascertained whether the effects on the
needle are simultaneous with any particular class of phenomena
connected with the aurora; whether these effects are dependent
on the production of beams and corruscations, or on the forma-
tion of luminous arches ; or whether any difference exists in the
effects produced by these. In order to determine this, it is ne-
cessary that the times of the occurrence of the different pha-
nomena, and also of the changes in the directions of the needles,
should be accurately noted; and for such observations, three
observers appear to be indispensable.
REPORT ON THE MAGNETISM OF THE EARTH. 127
Whether the direction of the needle may be influenced by
_ the electrical state of the clouds, is much more doubtful than
the influence of the aurora. I am not aware of any extended
series of observations made with a view to determine this point.
Having adjusted, in a particular manner, a needle between two
magnets, so that the directive force was considerably diminished,
I found that the changes in the positions of electric clouds was
accompanied by changes in the direction of the needle; but,
although the observations indicate that the needle was thus
affected, they are of too limited a nature to draw any general
conclusion from*. Some observations of Captain Sir Everard
Home, however, indicate the same kind of influence. Ina con-
versation which I had with him last year, having referred to the
effect I had observed to be produced by the sun’s rays, of bring-
ing a vibrating needle to rest, it brought to his mind a similar
effect which he observed during a thunder-storm. He has fa-
voured me with his observations, and from these it appears
that, in two instances, a needle came sooner to rest during a
thunder-storm than it had previous or subsequent to it. The
are at which the vibrations ceased to be counted is not recorded,
but the number of vibrations was reduced in one case from 100
to 40, and in another from 200 to 120. I have, in consequence
of these observations, requested Lieutenant Barnett of the Royal
Navy, who is engaged in the survey of the southern coast of the
Gulf of Mexico, to make similar observations, should he have
an opportunity; and as thunder-storms are so frequent, and of
such intensity on that coast, I think he may obtain some im-
portant results as connected with the influence of the electric
state of the atmosphere upon the vibrations and direction of
the needle.
- Upon a review of all the phenomena of terrestrial magnetism,
and considering the intimate relation which has been established
between magnetism and electricity, by which it appears that, if
not identical, they are only different modifications of the same
principle, there can, I think, be little doubt that they are due
to electric currents circulating round the earth. How these
currents are excited, whether by heat, by the action of another
body, or in consequence of rotation, we are not at present able
to determine; but however excited, they must, though not
wholly dependent upon them, be greatly modified by the phy-
sical constitution of the earth’s surface. We are, therefore, not
to expect that symmetry in their course which would be the
_ * Philosophical Transactions, 1823, p.354. The arrangements which I have
just described for determining the influence of the aurora borealis are well
adapted for deciding this point. ,
128 THIRD REPORT—1833.
consequence of a symmetrical constitution of that surface. But
even if such symmetry did exist, the action of all the currents
at different stations on the surface could scarcely be referred
to the same two points as centres of force; and without this
symmetry, it would be absurd to expect it. The hypothesis,
therefore, of only two poles, as explanatory of the phenomena,
must be rejected; and if we are to refer these phenomena to
centres of action, we must, besides two principal ones, admit
the existence of others depending, upon local causes.
It has been said that if we refer the magnetism of the earth
to another body, we only remove the difficulty, and gain little
by the supposition*. It, however, appears to me, that if we
could show that the magnetism of the earth is due to the action
of the sun, independent of its heat,—which, however, I think
the more probable cause,—the problem would be reduced to
the same class as that of accounting for the light of the sun, the
heating and chemical properties of its rays: we only know the
facts, and are not likely to know more.
If difficulties meet us at every step when we attempt to ex-
plain the general phenomena of terrestrial magnetism, these
difficulties become absolutely insurmountable when we come to
the cause of their progressive changes. Here, at least, we
must for the present be satisfied with endeavouring to discover
whether these changes are governed by any general laws:
should they be so, their cause may possibly be discovered.
Diligent and careful observation is the only means by which
we can hope to attain this end, and indeed is that on which we
must principally rely for gaining a more correct knowledge of
all the phenomena, and of their causes ; and, consequently, im-
provements in the methods of observation, and in the instru-
ments to be employed, become of the highest importance.
This Report has already so far exceeded the limits within
which I wished to have confined it, that I must restrict the re-
marks on this part of the subject to a few points.
In the observations of Humboldt, in those of M. Rossel, of
Captain Sabine, and of Captain Foster, the terrestrial magnetic
intensity had been determined by the vibrations of a dipping
needle in the plane of the magnetic meridian; but as there is
by this means, in consequence of the friction upon the axis, a
difficulty in obtaining a sufficient number of vibrations to ensure’
accuracy, and a dipping instrument is besides ill adapted for
carriage, Professor Hanstegn proposed to determine the same
by means of a small needle suspended horizontally by a few
* Hansteen’s Inquiries concerning the Magnetism of the Earth.
P
REPORT ON THE MAGNETISM OF THE EARTH. 129
untwisted fibres of silk, The advantages, however, attending
this method of Professor Hansteen, I consider to be more ap-
parent than real; for without determining the dip, the hori-
zontal force, deduced from the vibrations of the horizontal
needle, cannot be reduced to the force in the direction of the
dip; and if the dip is determined, two instruments become ne-
cessary where, before, only one was requisite.
In order to obviate the inconveniences attending each of these
methods, I have proposed a construction for a dipping needle,
by means of which the observations which determine the di-
rection of the terrestrial force will also give a measure of its
intensity. The general principle of the construction is simply,
that the centre of gravity of the needle should not be in its
centre of figure, but in a line drawn from that centre at right
angles, both to its axis of motion and to its magnetic axis; so
that, by two observations, one with the centre of gravity up-
wards, and the other with it downwards, the dip, and likewise
the relation which the static momentum of its weight bears to
that of the terrestrial magnetic force acting upon the magnetism
of the needle, may be determined. The principles on which
these determinations depend, and. the advantages which I pro-
pose from the adoption of this construction, are fully described
in a paper read before the Royal Society, and which will appear
in the Philosophical Transactions of this year.
_ Professor Gauss has proposed a method of determining the
intensity and the changes it undergoes, by which he hopes to
reduce magnetical observations to the accuracy of astronomical
ones. By the vibrations of a magnetized bar he determines the
product of the terrestrial magnetic intensity by the static mo-
mentum of its free magnetism. By introducing a second bar,
and by observing at different:distances the joint effects of the
first; and of the terrestrial magnetism on this, he determines
the ratio of the terrestrial intensity to the static momentum of
the free magnetism of the first.. Eliminating this last from the
two equations, he obtains an absolute measure of the terres-
trial magnetic intensity, independent of the magnetism of the
bar. This is a most important result, for we shall thus be en-
abled to. determine the changes which the terrestrial intensity
- undergoes:in long intervals of time. It is, however, to be ob
served, that it is only the horizontal intensity which is thus:
determined, and that, in order to determine the intensity of the
whole force, another element, namely, the dip, must also be: ob-
served; and I fear much that the introduction of this element
will, in a great measure, counteract that accuracy of which the
merged proposed for determining the times of vibration appear
; K
130 THIRD REPORT—1833.
capable. This must be an objection, even where the observa-
tions are made in a fixed observatory ; but where an apparatus
has to be moved from one station to another, I think the method
could scarcely be applied successfully, principally on account
of the delicacy of the preliminary observations, and of the time
requisite for making them, in addition to that required for the
observations by which the terrestrial intensity and its variations
are to be determined. However greatly I may admire the saga-
city which Professor Gauss has shown in devising means for.
the determination of an absolute measure of the horizontal in-
tensity, I cannot avoid seeing the difficulties which may occur .
in its practical application.
The method which Professor Gauss proposes, and has prac-
tised, of observing the course of the daily variation, and of de-
termining the time of vibration, by means of a plane mirror
fixed on the end of the needle, perpendicularly to its axis, and
observing the reflected image of the divisions of a scale by
means of a theodolite fixed at a distance, appears to admit of
the greatest possible precision, and will probably supersede
other methods of observing the daily variation.
I have adverted to the necessity of careful and diligent ob-
servation of all the phenomena of terrestrial magnetism, as the
surest means of arriving at a knowledge of their causes: it is
with reluctance I state it, but I believe it to be a fact, that this
is the only country in Europe in which such observations are not
regularly carried on ina national observatory. Such an omission
is the more to be regretted, seeing that no one has, I believe,
carried on a regular series of observations on the diurnal va-
riation, since the valuable ones by Colonel Beaufoy were inter-
rupted by his death, this interruption happening at a time when
it was peculiarly desirable that the series should be unbroken.
At this time the needle near London had begun to show a re-
turn towards the true meridian; but whether this was one of
those oscillations which have occasionally been observed, or
that, having really attained its maximum of westerly deviation,
it was returning in the contrary direction, is, I believe, undecided
at. the present moment. Of all the data requisite for deter-
mining the laws which govern the phenomenon of the variation,
the time of the maxima and their magnitude are the most im-
portant. I trust that ere long the important desideratum will
be supplied of a regular series of magnetical observations in
the national Observatory of Great Britain.
Royal Military Academy,
_ 22nd June, 1833.
————
£1816]
Report on the present State of the Analytical Theory of H: ydro-
statics and Hydrodynamics. By the Ruy. J. Cuauuis, late
Fellow of Trinity College Cambridge.
Tue problems relating to fluids, which have engaged the atten-
tion of mathematicians, may be classed under two heads,—thosé
which involve the consideration of the attractions of the con-
stituent molecules, and the repulsion of their caloric; and those
in which these forces are not explicitly taken’ account of. In
the latter class the reasoning is made to depend on some pro-
perty derived from observation. For instance, water is observed
to be very difficult of compression; and this has led to the
assumption of absolute incompressibility, as the basis of thé
mathematical reasoning: air at rest, and under a given state of
temperature, is observed to maintain a certain relation between
the pressure and the density ; hence the fundamental property
of the fluid which is the subject of calculation is assumed to be
the constancy of this relation, to the exclusion of all the circums
stances which may cause it to vary. The fluids treated of in
this kind of problems are rather hypothetical than real, yet not
so different from real fluids but that the mathematical deduc-
tions obtained respecting them admit of having the test of ex~
periment applied. I propose in this Report to confine myself
entirely to problems of the second class,—those in the common
theory of fluids. The reasons for making this limitation are,
that both kinds together would afford too ample matter for one
Report, and that those which I have selected are distinguished
from the others by the different purpose in regard to science
which correct solutions of them would answer: for the treat-
ment of any hydrostatical or hydrodynamical questions which
involve the consideration of molecular attraction and the repul:
sion of heat, must proceed upon certain hypotheses respecting
the mode of action of these forees, and the interior constitution
of the fluid, as these are circumstances which from their nature
cannot be data of observation; and hence, assuming the ma+
thematical reasoning founded on'the hypotheses to be correct,
a satisfactory comparison of the theoretical deductions with
facts must serve principally to establish the truth of the hypo-
theses, and so to let us into secrets of nature which probably
could never be known by any other process. But when the
K2
132 THIRD REPORT—1833.
basis of calculation, as in the questions that will come before
us, is some observed and acknowledged fact, solutions which
satisfy experiments will first of all serve to confirm the truth of
the mathematical reasoning, and then give us confidence in the
theoretical results, which, as often happens, cannot readily re-
ceive the test of experiment. Calculations of this kind do not
add much to our conviction that the facts applied as the test of
the theory are really consequences of those which are the basis
of it. For instance, we feel satisfied, independently of any ma-
thematical reasoning, that the motions of waves on the surface
of water are consequences of the incompressibility of the fluid,
and the law of equal pressure. But the purpose which these
calculations answer of confirming methods of applying analysis
is very important, particularly in regard to the higher class of
physical questions, which M. Poisson has proposed to refer to
a distinct department of science, under the title of Mathéma-
tiqgue Physique, viz. those that require in their theoretical treat-
ment some hypotheses respecting the interior constitution of
‘bodies, and the laws of corpuscular action: for in questions of
this nature, as well as in problems in the common theory of
fluids, the mathematical reasoning conducts to partial differen-
tial equations; and if the method of treating these, and of
drawing inferences from their integrals, be established in one
kind, it may be a guide to the method to be adopted in the
other. It is plainly, then, desirable that the mathematical pro-
cesses be first confirmed in the cases in which the basis of rea-
soning is an observed fact, that the reasoning may proceed with
certainty in those cases where it is based on an hypothesis, the
truth of which it proposes to ascertain.
_ The subjects of this Report may now be stated to be, the
leading hydrostatical and hydrodynamical problems recently
discussed, which proceed upon the supposition of an incom-
pressible fluid, or of a fluid in which the quotient of the pres-
sure divided by the density is a constant; and the end it has
in view is, to ascertain to what extent, and with what success,
analysis has been employed as an instrument of inquiry in these
problems. Iam desirous it should be understood that I have
not attempted to make a complete enumeration either of the
questions that have been discussed in this department of science,
or of the labours of mathematicians in those which have come
under notice. It has rather been my endeavour to give some
idea of the most approved methods of treating the leading
problems, and the possible sources of error or defect in the
solutions. In taking this course I hope I may be considered. to
have acted sufficiently in accordance with the recommendation
ae
REPORT ON HYDROSTATICS AND HYDRODYNAMICS. 133
of the Committee for Mathematics, which was the occasion of
my receiving the honour of a request to take this Report in
hand.
With the limitation above stated as to the subjects our Re-
port is to embrace, we shall have scarcely anything to say on
the analytical theory of hydrostatics. The problems of interest
in this department were early*solved, and present no difficulty
in principle, and little in the detail of calculation. The deter~
mination of the height of mountains by the barometer is a
hydrostatical question, the difficulty of which does not consist
in the analytical calculation, but only in ascertaining the law of
the distribution of the atmospheric temperature. We shall not
have to speak of the theories that have been invented to over-
come this difficulty. Neither does it fall within the scope of this
Report to notice the very valuable memoir of M. Poisson on
the equilibrium of fluids*, which has for its object the deriva-
tion of the general equations of equilibrium from a consideration
of molecular attraction and the repulsion of caloric, and seems
to have been composed in immediate reference to the theory
of capillary attraction, which the author subsequently pub-
lished. With regard to the problem of capillary attraction, we
may remark, that it is not possible by any supposition respect-
ing the forces which sustain or depress the fluid in the tube,
to solve it as a question in the common theory of hydrostatics.
M. Poisson has shown the insufficiency of Laplace’s theory,
and by taking into account the molecular forces and the effect
of heat, has proved that the explanation of the phenomenon is
essentially dependent on a modification of the property which.
is the basis of the common theory, viz. the incompressibility of
the fluid. It does not fall within our province to say more on
the celebrated theory of M. Poisson.
One improvement I consider to have been recently made in
the common theory of fluids. It has been usual to take the law
of equal pressure as a datum of observation. Professor Airy,
in his Lectures in the University of Cambridge, has shown that
this property may be derived, by reasoning according to esta-
blished mechanical principles, from another of a simpler kind,
the notion of which may be gathered from observation, viz.
that the division of a perfect fluid may be effected without the
application of sensible force; from which it immediately follows
that the state of equilibrium or motion of a fluid mass is not
altered by mere separation of its parts by an indefinitely thin
partition. A definition of fluids founded on this principle, and
* Mémoires de U Académie des Sciences, Paris, tom, ix. 1830.
134 THIRD REPORT—1833.
a proof of the Jaw of equal pressure, are given at the beginning
of the Elements of Hydrostatics and Hydrodynamics of Pro-
fessor Miller*. Several advantages attend this mode of com-
mencing the mathematical treatment of fluids. The principle
is one which perfectly characterizes fluids, as distinguished in
the internal arrangement of their particles from solids. It may
be rendered familiar to the senses. It is, I think, necessary for
the solutions of some hydrostatical and hydrodynamical pro-
blems, particularly those of reflection}. Lastly, in reference
to the department of science proposed to be called Physical
Mathematics, the propositions of the common theory ought to
be placed on the simplest possible basis, because the questions
of most interest in that department are those which have in
view the explanation of the phenomena that are the founda-
tions of the reasoning in the other kind. ‘The solution of one
such question is a great step in scientific generalization. It is
plainly, therefore, of importance that the fact proposed for ex-
planation should be the simplest that direct observation can
come at.
- The analytical theory of hydrodynamics is of a much more
difficult nature than that of hydrostatics. The assumptions it is
necessary to make to obtain even approximate solutions of the
simplest problems of fluid motion betray the difficulty and im-
perfection of this part of science. There are cases, however, of
steady motion, that is, of motion which has arrived at a perma-
nent state, so that the velocity is constantly the same in quantity
and direction at the same point, which require a much more
simple analysis than those which do not satisfy this condition. It
does not appear that the equations applicable to this kind of mo-
tion were obtained in any general manner till they were given in
an Elementary Treatise on Hydrostatics and Hydrodynamics
by Mr. Moseley t, who has derived them from a principle of so
simple a nature, that, as it can be stated ina few words, it may
be mentioned here. When the motion is steady, each particle
in passing from one point to another, passes successively through
the states of motion of all the particles which at any instant le
on its path. 'This principle is valuable for its generality: it is
equally applicable to all kinds of fluids, and will be true, whe-
ther or not the effect of heat be taken into account, if only the
condition of steadiness remains. The equations of motion are
readily derived from it, because it enables us to consider the
_* Cambridge 1831.
+ Dr. Young employed an equivalent principle to determine the manner of
the reflection of waves of water. See his Natural Philosophy, vol. ii. p. 64.
} Cambridge 1830.
ee eee
REPORT ON HYDROSTATICS AND HYDRODYNAMIcS. 135
motion of a single particle, in the place of the motion of an
aggregate of particles. Though this mode of deriving them is
the best possible on account of its simplicity, it was yet de-
sirable to know how they may be obtained from the general
equations of fluid motion. In a paper contained in the Trans-
actions of the Philosophical Society of Cambridge*, the author
of this Report has given a method of doing this, both for incom-
pressible and elastic fluids, and has shown that a term in the
general formule which gives rise to the complexity common to
most hydrodynamical questions, disappears for this kind of
motion. Euler had already done the same for incompressible
fluids}. The instances in nature of fluid motion of the steady
kind are far from uncommon; and it is probable that when the
equations applicable to them are better known, and studied
longer, they may be employed in very interesting researches.
The motion of the atmosphere, as affected by the rotation of
the earth, and a given distribution of the temperature due to
solar heat, seems to be an instance of this kind.
We will now proceed to consider in order the principal hydro-
dynamical problems that have recently engaged the attention
of mathematicians. For convenience we shall class them as
follows :—I. Motion in pipes and vessels. II. The velocity of
propagation in elastic fluids. III. Musical vibrations in tubes.
IV. Waves at the surface of water. V. The resistance to the
motion of a ball-pendulum.
I. The motion of fluids in pipes and vessels has not been
treated with any success, except in the cases in which the con-
dition of steadiness is fulfilled. ‘The paper above alluded to,
in the Transactions of the Philosophical Society of Cambridge,
contains some applications of the equation of steady motion for
incompressible fluids, to determine the velocity of water issuing
from different kinds of adjutages in vessels of any shape: also
-a theoretical explanation of a phenomenon which a short while
ago excited some attention,—that of the attraction of a disc to
an orifice through which a steady current either of water or air
is issuing.
In the Memoirs of the Paris Academy of Sciences there is
an Essay by M. Navier on the motion of elastic fluids in ves-
sels, and through different kinds of adjutages into the sur-
rounding air, or from one vessel into another. For the sake of
simplicity the author considers the fluid to be subject to a con-
stant pressure, and consequently the motion to have arrived at
a state of permanence. His calculations are founded upon the
* Vol. iii. Part II]. + Mémoires de UV Académie de Berlin, 1755, p. 344.
+ Tom. ix. 1830.
136 AH THIRD REPORT—1833.
hypothesis of parallel slices, which assumes the velocity to be
the same, and in the same direction, and the density to be the
same at all points of any section transverse to the axis of the
vessel or pipe. This hypothesis is one of those that the theory
of hydrodynamics has borrowed from experience to supply its
defects. Lagrange has, however, shown theoretically * that it
always furnishes a first approximation, the breadth of the ves-
sel being considered a quantity of the first order, and the effect
of the adhesion of the fluid to the sides of the vessel being neg-
lected. It is right to observe, that in the problems M. Navier
has considered, this hypothesis might have been in a great
measure dispensed with: the expression he has given,—more
correct than that commonly adopted for the velocity of issuing
through a small aperture by which airs of different densities
communicate,—might have been obtained by employing the equa-
tion above mentioned of steady motion, as, in fact, Mr. Moseley
has done}. This would be a preferable mode of treating such
questions, because in every instance in which these auxiliary
hypotheses are got rid of, something is gained on the side of
theory. This memoir contains another hypothesis, which can-
not be so readily dispensed with. Theory is at present quite
inadequate to determine the retardation in the flow of fluids
occasioned by sudden contractions or widenings in the bore of
the pipe. It is found by experiments with water, that the re-
tardation is sufficiently represented by taking account of the
loss of vs viva which, on the hypothesis of parallel slices, will
result from the sudden changes of velocity which must be sup-
posed to take place at the abrupt changes in the bore of the
pipe. M. Navier extends these considerations to elastic fluids.
The theory manifests a sufficient agreement with the experi-
ments it is compared with, and is valuable on account of the
applications it may receive.
II. The most interesting class of problems in hydrodynamics
are perhaps those which relate to small oscillations. Newton
was the first to submit the vibrations of the air to mathema-
tical calculation. The propositions in the second book of the
Principia, devoted to this subject, and to the determination of
the velocity of sound, may be ranked among the highest pro-
ductions of his genius. He has assumed that the vibratory
motion of the particles follows the law of the motion of an oscil-
lating pendulum. It was soon discovered that many other
assumed laws of vibration would, by the same mode of reasoning,
* Mécanique Analytique, Part II. § xi. art. 34.
+ Elementary Treatise, p. 204.
REPORT ON HYDROSTATICS AND HYDRODYNAMICS. 137
conduct to the same velocity of propagation. This, which was
thought to be an objection to the reasoning, is an evidence of
its correctness: for the plain consequence is, that the velocity
of propagation is independent of the kind of vibration which
we may arbitrarily impress on the fluid;—and so experience
finds it to be.
When the partial differential equation, which applies equally
to the vibrations of the air and those of an elastic chord, had
been formed and integrated, a celebrated discussion arose
between Euler and D’Alembert as to the extent to which the
integral could be applied; whether only to cases in which the
motion was defined by a continuous curve, or also to motion
defined by a broken and discontinuous line. It is well known
that the question was set at rest by Lagrange, in two Disser-
tations published in vol. i. and vol. ii. of the Miscellanea Tau-
rinensia. The difficulty that arrested the attention of these
eminent mathematicians was one of a novel kind, and peculiar
to physical questions that require for their solution the integrals
of partial differential equations. The difficulty of integration,
which is the obstacle in most instances, had been overcome by
D’Alembert. It remained to draw inferences from the inte-
gral,—to interpret the language of analysis. When an aggre-
gate of points, as a mass of fluid or an elastic chord, receives
an arbitrary and irregular impulse, any point not immediately
acted upon may have a correspondent irregular movement after
the initial disturbance has ceased. This is a matter of experi-
ence. Was it possible, then, that these irregular impulses, and
the consequent motions, were embraced by the analytical calcu-
lation? From Lagrange’s researches it follows that the func-
tions introduced by integration are arbitrary to the same degree
that the motion is so practically, and that they will therefore
apply to discontinuous motions. (Of course we must except
the practical disturbances which the limitations of the calcula-
tion exclude,—those which are very abrupt, or very large.)
This has been a great advance made in tke application of ana-
lysis to physical questions. Had a different conclusion been
arrived at, many facts of nature could never have come under
the power of calculation.. The Researches of Lagrange, which
will ever form an epoch.in the science of applied mathematics,
establish two points principally: First, That the arbitrary func-
tions, as we have been just saying, are not necessarily conti-
nuous: Secondly, That (in the instance he considered) they are
equivalent to an infinite series of terms having arbitrary con-
stants for coefficients, and proceeding according to the sines of
multiple arcs. This latter result, which appears to be true for
1388 THIRD REPORT—1833.
all linear partial differential equations of the second order, with
constant coefficients, is valuable as presenting an analogy be-
tween arbitrary constants and arbitrary functions.
But the way in which Lagrange, after establishing these two
points, proceeds to find the velocity of propagation, does not
appear to me equally satisfactory with the rest of his reasoning.
His method seems to be a departure from the principle which
may be gathered from that of Newton. For, as was mentioned
above, the reasoning of the Principia shows that the velocity of
propagation is independent of all that is arbitrary. It seems
important to the truth of the analytic reasoning, that it should
not only obtain a constant velocity of propagation, but arrive at
it by a process which is independent of the arbitrary nature of
the functions; whereas the method which the name of La-
grange has sanctioned, is essentially dependent on the discon-
tinuity of the functions, that is, on their being arbitrary. With
a view of calling attention to this difficulty, and as far as possi-
ble removing it, the author of this Report read a paper before
the Philosophical Society of Cambridge, which is published in
Vol. iii. Part I. of their Transactions. Iam far from assert-
ing that that Essay has been successful; but some service, I
think, will be done to science if it should lead mathematicians to
a reconsideration of the mode of mathematical reasoning to be
employed in regard to the applications of arbitrary functions.
if the. determination of the velocity of propagation in elastic
fluids were the only problem affected by this treatment of arbi-
trary functions, it would not be worth while to raise a question
respecting the principle of the received method, as no doubt
attaches to the result obtained by it; but there are other pro-
blems, (one we shall have to consider,) the correct solutions of
which mainly depend on the construction to be put upon these
functions. The difficulty I am speaking of, which is one of a
delicate and abstract nature, will perhaps be best understood
by the following queries, which seem calculated to bring the
point to an issue :—Can the arbitrary functions be immediately
applied to any but the parts of the fluid immediately acted upon
by the arbitrary disturbance, and to parts indefinitely near to
these? To apply them to parts more remote, is it not necessary
first to obtain the law of propagation? And do not the arbi-
trary functions themselves, by the quantities they involve, fur-
nish us with means of ascertaining the law of propagation,
independently of any consideration of discontinuity ?
Kuler and Lagrange determined the velocity of propagation
in having regard tothe three dimensions of the fluid, on the li-
mited: supposition that the initial disturbance is the same as’ to
REPORT ON HYDROSTATICS AND HYDRODYNAMICS. 139
dénsity and velocity, at the same distance in every direction
from a fixed point, which is the centre of it. Laplace first dis-
pensed with this limitation in the case in which two dimensions
only of the fluid are taken account of*. The principal cha-
racter of his analysis is a new method of employing definite
integrals. Finally, M. Poisson solved the same problem for
three dimensions of the fluid}. This memoir deserves to be
particularly mentioned for the interesting matter it contains.
The object of the author is to demonstrate, in a more general
manner than had been before done, some circumstances of the
motions of elastic fluids which are independent of the particular
motions of the fluid particles, such as propagation and reflection.
The general problem of propagation just mentioned he solves
by developing the integral of the partial differential equation of
the second order in x, y, 2, and ¢, applicable to this case, in a
series proceeding according to decreasing powers of the di-
stance from the centre of disturbance, as it cannot be obtained.
in finite terms, and then transforming the series into a definite
integral,—a method which has of late been extensively em-
ployed. The crossing of waves simultaneously produced by
disturbances at several centres, is next considered, and this
leads to a general solution of the problem of reflection at a plane
surface. For the case in which the motions of the aérial parti-
cles are not supposed small, the velocity of propagation along
a line of air is shown to be the same as when they are small.
This result is an inference drawn from the arbitrary disconti-
nuity of the motion, on which it does not seem to depend. In
a paper before alluded to}, the same result is obtained without
reference to the principle of discontinuity. M. Poisson treats
also of propagation in a mass of air of variable density, such as
the earth’s atmosphere. His analysis is competent to prove, in
accordance with experience, that the velocity of sound is the
same as in a mass of uniform density, and that its intensity at
any place depends, in addition to the distance from the point
of agitation, only on the density of the air where the disturbancé
is made. So that a bell rung in the upper regions of the air
will not sound so loud as when rung by the same effort below,
but will sound equally loud at all equal distances from the place
where it is rung.
In seeking for the general equations of the motion of fluids,
(first obtained by Euler,).a quantity § is met with which, if it be
* Mémoires de V Académie, An 1779. ;
+ “Mémoire sur la Théorie du Son,”. Journal de l’Ecole Polytechnique,
tom. vii. cah, xiv.
} Transactions of the Philosophical Society of Cambridge, vol. iii. Part II.
§ In M. Poisson’s writings this quantity is udz + vdy +udz.
140 THIRD REPORT—1833. -
an exact differential of a function of three variables, renders the
subsequent analytical reasoning much simpler than it would be
in the contrary case. This simplification has been proved by
Lagrange to obtain in most of the problems of interest that are
proposed for our solution*. Euler showed that the differential
is inexact when the mass of fluid revolves round an axis so that
the velocity is some function of the distance from the axis +.
But no general method exists of distinguishing the instances in
which the quantity in question is a complete differential, and
when it is not. Nor is it known to what physical circumstance
this peculiarity of the analysis refers. To clear up this point
is a desideratum in the theory of hydrodynamics. M. Poisson
has left nothing to be desired in the generality with which he
has solved the problem of propagation of motion in elastic fluids ;
for in the Memoirs of the Academy of Parist he has given
a solution of the question, without supposing the initial disturb-
ance to be such as to make the above-mentioned quantity an
exact differential. His conclusions’ are, that the velocity of
propagation is the same as when this supposition is made ; that
the part of the motion which depends on the initial condensa-
tions or dilations follows the same laws as in that case, but
the part depending on the initial velocity does not return com-
pletely to a state of repose after a determinate interval of time;
that at great distances from the place of agitation there is no
essential difference between the motion in the two cases.
III. We turn now to the theory of musical vibrations of the
air in cylindrical tubes of finite length. Little has been effected
by analysis in regard to this interesting subject. The principal
difficulty consists in determining the manner in which the mo-
tion is affected by the extremities of the tube, whether open or
closed, but particularly the openend. Those who first handled
the question reasoned on the hypotheses, that at the open end
the air is always of the same density as the external air to
maintain an equilibrium with it, and at the closed end always
stationary by reason of the stop. The latter supposition will
be true only when the stop is perfectly rigid. It does not ma-
terially affect the truth of the reasoning ; but if the other sup-
position were strictly true, the sound from the vibrating column
of air in the tube would not cease so suddenly as experience
shows it does, when the disturbing cause is removed; neither
on this hypothesis could the external air be acted on so as to
receive alternate condensations and rarefactions, and transmit
* Mécanique Analytique, Part II. § xi. art. 16.
+ Mémoires de ! Académie de Berlin, 1755, p. 292.
ft tom. x. 1831. :
REPORT ON HYDROSTATICS AND uypropynamics. 141
sonorous waves. ‘These objections to the old theory have been
stated by M. Poisson, who proposes a new mode of considering
the problem*. He reasons on an hypothesis which embraces
both the case of an open and a closed end, viz. that the velo-
city at each is in a constant ratio to the condensation. This
ratio will be very large for the open end, and a very small frac-
tion for the closed end. Its exact value in the latter case de-
pends on the elasticity of the stop, and in the other on the mode
of action of the vibrations on the external air,—to determine
which is a problem of great difficulty, which M. Poisson has
forborne to meddle with. His theory is not competent to assign
a priori either the series of tones or the gravest that can be
sounded by a tube of given length, but is more successful in
determining the number of nodes and loops, and the intervals
between them, when a given tone is sounded. To find the di-
stances of the nodes and loops from the extremities of the tubes,
he has recourse to the hypotheses of the old theory, which
make the closed end the position of a node, and the open end
the position of aloop. This, he says, will not be sensibly dif-
ferent from the truth, if, in the one case, the stop be very un-
yielding, and, in the other, the diameter of the tube be small.
Recent researches on this subject, which we shall presently
speak of, show that when the diameter is not very small the
position of the loop is perceptibly distant from the open end.
" The latter part of M. Poisson's memoir contains an applica-
tion of the principles of the foregoing part to the vibrations of
air in a tube composed of two or more cylinders of different dia-
meters, and to the motion of two different fluids superimposed
in the same tube. In the course of this latter inquiry, the au-
thor determines the reflection which sound experiences at the
junction of two fluids; and by an extension of like considerations
to luminous undulations, obtains the same expressions for the
relative intensities of light perpendicularly incident, and re-
flected at a plane surface, as those given by Dr. Young in the
Article Curomatics of the Supplement to the Encyclopedia
Britannica. This subject was afterwards resumed by M. Pois-
son at greater length in a very elaborate memoir ‘ On the Mo-
tion of two Elastic Fluids superimposed +,” which is chiefly
remarkable for the bearing which the results have upon the
theory of light.
_ At the last meeting, in May this year, of the Philosophical So-
ciety of Cambridge, a paper was read by Mr. Hopkins, in which,
* Mémoires de U Académie des Sciences, Paris, An 1817.
+ Ibid. tom. x. p. 317.
142 THIRD REPORT—1833.
by combining analysis with a delicate set of experiments, te~
sults are obtained which are a valuable addition to this part of
the theory of fluid motion. His experiments were made on a
tube open at both ends, and the column of air within it was put
in motion by the vibrations of a plate of glass applied close to
one end. ‘The following are the principal results. The nodes
are not points of quiescence, but of minimum vibration ;—the
extremity of the tube most remote from the disturbance is not
a place of maximum vibration, but the whole system of places
of maximum and minimum vibration is shifted in a very sensible
degree towards it ;—the distances of the places of maximum
and minimum vibration from each other, and from that extre-
mity, remain the same for the same disturbance, whatever be the
length of the tube. This last fact Mr. Hopkins proves by his
analysis must obtain. The shifting of the places of maximum
and minimum vibration is not accounted for by the theory: nor
is it probable that it can be, unless the consideration of the
mode of action of the vibrations on the external air be entered
upon,—an important inquiry, but, as I said before, one of great
difficulty. I think also that the effect of the vibrations of the
tube itself on the contained air ought to be taken into account.
IV. The problem of waves at the surface of water is princi-
pally interesting as furnishing an exercise of analysis. ‘The
general differential equations of fluid motion assume a very sim-
ple form for the case of oscillations of small velocity and extent,
and seem to offer a favourable opportunity for the application
of analytical reasoning. Yet mathematicians have not succeed-
ed in giving a solution of the problem in any degree satisfactory,
which does not involve calculations of a complex nature. We
need not stay to inquire in what way Newton found the velo-
city of the propagation of waves to vary as the square root of
their breadths: he was himself aware of the imperfection of his
theory. The question cannot be well entered upon without
partial differential equations. Laplace was the first to apply to
it a regular analysis. His essay is inserted at the end of a
memoir on the oscillations of the sea and the atmosphere, in
the volume of the Paris Academy of Sciences for the year 1776.
The differential equations of the motion are there formed on
the supposition that the velocities and oscillations are always so
small that their products, and the powers superior to the first,
may be neglected. The problem without this limitation be-
comes so complicated that no one has dared to attempt it. La-
place’s reasoning conducts to a linear partial differential equa-
tion of the second order, consisting of two terms, which is
readily integrated; but on account of the difficulty of obtaining a
REPORT ON HYDROSTATICS AND HYDRODYNAMICS. 143
general solution from this integral, he makes a particular sup-
position, which is equivalent to considering the fluid to be de-
ranged from its state of equilibrium by causing the surface in
its whole extent to take the form of a trochoid, ¢. e. a serpentine
curve, of which the vertical ordinate varies as the cosine of the
horizontal abscissa. The solution in question is of so limited
a nature, that we may dispense with stating the results arrived
at.
In the volume of the Memoirs of the Academy of Berlin for
the year 1786, Lagrange has given* a very simple way of
proving, in the Newtonian method of reasoning, that the ve-
locity of propagation of waves along a canal of small and con-
stant depth and uniform width, is that acquired by a heavy
body falling through half the depth. In the Mécanique Ana-
lytique+ the same result is obtained analytically. ‘The princi-
al feature of the analysis in this solution is, that the linear
partial differential equation of the second order and of four va-
riables, to which the reasoning conducts, is integrated approxi-
mately in a series. Lagrange is of opinion, that on account of
the tenacity and mutual adherence of the parts of the fluid, the
motion extends only to a small distance vertically below the
surface agitated by the waves, of whatever depth the fluid may
be; and that his solution will consequently apply to a mass of
fluid of any depth, and will serve to determine, from the ob-
served velocity of propagation, the distance to which the motion
extends downwards.
The problem of waves was proposed by the French Institute
for the prize subject of 1816. M. Poisson, whose labours are
preeminent in every important question of Hydrodynamics, had
already given this his attention. His essay, which was the first
deposited in the bureau of the Institute, was read Oct. 2, 1815,
just at the expiration of the period allowed for competition. It
forms the first part of the memoir ‘‘ On the Theory of Waves,”
published in the volume of the Academy for the year 1816, and
contains the general formulz required for the complete solution
of the problem, and the theory, derived from these formule, of
waves propagated with a uniformly accelerated motion. In the
month of December following, an additional paper was read by
M. Poisson on the same subject, which forms the second part
of the memoir just mentioned, and contains the theory of waves
propagated with a constant velocity. These are much more
sensible than the waves propagated with an accelerated motion,
and are in fact those which are commonly seen to spread in
* p. 192, + Part II. sect. xi. art. 36.
144: THIRD REPORT—1833.
circles round any disturbance made at the surface of water.
No theory of waves which does not embrace these can be con-
sidered complete. In the essay of M. Cauchy, which obtained
the prize, and is printed in the Mémoires des Savans*, the
theory of only the first kind of waves is given. This essay,
however, claims to be more complete than the first part of
M. Poisson’s memoir, because it leaves the function relative to
the initial form of the fluid surface entirely arbitrary, and conse-
quently allows of applying the analysis to any form of the body
immersed to produce the initial disturbance. M. Poisson re-
stricts his reasoning to a body, of the form of an elliptic para-
boloid, immersed a little in the fluid, with its vertex downward
and axis vertical; and as this form may have a contact of the
second order, with any continuous surface, the reasoning may
be legitimately extended to any bodies of a continuous form,
but not to such as have summits or edges, like the cone, cy-
linder and prism. This restriction having been objected to as a
defect in the theory}, M. Poisson answers} that his analysis.
is not at fault, but that one of the differential equations of the
problem, which expresses the condition that the same particles
of water remain at the surface during the whole time of motion,
very much restricts the form which the immersed body may be
supposed to have. When the initial motion is produced by the
immersion of a body whose surface presents summits or edges,
it is not possible, he thinks, to represent the velocities of the
fluid particles by analytical formule, especially at the first in-
stants of the agitation, when the motion must be very complicated,
and the same points will not remain constantly at the surface.
With the exception of the particular we have been mention-
ing, the two essays do not present mathematical processes es-
sentially different in principle. Attached to that of M. Cauchy,
which was published subsequently to M. Poisson’s memoir, are
valuable and copious additions, serving to clear up several
points of analysis that occur in the course of the work, and re-
ferring chiefly to integration by series and definite integrals,
and to the treatment of arbitrary functions. Among these is a
lengthened discussion of the theory of the waves uniformly
propagated, the existence of which, as indicated by the analysis,
had escaped the notice of both mathematicians in their first re-
searches. In this discussion the velocities of propagation are
determined of the two foremost waves produced by the immer-
* vol. iii.
+ Bulletin de la Société Philomatique, Septembre 1818, p. 129.
+ “Note sur le Probléme des Ondes,” tom. viii. of Mémoires de lV Académie
des Sciences, p. 571. :
REPORT ON HYDROSTATICS AND HYDRODYNAMICS, 145
sion and sudden elevation of bodies of the forms of a parabo-
loid, a cylinder, a cone, and a solid, generated by the revolution
of a parabola about a tangent at its vertex. To bodies of the
last three forms, M. Poisson objects to extending the reasoning;
and in the ‘‘ Note” above referred to, attempts to show that such
an extension leads to results inconsistent with the principle of
the coexistence of small vibrations. If we are not permitted to
receive the analysis of M. Cauchy in all the generality it lays
claim to, we must at least assent to the reasonableness of the
following conclusion it pretends to arrive at, viz. that ‘the
heights and velocities of the different waves produced by the
immersion of a cylindrical or prismatic body depend not only
on the width and height of the part immersed, but also on the
form of the surface which bounds this part.”. There is also
much appearance of probability in a remark made by the
same mathematician, that the number of the waves produced
may depend on the form of the immersed body and the depth
of immersion.
We proceed to say a few words on the contents of M. Pois-
son’s memoir. He commences by showing, as well by @ priort
reasoning as by an appeal to facts, that Lagrange’s solution
cannot be extended to fluid of any depth. In his own solution
he supposes the fluid to be of any uniform depth, but princi-
pally has regard to the case which most commonly occurs of a
very great depth: he neglects the square of the velocity of the
oscillating particles, as all have done who have attempted this
problem, and assumes, that a fluid particle which at any instant
is at the surface, remains there during the whole time of the
motion. This latter supposition seems necessary for the con-
dition of the continuity of the fluid. With regard to the neg-
lect of the square of the velocity, it does not seem that we can
tell to what extent it may affect the calculations so well as in
the case of the vibrations of elastic fluids, where the velocity of
the vibrating particle is neglected in comparison of a known and
constant velocity, that of propagation. M. Poisson treats first
the case in which the motion takes place in a canal of uniform
width, and, consequently, abstraction is made of one horizontal
dimension of the fluid; and afterwards. the case in which the
fluid is considered in its three dimensions. The former requires
for its solution the integration of the same differential equation
of two terms* as that occurring in Laplace’s theory. No use
is made of the common integral of this equation, as, on account
of the impossible quantities it involves, it would be difficult
* In M. Poisson’s works this equation is PD + #® = 0.
aux * dyr
1833. L i
146 THIRD REPORT—1833.
to make it serve to determine the laws of propagation. It is
remarkable that this integral is not necessary for solving the
problem, although, as M. Poisson has shown in his first me-
moir, ‘ On the Distribution of Heat in Solid Bodies,” and M.
Cauchy in the Notes added to his ‘‘ Theory of Waves,” a solu-
tion may be derived from it equivalent to that which they have
given without its aid. We may be permitted to doubt whether
its meaning is yet fully understood, and to hope that, by over-
coming some difficulty in the interpretation of this integral, the
problem of waves may receive a simpler solution than has hi-
therto been given. Be this as it may, the process of integration
adopted by M. Poisson leaves nothing to be wished for in regard
to generality. It is easy to obtain an unlimited number of par-
ticular equations not containing arbitrary functions, which will
satisfy the differential equation in question, and to combine
them all in an expression for the principal variable (¢), deve-
loped in series of real or imaginary exponentials. This will be
the most general integral the equation admits of, and (to use
the words of M. Poisson,) ‘‘ there exist theorems, by means of
which we may introduce into expressions of this nature, arbi-
trary functions, which represent the initial state of the fluid:
the difficulty of the question consists then in discussing the re-
sulting formule, and discovering from them all the laws of the
phenomenon. ‘The theory of waves furnishes at present the
most complete example of a discussion of this sort.”
In a Report like the present, it is not possible to give any
very precise idea of the analysis which has been employed for
solving the problem of waves. I have thought it proper to call
attention to a process of reasoning which has been very exten-
sively employed by the French mathematicians of the present
day, and indeed may be considered to be the principal feature
of their calculations in the more recent applications of mathe-
matics to physical and mechanical questions. To understand
fully the nature and power of the method, the works of Fourier,
particularly The Analytical Theory of Heat, the Notes, before
spoken of, to M. Cauchy’s “ ‘Theory of Waves,” and the two
memoirs of M. Poisson ‘ On the Distribution of Heat in Solid
Bodies,” must be studied. I will just refer to some parts of the
writings of the last-mentioned geometer, where he has been
careful to state in a concise manner the principle of the method
in question. ‘There are some remarks on the generality of a
main step in the process in the Bulletin de la Société Philoma-
tique*. 'The note before spoken of in the eighth volume of the
* An 1817, p. 180.
REPORT ON HYDROSTATICS AND HYDRODYNAMICS. 147
Memoirs of the Academy concludes with a brief account of the
history and principle of this way of expressing the complete
integral by a series of particular integrals, and introducing the
arbitrary function. But I would chiefly recommend the peru-
sal of the remarks at the end of a memoir by this author “ On
the Integration of some linear partial Differential Equations ;
and particularly the general Equation of the Motion of Elastic
Fluids.” To the memoir itself I beg to refer, by the way, as
presenting a demonstration of the constancy of the velocity of
propagation from an irregular disturbance in an elastic fluid,
more simple and direct than that in the Journal de l’ Ecole Po-
lytechnique. It contains also a general integral of the linear
partial differential equation of three terms, which occurs in the
problem of waves for the case in which the three dimensions of
the fluid are taken account of; but the author does not consider
this integral of much utility, because of the impossible quantities
involved in it, and rather recommends the method of express-
ing the principal variable by infinite series of exponentials. In
fact, in the ‘Theory of Waves” this case is treated in a manner
exactly analogous to that in which abstraction is made of one
dimension of the fluid.
It may be useful to state some of the principal results ob-
tained by theory respecting the nature of waves, to give an idea
of what the independent power of analysis has been able to ef-
fect.
With respect, first, to the canal of uniform width, the law of
the velocity of propagation found by Lagrange is confirmed by
M. Poisson’s theory when the depth is small, but not other-
wise.
When the canal is of unlimited depth, the following are the
chief results :
(1.) An impulse given to any point of the surface affects in-
stantaneously the whole extent of the fluid mass. ‘The theory
determines the magnitude and direction of the initial velocity of
each particle resulting from a given impulse.
_ (2.) “ The summit of each wave moves with a uniformly acce-
lerated motion.”
- This must be understood to refer to a series of very small
waves, called by M. Poisson dents, which perform their move-
ments as it were on the surface of the larger waves, which he
calls “ Jes ondes dentelées.” Each wave of the series is found
to have its proper velocity, independent of the primitive im-
pulse. Waves of this kind have been actually observed: they
are small from the first, and quickly disappear.
(3.) At considerable distances from the place of disturbance,
L2
148 THIRD REPORT—1833.
there are waves of much more sensible magnitude than the pre-
ceding. Their summits are propagated with a uniform velocity,
which varies as the square root of the breadth a@ fleur deau of
the fluid originally disturbed. Yet the different waves which
are formed in succession are propagated with different veloci-
ties: the foremost travels swiftest. The amplitude of oscilla-
tions of equal duration are reciprocally proportional to the
square root of the distances from the point of disturbance.
(4.) The vertical excursions of the particles situated directly
below the primitive impulse, vary according to the inverse ratio
of the depth below the surface. This law of decrease is not so
rapid but that the motion will be very sensible at very consider-
able depths: it will not be the true law, as the theory proves,
when the original disturbance extends over the whole surface
of the water, for the decrease of motion in this case will be
much more rapid.
The results of the theory, when the three dimensions of the
fluid are considered, are analogous to the preceding, (1), (2), (8),
(4), and may be stated in the same terms, excepting that the am-
plitudes of the oscillations are inversely as the distances from
the origin of disturbance, and the vertical excursions of the par-
ticles situated directly below the disturbance vary inversely as
the square of the depth.
There is a good analysis of M. Poisson’s theory, and a com-
parison of many of the results with experiments, in a Treatise
by M. Weber, entitled Wellenlehre auf Experimente gegriin-
det*. The experiments of M. Weber were made in a manner
not sufficiently agreeing with the conditions supposed in the
theory to be a correct test of it. They, however, manifest a
general accordance with it, and confirm the existence of the
small accelerated waves near the place of disturbance, and of a
sensible motion of the fluid particles at considerable depths
below the surface. In one particular, in which the theory ad-
mits of easy comparison with experiment, it is not found to
agree. When the body employed to cause the initial agitation
of the water is an elliptic paraboloid, with its vertex downwards
and axis vertical, and consequently the section in the plane of
the surface of the water an ellipse, theory determines the velo-
city of propagation to be greater in the direction of the major
axis than in that of the minor in the proportion of the square
root of the one to the square root of the other. This result,
which it must be confessed has not an appearance of probabi-
lity, is not borne out by experience.
* Leipzig, 1825,
REPORT ON HYDROSTATICS AND HYDRODYNAMICS, 149
The theory has been also put to the test of*experiment by
M. bidone, who succeeded in overcoming in great measure an
obstacle in the way of making the experiments according to the
conditions supposed in the theory, arising from the adhesion of
the water to the immersed body*. His observations confirm
the existence and laws of motion of the accelerated waves. -
V. Scarcely anything worth mentioning has been effected
by theory in regard to the resistance of fluids to bodies moving
in them. The defect of every attempt hitherto made has
arisen from its proceeding upon some hypothesis respecting
the law of the resistance; for instance, that it varies as the ve-
locity, or as the square of the velocity: whereas the law, which
cannot be known @ priori, ought to be a result of the calcula-
tion, which should embrace not only the motion of the body,
but that of every particle of the fluid which moves simulta-
neously with it. The only problem that has been attempted
to be solved on this principle, is one of very considerable in-
terest, relating to the correction to be applied to the pendulum
to effect the reduction to a vacuum. ‘The memoir of M. Pois-
son, ‘‘ On the Simultaneous Motions of a Pendulum and of the
surrounding Air,” was read before the Royal Academy of Paris
in August 1831, and is inserted in vol. xi. of their Memoires.
He takes the case of a spherical ball suspended by a very slen-
der thread, the effect of which is neglected in the calculations;
the ball is supposed to perform oscillations of very small ampli-
tude, so that the air in contact with its surface is sensibly the
same during the motion. A simpler problem of resistance can-
not be conceived. M. Poisson considers the effect which the
friction of the particles of air against the surface of the ball
may have on its motion, and comes to the conclusion that'the
time of the oscillations is not affected by it, but only their ex-
tent. The most important result of the theoretical calculation
is, that the correction which has been usually applied for the
reduction to a vacuum, and calculated without considering the
motion of the air, must be increased by one half. This he finds
to agree sufficiently with some experiments of Captain Sabine.
He also adduces forty-four experiments of Dubuat, made fifty
years ago, upon oscillations in water, and three upon oscilla-
tions in air. These give nearly the same numerical result, and
agreeing nearly with the value 14. ‘The experiments, however,
of M. Bessel give results which coincide with Dubuat’s for os-
' cillations in water, but determine the correction in air for re-
duction to a vacuum to be very nearly double that hitherto
* See vol. xxv. of the Memoirs of the Royal Academy of Turin.
150 THIRD REPORT—1833.
applied, instead of once and a half. M. Poisson thinks that
the calculations of M. Bessel leave some room for doubt, and
objects to the discordance of the values obtained for air and
water, which, according to his own theory, ought to agree.
More recent experiments of Mr. Baily *, which, from their num-
ber and variety, and the care taken in performing them, are
entitled to the utmost confidence, give the value 1°864 for
spheres of different materials one inch and a half in diameter,
and 1°748 for spheres two inches in diameter, the latter bein
nearly the size of those for which M. Bessel obtained 1:946.
The theory of M. Poisson does not recognise any difference in
the value of the coefficient for spheres of different diameters.
The discrepancies that thus appear between theory and expe-
riment, and between the experiments themselves, show that
there is much that requires clearing up in this important sub-
ject. As far as theory is concerned, it is easily conceivable that
much must depend upon the way in which the law of trans-
mission of the motion from the parts of the fluid immediately
acted on by the sphere to the parts more remote is to be deter-
mined: and, as it is the province of this Report to point out
any possible source of error in theory, I will venture again
to express my doubts of the correctness of the principle em-
‘ployed in the solution of this problem, of making the deter-
mination of the law of transmission depend on the arbitrary
discontinuity of the functions introduced by integration, the law
itself not being arbitrary +.
A singular fact, relating to the resistance to the motion of
bodies partly immersed in water, has been recently established
by experiments on canal navigation, by which it appears that a
boat, drawn with a velocity of more than four or five miles an
hour, rises perceptibly out of the water, so that the water-line
is not so distant from the keel as in a state of rest, and the re-
sistance is less than it would be if no such effect took place.
Theory, although it has never predicted anything of this na-
ture, now that the fact is proposed for explanation, will proba-
bly soon be able to account for it on known mechanical prin-
ciples.
The foregoing review of the theory of fluid motion, incom-
* Philosophical Transactions for 1832, p. 399.
+ In an attempt at this problem made by myself, and published subsequently
to the Meeting of the Association, the value of the coefficient is found to be 2,
without accounting for any difference for spheres of different diameters. See
ra London and Edinburgh Philosophical Magazine and Journal for Septem-
er 1833.
REPORT ON HYDROSTATICS AND HYDRODYNAMICS. 151
plete as it is, may suffice to show that this department of science
is in an extremely imperfect state. Possibly it may on that ac-
count be the more likely to receive improvements; and I am
disposed to think that such will be the case. But these im-
provements, I expect, will be available not so much in practical
applications, as in reference to the great physical questions of
light, heat and electricity, which have been so long the subjects
of experiment, and the theories of which require to be perfected.
For this purpose a more complete knowledge of the analytical
calculation proper for the treatment of fluids in motion may be
of great utility.
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[ 153 ]
Report on the Progress and Present State of our Knowledge
of Hydraulics as a Branch of Engineering. By GEorGE
Rennit, Esq., F.R.S., §e. Sc.
Parr I.
THE paper now communicated to the British Association for
the Advancement of Science comprises a Report on the pro-
gress and present state of our knowledge of Hydraulics as a
branch of Engineering, with reference to the principles already
established on that subject.
Technically speaking, the term hydraulics signifies that
branch of the science of hydrodynamics which treats of the
motion of fluids issuing from orifices and tubes in reservoirs,
or moving in pipes, canals or rivers, oscillating in waves, or
opposing a resistance to the progress of solid bodies at rest.
We can readily imagine that if a hole of given dimensions be
pierced in the sides or bottom of a vessel kept constantly full,
the expenditure ought to be measured by the amplitude of the
opening, and the height of the liquid column.
If we isolate the column above the orifice by a tube, it ap-
pears evident that the fluid will fall freely, and follow the laws
of gravity. But experiment proves that this is not exactly the
case, on account of the resistances and forces which act in a
contrary direction, and destroy part of, or the whole, effect.
The development of these forces is so extremely complicated
that it becomes necessary to adopt some auxiliary hypothesis
or abbreviation in order to obtain approximate results. Hence
the science of hydrodynamics is entirely indebted to experi-
ment. The fundamental problem of it is to determine the efflux
of a vein of water or any other fluid issuing from an aperture
made in the sides or bottom of a vessel kept constantly full, or
allowed to empty itself. Torricelli had demonstrated that,
abstracting the resistances, the velocities of fluids issuing from
very small orifices followed the subduplicate ratio of the pres-
sures. This law had been, in a measure, confused by sub-
sequent writers, in consequence of the discrepancies which
appeared to exist between the theory and experiment; until
_Varignon remarked, that when water escaped from a small
opening made in’ the bottom of a cylindrical vessel, there ap-
peared to be very little, or scarcely any, sensible motion in the
‘
154 THIRD REPORT—1835.
particles of the water; from which he concluded that the law
of acceleration existed, and that the particles which escaped at
every instant of time received their motion simply from the
pressure produced by the weight of the fluid column above the
orifice, and that the weight of this column of fluid ought to
represent the pressure on the particles which continually escape
from the orifice; and that the quantity of motion or expenditure
is in the ratio of the breadth of the orifice, multiplied by the
square of the velocity, or, in other words, that the height of
the water in the vessel is proportional to the square of the ve-
locity with which it escapes; which is precisely the theorem of
Torricelli. This mode of reasoning is in some degree vague,
because it supposes that the small mass which escapes from
the vessel at each instant of time acquires its velocity from the
pressure of the column immediately above the orifice. But
supposing, as is natural, that the weight of the column acts on
the particle during the time it takes to issue from the vessel, it
is clear that this particle will receive an accelerated motion,
whose quantity in a given time will be proportional to the
pressure multiplied by the time: hence the product of the
weight of the column by the time of its issuing from the orifice,
will be equal to the product of the mass of this particle by the
velocity it will have acquired; and as the mass is the product
of the opening of the orifice, by the small space which the
particle describes in issuing from the orifice, it follows that the
height of the column will be as the square of the velocity ac-
quired. This theory is the more correct the more the fluid
approaches to a perfect state of repose, and the more the
dimensions of the vessel exceed the dimensions of the orifice.
By a contrary mode of reasoning this theory became insufficient
to determine the motions of fluids through pipes of small dia-
meters. It is necessary, therefore, to consider all the motions
of the particies of fluids, and examine how they are changed
and altered by the figure of the conduit. But experiment teaches
us that when a pipe has a different direction from the vertical
one, the different horizontal sections of the fluid preserve their
parallelism, the sections following taking the place of the pre-
ceding ones, and so on; from which it follows (on account of
the incompressibility of the fluid) that the velocity of each
horizontal section or plate, taken vertically, ought to be in
the. inverse ratio of the diameter of the section. It suffices,
therefore, to determine the motion of a single section, and the
problem then becomes analogous to the vibration of a com-
pound pendulum, by which, according to the theory of James
Bernoulli, the motions acquired and lost at each instant of time
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 155
form an equilibrium, as may be supposed to take place with
the different sections of a fluid in a pipe, each section being
animated with velocities acquired and lost at every instant of
time.
The theory of Bernoulli had not been proposed by him until
long after the discovery of the indirect principle of vs viva by
Huygens. The same was the case with the problem of the mo-
tions of fluids issuing from vessels, and it is surprising that no
advantage had been taken of it earlier. Michelotti, in his experi
mental researches de Separatione Fluidorum in Corpore Ani-
mali, in rejecting the theory of the Newtonian cataract, (which
had been advanced in Newton’s Mathematical Principles, in
the year 1687, but afterwards corrected in the year 1714,) sup-
poses the water to escape from an orifice in the bottom of a
vessel kept constantly full, with a velocity produced by the
height of the superior surface ; and that if, immediately above
the lowest plate of water escaping from the orifice, the column
of water be frozen, the weight of the column will have no effect
on the velocity of the water issuing from the orifice; and that
if this solid column be at once changed to its liquid state, the
effect will remain the same. The Marquis Poleni, in his work
De Castellis per que derivantur Fluviorum Aque, published at
Padua in the year 1718, shows, from many experiments, that
if A be the orifice, and H the height of the column above it,
the quantity of water which issues in a given time is represented
by 2AH x baad, whereas if it spouted out from the orifice
with a velocity acquired by falling from the height H, it ought
to be exactly 2 A H, so that experiment only gives a little more
than half the quantity promised by the theory; hence, if we
were to calculate from these experiments the velocity that the
water ought to have to furnish the necessary quantity, we
should find that it would hardly make it reascend 4rd of its
height. These experiments would have been quite contrary
to expectation, had not Sir Isaac Newton observed that water
issuing from an orifice ths of an inch in diameter, was contracted
$3ths of the diameter of the orifice, so that the cylinder of water
which actually issued was less than it ought to have been,
according to the theory, in the ratio of 441 to 625; and aug-
menting it in this proportion, the opening should have been
2AH oan or #ths of the quantity which ought to have issued
on the supposition that the velocity was in the ratio of the
square root of the height; from which it was inferred that the
theory was correct, but that the discrepancy was owing to cer-
156 THIRD REPORT—1833.
tain resistances, which experiment could alone determine. The
accuracy of the general conclusion was affected by several
assumptions, namely, the perfect fluidity and sensibility of the
mass, which was neither affected by friction nor cohesion, and
an infinitely small thickness in the edge of the aperture. :
Daniel Bernoulli, in his great work, Hydrodynamica, seu de
Viribus et Motibus Fluidorum Commentaria, published at Stras-
burgh in the year 1738, in considering the efflux of water from
an orifice in the bottom of a vessel, conceives the fluid to be
divided into an infinite number of horizontal strata, on the fol-
lowing suppositions, namely, that the upper surface of the fluid
always preserves its horizontality; that the fluid forms a con-
tinuous mass; that the velocities vary by insensible gradations,
like those of heavy bodies; and that every point of the same
stratum descends vertically with the same velocity, which is
inversely proportional to the area of the base of the stratum ;
that all sections thus retaining their parallelism are contiguous,
and change their velocities imperceptibly ; and that there is
always an equality between the vertical descent and ascent, or
vis viva: hence he arrives, by a very simple and elegant pro-
cess, to the equations of the problem, and applies its general
formulz to several cases of practical utility. When the figure
of the vessel is not subject to the law of continuity, or when
sudden and finite changes take place in the velocities of the
sections, there is a loss of vis viva, and the equations require
to be modified. John Bernoulli and Maclaurin arrived at the
same conclusions by different steps, somewhat analogous to the
cataract of Newton. The investigations of D’Alembert had
been directed principally to the dynamics of solid bodies, until
it occurred to him to apply them to fluids ; but in following the
steps of Bernoulli he discovered a formula applicable to the
motions of fluid, and reducible to the ordinary laws of hydro-
statics. The application of his theory to elastic and non-elastic
bodies, and the determination of the motions of fluids in flexible
pipes, together with his investigations relative to the resistance
of pipes, place him high in the ranks of those who have contri-
buted to the perfection of the science.
The celebrated Euler, to whom every branch of science owes
such deep obligations, seems to have paid particular attention
to the subject of hydrodynamics ; and in attempting to reduce
the whole of it to uniform and general formule, he exhibited a
beautiful example of the application of analytical investigation
to the solution of a great variety of problems for which he was
so famous. The Memoirs of the Academy of Berlin, from the
year 1768 to 1771, contain numerous papers relative to fluids
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 157
flowing from orifices in vessels, and through pipes of constant
or variable diameters. “ But it is greatly to be regretted,”
says M. Prony, “that Euler had not treated of friction and
cohesion, as his theory of the linear motion of air would have
applied to the motions of fluids through pipes and conduits,
had he not always reasoned on the hypotheses of mathematical
fluidity, independently of the resistances which modify it.”
In the year 1765 a very complete work was published at
Milan by Pau] Lecchi, a celebrated Milanese engineer, entitled
Idrostatica esaminata ne’ suoi Principi e Stabilite nelle suot
Regole della Mensura della Acque correnti, containing a com-
plete examination of all the different theories which had been
proposed to explain the phenomena of effluent water, and the
doctrine of the resistance of fluids. The author treats of the
velocity and quantity of water, whether absolutely or relatively,
which issues from orifices in vessels and reservoirs, according
to their different altitudes, and inquires how far the law applies
to masses of water flowing in canals and rivers, the velocities
and quantities of which he gives the methods of measuring.
The extensive and successful practice of Lecchi as an engineer
added much to the reputation of his work *.
In the year 1764 Professor Michelotti of Turin undertook,
at the expense of the King of Sardinia, a very extensive series
of experiments on running water issuing through orifices and
additional tubes placed at different heights in a tower of the
finest masonry, twenty feet in height and three feet square
inside. The water was supplied by a channel two feet in width,
and under pressures of from five to twenty-two feet. ‘The
effluent waters were conveyed into a reservoir of ample area,
by canals of brick-work lined with stucco, and having various
forms and declivities; and the experiments, particularly on the
efflux of water through differently shaped orifices, and addi-
tional tubes of different lengths, were most numerous and
accurate, and Michelotti was the first who gave representations
of the changes which take place in the figure of the fluid vein,
after it has issued from the orifice. His experiments on the
velocities of rivers, by means of the bent tube of Pitot, and by
an, instrument resembling a water-wheel, called the stadera
idraulica, are numerous and interesting; but, unfortunately,
their reduction is complicated with such various circumstances
that it is difficult to derive from them any satisfactory conclu-
sions. But Michelotti is justly entitled to the merit of having
made the greatest revolution in the science by experimental
* See also Memorie Idrostatico-storiche, 17738.
158 THIRD REPORT—1833.
investigation*. ‘The example of Michelotti gave a fresh sti-
mulus to the exertions of the French philosophers, to whom,
after the Italians, the science owes the greatest obligations.
Accordingly, the Abbé Bossut, a most zealous and enlight-
ened cultivator of hydrodynamics, undertook, at the expense
of the French Government, a most extensive and accurate se-
ries of experiments, which he published in the year 1771,
and a more enlarged edition, in two volumes, in the year
1786, entitled Traité Théorique et Expérimental d’Hydro-
namique. ‘The first volume treats of the general principles of
hydrostatics and hydraulics, including the pressure and equili-
brium of non-elastic and elastic fluids against inflexible and
flexible vessels; the thickness of pipes to resist the pressure
of stagnant fluids; the rise of water in barometers and pumps,
and the pressure and equilibrium of floating bodies; the ge-
neral principles of the motions of fluids through orifices of dif-
ferent shapes, and their friction and resistance against the
orifices; the oscillations of water in siphons; the percussion
and resistance of fluids against solids; and machines moved by
the action and reaction of water. ‘The second volume gives a
great variety of experiments on the motions of water through
orifices and pipes and fountains; their resistances in rectan-
gular or curvilinear channels, and against solids moving through
them; and lastly, of the fire- or steam-engine. In the course
of these experiments he found that when the water flowed
through an orifice in a thin plate, the contraction of the fluid
vein diminished the discharge in the ratio of 16 to 10; and when
the fluid was discharged through an additional tube, two or
three inches in length, the theoretical discharge was diminished
only in the ratio of 16 to 13. In examining the effects of fric-
tion, Bossut found that small orifices discharged less water in
proportion than large ones, on account of friction, and that, as
the height of the reservoir augmented, the fluid vein contracted
likewise; and by combining these two circumstances together,
he has furnished the means of measuring with precision the
quantity of water discharged either from simple orifices or
additional tubes, whether the vessels be constantly full, or be
allowed to empty themselves. He endeavoured to point out
the law by which the diminution of expenditure takes place,
according to the increase in the length of the pipe or the num-
ber of its bends; he examined the effect of friction in dimi-
nishing the velocity of a stream in rectangular and curvilinear
channels; and showed that in an open canal, with the same
* Sperimenti Idraulici, 1767 and 1771.
ON HYDRAULICS AS A BRANCH OF EGINEERING. 159
height of reservoir, the same quantity of water is always dis-
charged, whatever be the declivity and length; that the ve-
locities of the waters in the canal are not as the square roots
of the declivities, and that in equal declivities and depth of the
canal’the velocities are not exactly as the quantities of water
discharged ; and he considers the variations which take place
in the velocity and level of the waters when two rivers unite,
and the manner in which they establish their beds.
His experiments, in conjunction with D’Alembert and Con-
dorcet, on the resistance of fluids, in the year 1777, and his
subsequent application of them to all kinds of surfaces, in-
cluding the shock and resistance of water-wheels, have justly
entitled him to the gratitude of posterity. The Abbé Bossut
had opened out a new career of experiments ; but the most dif-
ficult and important problem remaining to be solved related to
rivers. It was easy to perform experiments with water running
through pipes and conduits on a small scale, under given and
determined circumstances: but when the mass of fluid rolled
in channels of unequal capacities, and which were composed of
every kind of material, from the rocks amongst which it accu-
mulated to the gravel and sand through which it forced a pass-
age,—at first a rapid and impetuous torrent, but latterly hold-
ing a calm and majestic course,—sometimes forming sand-banks
andislands, at other times destroying them, at all times capri-
cious, and subject to variation in its force and direction by
the slightest obstacles,—it appeared impossible to submit them
to any general law.
Unappalled, however, by these difficulties, the Chevalier
Buat, after perusing attentively M. Bossut’s work, undertook
to solve them by means of a theorem which appeared to him
to be the key of the whole science of hydraulics. He consi-
dered that if water was in a perfect state of fluidity, and ran in
a bed from which it experienced no resistance whatever, its
motion would be constantly accelerated, like the motion of a
heavy body descending an inclined plane; but as the velocity
of a river is not accelerated ad infinitum, but arrives at a state
of uniformity, it follows that there exists some obstacle which
destroys the accelerating force, and prevents it from impressing
‘upon the water a new degree of velocity. This obstacle must
therefore be owing either to the viscidity of the water, or to
the resistance it experiences against the bed of the river; from
which Dubuat derives the following principle:—That when
water runs uniformly in any channel, the accelerating force
which obliges it to run is equal to the sum of all the resistances
which it experiences, whether arising from the viscidity of the
water or the friction of its bed. Encouraged by this discovery,
160. THIRD REPORT—1833.
and by the application of its principles to the solution of a great
many cases in practice, Dubuat*was convinced that the motion
of water in a conduit pipe was analogous to the uniform motion
of a river, since in both cases gravity was the cause of motion,
and the resistance of the channel or perimeter of the pipes the
modifiers. He then availed himself of the experiments of Bossut
on conduit pipes and artificial channels to explain his theory:
the results of which investigations were published in the year
1779. M. Dubuat was, however, sensible that a theory of so
much novelty, and at variance with the then received theory,
required to be supported by experiments more numerous and
direct than those formerly undertaken, as he was constrained
to suppose that the friction of the water did not depend upon
the pressure, but on the surface and square of the velocity.
Accordingly, he devoted three years to making fresh experi-
ments, and, with ample funds and assistance provided by the
French Government, was enabled to publish his great work,
entitled Principes d Hydraulique vérifiés par un grand nombre
d Expériences, faites par Ordre du Gouvernement, 2 vols. 1786,
(a third volume, entitled Principes d Hydraulique et Hydro-
namique, appeared in 1816);—in the first instance, by repeating
and enlarging the scale of Bossut’s experiments on pipes (with
water running in them) of different inclinations or angles, of
from 90° to gguth part of a right angle, and in channels of from
1} line in diameter to 7 and 8 square toises of surface, and sub-
sequently to water running in open channels, in which he ex-
perienced great difficulties in rendering the motion uniform:
but he was amply recompensed by the results he obtained on
the diminution of the velocity of the different parts of a uniform
current, and of the relation of the velocities at the surface and
bottom, by which the water works its own channel, and by the
knowledge of the resistances which different kinds of beds pro-
duce, such as clay, sand and gravel; and varying the experiments
on the effect of sluices, and the piers of bridges, &c., he was ena-
bled to obtain a formula applicable to most cases in practice*.
Thus, let V = mean velocity per second, in inches.
d = hydraulic mean depth, or quotient which arises
from dividing the area or section of the canal,
in square inches, by the perimeter of the part
in contact with the water, in linear inches.
s = the slope or declivity of the pipe, or the sur-
face of the water. =
16:087, the velocity in inches which a body
acquires in falling one second of time.
ve)
II
* Edinburgh Encyclopedia, Art. Hypropynamics, by Brewster.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 161
nm = an abstract number, which was found by ex-
periment to be equal to 243-7.
/ng (Vd — 01)
Ws — log. Ws +16
Such are some of the objects of M. Dubuat’s work. But his
hypotheses are unfortunately founded upon assumptions which
render the applications of his theory of little use. It is evident
that the supposition of a constant and uniform velocity in rivers
cannot hold: nevertheless he has rendered great services to
the science by the solution of many important questions relating
to it; and although he has left on some points a vast field open
to research, he is justly entitled to the merit of originality and
accuracy.
Contemporary with Dubuat was M. Chezy, one of the most
skilful engmeers of his time: he was director of the Ecole des
Ponts et Chaussées, and reported, conjointly with M. Perronet,
on the Canal Yvette. He endeavoured to assign, by experiment,
the relation existing between the inclination, length, trans-
versal section, and velocity of a canal. In the course of this
investigation he obtained a very simple expression of the velo-
city, involving three different variable quantities, and capable,
by means of a wii experiment, of being applied to all cur-
rents whatever. He assimilates the resistance of the sides and
bottom of the canal to known resistances, which follow the law
of the square of the velocity, and he obtains the following sim-
ple formula :
v= Ved
28S
then v
ll
— 0:3 (/d — 0'1).
, where g is = 16-087 feet, the velocity acquired
by a heavy body after falling one second.
d = hydraulic mean depth, equal to the area of the section
divided by the perimeter of the part of the canal in
contact with the water.
$ = the slope or declivity of the pipe.
2 = an abstract number, to be determined by experiment.
In the year 1784, M. Lespinasse published in the Memoirs
of the Academy of Sciences at Toulouse two papers, contain-
ing some interesting observations on the expenditure of water
through large orifices, and on the junction and separation of
rivers. The author had performed the experiments contained
in his last paper on the rivers Fresquel and Aude, and on that
part of the canal of Languedoc below the Fresquel lock, towards
its junction with that river.
As we before stated, M. Dubuat had classified with much
1833. M
162 THIRD REPORT—1833.
sagacity his observations on the different kinds of resistance
experienced in the motion of fluids, and which might have led
him to express the sum of the resistances by a rational function
of the velocity composed of two or three terms only. Yet the
merit of this determination was reserved to M. Coulomb, who,
in a beautiful paper, entitled ‘‘ Expériences destinées a déter-
miner la Cohérence des Fluides et les Lois de leurs Résistances
dans les Mouvemens trés lents,” proves, by reasoning and facts,
Ist, That in extremely slow motions the part of the resist-
ance is proportional to the square of the velocity.
2ndly, ‘That the resistance is not sensibly increased by in-
creasing the height of the fluid above the resisting body.
ordly, That the resistance arises solely from the mutual co-
hesion of the fluid particles, and not from their adhesion to the
body upon which they act.
4thly, That the resistance in clarified oil, at the temperature
of 69° Fahrenheit, is to that of water as 17-5:1; a proportion
which expresses the ratio of the mutual cohesion of the par-
ticles of oil to the mutual cohesion of the particles of water.
M. Coulomb concludes his experiments by ascertaining the
resistance experienced by cylinders that move very slowly and
perpendicularly to their axes, &c.
This eminent philosopher, who had applied the doctrine of
torsion with such distinguished success in investigating the
phenomena of electricity and magnetism, entertained the idea
of examining in a similar manner the resistance of fluids, con-
trary to the doctrines of resistance previously laid down.
M. Coulomb proved, that in the resistance of fluids against
solids, there was no constant quantity of sufficient magnitude
to be detected; and that the pressure sustained by a moving
body is represented by two terms, one which varies as the
simple velocity, and the other with its square.
The apparatus with which these results were obtained con-
sisted of discs of various sizes, which were fixed to the lower
extremity of a brass wire, and were made to oscillate under a
fluid by the force of torsion of the wire. By observing the
successive diminution of the oscillations, the law of resistance
was easily found. The oscillations which were best suited to
these experiments continued for twenty or thirty seconds, and
the amplitude of the oscillation (that gave the most regular re-
sults) was between 480 the entire division ofthe disc, and 8 or
10 divisions from zero.
The first who had the happy idea of applying the law of
Coulomb to the case of the velocities of water running in na-
tural or artificial channels was M. Girard, Ingénieur en chef
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 163
des. Ponts et Chaussées, and Director of the Works of the
Canal !Ourcgq at Paris *.
He is the author of several papers on the theory of running
waters, and of a valuable series of experiments on the motions
of fluids in capillary tubes.
M. Coulomb had given a common coefficient to the two terme
of his formula representing the resistance of a fluid,—one pro-
portional to the simple velocity, the other to the square of the
velocity. M. Girard found that this identity of the coefficients
was applicable only to particular fluids under certain circum-
stances ; and his conclusions were confirmed by the researches
of M. Prony, derived from a great many experiments, which
make the coefficients not only different, but very inferior to the
value of the motion of the filaments of the water contiguous to
the side of the pipe.
The object of M. Girard’s experiments was to determine
this velocity; and this he has effected in a very satisfactory
manner, by means of twelve hundred experiments, performed
with a series of copper tubes, from 1°83 to 2:96 millimetres in
diameter, and from 20 to 222 centimetres in length; from which
it appeared, that when the velocity was expressed by 10, and
the temperature was 0, centigrade, the velocity was increased
four times when the temperature amounted to 85°. When the
length of the capillary tube was below that limit, a variation of
temperature exercised very little influence upon the velocity
of the issuing fluid, &c.
It was in this state of the science that M. Prony (then having
under his direction different projects for canals,) undertook to
' reduce the solutions of many important problems on running
water to the most strict and rigorous principles, at the same
time capable of being applied with facility to practice.
For this purpose he selected fifty-one experiments which
corresponded best on conduit pipes, and thirty-one on open
conduits. Proceeding, therefore, on M. Girard’s theory of the
analogy between fluids and a system of corpuscular solids or
material bodies, gravitating in a curvilinear channel of indefinite
length, and occupying and abandoning successively the dif-
ferent parts of the length of channel, he was enabled to express
the velocity of the water, whether it flows in pipes or in open
conduits, by a simple formula, free of logarithms, and requiring
merely the extraction of the square root f.
* Essai sur le Mouvement des Eaux courantes: Paris 1804. Recherches
sur les Eaux publiques, §c. Devis général du Canal l’Ourcg, &c.
t Mémoires des Savans Etrangers, §c. 1815.
M2
164 THIRD REPORT—1833.
Thus v = — 0:0469754 + /%0:0022065 + 3041°47 x G,
which gives the velocity in metres: or, in English feet,
v = — 0°1541131 + /0:023751 + 328066 x G.
When this formula is applied to pipes, we must take G=iDK,
which is deduced from the equation K = PE aa When
it is applied to canals, we must take G = RI, which is deduced
from the equation I = a R being equal to the mean radius of
Dubuat on the hydraulic mean depth, and I equal to the sine
of inclination in the pipe or canal. M. Prony has drawn up ex-
tensive Tables, in which he has compared the observed velo-
cities with those which are calculated from the preceding for-
mulz, and from those of Dubuat and Girard. In both cases
the coincidence of the observed results with the formule are
very remarkable, but particularly with the formule of M. Prony.
But the great work of M. Prony is his Nouvelle Architecture
Aydraulique, published in the year 1790. This able produc-
tion is divided into five sections, viz. Statics, Dynamics, Hydro-
statics, Hydrodynamics, and on the physical circumstances
that influence the motions of Machines. The chapter on hydro-
dynamics is particularly copious and explanatory of the motions
of compressible and incompressible fluids in pipes and vessels,
on the principle of the parallelism of the fluid filaments, and
the efflux of water through different kinds of orifices made in
vessels kept constantly full, or permitted to empty themselves ;
he details the theory of the clepsydra, and the curves described
by spouting fluids; and having noticed the different phenomena
of the contraction of the fluid vein, and given an account of the ex-
periments of Bossut, M. Prony deduces formule by which the re-
sults may be expressed with all the accuracy required in practice.
In treating of the impulse and resistance of fluids, M. Prony
explains the theory of Don George Juan, which he finds con-
formable to the experiments of Smeaton, but to differ very ma-
terially from the previously received law of the product of the
surfaces by the squares of the velocities, as established by the
joint experiments of D’Alembert, Condorcet and Bossut, in the
year 1775. The concluding part of the fourth section is de-
voted to an examination of the theory of the equilibrium and
motion of fluids according to Euler and D’Alembert; and by a
rigorous investigation of the nature of the questions to be de-
termined, the whole theory is reduced to two equations only, in
narrow pipes, according to the theory of Euler, showing its
approximation to the hypothesis of the parallelism of filaments.
|
|
i
|
|
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 165
The fifth and last section investigates the different circum-
stances (such as friction, adhesion and rigidity,) which influence
the motions of machines.
A second volume, published in the year 1796, is devoted to
the theory and practice of the steam-engine. Previously to the
memoir of M. Prony, Sur le Jaugeage des Eaux courantes, in
the year 1802, no attempt had been made to establish with cer-
tainty the correction to be applied to the theoretical expendi-
tures of fluids through orifices and additional tubes. The phe-
nomenon had been long noticed by Sir Isaac Newton, and illus-
trated by Michelotti by a magnificent series of experiments,
which, although involving some intricacies, have certainly
formed the groundwork of all the subsequent experiments upon
this particular subject. _
By the method of interpolation, M. Prony has succeeded in
discovering a series of formulz applicable to the expenditures
of currents out of vertical and horizontal orifices, and to the con-
traction of the fluid vein; and in a subsequent work, entitled
Recherches sur le Mouvemens des Eaux courantes, he establishes
the following formule for the mean velocities of rivers.
When V = velocity at the surface,
and U = mean velocity,
U = 0°816458 V,
which is about + V.
These velocities are determined by two methods. Ist, By a
small water-wheel for the velocity at the surface, and the im-
proved tube of Pitot for the velocities at different depths below
the surface.
If h = the height of the water in the vertical tube above the
level of the current, the velocity due to this height will be deter-
eo ee metres
mined by the formula V = /2¢h = \/ 19-606 h = 4°429 Wh.
When water runs in channels, the inclination usually given
amounts to between z3,th and ,3,th part of the length, which
will give a velocity of nearly 14 mile per hour, sufficient to
allow the water to run freely in earth. We have seen the incli-
nation very conveniently applied in cases of drainage at 745th
and 55th, and some rivers are said to have g,55th only.
__M. Prony gives the following formule, from a great number
~ of observations :
If U = mean velocity of the water in the canal,
I = the inclination of the canal per metre,
R = the relation of the area to the profile of its perimeter,
we shall have
U = — 0:07 + 0-005 + 3233. R.1;
166 THIRD REPORT—1833.
and for conduit pipes,
calling U = the mean velocity,
Z = the head of water in the inferior orifice of the pipe,
L = the length of the pipe in metres,
D = the diameter of the pipe,
we shall have
U = — 0:0248829 + /0:000619159 + 717-857 DZ
ap
or, where the velocity is small,
U = 26°79 / DZ;
L
that is, the mean velocities approximate to a direct ratio com-
pounded of the squares of the diameters and heads of water,
and inversely as the square root of the length of the pipes:
and by experiments made with great care, M. Prony has found
that the formula
U = — 0:0248829 + /0-000619159 + 717-857 D Z
L
scarcely differs more or less from experiments than J, or 24.
The preceding formule suppose that the horizontal sections,
both of the reservoir and the recipient, are great in relation
to the transverse section of the pipe, and that the pipe is kept
constantly full *.
In comparing the formule given for open and close canals,
M. Prony has remarked that these formule are not only similar,
but the constants which enter into their composition are nearly
the same; so that either of them may represent the two series
of phenomena with sufficient exactness.
The following formula applies equally to open or close canals:
U = — 00469734 + +/(0-0022065 + 3041-47 4).
But the most useful of the numerous formule given by M. Prony
for open canals is the following :
* According to Mr. Jardine’s experiments on the quantity of water delivered
by the Coniston Main from Coniston to Edinburgh, the following is a compa-
rison : Scots Pints.
Actual delivery of Coniston Main.........sceesceeeeeeees 189-4
Ditto by Eytelwein’s formula .........see+e++e+e0s 189:77
Ditto by Girard’s formula ..........-.eseeseeeeees 188-26
Ditto by Dubuat’s formula ..............ceseeeeees 188-13
Ditto by Prony’s simple formula......... es
Ditto by Prony’s tables......... ne ache ei ctube sees 180°7
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 167
Let g = the velocity of a body falling in one second,
w = the area of the transverse section,
. p = the perimeter of that section,
I = the inclination of the canal,
Q = the constant volume of water through the section,
U = the mean velocity of the water,
R = the relation of the area to the perimeter of the section;
then Ist, 0-000436 U + 0-003034 U? = g IR = g ta
10 ais Oke Q,
Ww
ordly, Rw? — 0:0000444499 . w . — 0:000309314:
This last equation, containing the quantities
~~ QI wand R = =
shows how to determine one of them, and, knowing the three
others, we shall have the following equations: ;
Iw?
Q? _
Aielae es
thly, p= TO00ISEO w + ONSET
s . 2
sey, 1 = 200000159 @ w+ 7000300814 @")
* 2 *
Ginly, w = 0-000196 4 0000486)" + 4(0-008084) gR 1] Q
2¢eRI1
_ These formulz are, however, modified in rivers by circum-
stances, such as weeds, vessels and other obstacles in the
rivers; in which case M. Girard has conceived it necessary to
introduce into the formule the coefficient of correction = 1°7
as a multiplier of the perimeter, by which the equations will be,
-* p — 1°7(0:000436 U + 0-:003034 U?) = gIw.
The preceding are among the principal researches of this
distinguished philosopher *.
' In the year 1798, Professor Venturi of Modena published a
very interesting memoir, entitled Sur la Communication laté-
rale du Mouvement des Fluides. Sir Isaac Newton was well
acquainted with this communication, having deduced from it
the propagation of rotary motion from the interior to the exte-
vior of a whirlpool; and had affirmed that when motion is pro-
_ pagated in a fluid, and has passed beyond the aperture, the
* Recherches Physico-mathématiques sur la Théorie des Eaux courantes,
par M. Prony.
168 THIRD REPORT—1833.
motion diverges from that opening, as from a centre, and is
propagated in right lines towards the lateral parts. The sim-
ple and immediate application of this theorem cannot be made
to a jet or aperture at the surface of still water. Circumstances
enter into this case which transform the results of the principle
into particular motions. It is nevertheless true that the jet
communicates its motion to the lateral parts without the orifice,
but does not repel it in a radial divergency. M. Venturi illus-
trates his theory by experiments on the form and expenditure
of fluid veins issuing from orifices, and shows how the velocity
and expenditure are increased by the application of additional
tubes; and that in descending cylindrical tubes, the upper ends
of which possess the form of the contracted vein, the expense
is such as corresponds with the height of the fluid above the
inferior extremity of the tube. The ancients remarked that a
descending tube applied to a reservoir increased the expendi-
ture*. D’Alembert, Euler and Bernoulli attributed it to the
pressure of the atmosphere. Gravesend, Guglielmini and others
sought for the cause of this augmentation in the weight of the
atmosphere, and determined the velocity at the bottom of the
tube to be the same as would arise from the whole height of
the column, including the height of the reservoir. Guglielmini
supposed that the pressure at the orifice below is the same for
a state of motion as for that of rest, which is not true. In the
experiments he made for that purpose, he paid no regard either
to the diminution of expenditure produced by the irregularity
of the inner surface of the tubes, or the augmentation occa-
sioned by the form of the tubes themselves. But Venturi esta-
blished the proposition upon the principle of vertical ascension
combined with the pressure of the atmosphere, as follows :
Ist, That in additional conical tubes the pressure of the at-
mosphere increases the expenditure in the proportion of the
exterior section of the tube to the section of the contracted
vein, whatever be the position of the tube.
2ndly, That in cylindrical pipes the expenditure is less than
through conical pipes, which diverge from the contracted vein,
and have the same exterior diameter. This is illustrated by
experiments with differently formed tubes, as compared with a
plate orifice and a cylindrical tube, by which the ratios in point
of time were found to be 41", 31" and 27", showing the advan-
tage of the conical tube.
ordly, That the expenditure may be still further increased,
* “Calix devexus amplits rapit.’”—Jrontinus de -Aqueductibus. See also
Pneumatics of Hero.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 169
in the ratio of 24 to 10, by a certain form of tube,—a circum-
stance of which he supposes the Romans were well aware, as
appears from their restricting the length of the pipes of con-
veyance from the public reservoirs to fifty feet; but it was not
perceived that the law might be equally evaded by applying a
conical frustrum to the extremity of the tube.
M. Venturi then examines the causes of eddies in rivers;
whence he deduces from his experiments on tubes with en-
larged parts, that every eddy destroys part of the moving force
of the current of the river, of which the course is permanent
and the sections of the bed unequal, the water continues more
elevated than it would have done if the whole river had been
equally contracted to the dimensions of its smallest section,—a
consequence extremely important in the theory of rivers, as the
retardation experienced by the water in rivers is not only due
to the friction over the beds, but to eddies produced from the
irregularities in the bed, and the flexures or windings of its
course: a part of the current is thus employed to restore an
equilibrium of motion, which the current itself continually de-
ranges. As respects the contracted vein, it had been pretended
by the Marquis de Lorgna* that the contracted vein was. no-
thing else but a continuation of the Newtonian cataract; and
that the celerity of the fluid issuing from an orifice in a thin
plate is much less than that of a body which falls from the
height of the charge. But Venturi proved that the contraction
of the vein is incomparably greater than can be produced by
the acceleration of gravity, even in descending streams, the
contraction of the stream being 0°64, and the velocity nearly
the same as that of a heavy body which may have fallen through
the height of the charge. ‘These experimental principles, which
are in accordance with the results of Bossut, Michelotti and
Poleni, are strictly true in all cases where the orifice is small in
proportion to the section of the reservoir, and when that orifice
is made in a thin plate, and the internal afflux of the filaments
is made in an uniform manner round the orifice itself. Venturi
then shows the form and contraction of the fluid vein by in-
creased charges. His experiments with the cone are curious ;
and it would have been greatly to be regretted that he had
stopped short in his investigations, but for the more extensive
researches of Bidone and Lesbros. M. Hachette, in opposition
to the theory of Venturi, assigns, as a cause of the increase by
additional tubes, the adhesion of the fluid to the sides of the.
tubes arising from capillary attraction.
* Memorie della Societa Italiana, vol. iv.
170 ; THIRD REPORT—1833.
. In the year 1801, M. Eytelwein, a gentleman well known to
the public by his translation of M. Dubuat’s work into German,
(with important additions of his own,) published a valuable
compendium of hydraulics, entitled Handbuch der Mechanik
und der Hydraulik, in which he lays down the following rules.
1. That when water flows from a notch made in the side of
a dam, its velocity is as the square of the height of
the head of the water; that is, that the pressure and
consequent height are as the square of the velocity, the
proportional velocities being nearly the same as those
of Bossut.
. That the contraction of the fluid vein from a simple orifice
in a thin plate is reduced to 0°64.
. For additional pipes the coefficient is 0°65.
For a conical tube similar to the curve of contraction 0°98.
. For the whole velocity due to the height, the coefficient
by its square must be multiplied by 8-0458.
. For an orifice the coefficient must be multiplied by 7°8.
. For wide openings in bridges, sluices, &c., by 6°9.
- For short pipes 6°6.
For openings in sluices without side walls 5:1.
Of the twenty-four chapters into which M. Eytelwein’s * work
is divided, the seventh is the most important. The late Dr,
Thomas Young, in commenting upon this chapter, says:
. The simple theorem by which the velocity of a river is de-
termined, appears to be the most valuable of M. Eytelwein’s
improvements, although the reasoning from which it is deduced
is somewhat exceptionable. ‘The friction is nearly as the square
of the velocity, not because a number of particles proportional
to the velocity is torn asunder in a time proportionally short,—
for, according to the analogy of solid bodies, no more falcon is
destroyed by friction when the motion is rapid than when slow,
—but because when a body is moving in lines of a given curva-
ture, the deflecting forces are as the squares of the velocities ;
and the particles of water in contact with the sides and bottom
must be deflected, in consequence of the minute irregularities
of the surfaces on which they slide, nearly in the same curvi-
linear path, whatever their velocity may be. At any rate (he
continues) we may safely set out with this hypothesis, that the
principal part of the friction is as the square of the velocity,
and the friction is nearly the same at all depths}; for Professor
. Robison found that the time of oscillation of the fluid ina bent
es)
Or 09
Nolo hs eer)
* See Nicholson’s translation of Eytelwein’s work. z
+ See my “Experiments on the Friction and Resistance of Fluids,” Philo-
sophical Transactions for 1831.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 171
tube was not increased. by increasing the pressure against the
sides, being nearly the same when the principal part was si-
tuated horizontally, as when vertically. The friction will, how-
ever, vary, according to the surface of the fluid which is in
contact with the solid, in proportion to the whole quantity of
fluid; that is, the friction for any given quantity of water will
be as the surface of the bottom and sides of a river directly,
and as the whole quantity in the river inversely ; or, supposing
the whole quantity of water to be spread on a horizontal sur-
face equal to the bottom and sides, the friction is inversely as
the height at which the river would then stand, which is called
the hydraulic mean depth*.” It is, therefore, calculated that
the velocities will be a mean proportional between the hydraulic
mean depth and the fall, or +4ths of the velocity per second.
Professor Robison informs us, that by the experiments of
Mr. Watt on a canal eighteen feet wide at the top, seven feet
at the bottom, and four feet deep, having a fall of four inches
per mile, the velocities were seventeen inches per second at the
surface, fourteen inches per second in the middle, and ten inches
per second at the bottom, making a mean velocity of fourteen
inches per second; then finding the hydraulic mean depth, and
dividing the area of the section by the perimeter, we have a
_ or 29°13 inches ; and the fall in two miles being eight inches,
we have 4/(8 x 29°13) = 15-26 for the mean proportional of
+aths, or 13-9 inches, which agrees very nearly with Mr. Watt's
velocity.
The Professor has, however, deduced from Dubuat’s elabo=
rate theories 12568 inches. But this simple theorem applies
only to the straight and equable channels of a river. Ina
curved channel the theorem becomes more complicated ; and,
from observations made in the Po, Arno, Rhine, and other
rivers, there appears to be no general rule for the decrease of
velocity going downwards. M. Eytelwein directs us to deduct
from the superficial velocity ;;3 for every foot of the whole
depth. Dr. Young thinks ;3,ths of the superficial velocity suf-
ficient. According to Major Rennell, the windings of the river
Ganges in a length of sixty miles are so numerous as to reduce
the declivity of the bed to four inches per mile, the medium
rate of motion being about three miles per hour, so that a mean
hydraulic depth of thirty feet, as stated to be 2rds of the
velocity per second, will be 4°47 feet, or three miles per hour.
Again, the river when full has thrice the volume of water in it,
and its motion is also accelerated in the proportion of 5 to 3;
* See Nicholson’s Journal for 1802, vol. iii. p. 31.
172 THIRD REPORT—1835. ‘
and, assuming the hydraulicmean depth to be doubled at the
time of the inundation, the velocity will be increased in the
ratio of 7 to 5; but the inclination of the surface is probably
increased also, and consequently produces a further velocity of
from 1:4 to 1:7. M. Eytelwein agrees with Genneté*, that a
river may absorb the whole of the water of another river equal
in magnitude to itself, without producing any sensible elevation
in its surface. This apparent paradox Genneté pretends to
prove by experiments, from observing that the Danube absorbs
the Inn, and the Rhine the Mayne rivers; but the author evi-
dently has not attended to the fact, as may be witnessed in the
junction of rivers in marshes and fenny countries,—the various
rivers which run through the Pontine and other marshes in
Italy, and in Cambridgeshire and Lincolnshire in this country :
hence the familiar expression of the waters being overridden is
founded in facts continually observed in these districts. We
have also the experiments of Brunings in the Architecture Hy-
draulique Générale de Wiebeking, Wattmann’s Mémoires sur
U Art de construire les Canaux, and Funk Sur l Architecture
Hydraulique générale, which are sufficient to determine the
coefficients under different circumstances, from velocities of
2ths to 74 feet, and of transverse sections from 1 to 19135
square feet. The experiments of Dubuat were made on the
canal of Jard and the river Hayne; those of Brunings in the
Rhine, the Waal and Ifrel; and those of Wattmann in the
drains near Cuxhaven.
M. Eytelwein’s paper contains formule for the contraction
of fluid veins through orifices +, and the resistances of fluids
passing through pipes and beds of canals and rivers, according
to the experiments of Couplet, Michelotti, Bossut, Venturi,
Dubuat, Wattmann, Brunings, Funk and Bidone.
In the ninth chapter of the Handbuch, the author has en-
deavoured to simplify, nearly in the same manner as the motion
of rivers, the theory of the motion of water in pipes, observing
that the head of water may be divided into two parts, one to
produce velocity, the other to overcome the friction; and that
the height must be as the length and circumference of the sec-
tion of the pipe directly, or as the diameter,—and inversely as
the area of the section, or as the square of the diameter.
* Expériences sur le Cours des Fleuves, ou Lettre & un Magistrat Hollandais,
par M. Genneté. Paris 1760.
+ “Recherches sur le Mouvement de |’Eau, en ayant egard 4 la Contraction
qui a lieu au Passage par divers Orifices, et 4 la Resistance qui retard le Mouve-
ment, le long des Parois des Vases ; par M. Eytelwein,”"—Mémoires de ' Aca-
démie de Berlin, 1814 and 1815.
amon
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 173
In the allowance for flexure, the product of its square, multi-
plied by the sum of the sines of the several angles of inflection,
and then by ‘0038, will give the degree of pressure employed
in overcoming the resistance occasioned by the angles; and de-
ducting this height from the height corresponding to the velo-
city, will give the corrected velocity *.
M. Eytelwein investigates, both theoretically and experi-
mentally, the discharge of water by compound pipes,—the mo-
tions of jets, and their impulses against plane and oblique sur-
faces, as in water-wheels, in which it is shown that the hydraulic
pressure must be twice the weight of the generating column, as
deduced from the experiments of Bossut and Langsdorft; and
in the case of oblique surfaces, the effect is stated to vary as the
square of the sine of the angle of incidence; but for motions
in open water about 2ths of the difference of the sine from the
radius must be added to this square.
The author is evidently wrong in calculating upon impulse
as forming part of the motion of overshot wheels; but his
theory, that the perimeter of a water-wheel should move with
half the velocity of a given stream to produce a maximum effect,
agrees perfectly with the experiments of Smeaton and others +.
The author concludes his highly interesting work by exa-
mining the effects of air as far as they relate to hydraulic ma-
chines, including its impulse against plane surfaces on siphons
* Hence, if f denote the height due to the friction,
d = the diameter of the pipe,
rf @ = a constant quantity,
we shall have, firs we and V? =e
But the height employed in overcoming the friction corresponds to the differ-
ence between the actual velocity and the actual height, that is, f= h — a
where b is the coefficient for finding the velocity from the height.
al ieh _bBdh—dVv? VP dah
PSMA TOT ee aoe
Now Dubuat found 0 to be 6°6, and a4? was found to be 0-0211, particularly
when the velocity is between six and twenty-four inches per second. Hence
_ Hence we have, vy?
, 436 dh dh
ales = 45:5 ai al a
> a = ponte Y= 3 ,
2) Vv (i
or more accurately, V=50 i+ 50a)"
__ + The author of this paper has made a great many experiments on the max-
imum effect of water-wheels ; but the recent experiments of the Franklin Insti-
tution, made on a more magnificent scale, and now in the course of trial, eclipse
everything that has yet been effected on this subject. See also Poncelet, Mé-
moire sur les Roues Hydrauliques, and Aubes Courbes par dessous, §c. 1827.
174 THIRD REPORT—1833.
and pumps of different descriptions, horizontal and inclined
helices, bucket-wheels, throwing-wheels, and lastly, on instru-
ments for measuring the velocity of streams of water. A very
detailed account of the work was given in the Journal of the
Royal Institution, by the late Dr. Young. But it is due to
MM. Dubuat and Prony to state, that M. Eytelwein has
exactly followed the steps of these gentlemen in his Theory of
the Motion of Water in open Channels.
In the year 1809 a valuable series of experiments upon the
motions of waters through pipes, was made by MM. Mallet
and Vici at Rome, and afterwards by M. Prony*.
It had been proved, by experiments made with great care,
that the diminution of velocity, and consequent expenditure in
pipes, was not in the ratio of the capacity of the pipes, as Fron-
tinus had supposed in his valuation of the product of the an-
cient module or calice ; and as it was desirable to ascertain the
actual product of the three fountains now used at Rome, a se-
ries of experiments was undertaken by these gentlemen; the
principal result of which was, that a pipe, of which the gauge
was five onces}, furnished }th more water than five pipes of
one once, on account of the diminution of the velocity by
friction in the ratio of the perimeters of the orifices as com-
pared with their areas.
M. Mallet also made a great many researches relative to the
distribution of water in the different cities and towns of En-
land and France, with a view to their application at Paris; of
all of which he has published an account.
The researches that had been made hitherto on the expendi-
ture of water through orifices, had for their object the deter-
mination of the velocity and magnitude of the section, by which
it is necessary to multiply the velocity to obtain the expense.
But although these be the'first elements for consideration, they
are not sufficient; for the fluid vein presents other phenomena
equally important, both in the theory and its application,
namely, the form and direction of the vein after it has issued
from the orifice. The former phenomena, as we before stated,
had been long noticed by Michelotti and others, but nothing
precise had been established on the forms and remarkable phe-
nomena of the fluid vein itself. Venturi had given three ex-
amples.
M. Hachette, in two memoirs presented to the Académie
Royale des Sciences in 1815 and 1816, also considered the.
* Notices Historiques, par M. Mallet. Paris 1830.
+ French measure, or 0°03059 French kilolitres.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 175
form of veins; and in his Traité des Machines, he states that
he had already given a description of veins issuing from circu-
lar, elliptical, triangular and square orifices, without having
entered into any detail respecting them, so that that part of
the subject was in a great measure involved in doubt. In 1829
a paper, entitled ‘‘ Expériences sur Ja Forme et sur la Direction
desVeines et des Courans d’ Eau, lancés par diverses Ouvertures,”
was read to the Academy of Sciences at Turin by M. Bidone,.
iving an account of a series of experiments made in the years
1826 and 1827, in the Hydraulic Establishment of the Royal
University. The results of these experiments are divided into:
five articles. The first. gives, a description of the apparatus
and mode of proceeding, and the. figures obtained from veins
expended from rectilinear and curvilinear orifices, with salient
angles pierced. in. vertical plates, and whose perimeters are
formed by straight and curved lines, varying upwards of fifty
different ways, with variable and invariable changes, from zero
to twenty-two French, feet: the area.of water was equal to one
square inch. The sections of the veins were taken at different
distances from the aperture. .The results are extremely curi-
ous, as illustrating the influence of pressure and divergence on
part of a fluid mass not in equilibrio, and may be assimilated to
the phenomena presented by the undulation of streams of
light. The author contents himself with stating the results,
which are further illustrated by diagrams.
In a second paper, read to the Accademia delle Scienze in
April following of the same year (1829), M. Bidone enters into
a theoretical consideration of his experiments, in which he re-
presents the greatest contraction of the fluid vein to take place
at a distance not exceeding the greatest diameter of the orifice,
whatever be the shape; from which it results that the expres-
sion for the expense of the orifice is equal to the sum of the
product of each superficial element multiplied by the velocity.
of the fluid vein; and as it was determined by experiment
that the area of the vena contracta was from 0°60 to 0°62 of
the area of the orifice, it follows that this coefficient of con-;
traction, multiplied by the velocity due to the charge, repre-
sents the expenditure.
’ M. Bidone considers the case of a fluid vein reduced to a
of the component filaments, but solely on their direction, a re-
sult conformable to experiment.
176 THIRD REPORT—1833.
He then determines, from the results of M. Venturoli*, the
absolute magnitude of the contracted section of the vein (issuing
from a circular orifice) to be exactly 2rds of the orifice, the
correction due to the contraction depending upon the ad-
hesion and friction of the fluid against the perimeter of the ori-
fice, and the ratio of the area of the vein to the area of the
orifice: the same for all orifices. Hitherto the magnitude of
fluid veins, as determined by direct measurements, had given
greater coefficients than the effective expenditure allowed.
Michelotti, with a pressure of twenty feet, with orifices of one
and two inches in diameter, found the coefficient 0-649
Bassuth: Macraitqagoels (00s eice 214 OnE
petdackiadeepawal..0 iabais ogls peipag OES
Mientras aid yeu. pegs ise da9 ti Obae
Biytelborgimn ds: thay hed: nde LOO W aide AGA
Hachette... 2h cian naalbes iyo du soe
Mewaomis ia sualsise seis ariel! ocat Abit tO
Heebshatuuas atsiite 10.0 seigtihhe 1:2 volhinge be, GEO
Brindley and Smeaton . . . «. . . 0°631
Banke na wie Alagus Ap iid Obs eae
Rennie $yics. s1sej sag, ery eageuder, ideas] a
In several experiments the ratio rarely exceeded 0°620; so
that the discrepancy must have arisen from inaccuracies in the
measurement of the fluid vein and orifice.
In the year 1827, it having been considered desirable to re-
peat the experiments of Bossut and Dubuat, application was
made to the French Government by General Sabatier, Com-
mander-in-chief of the Military School at Metz, for permission
to undertake a series of experiments on a scale of magnitude
sufficient to establish the principles laid down by those authors,
and serve as valuable practical rules for future calculations.
The apparatus consisted, Ist, of an immense basin, having
an area of 25,000 square metres; 2nd, of a smaller reservoir,
having a superficial area of 1500 square metres, and a depth
of 3°70 metres, so contrived, by means’of sluices, as to have a
complete command of the level of the water during the experi-
ment; 3rd, of a basin directly communicating with the second
basin, 3°68 metres in length, and 3 metres in width, to receive
the product of the orifices; 4th, a basin or gauge capable of
containing 24,000 litres.
* Elementi di Meccanica e d’Idraulica: Milano 1818. Recherche Geome-
triche fatte nella Scuola degli Ingegneri pontifici d’ Acque e Strade, Tanno
1821. Milano.
+ “On the Friction and Resistance of Fluids,” Philosophical Transactions of
1831.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. Vit
The time was constantly noticed by an excellent stop-watch,
made by Breguet; and the opening of the orifices, the charges
of the fluid in the reservoir, as well as the level of the water in
the gauge basin relative to each expense of fluid, were always
measured to the tenth of a millimetre, so that, even under the
most unfavourable circumstances, the approximation was at least
to z4,dth part of the total result. The total disposable fall or
height, counting from the ordinary surface of the Moselle river,
was four metres, from which two metres were deducted for the
gauge basin, leaving only a fall of two metres under the most
favourable circumstances; and in the subsequent experiments
of 1828 the height never exceeded 1°60 metre, sufficiently
high for all practical purposes. An apparatus was provided
for regulating the height of the orifice and the surface of the
water in the reservoirs, and for tracing with the greatest accu-
racy the forms and sections of the fluid veins before and after
issuing from the orifices, and the depressions experienced by
the surface of the water previously to its issuing from an open-
ing of twenty centimetres square, the upper side of which was
on a level with the surface of the water in the reservoir. These
depressions are recorded in the Tables,
Ist, On the expenditure of water through rectangular verti-
cal orifices, twenty centimetres square, and varying in height
from one to twenty centimetres, under charges of from ‘0174
of a metre to 16901 metre:
2ndly, On the expenditures of water from the similar-sized.
orifices, open at the top, but under charges of from two to
twenty-two centimetres.
The whole is comprised in eleven Tables of 241 experiments,
to which is added a twelfth Table, showing the value of the co-
efficients of contraction for complete orifices, from twenty cen-
timetres square to one centimetre, calculated according to the
following formula:
D for the height of the orifices, where*
D=loV2gh=I1(h—-h) V2¢ — being the_theo-
retical expense relative to the velocity ;
D’=21 /2¢ (hE —W3)= 81 (hV 2gh—-WV 2h)
or the theoretical expense, having regard to the influence of
the orifice.
* That is, where / = 0-20 metre, being the horizontal breadth of all the orifices;
h = the charge of the fluid on the lower part of the orifice ;
h'= the charge in the upper or variable side of the orifice ;
o = h —h' the thickness of the vein of water.
1833, =
178 THIRD REPORT—1833.
The conclusions to be derived from these Tables are,
Ist, That for complete orifices of twenty centimetres square
and high charges, the coefficient is 0-600; with the charge
equal to four or five times the opening of the orifice, the co-
efficient augments to 0°605; but beyond that charge the co-
efficient diminishes to 0°593. :
2ndly, That the same law maintains for orifices of ten and
five centimetres in height, the coefficients being for ten centi-
metres 0°611, 0-618, 0°611 respectively, and for five centi-
metres in height 0°618, 0°631, 0°623.
Lastly, That with orifices of three, two and one centimetres
in height, the law changes very rapidly, and the coefficients
increase as the opening of the orifice becomes less, being for
one centimetre 0°698, the smallest height of the orifice, to 0°640
for three centimetres.
These remarkable discrepancies from the results of Bidone
and others are attributed by MM. Lesbros and Poncelet to
differences in the construction of the apparatus or in the mode
of measurement adopted by the latter gentlemen; but in gene-
ral the coincidences are sufficiently satisfactory, and they are
the more accurately confirmed by the subsequent investigations
‘of MM. D’Aubuisson and Castel at Toulouse *. As respects
water issuing from the openings or notches made in the sides
of dams, or what we should term incomplete orifices, it appears
that the coefficient obtained by the ordinary formula of Dubuat,
or Lhi/ 2 gh, augments from the total charge of twenty-two cen-
timetres when it is from 0°389 to two centimetres when it be-
comes 0:415 ; hence we may safely adopt M. Bidone’s coefficient
of 0:405, or, according to MM. Poncelet and Lesbros’ theory
0-400, for calculating expenditures through notches in dams.
From these and other experiments the authors are led to con-
clude, that the law of continuity maintains for indefinite heights
both with complete and incomplete orifices, and that the same
coefficient can be obtained by adopting in both cases the same
formula. The authors observe that the area of the section of
the greatest contraction of the vein, considered as a true
square, is exactly two thirds of the area of the orifice; a fact
which goes to prove that there is no certain comparison be-
tween the mean theoretical or calculated velocities, by means
of the formula now used, and the mean effective velocities de-
rived from the expenditure. P
The authors conclude their memoir by recommending. their
experiments for adoption in all cases of plate orifices situated
* Annales de Chimie et de Physique for 1880, tom.*xliv. p. 225.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 179
at a distance from the sides and bottom of the reservoir, pro-
mising to investigate with similaraccuracy in a future memoir
the cases which may occur to the contrary.
A note is appended to the memoir by M. Lesbros, contain-
ing formule for calculating the effective expenditure of com-
plete orifices; and also a 'l'able of constants, which gives the
effective expenditure of each orifice as compared with experi-
ment. We have been thus particular in detailing the results of
MM. Lesbros and Poncelet’s work, because they have com-
prehended all the cases upon which there remained any doubts,
and with very few exceptions are in accordance with the expe-
riments of Brunacci, Navier, Christian, Gueymard, D’Aubuis-
son, and by the author of this paper*. So that in point of
accuracy and laborious investigation, the authors of these va-
luable accessions to our knowledge, not only merit our grati-
tude, but have very amply replied to the liberality of the French
Government.
_ Having thus endeavoured to elucidate the labours of the
foreign philosophers who have contributed so greatly to the
progress of hydraulics, it only remains for us to notice the
scanty contributions of our countrymen to the science. While
France and Germany were rapidly advancing upon the traces
of Italy, England remained an inactive spectator of their pro-
‘gress, contented with the splendour of her own Newton, to
receive from foreigners whatever was original or valuable in
the science. The Philosophical Transactions, rich as they
are in other respects, scarcely contain a single paper on this
subject founded on any experimental investigations. Some
erroneous and inconclusive inferences from Newton, by Dr.
Jurin; a paper on the Measure of Force, by Mr. Eames; a
paper on Wiers, by Mr. Roberts; another on the Motion and
Resistance of Fluids, by Dr. Vince; and a summary of Bossut
and Dubuat’s Experiments on the Motions of Fluids through
‘Tubes, by Dr. Thomas Young, comprise nearly the whole of
the papers on hydraulics in the Philosophical Transactions.
The various treatises on the subject published by Maclaurin,
Emerson, Dr. Matthew Young, Desaguliers, Clare and Switzer,
with the exception of the theoretical investigations, are compiled
principally from the works of foreigners; and it was not until the
subject was taken up by Brindley, Smeaton, Robison, Banks
and Dr. Thomas Young, that we were at all aware of our defi-
ciency. Practical men were either necessitated to follow the un-
certain rules derived from their predecessors, or their own expe-
rience and sagacity, for the little knowledge they possessed.
' _ * Philosophical Transactions for 1831, .
N 2
180 THIRD REPORT—1833.
On the subject of hydrometry we were equally ignorant; and
although the Italian collection had been published several
years previously, and was well known on the Continent, it was
not until Mr. Mann published an abstract of that collection
that we were at all aware of the state of the science abroad.
Under these circumstances the author of this paper was in-
duced, in the year 1830, to undertake a series of experiments to
ascertain, Ist, The friction of water against the surface of a
cylinder, and discs revolving in it, at different depths and ve-
locities: from which it appeared, that with slow velocities the
friction approximated the ratio of the surfaces, but that an in-
crease of surface did not materially affect it with increased velo-
cities; and that with equal surfaces the resistances approxi-
mated to the squares of the velocities.
2ndly, To ascertain the direct resistances against globes
and dises revolving in air and water alternately: from which it
resulted, that the resistances in both cases were as the squares
of the velocities; and that the mean resistances of circular discs,
square plates, and globes of equal area, in atmospherical air,
were as under:
Circular discs . . 25°180 ...... 1:18
Square plates . . 22°010 im air, . . 1°36 in water.
Round globes. . 10°627..... . O75
3rdly, That with circular orifices made in brass plates of
eth of an inch in thickness, and having apertures of 4, 3, 2,2
of an inch respectively, under pressures varying from one to
four feet, the average coefficients of contraction were,
for altitudes of 1 foot. ...... 0-619
yO ss! | SP ra a 0°621
For additional tubes of glass the coefficient was,
TOR Bet eee rT aN 0°817
AREER VIE Oe 0°806-.
4thly, That the expenditures through orifices, additional
tubes, and pipes of different lengths, of equal areas and under
the same altitude as compared with the expenditure through a
pipe of 30 feet in length, are as
1:3 for orifices,
1:4 for additional tubes,
1 : 3-7 for a pipe 1 foot in length,
irs BG 8 feet ————-,
1:20 ——4 ,
1: 1-4 2 ———_———_..
5thly, That with bent rectangular pipes } an inch in diameter,
and 15 feet in length, the expenditures were diminished with
fourteen bends two thirds, as compared with a straight pipe,
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 181
and with twenty-four right angles, one third ; but did not seem
to observe any decided law.
In several experiments tried on a great scale, the results
gave from one fifth to one sixth of the altitude for the fric-
tion. In the case of the Coniston main, which conducts the
water from the reservoir at Coniston to the castle of Edin-
burgh, the diameter of which is 44 inches, the length 14,930
feet, and the altitude 51 feet, it was proved by Mr. Jardine
that the formule of Dubuat and Eytelwein approximated to
the real results very nearly; and in some experiments made on
a great scale by the author of this paper, these formulze were
found equally applicable. In several experiments made in the
year 1828, on the water-works at Grenoble, by M. Gueymard,
it was found that pipes of six and eight French inches in dia-
meter furnished only two thirds of the water indicated by the
formulz of M. Prony; but when of nine inches diameter, the
formula approximated very nearly. In M. Gueymard’s expe-
riment the altitude of the reservoir above the point of delivery
was 8°453 metres, or 27°73 English feet. The height to which
the water was required to be elevated was 5°514 metres, or
18 feet; the volume of water required was 954 litres, or 33°6
cubic feet; the length of the pipe was 3200 metres, or 10498
feet. ‘There were eight gentle curves in the system, but en-
larged beyond the average diameter of the parts of the pipe;
from which it resulted that the height to which, the water was
delivered was only two thirds of the height of the reservoir *.
In the preceding short but imperfect history of the science
of hydraulics we have confined our attention to the experi-
mental researches that have been made on spouting fluids only.
In a future communication I hope to examine the state of
our knowledge of the natural phenomena of rivers, and the
causes by which they are influenced; at present it is extremely
limited, and although we have many works upon the subject,
very little seems to be known either of their properties or of
the laws by which they are governed. ,
* According to M. Prony’s theory, the height raised would only have been
5°514 metres instead of 5°671 metres. The difficulty, however, of making ex-
periments on a great scale will always prove an obstacle to the right solution
of the question, in as much as it exacts that the pipe be of the same dia-
meter throughout, that is, perfectly straight, and free from bends, and the
charge of water invariable. For this purpose M. Prony has calculated Tables
showing the relation subsisting between the expenditure, diameter, length, the
total inclination of the pipes, and the difference of pressure at its extremities.
182 THIRD REPORT—1833; te
APPENDIX.
Since the foregoing Report was read to the British Associa-
tion a paper, entitled ‘“‘ Mémoire sur la Constitution des Veines
Liquides lancées par des Orifices Circulaires en mince paroi,”
has been communicated to the Academy of Sciences at Paris,
by M. Félix Savart, 26 Aott 1833. The author, after detailing
very minutely the different phanomena presented by liquid
veins issuing from circular orifices perforated in thin plates,
attached to the bottom and sides of vessels, illustrates his po-
sitions by a series of curious experiments on the vibrations and
sounds of the drops which issue from the annular rings or pipes
formed by the troubled part of the liquid. The results of these
experiments are best given in his own words.
«1°, Toute veine liquide lancée verticalement de haut en bas
par un orifice circulaire pratiqué dans une paroi plane et hori-
zontale est toujours composée de deux parties bien distinctes
par l’aspect et la constitution. La partie qui touche a l orifice est
un solide de révolution dont toutes les sections horizontales
vont en décroissant graduellement de diameétre. Cette premiére
partie de la veine est calme et transparente, et ressemble 4 un
tige de cristal. La seconde partie, au contraire, est toujours
agitée, et parait dénuée de transparence, quoiqu elle soit ce-
pendant d’une forme assez réguliére pour qu'on puisse facile-
ment voir quelle est divisée en un certain nombre de ren-
flemens allongés dont le diamétre maximum est toujours plus
grand que celui de lorifice.
* 2°, Cette seconde partie de la veine est composée de gouttes
bien distinctes les unes des autres, qui subissent pendant leur
chute, des changemens périodiques de forme, auxquels sont dues
les apparences de ventres ou renflemens régulitrement espacés
que l’inspection directe fait reconnaitre dans cette partie de la
veine, dont la continuité apparente dépend de ce que les gouttes
se suecédent a des intervalles de temps qui sont moindres que.
la durée de la sensation produite sur la rétine par chaque goutte
en particulier.
“30, Les gouttes qui forment la partie trouble de la veine
sont produites par des renflemens annulaires qui prennent
naissance trés pres de lorifice, et qui se propagent a des inter-
valles de temps égaux, le long de la partie limpide de la veine,.
en augmentant de volume A mesure quiils descendent, et qui
enfin se séparent de l'extrémité inférieure de la partie limpide:
et continue 4 des intervalles de temps égaux 4 ceux de leur
production et de leur propagation.
ON HYDRAULICS AS A BRANCH OF ENGINEERING. 183.
«40, Ces renflemens annulaires sont engendrés par une suc-
eession périodique de pulsations qui ont lieu 4 l’orifice méme ;
de sorte que la vitesse de I’écoulement, au lieu d’étre uniforme,
est périodiquement variable.
_ “5°, Le nombre de ces pulsations, méme pour des charges
foibles, est toujours assez grand, dans un temps donné, pour
qu’elles soient de l’ordre de celles qui, par la fréquence de leur
retour, peuvent donner lieu a des sons perceptibles et compa-
rables. Ce nombre ne dépend que de la vitesse de l’écoule-
ment, a laquelle il est directement proportionnel, et du diamétre
des orifices, auquel il est inversement proportionnel. [I ne pa-
rait altéré ni par la nature du liquide, ni par la température.
«6°, L’amplitude de ces pulsations peut étre considérable-
ment augmentée par des vibrations de méme période commu-
niquées A la masse entiére du liquide et aux parois du réservoir
qui le contient. Sous cette influence étrangére, les dimensions
et état de la veine peuvent subir des changemens remarqua-
bles: la longueur de la partie limpide et continue peut se
réduire presqu’a rien, tandis que les ventres de la partie trouble
acquiérent une régularité de forme et une transparence qu’ils
ne possédent pas ordinairement. Lorsque le nombre des vibra-
tions communiquées est différent de celui des pulsations qui
ont lieu a Yorifice, leur influence peut méme aller jusqu’a
changer le nombre de ces pulsations, mais seulement entre de
certaines limites.
«7°, La dépense ne parait pas altérée par l’amplitude des
pulsations, ni méme par leur nombre.
** 8°. La resistance de lair n’influe pas sensiblement sur la
forme et les dimensions des veines, non plus que sur le nombre
des pulsations.
«9°, La constitution des veines lancées horizontalement ou
méme obliquement de bas en haut ne différe pas essentiellement
de celle des veines lancées verticalement de haut en bas ; seule-
ment le nombre des pulsations a l’orifice parait devenir d’autant
moindre que le jet approche plus d’étre lancé verticalement de
bas en haut.
** 10°. Quelle que soit la direction de la veine, son diamétre
décroit toujours trés rapidement jusqu’a une petite distance de
Yorifice ; mais quand la veine tombe verticalement, le décroisse-
ment continue jusqu’a ce que la partie limpide se perde dans
la partie trouble: il en est encore de méme quand la veine est
lancée horizontalement, quoiqu’alors le décroissement suive une
loi moins rapide. Lorsque le jet est lancé obliquement de
bas en haut, et qu'il forme avec lhorizon un angle de 25° 4 45°,
toutes les sections normales a la courbe qu'il décrit deviennent
184 THIRD REPORT—1833.
sensiblement égales entre elles, 4 partir de la partie contractée
que touche a l’orifice. Enfin, pour des angles plus grands que
45°, le diamétre de la veine va en augmentant depuis la partie
contractée jusqu’a la naissance de la portion trouble; de sorte
que c’est seulement alors qu'il existe une section qu’on peut
4 juste titre appeler section contractée.”
185
Report on the Recent Progress and Present State of certain
Branches of Analysis. By Grorcs Peacock, M.A., F.R.S.,
E.G.S., F.Z.S., £.R.A.S., F.C.P.S., Fellow and Tutor of
Trinity College, Cambridge.
Tux present Report was intended in the first instance to have
comprehended some notice of the recent progress and present
state of analytical science in general, including algebra, the
application of algebra to geometry, the differential and integral
calculus, and the theory of series: a very little progress, how-
ever, in the inquiries which were required for the execution of
this undertaking convinced me of the necessity of confining
them within much narrower limits, unless I should have ven-
tured to occupy a much larger space in the annual publication
of the Proceedings and Reports of the British Association than
could be properly or conveniently allotted to one department
of science, when so many others were required to be noticed.
It is for these reasons that I shall restrict my observations,
in the following Report, to Algebra, Trigonometry, and the
Arithmetic of Sines; at the same time I venture to indulge a
hope of being allowed, upon some future occasion, to bring
before the Members of the Association some notice of those
higher branches of analysis which at present I feel myself
compelled, though reluctantly, to omit. .
Algebra.—The science of algebra may be considered under
two points of view, the one having reference to its principles,
and the other to its applications: the first regards its complete-
ness as an independent science; the second its usefulness and
power as an instrument of investigation and discovery, whether
as respects the merely symbolical results which are deducible
from the systematic developement of its principles, or the ap-
plication of those results, by interpretation, to the physical
sciences.
Algebra, considered with reference to its principles, has re-
ceived very little attention, and consequently very little im-
provement, during the last century; whilst its applications,
using that term in its largest sense, have been in a state of
continued advancement. Many causes have contributed to this
comparative neglect of the accurate and logical examination of
the first principles of algebra: in the first place, the proper
186 THIRD REPORT—1833.
assumption and establishment of those principles involve meta-
physical difficulties of a very serious kind, which present them-
selves to a learner at a period of his studies when his mind has
not been subjected to such a system of mathematical discipline
as may enable it to cope with them: in the second place, we are
commonly taught to approach those difficulties under the cover
of a much more simple and much less general science, by steps
which are studiously smoothed down, in order to render the
transition from one science to the other as gentle and as little
startling as possible; and lastly, from the peculiar relation
which the first principles of algebra, in common with those of
other scierices of strict demonstration, bear to the great mass
of facts and reasonings of which those sciences are composed. |
It is this last circumstance which constitutes a marked distine-
tion between those sciences which, like algebra and geometry,
are founded upon assumed principles and definitions, and the
physical sciences: in one case we consider those principles and
definitions as ultimate facts, from which our investigations pro-
ceed in one direction only, giving rise to a series of conclusions
which have reference to those facts alone, and whose correct-
ness or truth involves no other condition than the existence of
a necessary connexion between them, in whatever manner the
evidence of that existence may be made manifest ; whilst in the
physical sciences there are no such ultimate facts which can be
considered as the natural or the assumable limits of our inves-
tigations. It is true, indeed, that in the application of algebra
or geometry to such sciences, we assume certain facts or prin-
ciples as possessing a necessary existence or truth, investing
them, as it were, with a strictly mathematical character, and
making them the foundation of a system of propositions, whose
connexion involves the same species of evidence with that of the
succession of propositions in the abstract sciences; but in as-
signing to such propositions their proper interpretation in the
physical world, our conclusions are only true to an extent which
is commensurate with the truth and universality of application
of our fundamental assumptions, and of the various conditions
by which the investigation of those propositions has been sup-
posed to be limited; in other words, such conclusions can be
considered as approximations only to physical truth; for such
assumed first principles, however vast may be the superstrue>
ture which is raised upon them, form only one or more links in
the great chain of propositions, the termination and foundation
of which must be for ever veiled in the mystery of the first
cause. : ‘
It is not my intention to enter upon the examination of the
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 187
general relations which exist between the speculative and physi-
cal sciences, but merely to point out the distinction between the
ultimate objects of our reasonings in the one class and in the
other: in the first, we merely regard the results of the science
itself, and the logical accuracy of the reasoning by which they
are deduced from assumed first principles; and all our conclu-
sions possess a necessary existence, without seeking either for
their strict or for their approximate interpretation in the nature
of things: in the second, we found our reasonings equally upon
assumed first principles, and we equally seek for logical accu-
racy in the deduction of our conclusions from them ; but both
in the principles themselves and in the conclusions from them,
we look to the external world as furnishing by interpretation
corresponding principles and corresponding conclusions ; and
the physical sciences become more or less adapted to the ap-
plication of mathematics, in proportion to the extent to which
our assumed first principles can be made to approach to the
most simple and general facts or principles which are discover-
able in those sciences by observation or experiment, when di-
vested of all incidental and foreign causes of variation; and
still more so, when the causes of such variation can be di-
stinctly pointed out, and when their extent and influence are
reducible to approximate at least, if not to accurate estimation.
The first principles, therefore, which form the foundation
of our mathematical reasonings in the physical sciences being
neither arbitrary assumptions nor necessary truths, but really
forming part of the series of propositions of which those sci-
enees are composed, can never cease to be more or less the
subject of examination and inquiry at any point of our re-
searches: they form the basis of those interpretations which
are perpetually required to connect our mathematical with the
corresponding physical conclusions; and even supposing the
immediate appeal to them to be superseded, as will frequently
be the case, by other propositions which are deducible from
them, they still continue to claim our attention as the proposi-
tions which terminate those physical and logical inquiries at
which our mathematical reasonings begin. But in the abstract
sciences of geometry and algebra, those principles which are
the foundation of those sciences are also the proper limits of
our inquiries; for if they are in any way connected with the phy-
sical sciences, the connexion is arbitrary, and in no respect af-
fects the truth of our conclusions, which respects the evidence
of their connexion with the first principles only, and does not
require, though it may allow, the aid of physical interpretation.
- It is true that there exists a connexion between physical and
188 THIRD REPORT—1833.
-
speculative geometry, as well as between physical and specula-
tive mechanics; and if in speculative geometry we regarded
the actual construction and mensuration of the figures and solids
in physical geometry alone, the transition from one science to
the other being made by interpretation, then speculative geo-
metry and speculative mechanics must be regarded as sciences
which were similar in their character, though different in
their objects: but we cultivate speculative geometry without
any such exclusive reference to physical geometry, as an in-
strument of investigation more or less applicable, by means
of interpretation, to all sciences which are reducible to mea-
sure, and whose abstract conclusions, in whatever manner
suggested or derived, possess a great practical value altogether
apart from their applications to practical geometry; whilst the
conclusions in speculative mechanics are valuable from their
applications to physical mechanics only, and are not other-
wise separable from the conclusions of those abstract sciences
which are employed as instruments in their investigation.
This separation of speculative and physical geometry was
perfectly understood by the ancients, though their views of its
application to the physical sciences were extremely limited ;
and it is to the complete abstraction of the principles of specu-
lative geometry that we must in a great measure attribute the
vast discoveries which were made by its aid in the hands of
Newton and his predecessors, when a more enlarged and phi-
losophical knowledge of the laws of nature supplied those phy-
sical axioms or truths which were required as the medium of
its applications ; and though it was destined to be superseded,
at least in a great degree, by another abstract science of much
greater extent and applicability, yet it was enabled to maintain
its ground for a considerable time against its more powerful
rival, in consequence of the superior precision of its prin-
ciples and the superior evidence of its conclusions, when con-
sidered with reference to the form under which the principles
and conclusions of algebra were known or exhibited at that
period.
Algebra was denominated in the time of Newton specious or
universal arithmetic, and the view of its principles which gave
rise to this synonym (if such a term may be used) has more or
less prevailed in almost every treatise upon this subject which
has appeared since his time. In a similar sense, algebra has
been said to be a science which arises from that generalization
of the processes of arithmetic which results from the use of
symbolical language: but though in the exposition of the prin-
ciples of algebra, arithmetic has always been taken for its foun-
REPORT ON CERTAIN BRANCHES OF ANALYSIS, 189
dation, and the names of the fundamental operations in one
science have been transferred to the other without any imme-
diate change of their meaning, yet it has generally been found
necessary subsequently to enlarge this very narrow basis of so
very general a science, though the reason of the necessity of
doing so, and the precise point at which, or the extent to which,
it was done, has usually been passed over without notice. The
science which was thus formed was perfectly abstract, in what-
ever manner we arrived at its fundamental conclusions; and
those conclusions were the same whatever view was taken of
their origin, or in whatever manner they were deduced; but a
serious error was committed in considering it as a science which
admitted of strict and rigorous demonstration, when it certainly
possessed no adequate principles of its own, whether assumed
or demonstrated, which could properly justify the character
which was thus given to it. |
There are, in fact, two distinct sciences, arithmetical and
symbolical algebra, which are closely connected with each
other, though the existence of one does not necessarily deter-
mine the existence of the other. The first of these sciences
would be, properly speaking, wniversal arithmetic: its general
symbols would represent numbers only; its fundamental ope-
rations, and the signs used to denote them, would have the same
meaning as in common arithmetic; it would reject the inde-
pendent use of the signs + and —, though it would recognise the
common rules for their incorporation, when they were preceded
by other quantities or symbols: the operation of subtraction
would -be impossible when the subtrahend was greater than
the quantity from which it was required to be taken, and there-
fore the proper zmpossible quantities of such a scienee-would
be the negative quantities of symbolical algebra; it would re-
ject also the consideration of the multiple values of simple
roots, as well as of the negative and impossible roots of equa-
tions of the second and higher degree: it is this species of al-
gebra which alone can be legitimately founded upon arithmetic
as its basis.
Mr. Frend *, Baron Maseres, and others, about the latter
end of the last century, attempted to introduce arithmetical
* The Principles of Algebra, by William Frend, 1796; and The true The-
ory of Equations, established on Mathematical Demonstration, 1799. The fol-
Towing extracts from his prefaces to these works will explain the nature of his
‘views :
“ The ideas of number are the clearest and most distinct of the human mind:
the acts of the mind upon them are equally simple and clear. There cannot
be confusion in them, unless numbers too great for the comprehension of the
190 THIRD REPORT— 1833.
to the exclusion of symbolical algebra, .as the only form of it
which was capable of strict demonstration, and which alone,
therefore, was entitled to be considered as a science of strict and
logical reasoning. ‘The arguments which they made use of
“were unanswerable, when advanced against the form under
which the principles of algebra were exhibited in the elemen-
tary and all other works of that period, and which they have
continued to retain ever since, with very trifling and unimpor-
tant alterations; and the system of algebra which was formed
by the first of these authors was perfectly logical and complete,
the corinexion of all its parts being capable of strict demon-
stration; but there were a great multitude of algebraical re-
sults and propositions, of unquestionable value and of unques-
tionable consistency with each other, which were irreconcila-
ble with such a system, or, at all events, not deducible from it;
and amongst them, the theory of the composition of equations,
which Harriot had left in so complete a form, and which made
it necessary to consider negative and even impossible quan-
learner are employed, or some arts are used which are not justifiable. The
first error in teaching the first principles of algebra is obvious on perusing a few
pages only of the first part of Maclaurin’s Algebra. Numbers are there divided
Into two sorts, positive and negative: and an attempt is made to explain the
nature of negative numbers, by allusions to book debts and other arts. Now
when a person cannot explain the principles of a science, without reference to
a metaphor, the probability is, that he has never thought accurately upon the
subject. A number may be greater or less than another number: it may be
added to, taken from, multiplied into, or divided by, another number ; but in
other respects it is very intractable; though the whole world should be destroyed,
one will be one, and three will be three, and no art whatever can change their
nature. You may put a mark before one, which it will obey; it submits to be
taken away from another number greater than itself, but to attempt to take it
away from a number less than itself is ridiculous. Yet this is attempted by
algebraists, who talk of a number less than nothing, of multiplying a negative
number into a negative number, and thus producing a positive number, of a
number being imaginary. Hence they talk of two roots to every equation of
the second order, and the learner is to try which will succeed in a given equa-
tion: they talk of solving an equation which requires two impossible roots to
make it soluble: they can find out some impossible numbers, which being
multiplied together produce unity. This is all jargon, at which common sense
recoils; but from its having been once adopted, like many other figments, it
finds the most strenuous supporters among those who love to take things upon
trust and hate the colour of a serious thought.”
“ From the age of Vieta, the father, to this of Maseres, the restorer of alge-
bra, many men of the greatest abilities have employed themselves in the pursuit
of an idle hypothesis, and have laid down rules not founded in truth, nor of any
sort of use in a science admitting in every step of the plainest principles of
reasoning. If the name of Sir Isaac Newton appears in this list, the number
of advocates for errour must be considerable. It is, however, to be recollected,
that for a much longer period, men scarcely inferiour to Newton in genius, and
his equals, probably, in industry, maintained a variety of positions in philoso-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 191
tities as having a real existence in algebra, however vain might
be the attempt to interpret their meaning.
Both Mr. Frend and Baron Maseres were sensible of the con-
sequences of admitting the truth of this theory of the compo-
sition of equations as far as their system was concerned, and it
must be allowed that they have struggled against it with con-
siderable ingenuity: they admitted the possibility of multiple
real, that is, positive roots, and which are all equally congruous
to the problem whose solution was required through the medium
of the equation, indicating an imdetermination in the problem
proposed: but it would be easy to propose problems leading to
equations whose roots were real and positive, and yet not con-
gruous to the problem proposed, whose existence must be ad-
mitted upon their own principles; and if so, why not admit the
‘existence of other roots, whether negative or impossible, to
which the algebraical solution of the problem might lead, though
they might admit of no very direct interpretation, in conformity
with the expressed conditions of the problem*?
phy, which were overthrown by a more accurate investigation of nature; and
if the name Ptolemy can no longer support his epicycles, nor that of Des
Cartes his vortices, Newton’s dereliction of the principles of reasoning cannot
establish the fallacious notion, that every equation has as many roots.as it has
dimensions.”
This notion of Newton and others is founded on precipitation. Instead of
a patient examination of the subject, an hypothesis which accounts for many
appearances is formed; where it fails, unintelligible terms are used; in those
terms indolence acquiesces: much time is wasted on a jargon which has the
_ ‘appearance of science, and real knowledge is retarded. Thus volumes upon
volumes have been written on the stupid dreams of Athanasius, and on the im-
possible roots of an equation of n dimensions.”
This work of Mr. Frend, though containing many assertions which show
great distrust of the results of algebraical science which were in existence at
the time it was written, presents a very clear and logical view of the principles
of arithmetical algebra.
The voluminous labours of Baron Maseres are contained in his Scriptores
Logarithmici, and in a thick volume of Tracts on the Resolution of Cubic and
Biquadratic Equations. He seems generally to have forgotten that any change
_ had taken place in the science of algebra between the age of Ferrari, Cardar,
Des Cartes, and Harriot, and the end of the 18th century; and by considering
all algebraical formule as essentially arithmetical, he is speedily overwhelmed
by the same multiplicity of eases (which are all included in the same really al-
gebraical formula) which embarrassed and confounded the first authors of the
science.
' * Thus, in the solution of the following problem: ‘Sold a horse for 24/.,
and by so doing lost as much per cent. as the horse cost me: required the
prime cost of the horse?”’ we arrive at the equation
; 100 # — #? = 2400;
if we subtract both sides of this equation from 2500, we get
2500 — 100 2 + a? = 100,
dedi or a? — 1007 + 2500 = 100,
inasmuch as the quantities upon each side of the sign = are in both cases
192 THIRD REPORT—1833.
If the authors of this attempt at algebraical reform had been
better acquainted with the more modern results of the science,
they would have felt the total inadequacy of the very limited
science of arithmetical algebra to replace it; and they would
probably have directed their attention to discover whether any
principles were necessary to be assumed, which were not neces-
sarily deducible as propositions from arithmetic or arithmetical
algebra, though they might be suggested by them. As it was,
however, these speculations did not receive the consideration
which they really merited; and it is very possible that the
attempt which was made by one of their authors to connect the
errors in reasoning, which he attacked, as forming part only of
a much more extensive class to which the human mind is liable
from the influence of prejudice or fashion, had a tendency to
divert men of an enlarged acquaintance with the results of
algebra from such a cautious and sustained examination of them
as was required for their refutation, or rather for such a correc-
tion of them as was really necessary to establish the science of
algebra upon its proper basis.
I know that it is the opinion of many persons, even amongst
the masters * of algebraical science, that arithmetic does supply
identical with each other: if we extract the square root on both sides, re-
jecting the negative value of the square root, we’get in the first case
50 — x = 10,
and in the second,
az — 50= 10.
The first of these simple equations gives us x =40, and the second « = 60, both
of which satisfy the conditions of the problem proposed: the two roots which
are thus obtained, strictly by means of arithmetical algebra, show that the pro-
blem proposed is to a certain. extent indeterminate, Mr. Frend and Baron
Maseres contended that multiple real roots, which are always the indication
of a similar indetermination in the problems which lead to such equations,
might be obtained by arithmetical algebra alone, and that all other roots were
useless fictions, which could lead to no practical conclusions. But it is very easy
to show, that incongruous and real, as well as negative and impossible roots,
may equally indicate the impossibility of the problem proposed: thus, if it
was proposed “to find a number the double of whose square exceeds three
times the number itself by 5,”’ we shall find } and — 1 for the roots of the
resulting equation, both of which equally indicate the impossibility of the pro-
blem proposed, if by number be meant a whole positive number.
* Cauchy, who has enriched analysis with many important discoveries,
and who is justly celebrated for his almost unequalled command over its lan-
guage, has made it the principal object of his admirable work, entitled Cours
d@’ Analyse de l’ Ecole Royale Polytechnique, to meet the difficulties which pre-
sent themselves in the transition from arithmetical to symbolical algebra : and
though he admits to the fullest extent the essential distinction between them,
in the ultimate form which the latter science assumes, yet he considers the
principles of one as deducible from those of the other, and presents the rules
for the concurrence and incorporation of signs ; for the inverse relation of the
operations called addition and subtraction, multiplication and division; for
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 193
a sufficient basis for symbolical algebra. considered under its
most. general form; that symbols, considered as representing
numbers, may represent every kind of concrete magnitude ;
the indifference of the order of succession of different algebraical operations,
as so many theorems founded upon the ordinary principles and reasonings of
arithmetic. In order to show, however, the extraordinary vagueness of the
reasoning which is employed to establish these theorems, we will notice some
of them in detail: On représente, says he, les grandeurs qui doivent servir d’ac-
croissements, par des nombres précédés du signe +, et les grandeurs qui doivent
servir de diminutions par des nombres précédés du signe —. Cela posé, les signes
+ et — placés devant les nombres peuvent étre compares, suivant la remarque
quien a été faite}, & des adjectifs placés aupres de leurs substantifs. It is unques-
tionable, however, that in the most common cases of the interpretation of
specific magnitudes affected with the signs + and —, there is no direct refer-
ence either to increase or diminution, to addition or to subtraction. Hesub-
sequently gives those signs a conventional interpretation, as denoting quan-
tities which are opposed to each other; and assuming the existence of quan-
tities affected by independent signs, and denoting + A by a, and — A by 8,
he says that
+a=+A +6=-—A
—a=—A —b=+A4;
and therefore,
+(fA)=4+A +(-AN =A
—(+A)=—A —(-A=++A4;
which he considers as a sufficient proof of the rule of the concurrence of
signs in whatever operations they may occur ; though it requires a very slight
examination of this process of reasoning to show that it involves several ar-
bitrary assumptions and interpretations which may or may not be consistent
with each other. In the proofs which he has given of the other fundamental
theorems which we have mentioned above, we shall find many other instances
of similar confusion both in language and in reasoning: thus, ‘‘ subtraction
is the inverse of addition in arithmetic; then therefore, also, subtraction is
the inverse of addition in algebra, even when applied to quantities affected
with the signs + and —, and whatever those quantities may be.” But is
this a conclusion or an assumption? or in what manner can we explain in
words the process which the mind follows in effecting such a deduction?
“If a and b be whole numbers, it may be proved that a 0 is identical with
ba: therefore, a b is identical with 5 a, whatever a and b may denote, and
whatever may be the interpretation of the operation which connects them.”
But any attempt to establish this conclusion, without a previous definition
of the meaning of the operation of multiplication when applied to such quanti-
ties, will show it to be altogether impracticable. The system which he has fol-
lowed, not merely in the establishment of the fundamental operations, but
likewise in the interpretation of what he terms symbolical expressions and
symbolical equations, requires the introduction of new conventions, which are not
the less arbitrary because they are rendered necessary for the purpose of
making the results of the science consistent with each other: some of those
conventions I believe to be necessary, and others not; but in almost every in-
stance I should consider them introduced at the wrong place, and more or
pee eenieeatly with the professed grounds upon which the science is
ounded.
. 1} By Buée in the Philosophical Transactions, 1806.
1833. oO
194 THIRD REPORT—1833.
that the operations of addition, subtraction, multiplication and
division are used in one science and in the other in no sense
which the mind may not comprehend by a practicable, though
it may not be by a very simple, process of generalization ; that
we may be enabled by similar means to conceive both the use
and the meaning of the signs + and —, when used independ-
ently ; and that though we may be startled and somewhat em-
barrassed by the occurrence of impossible quantities, yet that
investigations in which they present themselves may generally
be conducted by other means, and those difficulties may be
evaded which it may not be very easy or very prudent to en-
counter directly and openly.
In reply, however, to such opinions, it ought to be remarked
that arithmetic and algebra, under no view of their relation to
each other, can be considered as one science, whatever may be
the nature of their connexion with each other; that there is
nothing in the nature of the symbols of algebra which can es-
sentially confine or limit their signification or value; that it is
an abuse of the term generalization* to apply it to designate
the process of mind by which we pass from the meaning of a—b,
when a is greater than 8, to its meaning when a is less than 0,
or from that of the product a b, when a and 6 are abstract num-
bers, to its meaning when a and 6 are concrete numbers of the
same or of a different kind; and similarly in every case where
a result is either to be obtained or explained, where no pre-
vious definition or explanation can be given of the operation
upon which it depends: and even if we should grant the legiti-
macy of such generalizations, we do necessarily arrive at a new
science much more general than arithmetic, whose principles,
however derived, may be considered as the immediate, though
not the ultimate foundation of that system of combinations of
symbols which constitutes the science of algebra. It is more
natural and philosophical, therefore, to assume such principles
as independent and ultimate, as far as the science itself is con-
cerned, in whatever manner they may have been suggested, so
that it may thus become essentially a science of symbols and
their combinations, constructed upon its own rules, which may
* The operations in arithmetical algebra can be previously defined, whilst
those in symbolical algebra, though bearing the same name, cannot: their
meaning, however, when the nature of the symbols is known, can be generally,
but by no means necessarily, interpreted. The process, therefore, by which we
pass from one science to the other is not an ascent from particulars to generals,
which is properly called generalization, but one which is essentially arbitrary,
though restricted with a specific view to its operations and their results admit-
ting of such interpretations as may make its applications most generally useful.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 195
be applied to’ arithmetic and to all other sciences by interpreta-
tion: by this means, interpretation will follow, and not precede,
the operations of algebra and their results; an order of suc-
cession which a very slight examination of their necessary
changes of meaning, corresponding to, the changes in the spe-
cific values and applications of the symbols involved, will very
speedily make manifest.
But though the science of arithmetic, or of arithmetical al-
gebra, does not furnish an adequate foundation for the science
of symbolical algebra, it necessarily suggests its principles, or
rather its laws of combination; for in as much as symbolical al-
gebra, though arbitrary in the authority of its principles, is not
arbitrary in their application, being required to include arith-
metical algebra as well as other sciences, it is evident that their
rules must be identical with each other, as far as those sciences
proceed together in common: the real distinction between them
will arise from the supposition or assumption that the symbols
in symbolical algebra are perfectly general and unlimited both
in value and representation, and that the operations to which
they are subject are equally general likewise. Let us now
consider some of the consequences of such an assumption.
A system of symbolical algebra will require the assumption
of the independent use of the signs + and —.
For the general rule in arithmetical algebra* informs us,
that the result of the subtraction of 6 + ¢ from a is denoted
by a — b —c, or that a — (b +c) = a — b —¢, its application
being limited by the necessity of supposing that b + ¢ is less
than a. The general hypothesis made in symbolical algebra,
namely, that symbols are unlimited in value, and that operations
are equally applicable in all cases, would necessarily lead us
to the conclusion that a — (6 +c) =a—6-—ce for all values
of the symbols, and therefore, also, when 6 = a, in which case
we have
a—(@+c)=a-—-a-c=—Cc.
In a similar manner, also, we find
a—(a—ec)=a-—a+c=+ec=C¢}.
We are thus necessarily led to the assumption of. the exist-
ence of such quantities as — ¢ and + ce, or of symbols preceded
.* Whatever general symbolical conclusions are true in arithmetical algebra
must be true likewise in symbolical, algebra, otherwise one science could not
include the other, This is a most important principle, and will be the subject
of particular notice. hereafter. ,
¢ For it appears from arithmetical algebra that a —a= 0, and thata —a@
+b=5
02
196 THIRD REPORT—1833.
by the independent signs * + and —, which no longer denote
operations, though they may denote affections of quantity. It
appears likewise that + ¢ is identical with c, but that — cis a
quantity of a different nature from ¢: the interpretation of its
meaning must depend upon the joint consideration of the spe-
cific nature of the magnitude denoted by a, and of the symbolical
conditions which the sign —, thus used, is required to satisfy}.
In a similar manner, the result of the operation, or rather
the operation itself, of extracting the square root of such a
quantity as a — b is impossible, unless a is greater than b. To
remove the limitation in such cases, (an essential condition in
symbolical algebra,) we assume the existence of a sign such
as “ —1; so that if we should suppose b = a+ c, we should
get /(a —b) = V {a—(a+c)} = V(a—a—c) = V(—o)
= 7% —I1c{. Ina similar manner, in order to make the ope-
ration universally applicable, when the nx root of a — 6 is
required, we assume the existence of a sign / —1, for which,
as will afterwards appear, equivalent symbolical forms ‘can al-
ways be found, involving “ —1 and numerical quantities.
By assuming, therefore, the independent existence of the
signs +, —, V1, and 7 —1, (1), and (—1)*§, we shall obtain
a symbolical result in all those operations, which we call addi-
tion, subtraction, multiplication, division, extraction of roots,
and raising of powers, though their meaning may or may not be
identical with that which they possess in arithmetic. Let us
now inquire a little further into the assumptions which deter-
mine the symbolical character and relation of these funda-
mental operations.
The operations called addition and subtraction are denoted
by the signs + and —.
They are the inverse of each other.
* That is, not preceded by other symbols as in the expressions a — c and
a+e.
+ Amongst these conditions, the principal is, that if —c be subjected to
the operation denoted by the sign —, it will become identical with + ec: thus,
a—(—c)=a-+c. It does not follow, however, that the sign — thus used,
must necessarily admit of interpretation.
+ The symbolical form, however, of this and of similar signs is not arbi-
trary, but dependent upon the general laws of symbolical combination.
I do not assert the necessity of considering such signs as 4/—1, (1)*,
(—1)", as forming essentially a part of the earliest and most fundamental as-
sumptions of algebra: the necessity for their introduction will arise when
those operations with which they are connected are first required to be con-
sidered, and will in all cases be governed by the general principle above men-
tioned. F
REPORT ON. CERTAIN BRANCHES OF ANALYSIS. 197
‘In the concurrence of the signs + and —, in whatever man-
ner used, if two like signs come together, whether + and +, or
— and —, they are replaced by the single sign + ; and when
two unlike signs come together, whether + and —, or — and +,
they are replaced by the single sign —.
‘When different operations are performed or indicated, it is
indifferent in what order they succeed each other.
The operations called multiplication and division are de-
noted by the signs x and ~, or more frequently by a conven-
tional position of the quantities or symbols with respect to
each other: thus, the product of a and 6 is denoted by a x 8,
a.b, orab; the quotient of a divided by 6 is denoted by
~ b, or by ©.
a ‘ate Ys
The operations of multiplication and division are the inverse
of each other.
In the concurrence of the signs + and — in multiplication or
division, if two like signs come together, whether + and +, or
— and —, they are replaced by the single sign +; and if two un-
like signs come together, whether + and —, or — and +, they
are replaced by the single sign —.
When different operations succeed each other, it is not indif-
rent in what order they are taken.
We arrive at all these rules, when the operations are defined
and when the symbols are numbers, by deductions, not from
each other, but from the definitions themselves: in other words,
these conclusions are not dependent upon each other, but upon
‘the definitions only. In the absence, therefore, of such defini-
tions of the meaning of the operations which these signs or
forms of notation indicate, they become assumptions, which are
‘independent of each other, and which serve to define, or rather
to interpret* the operations, when the specific nature of the
symbols is known; and which also identify the results of those
operations with the corresponding results in arithmetical alge-
bra, when the symbols are numbers and when the operations are
arithmetical operations.
The rules of symbolical combination which are thus assumed
* To define, is to assign beforehand the meaning or conditions ofa term or
operation ; to interpret, is to determine the meaning of a term or operation
conformably to definitions or to conditions previously given or assigned. It is
for this reason, that we define operations in arithmetic and arithmetical alge-
bra conformably to their popular meaning, and we interpret them in symboli-
a ai conformably to the symbolical conditions to which they are sub-
ject.
198 THIRD REPORT—1883.
have been suggested only by the corresponding rules in arith-
metical algebra. They cannot be said to be founded upon them,
for they are not deducible from them; for though the opera-
tions of addition and subtraction, in their arithmetical sense,
are applicable to all quantities of the same kind, yet they ne-
cessarily require a different meaning when applied to quanti-
ties which are different in their nature, whether that difference
consists in the kind of quantity expressed by the unaffected
symbols, or in the different signs of affection of symbols de-
noting the same quantity; neither does it necessarily follow
that in such cases there exists any interpretation which can be
given of the operations, which is competent to satisfy the re-
quired symbolical conditions. It is for such reasons that the
investigation of such interpretations, when they are discover-
able, becomes one of the most important and most essential of
the deductive processes which are required in algebra and its
applications.
Supposing that all the operations which are required to be
performed in algebra are capable of being symbolically de-
noted, the results of those operations will constitute what are
called equivalent forms, the discovery and determination of
which form the principal business of algebra. The greatest
part of such equivalent forms result from the direct applica-
tion of the rules for the fundamental operations of algebra,
when these rules regard symbolical combinations only: but
in other cases, the operations which produce them being nei-
ther previously defined nor reduced to symbolical rules, unless
for some specific values of the symbols, we are compelled to
resort, as we have already done in the discovery and assump-
tion of the fundamental rules of algebra themselves, to the re-
sults obtained for such specific values, for the purpose of dis-
covering the rules which determine the symbolical nature of
the operation for ald values of the symbols. As this principle,
which may be termed the principle of the permanence of equi-
valent forms, constitutes the real foundation of all the rules of
symbolical algebra, when viewed in connexion with arithmeti-
cal algebra considered as a science of suggestion, it may be
proper to express it in its most general form, so that its autho-
rity may be distinctly appealed to, and some of the most im-
portant of its consequences may be pointed out.
Direct proposition:
Whatever form is algebraically equivalent to another when
expressed in general symbols, must continue to be equivalent,
whatever those symbols denote.
Converse proposition :
REPORT ON. CERTAIN BRANCHES OF ANALYSIS. 199
Whatever equivalent form is discoverable in arithmetical
algebra considered as the science of suggestion, when the sym-
bols are general in their form, though specific in their value,
will continue to be an equivalent form when the symbols are
general in their nature as well as in their form *.
The direct proposition must be true, since the laws of com-
bination of symbols by which such equivalent forms are de-
duced, have no reference to the specific values of the symbols.
‘The converse proposition must be true, for the following
reasons :
If there be an equivalent form when the symbols are general
in their nature as well as in their form, it must coincide with
the form discovered and proved in arithmetical algebra, where
the symbols are general in their form but specific in their na-
ture ; for in passing from the first to the second, no change in
its form can take place by the first proposition.
Secondly, we may assume the existence of such an equivalent
form in symbols which are general both in their form and in
their nature, since it will satisfy the only condition to which
all such forms are subject, which is, that of perfect coincidence
with the results of arithmetical algebra, as far as such results.
are common to both sciences.
Equivalent forms may be said to have a necessary existence
when the operation which produces them admits of being de-
fined, or the rules for performing it of being expressly laid
down: in all other cases their existence may be said to be
conventional or assumed. Such conventional results, however,
are as much real results as those which have a necessary ex-
istence, in as much as they satisfy the only condition of their
existence, which the principle of the permanence of equivalent
forms imposes upon them: thus, the series for (1 + x)" has a
necessary existence whenever the nature of the operation upon
1 + 2 which it indicates can be defined; that is, when» is a
whole or a fractional, a positive or negative, number +; but for
all other values of x, where no previous definition or interpre-
tation of the nature of the operation which connects it with its
equivalent series can be given, then its existence is conventional
only, though, sythBolically speaking, it is equally entitled to be
considered as an equivalent form in one case as in the other.
It is evident that a system of symbolical algebra might be
_ * Peacock’s Algebra, Art. 132. 1
_ + The meaning of (1 + x)" cannot properly be said to be defined when n
is a fractional number, whether positive or negative, or a negative whole num-
ber, but to be ascertained by interpretation conformably to the principle of
‘the permanence of qquivalent forms. '
200 THIRD REPORT—1833.
formed, in which the symbols and the conventional operations
to which they were required to be subjected would be perfectly
general both in value and application. If, however, in the con-
struction of such a system, we looked to the assumption of such
rules of operation or of combination only, as would be sufficient,
and not more than suflicient, for deducing equivalent forms,
without any reference to any subordinate science, we should be
altogether without any means of interpreting either our opera-
tions or their results, and the science thus formed would be
one of symbols only, admitting of no applications whatever. It
is for this reason that we adopt a subordinate science as a sci-
ence of suggestion, and we frame our assumptions so that our
results shall be the same as those of that science, when the
symbols and the operations upon them become identical like-
wise : and in as much as arithmetic is the science of calculation,
comprehending all sciences which are reducible to measure and
to number ; and in as much as arithmetical algebra is the imme-
diate form which arithmetic takes when its digits are replaced
by symbols and when the fundamental operations of arithmetic
are applied to them, those symbols being general in form,
though specific in value, it is most convenient to assume it as -
the subordinate science, which our system of symbolical algebra
must be required to comprehend in all its parts. 'The principle
of the permanence of equivalent forms is the most general ex-
pression of this law, in as much as its truth is absolutely neces-
sary to the identity of the results of the two sciences, when the
symbols in both denote the same things and are subject to the
same conditions. It was with reference to this principle that
the fundamental assumptions respecting the operations of ad-
dition, subtraction, multiplication and division were said to be
suggested by the ascertained rules of the operations bearing
the same names in arithmetical algebra. The independent use
of the signs + and —, and of other signs of affection, was an as-
sumption requisite to satisfy the still more general principle of
symbolical algebra, that its symbols should be unlimited in value
and representation, and the operations to which they are sub-
ject unlimited in their application.
In arithmetical algebra, the definitions of the operations de-
termine the rules; in symbolical algebra, the rules determine
the meaning of the operations, or more properly speaking, they
furnish the means of interpreting them: but the rules of the
former science are invariably the same as those of the latter,
in as much as the rules of the latter are assumed with this view,
and merely differ from the former in the universality of their
applications: and in order to secure this universality of their
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 201
applications, such additional signs * are assumed, and of such a
symbolical form, as those applications may render necessary.
We call those rules, or their equivalent symbolical consequences,
assumptions,in as much as they are not deducible as conclusions
from any previous knowledge of those operations which have
corresponding names: and we might call them arbitrary as-
sumptions, in as much as they are arbitrarily imposed upon a
science of symbols and their combinations, which might ‘be
adapted to any other assumed system of consistent rules. In
the assumption, therefore, of a system of rules such as will make
its symbolical conclusions necessarily coincident with those of
arithmetical algebra, as far as they can exist in common, we in
no respect derogate from the authority or completeness of sym-
bolical algebra, considered with reference to its own conclu-
sions_and to their connexion with each other, at the same time
that we give to them a meaning and an application which they
would not otherwise possess.
It follows from this view of the relation of arithmetical and
symbolical algebra, that all the results of arithmetical algebra
which are general in form are true likewise in symbolical.
algebra, whatever the symbols may denote. This conclusion
may be said to be true in virtue of the principle of the perma-
nence of equivalent forms, or rather it may be said to be the
proper expression of that principle. Its consequences are most
important, as far as the investigation of the fundamental pro-
positions of the science are concerned, in as much as it enables
us to investigate them in the most simple cases, when the
operations which produce them are perfectly defined and un-
derstood, and when the general symbols denote positive whole
numbets. If the conclusions thus obtained do not involve in
their expression any condition which is essentially connected
with the specific values of the symbols, they may be at once
transferred to symbolical algebra, and considered as true for
all values of the symbols whatsoever +.
Thus, coefficients in arithmetical algebra, such as m in m a,
which are general in form, lead to the interpretation of such
* There is no necessary limit to the multiplication of such signs : the signs
++, —, (1)” and (—1)? and their equivalents (for the symbolical form of such
signs is not arbitrary), comprehend all those signs of affection which are re-
quired by those operations with which we are at present acquainted.
- F Some formule are essentially arithmetical: of this kindis1.2.3...7,
in which r must be a whole number. The formula spite
is symbolical with respect to m, but arithmetical with respect to 7. Such cases,
and their extension to general values of r, will be more particularly considered
hereafter.
202 THIRD REPORT—1833.
>.
expressions as ma in symbolical algebra, when m is a number
whole or fractional, and a any symbol whatsoever. When m, n
and a are whole numbers, it very readily appears that ma + na
= (m + n) a, and that ma — na = (m — n)a: the same con-
clusions are true likewise for all values of m, x and a. In
arithmetical algebra we assume a’, a®, a‘, &c., to represent aa,
aaa,aaaa, &c., and we readily arrive at the conclusion that
a”™ x a®* = a”™*", when m and m are whole numbers: the same
conclusion must be true also when m and z are any quantities
whatsoever. In a similar manner we pass from the result
(a”)" = a™”, when z is a whole number, to the same conclusion
for all values of the symbols *.
The preceding conclusions are extremely simple and element-
ary, but they are not obtainable for all values of the symbols
by the aid of any other principle than that of the permanence
of equivalent forms: they are assumptions which are made in
conformity with that principle, or rather for the purpose of
rendering that principle universal; and it will of course follow
that all interpretations of those expressions where m and n are
not whole numbers must be subordinate to such assumptions.
1 1
Thus, + oe 3 = (G ta a) a@ =a, and therefore 5 must
mean one half of a, whatever a may be; a xad=at?
1
=a =, and therefore a® must mean the square root of a,
whatever a@ may be, whenever such an operation admits of
é e anny a Z
interpretation. In a similar manner 3 must mean one third
3
part, and a* the cube root of a, whatever a may be, and simi-
larly in other cases: it follows, therefore, that the interpreta-
tion of the meaning of a, a’, &c., is determined by the general
* The genera] theorems ma + na= (m+n) aandma—na=(m—n)a,
1 m
™m _ =
a™ x a® = a™t" and “= a™—™, (a™)" = a™" and (a) * =a”? which
a
are deduced by the principle of the permanence of equivalent forms, and which
are supplementary to the fundamental rules of algebra, are of the most essen-
tial importance in the simplification and abridgement of the results of those
operations, though not necessary for the formation of the equivalent results
themselves. It also appears from the four last of the above-mentioned theorems
that the operations of multiplication and division, involution and evolution, are
performed by the addition and subtraction, multiplication and division, of the
indices, when adapted to the same symbol or base. If such indices or logarithms
be calculated and registered with reference to a scale of their corresponding
numbers, they will enable us to reduce the order of arithmetical operations by
two unities, if their orders be regulated by the following scale ; addition (1), sub-
traction (2), multiplication (3), division (4), involution (5), and evolution (6).
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 203
principle of indices, and also that we ought not to say that we
assume a? to denote Wa, and a’ to denote 4/a, as is commonly
done*, in as much as such phrases would seem to indicate that
such assumptions are independent, and not subject to the same
common principle in all cases.
In all cases of indices which involve or designate the inverse
processes of evolution, we must have regard likewise to the
other great principle of symbolical algebra, which authorizes
the existence of signs of affection. The square root of a may
be either affected with the sign + or with the sign —; for + a*
x + a’, and — a* x — a’, will equally have for their result
+ aora, by the general rule for the concurrence of similar
signs and the general principle of indices : in a similar manner
r
a> may be affected with the multiple sign of affection (1), if
x
there are any symbolical values of (1)? different from + 1 (equi-
valent to the sign +), which will satisfy the requisite symbo-
lical conditions. It is the possible existence of such signs of
affection, which is consequent upon the universality of alge-
braical operations, which makes it expedient to distinguish be-
tween the results which are not affected by such signs, and
the same results when affected by them. The first class of
results or values are such as are alone considered in arithmeti-
cal algebra, and we shall therefore term them arithmetical va-
lues, though the quantities themselves may not be arithmetical :
the second class may be termed algebraical values, in as much
as they are altogether, as far as they are different from the
arithmetical values, the results of the generality of the opera-
tions of symbolical algebra.
This distinction may generally be most conveniently ex-
pressed by considering such a sign as a factor, or a symbolical
quantity multiplied according to the rule for that operation
into the arithmetical value: in this sense + 1 and — 1 may be
considered as factors which are equivalent to the signs + and
—, that is, equivalent to affecting the quantities into which
they are multiplied with the signs + and —, according to the
* Wood’s Algebra, Derinirions.
+ That is, if there is any symbolical expression different from 1, such as
= tw and wae the cubes of which are identical with 1.
Tn a similar manner we may consider the existence of multiple values of 1" or
(— 1)", and, therefore, of multiple signs of affection corresponding to them, as
consequent upon the general laws of combination of symbolical algebra, and as
results to be determined from those laws, and whose existence, also, is de-
pendent upon them.
204: THIRD REPORT—1839.
general rule for the concurrence of signs. In a similar manner
we may consider (1)? (a)? as equivalent to (a)? ; (1) (a)? as
equivalent to (a)*; (1)” a” as equivalent to a"; (— 1)" (a)" as
equivalent to (— a)", and similarly in other cases: in all such
cases the algebraical quantity into which the equivalent sign
or its equivalent factor is multiplied, is supposed to possess its
arithmetical value only *.
The series for (1 + x)", when x is a whole number, may be
exhibited under a general form, which is independent of the
specific value of the index; for such a series may be continued
indefinitely in form, though all its terms after the (m + 1)th
must become equal to zero. Thus, the series
(yaya (yp (1 tae Sie
n(n—1)..(n—r-+41)
ade SEE aa
indefinitely continued, in which » is particular in value (a whole
number) though general in form, must be true also, in virtue
of the principle of the permanence of equivalent forms, when
nm is general in value as well as in form7.
This theorem, which, singly considered, is, of all others, the
most important in analysis, has been the subject of an almost
unlimited variety of demonstrations. Like all other theorems
whose consequences present themselves very extensively in
algebraical results, it is more or less easy to pass from some
one of those consequences to the theorem itself: but all the
demonstrations which have been given of it, with the excep-
tion of the principle of one given by Euler{, have been con-
fined to such values of the index, namely, whole or fractional
numbers, whether positive or negative, as made not only
the development depend upon definable operations, but like-
wise assumed the existence of the series itself, leaving the form
of its coefficients alone undetermined. It is evident, however,
that if there existed a general form of this series, its form could
+ a” + &e.)
* This separation of the symbolical sign of affection from its arithmetical
subject, or rather the expression of the signs of affection explicitly, and not im-
plicitly, is frequently important, and affords the only'means of explaining many
‘paradoxes (such as the question of the existence of real logarithms of negative
numbers), by which the greatest analysts have been more or less embarrassed.
+ If such a series should, for any assigned value of m, have more symbolical
values than one, one of them will be the arithmetical value, inasmuch as one
symbolical value of 1” is always 1.
+ In the Nov. Comm. Petropol. for 1774.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 205
be detected for any value of the index whatever, which was
general in form, and therefore, also, when that index was a
whole number ; a case in which the interpretation of the opera-
tion designated by the index, as well as the performance of the
operation itself, was the most simple and immediate.
That such a series, likewise, would satisfy the only sym-
bolical conditions which the general principles of indices im-
poses upon the binomial, might be very easily shown ; for if
m and n be whole numbers, then if the two series
m(m—1) 9
(1+ a2)" = 1" (1 + nx + ae a - &e.)
be multiplied together, according to the rule for that purpose,
we must obtain
(Pears e+" ( + (m+ n)x + it eh &e.)
a series in which m + has replaced m or n in its component
factors: and in as much as we must obtain the same symbolical
result of this multiplication, whatever be the specific values of
mand 2, it follows, that if the same form of these series repre-
sents the development of (1 + x)" and (1 + x)", whatever m and
n may be, then, likewise, the series for the product of (1 + a)”
and (1 + a)", or (1 + x)"*", would be that which arose from
putting m + n in the place of m or m in each of the component
factors. If, therefore, we assumed S (m) and S (nm) to represent
the series for (1 + 2)” and (1 + 2)", when m and n are any
quantities whatsoever, then (1 + xy x (1 + x) = (1+ x)"*"
=S(m +n) =S(m) x S(m); or, in other words, the series
will possess precisely the same symbolical properties with the
binomial to which they are required to be equivalent.
It is the equation a” x a” = a”*”, for all values of m and n,
which determines the interpretation of a” or a", when such an
interpretation is possible ; in other words, such quantities pos-
sess no properties which are independent of that equation. ‘The
same remark of course extends to (1 + 2)", for all values of n,
and similarly, likewise, to those series which are equivalent to
it. That all such series must possess the same form would be
evident from considering that the symbolical properties of
(1 + x)" undergo no change for a change in the value of n, and
that no series could be permanently equivalent to it whose form
206 THIRD REPORT—1833.
was not equally permanent likewise. In assuming, therefore, the
existence of such a permanent series, our symbolical conclu-
sions are necessarily consistent with each other, and it is the
interpretation of the operations which produce them, which
must be made in conformity with them. It is true that we can
extract the square or the cube root of 1 + a, and we can also
determine the corresponding series by the processes of arith-
metical algebra ; and we likewise interpret (1 + x)? and (1+ at
to mean the square and the cube root of 1 + a, in conformity
with the general principle of indices. The coincidence of the
series for (1 + 2)® and (1 + a), whether produced by the
processes of arithmetical algebra, or deduced by the principle ©
of the permanence of equivalent forms from the series for
(1 + 2x)", would be a proof of the correctness of our interpreta-
tion, not a condition of the truth of the general principle itself.
In order to distinguish more accurately the precise limits of
hypothesis and of proof in the establishment of the fundamental
propositions of symbolical algebra, it may be expedient to re-
state, at this point in the progress of our inquiry, the order in
which the hypotheses and the demonstrations succeed each
other.
We are supposed to be in possession of a science of arith-
metical algebra whose symbols denote numbers or arithmetical
quantities only, and whose laws of combination are capable of
strict demonstration, without the aid of any principle which is
not furnished by our knowledge of common arithmetic.
The symbols in arithmetical algebra, though general in form,
are not general in value, being subject to limitations, which are
necessary in many cases, in order to secure the practicability
or possibility of the operations to be performed. In order to
effect the transition from arithmetical to symbolical algebra, we
now make the following hypotheses :
(1.) The symbols are unlimited, both in value and in repre-
sentation.
(2.) The operations upon them, whatever they may be, are
possible in all cases.
(3.) The laws of combination of the symbols are of such a
kind as to coincide wniversally with those in arithmetical algebra
when the symbols are arithmetical quantities, and when the
operations to which they are subject are called by the same
names as in arithmetical algebra.
The most general expression of this last condition, and of its
connexion with the first hypothesis, is the Jaw of the perma-
-~
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 207
nence of equivalent forms, which is our proper guide in the
establishment of the fundamental propositions of symbolical
algebra, in the invention of the requisite signs, and in the de-
termination of their symbolical form: but in the absence of the
complete enunciation of that law, we may proceed with the in-
vestigation of the fundamental rules for addition, subtraction,
multiplication and division, and of the theorems for the collec-
tion of multiples, and for the multiplication and involution of
powers of the same symbol, which will, in fact, form a series of
assumptions which are not arbitrary, but subordinate to the
conditions which are imposed by our hypotheses : but if we
suppose those conditions to be incorporated into one general
law, whose truth and universality are admitted, then those as-
sumptions become necessary consequences of this law, and
must be considered in the same light with other propositions
which follow, directly or indirectly, from the first principles of
a demonstrative science. In the same manner, if we assume the
existence of such signs as are requisite to secure the universality
of the operations, the symbolical form of those signs, and the
laws which regulate their use, will be determined by the same
principles upon which the ordinary results of symbolical al-
gebra are founded.
The natural and necessary dependence of these two methods
of proceeding upon each other being once established, we may
adopt either one or the other, as may best suit the form of the
investigation which is under consideration : the great and im-
portant conclusion to which we arrive in both cases being, the
transfer of all the conclusions of arithmetical algebra which are
general in form (that is, which do not involve in their expres-
sion some restriction which limits the symbols to discontinuous
values,) to symbolical algebra, accompanied by the invention or
use of such signs (with determinate symbolical forms) as may
be necessary to satisfy so general an hypothesis.
There are many expressions which involve symbols which
are necessarily discontinuous in their value, either from the
form in which they present themselves in such expressions or
from some very obvious conventions in their use: thus, when
we say that
cos « = cos (2Qra+ 2),
and — cos x = cos { (2r+1)7+ x}
propositions which are only true when 7 is a whole number,
the limitation is conveyed (though imperfectly) by the con-
ventional use of 2r and 2 r + 1 to express even and odd num-
bers; for otherwise there would be no sufficient reason for not
208 THIRD REPORT—1833.
using the simple symbol r both in one case and the other. In
a similar manner, in the expression of Demoivre’s theorem
(cos 6+ /—I1 sin 6)"
= cos (2raxr+né6)+ /—l1sin (Qrnx + n),
we may suppose 7 to be any quantity whatsoever*, but 7 is ne-
cessarily a whole number. :
In some cases, however, the construction of the formula it-
self will sufficiently express the necessary restriction of the
values of one or more of its symbols, without the necessity of
resorting to any convention connected with their introduction:
thus, the formula 1 x 2 x 3......7, commencing from 1, is
essentially arithmetical, and limited by its form to whole and
positive values of r. The same is the case with the formula
r(r —1)....3.2.1, where some of the successive and strictly
arithmetical values of the terms of the series r, r — 1, &c., are
put down; but the formula r (r — 1) (ry — 2).... is subject to
no such restriction, in as much as any number of such factors
may be formed and multiplied together, whatever be the value
of r. In a similar manner, the formula
n(n —1)... (n—r + Vy
eae t
7a see 7
which is so extensively used in analysis, is unlimited with re-
spect to the symbol , and essentially limited with respect to
the symbol r: it is under such circumstances that it presents
itself in the development of (1 + «)”.
In the differential calculus we readily find
CE ig n—?r
Sa ly ————, gr® = >
dan-r +1 I (r)
it follows that r A = B, and therefore also that
: r 1
Ttit+n = T(r) or rT (r) = Tr(1+7),
which is the equation (1): and it is obvious that the transition from
qdn-r qdn—r+1
d an-r am to dan—-rt+l an
(which is equivalent to the simple differentiation of A 2’, when A is a
constant coefficient), will lead to the same relation between [' (1 + 7) and
r (r), whatever be the value of r, whether positive or negative, whole or frac-
tional. Legendre has apparently limited this equation to positive values of r,
P2 "
nm—rtl
a Fe OE co a ference
212 THIRD REPORT—1833.
also from this equation that if the values of the transcendent
I (r) can be determined for all values of 7 which are included
(Fonctions Elliptiques, tom. ii. p. 415,) a restriction which is obviously unne-
cessary.
There are two cases in which the coefficient of x"—7 in the equation -
aa PA +2)
dat ~ V(1+n2—r)
requires to be particularly considered: the first is that in which this coeffi-
cient becomes infinite ; the second, that in which it becomes equal to zero.
The numerator I' (1 +n) will be infinite when n is any negative whole
number; the denominator I’ (1 + ™—r) will become infinite when » — r is
any negative whole number, and in no other case: if n be a negative whole
number, and if r be a whole number, either positive or negative, such that n — r
g“n-Tr
uf
is negative, then the coefficient ep) becomes finite, in as much as
8 ra+n2—n
T'(0
IT (—2z) (if ¢ be a whole number) = mos De? and T' (0) disap-
Be Side 4 ab 1 5 e
pears, therefore, by division: thus all the coefficients of Baer etn infinite,
unless 7 be a negative whole number, such as — m, in which case it becomes
1.2..m.(—1)™, a result which is easily verified. In a similar manner it
dr 1 ;
would appear that the coefficients of = dcr ew infinite, when 7 is a posi-
tive number, unless r be a negative whole number equal to, or greater than, 2.
The coefficient ear ot m) 7) will become equalto zero, when 1+2—r
is, and when 1 + 2 is nof, equal to zero or to any negative whole number ; for,
under such circumstances, the denominator is infinite and the numerator is
Sinite.
As the most important consequences will be found to result from these
critical values of the coefficient of differentiation, we shall proceed to examine
them somewhat in detail.
(1.) The simple differentials or differential costicients of constant quantities -
are equal to zero, whilst the differentials or differential coefficients to general
indices (positive whole numbers being excepted,) are variable.
Thus
RE ec 5 A A SEH Per a al ada
dat da TG) ° Jae” qa *
a(Tl) 2 /Sx d—a TQ)
= + es =
T@ ° ors = ve da-| — TQ) a xt! = az;
and similarly in other cases. ~
(2.) The differentials of zero to general indices (positive whole numbers
being excepted) are not necessarily equal to zero.
Thus, if we suppose
aingk fa C
nape dg T (0) Sir Snare iat, aaalk 0) rd—s—r)"
if x be a positive whole number, I (1— ) = », and this expression is finite un-
less T (1 —n— 1) = , in which case it is zero: if 7 be also a positive whole
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 213
between any two successive whole numbers, they can. be de-
termined for all other values of r. Euler * first assigned the
number, it is always xero: if r= — 1, itis finite whenn=1: ifr = —2,
it is finite when n= 1 or n= 2: ifr = — 3, it is finite whenn = 1, orn = 2,
orn=3: and generally if r be any negative whole number, there will be
finite values corresponding to every value of n from 1 to — 7; we thus get
2 = Cxe+C)
—_ = ae + Cia+ Co
= = Seo + peer + Cn—2.@ + Cy-1.
This is the true theory of the introduction of complementary arbitrary func-
tions in the ordinary processes of integration. ny af
More generally, if 7 be not a whole number,
PO Cc Hunk (1 —n) an,
da? ro rda—nz—nr)
which will be finite when n is a positive whole number and when 1 —2 —r is.
not a negative whole number : thus if m be any number in the series 1, 2, 3..+,
and if r = 3, then
d? 0 Cc ing Cc F iO Higey
se ie OOF ——_— «&r
aoe CD rey "TCH
and so on for ever : consequently,
Chet tee
72 aes <4 =! + &c. in infinitum.
ct we ee x? a?
In a similar manner, we shall find
-F f 1 Ce C3
Be bank Ct yp ty + &e. i infinitum,
a
dx?
The knowledge of these complementary arbitrary functions will be found of
great importance for the purpose of explaining some results of the general
differentiation of the same function under different forms which would other-
wise be irreconcileable with each other.
~ (3.) The differential coefficient will be zero, when n is not, and whenn —r
is, a negative whole number.
Thus,
d2 x __ Baz a? ae d® at a? “Fayre
i Peg, ahi Same nie
d x* d x? dx *
and similarly in other cases.
(4.) The differentials of & are not necessarily equal to ©, but may be finite.
If we represent » by C I'(0), we shall find
* Commentarii Petrop., vol. y. 1731.
214 ' THIRD REPORT—1833.
value of I (5) = 7, by the aid of the very remarkable ex-
pression for 7, which Wallis derived from his theory of inter-
eee car
rs = CI(0) eae Ih wLigae(ns barry
whenever + is a positive whole oa
Conversely eke : ia a
Shelia 0 (0
ie ti ae) Saabs
a ie = I (0) a
d x-2 (2) ,
Gr Bret PMO) ing
d x-3 T (3) if
dr. a} — T (0) gr-)
CaO E Ye) Aonk*
the arbitrary complementary functions being omitted.
(5.) The occurrence of infinite values of the coefficient of differentiation will
generally be the indication of some essential change of form in the transition
from the primitive function to its corresponding differential coefficients.
Thus,
d-} 1 T (0)
peed EL VP ahi tices aes MOO bh ;
dx-1 x Tae * ERAS
this last result or value of y ro: x being obtained by the ordinary process
of integration: and generally,
ad". 4-1 Las T Tr (0) gr-) ar-l C, a7r—2 &
Br aa ay ae ee
the first term of which is infinite, in all ‘cases in which 7 is not a negative
whole number, in which case it becomes equal to (—1)-"1.2...(— 7) a7—},
the complementary arbitrary functions also disappearing. If we suppose,
0
however, 7 to be a positive whole number, and if we replace r oy - «9 by
its transcendental value chat determined, we shal] get
d-ra-l.. be gr-2
dar 35 G eee ta ait faead
which may be replaced by
af a-) _ gr-1 a ar-
STG {loge + (—1)r T(r). ra Arh Ob ihe Sw
which is in a form which is true for all values of tng 9h a aud which
coincides, for integral values of r, with the form determined by the ordinary
process of integration,
More generally,
+ &c.,
aah er) TO ¢) Le OPN hee Gyan
aban 7 are ee Se a ee se I (r—n) mite
which is finite, whilst r is less than x; and when r and x are whole numbers,
T (”—vr)
~ Ta
becomes = (— 1)”. ar—", omitting complementary functions.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 215:
polations; and subsequently, by a much more direct process,
which lead to the equation,
roy)rd n= a
Tv
~@ (when r at
If, under the same circumstances, 7 be greater than , the coefficient of dif-
ferentiation becomes infinite, and its value, determined as above, becomes
xar-n C; at="-!
=Tr@rer—nt+) {loge +C} + rT @7—n + &e.
arn
=Toprer w+) {log 2 + (—1)r TP @—a41) TP (n—r) + Cc}
’ ie: C, ar—n-1 a
' T@—n) ‘
which is in a form adapted to all values of r.
The cases which we have considered above are the only ones in which the
coefficient of differentiation will become infinite, in consequence of the intro-
duction of log z in the expression of its value. We shall have occasion here-
after to notice more particularly the meaning of infinite values of coefficients
as indications of a change in the constitution of the function into which they
are multiplied.
(6.) If w = (a + 6)”, then
du I (1+ 2) a Car-l
det, TAL at OPS A eye +
: d d3
Forifv=az+b, then 5~ =a and — = 0; and therefore
du T(1 +2) dv\t Car!
gait alee atl =) tir¢oyy a
Thus if u = (x + 1), we get
fe FO +n + hes
dat ee r(—y)e" r(— pat
@HI)® 4+ 4 Sy — + &e.
tae
If we replace (z + 1)? by 22 + 2 +2 1, we shall get
ds FG) 2 ena at) Ey
af a), eee ¢ Te ae
C on
fh Seep te bh ee)
Tiy)e r(—a)e*
8 3 4 1 2 C
a ae, ees Tes ge
It thus appears that the two results may be made to coincide with each
other, when (x + 1)? in the first of them is developed, by the aid of the proper
arbitrary functions.
The necessity of this introduction of arbitrary functions to restore the re-
quired identity of the expressions deduced for the same differential coefficients,
presents itself also in the ordinary processes of the integral colcaalncts thus,
if u= (x + 1)*, we find
216 Cane, THIRD REPORT—1833.
Legendre, following closely in the footsteps of this illustrious -
analyst, has succeeded in the investigation of methods by which
the values of this transcendent I (r) may be calculated to any
required degree of accuracy for all positive values of r, and has
(d-24u (x + 1)4
snhaMeea = Cogagct Oiectale
d-1y-" @ +138
3
at a3 a? 2 1
ag ct ig ih eg ok fp Pee Ge.
If we replace (x + 1)? by a? + 2” + 1, we find
d-2u at x3 =
da”, eeEst 3p at CA t Oe
d-2 : :
It is obvious that these two values of — cannot be made identical,
without the aid of the proper arbitrary functions.
dru
(7.) Let « = v" where v = f(x): and let it be required to find 7-5 -
dr ;
The general expression for —< , when 7 is a whole number, is generally
extremely complicated, though the law of formation of its terms can always
be assigned. If the inexplicable expressions in the resulting series be re~
placed by their proper transcendents, the expression may be generalized for
any value of r.
d2 dr
If a4 = p and if 8 =c, aconstant quantity, then —= n (n—1)
eee (n—7+1) v7 pr
r (r — 1) cv r(r—1)(r—2) (r—3) cw
Kae eT gf tie Gore Gare pt ef
20 AY (e a) 4 r(r—1)" | ev }
—~ T(l+n2—r) aie {1+ l.(n—r+1)° pP ut
C. 4 Cy +5
he rye Oe eT ee ey + &c.
which is in a form adapted to any value of r.
I ar
ie= Ji pa md" = -p> we shall find
1 —
a ——— az esa 1 Le: ais 5 Biss Py / te
ad Jima) = Ws {2 ae gags ~ QM go we. }
d x?
pp erty Oy ae
a x?
Rational functions of « may be resolved into a series of fractions, whose
denominators are of the form (x + a)”, and whose numerators are constant
quantities, whose rth differential coefficients may be found by the methods
givenabove. Irrational functions must he treated by general methods similar
to that followed in the example just given, which will be more or less com-
plicated according to the greater or less number of successive simple differ-
entials of the function beneath the radical sign, which are not equal to zero.
REPORT ON. CERTAIN BRANCHES OF ANALYSIS. QF
given tables of its logarithmic values to twelve places of decimals,
with columns of three orders of differences for 1000 equal in-
tervals between 1 and 2*; and similar tables have been given
by Bessel and by others. We may therefore consider ourselves
to be in possession of its numerical values under all circum-
stances, though we should not be justified in concluding from
thence that their explicit general symbolical forms are either
discoverable or that they are of such a nature as to be ex-
pressible by the existing language and signs of algebra.
The equation
T(r) =(r—1) @ —2).... YQ —m T(r —m),
P(r)
(ry = 1) @—2).. @ — my
where m is a whole number, will explain the mode of passing
from the fundamental transcendents, when included between
yr = 0 and 1, or between r = 1 and 2, to all the other derived
transcendents of their respective classes}. The most simple of
such classes of transcendents, are those which correspond to
r(}) =v
which alone require for their determination the aid of no higher
transcendents than circular arcs and logarithms. In all cases,
also, if we consider I(r) as expressing the arithmetical value of
the corresponding transcendent, its general form would require
the introduction of the factor 1”, considered as the recipient
of the multiple signs of affection which are proper for each dif-
ferential coefficient, if we use that term in its most general
sense.
In the note, p. 211, we have noticed the principal properties
of these fractional and general differential coefficients, partly
for the purpose of establishing upon general principles the
basis of a new and very interesting branch of analysist, and
or C(r —m) =
* Fonctions Elliptiques, tom. ii. p. 490.
1 3 1 ‘ 5 3al
Th ECL jaws pat (2 Neds ; (a =
+ Thus, F (= vnt( ~vmr(l)=43 vn,
a mae" pe ARN bic 28 Hi pit ot siBe
ee i v=, 0 (=) each aah audeaace
V x, &e.
{ The consideration of fractional and general indices of differentiation was
first suggested by Leibnitz, in many passages of his Commercium Epistolicum
with John Bernouilli, and elsewhere; but the first definite notice of their
theory was given by Euler in the Petersburgh Commentaries for 1731: they
have also been considered by Laplace and other writers, and particularly by
Fourier, inhis great work, La Théorie de la Propagation de la* Chaleur. The
last of these illustrious authors has considered the general differential coeffi-
218 THIRD REPORT—1833.
partly for the purpose of illustrating the principle of the per-
manence of equivalent forms in one of the most remarkable
examples of its application. The investigations which we have
given have been confined to the case of algebraical functions,
cients of algebraical functions, through the medium of their conversion into
transcendental functions by means of the very remarkable formula,
2 + © + ©
gent fl O(a)da f Q (a) dqcos g (« — @),
-@ -o
which immediately gives us,
ox 2 + +O dr
=f O(a)de f Q (a) aq gar cosg (&—%)5
re)
dT
dat
and the requisite definite integrations effected. If, indeed, we grant the prac-
ticability of such a conversion of @ (#) in all cases, and if we suppose the
difficulties attending the consideration of the resulting series, which arise
from the peculiar signs, whether of discontinuity or otherwise, which they
may implicitly involve, to be removed, then we shall experience no embarrass-
ment or difficulty whatever in the transition from integral to general indices
of differentiation.
In the thirteenth volume of the Journal de I’ Ecole Polytechnique for 1832,
there are three memoirs by M. Joseph Liouville, all relating to general in-
dices of differentiation, and one of them expressly devoted to the discussion
of their algebraical theory. The author defines the differential coefficient of
the order « of the exponential funetion e”” to be m” &”*, and consequently
the jth differential coefficient of a series of such functions denoted by 2 A,,¢””
must be represented by = Aj, m“ e"*. If it be granted that we can properly
define a general differential coefficient, antecedently to the exposition of any
general principles upon which its existence depends, then such a definition
ought to coincide with the necessary conclusions deduced by those principles
in their ordinary applications: but the question will at once present itself,
whether such a definition is dependent or not upon the definition of the simple
differential coefficient in this and in all other cases. In the first case it will be
a proposition, and not a definition, merely requiring the aid of the principle
of the permanence of equivalent forms for the purpose of giving at least an
which can be determined, therefore, if
cos g (« — «) can be determined,
: : apes E
hypothetical existence to — for general, as well as for integral values
of %. M. Liouville then supposes that all rational functions of # are ex-
pressible by means of series of exponentials, and that they are consequently
reducible to the form = A,, e”, and are thus brought under the operation of
his definition. Thus, if x be positive, we have,
1 lo 9)
Fs if S da,
es ee)
i =f e #7 (_ aw )hda,
d xk 0
and therefore,
REPORT ON.CERTAIN BRANCHES OF ANALYSIS. 219
and have been chiefly directed to meet the difficulties connected
with the estimation of the values of the coefficient of differen-
tiation in the case of fractional and general indices. If we
should extend those investigations to certain classes of tran-
which is easily reducible to the form,
dep
ae _ (Erte),
a gite
an expression which we have analysed in the note on p. 211. This part of
M. Liouville’s theory is evidently more or less included in M. Fourier’s views,
which we have noticed above. The difficulties which attend the complete
("TA +e)
gite
principle of equivalent forms alone can reconcile, will best show how little
developement of the formula for all values of «, which the
progress has been made when the «th differential coefficient of _ is reduced
to such a form. e
M. Liouville adopts an opinion, which has been unfortunately sanctioned by
the authority of the great uames.of Poisson and Cauchy, that diverging series
should be banished altogether from analysis, as generally leading to false
results ; and he is consequently compelled to modify his formule with refer-
ence to those values of the symbols involved, upon which the divergency or
convergency of the series resulting from his operations depend. In one sense,
as we shall hereafter endeavour to show, such a practice may be justified ; but
if we adopt the principle of the permanence of equivalent forms, we may
safely conclude that the limitations of the formule will be sufficiently ex-
pressed by means of those critical values which will at once suggest and re-
quire examination. The extreme multiplication of cases, which so remark-
ably characterizes M. Liouville’s researches, and many of the errors which he
has committed, may be principally attributed to his neglect of this important
principle.
It is easily shown, if 6 be an indefinitely smal] quantity, that
4 br e—hr . emBx __ e—NBz
"2B mane”
and that consequently any integral function La A, e+... Ap xP, involving _
integral and positive powers of x only, may be expressed by = Am ¢””, where
m is indefinitely small; and conversely, also, = A,, e”* may, under the same
circumstances, be always expressed by a similar integral function of «. M. Liou-
ville, by assuming a particular form,
2B yy sr
where C is arbitrary, and A indefinitely small, to represent zero, and differen-
tiating, according to his definition, gets
Gin @ yet Medes! gp Gau/=D,
sayy 2/8 2
but it is evident that by altering the form of this expression for zero we might
d® are
show that was equal either to zero or to infinity; and that in the latter
dx
220 | (THIRD REPORT—1833. |
scendental functions, such as e”*, sinm a, and cosma, we
shall encounter no such difficulties, in as much as the differen-
tials of those functions corresponding to indices which are ge-
neral in form, though denoting integral numbers, are in a form
case the critical value infinity might be merely the indication of the existence
1
a 0. which were
dat
not expressible by any rational function of e** under a finite form and. in-
volving indefinitely small indices only. And such, in fact, would be the re-
sult of any attempt to differentiate this exponential expression for 2 or its
powers, with respect to fractional or negative indices. It has resulted from
this very rash generalization of M. Liouville that he has assigned as the ge-
neral form of complementary arbitrary functions,
C+ C, «+ Ce 22 + C3 23 + &e.,
which is only true when the index of differentiation is a negative whole
number.
Most of the rules which M. Liouville has given for the differentiation of
algebraical functions are erroneous, partly in consequence of his fundamental
error in the theory of complementary arbitrary functions, and partly in
consequence of his imperfect knowledge of the constitution of the formula
LTA)” ‘thus, after deducing the formula
of negative or fractional powers of x in the expression for
Td+u—r)'
1
df o=4=— (—1)".a’. T(a+r)
EY iil ole Ga + ont .
aur
which is only true when ” is a whole number, he says that no difficulty pre-
sents itself in its treatment, whilst 2 + ris >0, but that T(n +r) be-
comes infinite, when x + r<{0, in which case he says that it must be
transformed into an expression containing finite quantities only, by the aid
of complementary functions; whilst, in reality, IT (~ +r) is only infinite
when n+ 71 is zero or a negative whole number, and the forms of the com-
plementary functions, such as he has assigned to them, are not competent to
effect the conversion required. In consequence of this and other mistakes,
1 : ’
i dr, ———_— P
in connexion with the important case (ax + 6)", nearly all his conclu-
d xr
sions with respect to the general differentials of rational functions, by means
of their resolution into partial fractions, are nearly or altogether erroneous.
The general differential coefficients of sines and cosines follow immediately
from those of exponentials, and present few difficulties upon any view of their
theory. In looking over, however, M. Liouville’s researches upon this sub-
ject, 1 observe one remarkable example of the abuse of the first principles of
1
d? Mie
reasoning in algebra. There are two values of ere *, one positive and
da?
the other negative, considered apart from the sign of m, whether positive or
: 1 3
negative: but if we put cosma = Zz cos me + gicos m=, We get
1 4
d? cosmax 3. d? cosmux
1
2 , if
Geos wae} CSRS 4 -oon,
aa? d x? d x"
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 228
which is adapted to the immediate application of the general
principle in question.
Thus; if w= e””, we get
du cy 1 Us Oh a) Loe d” u
hae ah i pease oa Te eT fe
‘when ris a whole number, and therefore, also, when 7 is any
quantity whatsoever.
— gm &
Syne 5
if : du Ph sat te ad? u fi
—! — =m Si a a | nee SI
uU sim mx, ne PD} ’ dx
d” u CEN te d
os + mx), 00's eae m sin (S + mz) when 7 is a whole
number, and therefore generally. In a similar manner if
u = cos ma, or rather u = cos m(1)* a, (introducing 1” as
a factor in order to express the double sign of m x, if de-
termined from the value of its cosine,) then we shall find
ve = (mV 1)" cos {75 + (m / 1) zl, whatever be the
x
value of r. Ifu = e"*cosmax, we get, by very obvious re-
eee ‘ ee ke Oy ie
ductions, making p = Gas and # = cos 5
d™u
d a
It is not necessary to mention the process to be followed in ob-
= pre"® cos (mx + n4).
de eT se te ne oe ee cee ee NET EAT TT ETE TERT oe LERE ROTELLA)
and if we combine arbitrarily the double values of the two parts of the second
member of this equation, we shall get four values of vee instead of
ie ; and, in a similar manner, if we should resolve cos pst any number
ciate ee
of parts, we should get double the number of values of ree eS, If this
principle of arbitrary combinations of algebraical values iid from a.com-
mon operation was admitted, we must consider. as having two values,
a
1—«z
and its equivalent series
: sin a+at tat + &e. :
as having an infinite number. But it is quite obvious that those expressions
which involve implicitly or explicitly a multiple sign must continue to be
estimated with respect to the same value of this sign, however often the reci-
pient of the multiple sign may be repeated in any derived series or expression.
The case is different in those cases where the several terms exist indepen-
dently of any explicit or implied process of derivation.
222 THIRD REPORT—1833.
taining the general differential coefficients of other expressions,
such as (cos x)", cos max x cos nx, &c., which present no kind
of difficulty. In all such cases the complementary arbitrary
functions will be supplied precisely in the same manner as for
the corresponding differential coefficients of algebraical func-
tions.
The transition from the consideration of integral to that of
fractional and general indices of differentiation is somewhat
startling when first presented to our view, in consequence of
our losing sight altogether of the principles which have been
employed in the derivation of differential coefficients whose in-
dices are whole numbers: but a similar difficulty will attend
the transition, in every case, from arithmetical to general values
of symbols, through the medium of the principle of the perma-
nence of equivalent forms, though habit and in some cases im-
perfect views of its theory, may have made it familiar to the
mind. We can form distinct conceptions of m.m, m.m.m,
m.m.m....(r), where m is a whole number repeated twice,
thrice, or 7 times, when r is also a whole number; and we
can readily pass from such expressions to their defined or as-
sumed equivalents m*, m°,...m”: ina similar manner we can rea-
dily pass from the factorials* 1.2,1.2.3,...1.2...7r, to
their assumed equivalents (3), (4), ... (1 +7), aslongas r
is a whole number. The transition from m” and I (1 + r) when
r is awhole number, to m’ and r'(1 + 7) when r is a general
symbol, is made by the principle of the equivalent forms; but by
no effort of mind can we conneet the first conclusion in each case
with the last, without the aid of the intermediate formula, involv-
ing symbols which are general in form though specific in value ;
and in no instance can we interpret the ultimate form, for
values of the symbols which are not included in the first, by
the aid of the definitions or assumptions which are employed
in the establishment of the primary form. In all such cases
the interpretation of the ultimate form, when such an interpre-
tation is discoverable, must be governed and determined by a
reference to those general properties of it which are inde-
pendent of the specific values of the symbols.
* Legendre has named the function T(1 +7) =1.2...r, the function
gamma. Kramp, who has written largely upon its properties, gave it, in his
Anulyse des Refractions Astronomiques, the name of faculté numérique; but in his
subsequent memoirs upon it in the earlier volumes of the Annales des Ma-
thématiques of Gergonne he has adopted the name of factorial function, which
Arbagost proposed, and which I think it expedient to retain, as recalling to
mind the continued product which suggests this creature of algebraical lan-
guage.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 293
The law of derivation of the terms in Taylor’s series,
du au =ih? Cu he
Ds ned Ba AN Maa net yee hh een trlenen
Birth pp rihink 7g Tigi th Tas PT aT
is the same as in the more general series
du! _ a u d™u h dtu he
dat dat! dat" 1 * dart?’ 1.2
u
and if we possess the law of derivation of As and of wed we
dx d x
can find all the terms of both these series, whatever be the
value of r. The first of these terms must be determined through
the ordinary definitions of the differential calculus ; the second
must be determined in form by the same principles, and gene-
ralized through the medium of the principle of equivalent
forms. Both these processes are indispensably necessary for
Tr
the determination of ots : but it is the second of them which
; - dt du
altogether separates the interpretation of os from that of ae
d’u
d a”
ticular cases in which the symbols in both are identical in
value.
There are two distinct processes in algebra, the direct and
the inverse, presenting generally very different degrees of dif-
ficulty. In the first case, we proceed from defined operations,
and by various processes of demonstrative reasoning we arrive
at results which are general in form though particular in value,
and which are subsequently generalized in value likewise: in
the second, we commence from the general result, and we are
either required to discover from its form and composition some
equivalent result, or, if defined operations have produced it, to
discover the primitive quantity from which those operations
have commenced. Of all these processes we have already given
examples, and nearly the whole business of analysis will consist
in their discussion and developement, under the infinitely varied
forms in which they will present themselves.
The disappearance of undulating and of determinate func-
tions with arbitrary constants, upon the introduction of inte-
gral or other specific values of certain symbols involved, is one
of the chief sources * of error in effecting transitions to equiva-
or rather of
when r is a whole number, unless in the par-
* The theory of discontinuous functions and of the signs of discontinuity
will show many others.
224. THIRD REPORT—1833.
lent forms, whethe'the process followed be “direct or inverse.
Many examples of the first kind may be found in the researches
of Poinsot respecting certain trigonometrical series, which
will be noticed hereafter, and which had been hastily gene-
ralized by Euler and Lagrange; and a remarkable example of
the latter has already been pointed out, in the disappearance
of the functions with arbitrary constants in the transition from
d” u
da’
ral discussion of such cases, however, would lead me to an
examination of the theory of the introduction of determinate
and arbitrary functions in the most difficult processes of the
integral calculus and of the calculus of functions, which would
carry me far beyond the proper limits and object of this Re-
port. I have merely thought it necessary to notice them in
this place for the purpose of showing the extreme caution
which must be used in the generalization of equivalent results
by means of the application of the principle of the permanence
of equivalent forms*.
The preceding view of the principles of algebra would not
only make the use and form of derivative signs, of whatever
kind they may be, to be the necessary results of the same ge-
neral principle, but would also show that the interpretation of
their meaning would not precede but follow the examination of
the circumstances attending their introduction. I consider it
to be extremely important to attend to this order of succession
between results and their interpretation, when those results
belong to symbolical and not to arithmetical algebra, in as much
as the neglect of it has been the occasion of much of the con-
fusion and inconsistency which prevail in the various theories
which have been given of algebraical signs. I speak of dera-
u to , when r becomes a whole positive number. The gene-
* Euler, in the Petersburgh Acts for 1774, has denied the universality of
this principle, and has adduced as an example of its failure the very remark-
able series
1—a™ (1—a™) (l—a™-!) | d@—a™) (i — a™—1) (1 — a™—2)
te * 1—a i 1—@ + &e.,
which is equal to m, when m is a whole number, but which is apparently not
equal to m, for other values of m, unless at the same time a= 1: the occur-
rence, however, of zero as a factor of the (m + 1)th and following terms in
: Os
the first case, and the reduction of every term to the form > in the second,
would form the proper indications of a change in the constitution of the equi-
valent function corresponding to these values of m and a, of which many ex-
amples will be given in the text.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 225.
vative signs as distinguished from those pilnitive signs of ope-
ration which are used in arithmetical algebra; but such signs,
though accurately defined and limited in their use in one sci-
ence, will cease to be so in the other, their meaning being de-
pendent in symbolical algebra, in common with all other signs
which are used in it, upon the symbolical conditions which they
are required to satisfy.
I will consider, in the first place, signs of affection, which are
those symbolical quantities which do not affect the magnitudes,
though they do affect the specific nature, of the quantities into
which they are incorporated.
Of this kind are the signs + and —, when used independ-
ently; or their equivalents + 1 and — 1, when considered as
symbolical factors ; the signs (+ 1)" and (— 1)", or their sym-
bolical equivalents
cos 2rna + /—] sn2rnz and cos (2r+1)n27+
¥—l sin (2r +1) a2;
dy errnaVv ai aad e@rt 1) na/—1
The affections symbolized by the signs + 1 and — 1 admit
of very general interpretation consistently with the symbolical
conditions which they are required to satisfy, and particularly
so in geometry: and it has been usual, in consequence of
the great facility of such interpretations, to consider all quan-
tities affected by them (which are not abstract) as possible,
that is, as quantities possessing in all cases relations of exist-
ence which are expressible by those signs. It should be kept
in mind, however, that such interpretations are in no respect
distinguished from those of other algebraical signs, except in
the extent and clearness with which their conditions are sym-
bolized in the nature of things.
The other signs of affection, different from + 1 and — 1,
which are included in (1)" and (— 1)", are expressible generally
by cos§ + “—1sin 6, or by a + B VW —1,where « and 6 may have
any values between 1 and — 1, zero included, and where «? + 6?
= 1. To all quantities, whether abstract or concrete, expressed
by symbols affected by such signs, the common term impossible
has been applied, in contradistinction to those possible magni-
tudes which are affected by the signs + and — only.
Tf, indeed, the affections symbolized by the signs included.
under the form cos § + “ —1 sin 4, admitted in no case of an in-
terpretation which was consistent with their symbolical condi-
tions, then the term impossible would be correctly applied to
a Tyeee affected by them: but in as much as the signs + and
. Q
226 THIRD REPORT—1833.
—, when used independently, and the sign cos 6+ “—I sin6,
when taken in its most enlarged sense, equally originate in the
generalization of the operations of algebra, and are equally in-
dependent of any previous definitions of the meaning and extent
of such operations, they are also equally the object of inter-
pretation, and are in this respect no otherwise distinguished
from each other than by the greater or less facility with which
it can be applied to them.
Many examples* of their consistent interpretation may be
pointed out in geometry as well as in other sciences: thus, if
+ aand — a denote two equal lines whose directions are op-
posite to each other, then (cos § + “—1 sin 4) a may denote
an equal line, making an angle @ with the line denoted by + a;
and consequently a “ —1 will denote a line which is perpen-
dicular to + a. This interpretation admits of very extensive
application, and is the foundation of many important conse-
quences in the application of algebra to geometry.
The signs of operation + and — may be immediately inter-
preted by the terms addition and subtraction, when applied to
unaffected symbols denoting magnitudes of the same kind: if
they are applied to symbols affected with the sign —, these
signs, and the terms used to interpret them, become convertible.
Thus a + (— 6) =a — 6, and a — (— 6b) = a + J; or the al-
ebraical swm and difference of a and — 5, is equivalent to the
algebraical difference and sum of a and b: but if they are applied
to lines denoted by symbols affected by the signs cos 6 + ” —1.
sin 6, and cos 6 + ” —1 sin @, the results will no longer de-
note the arithmetical (or geometrical) swm and difference of the
lines in question, but the magnitude and position of the dia-
gonals of the parallelogram constructed upon them, or upon
lines which are equal and parallelto =
them. Thus, if we denote the line
AB by a, and the line A C at right
angles to it by 6 / — 1, and if we
complete the parallelograms ABDC
and ABCE, thena + 6 VW — | will
denote the diagonal A D, and a — 6 —1 will denote the
other diagonal B C, or the equal and parallel line A E.
It is easily shown that a+b /W—1= V(@ + 5) (cos 4
ae cos-la -
+ 7% —1 sin $), (where 6 = Vien RB anda— b6 ¥—1
= /(a? + 5) {cosé — / —1 sin 4} ; it follows, therefore, that
' * Peacock’s Algebra, chap. xii. Art. 437, 447, 448, 449.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 227
a+b/%—1 anda—bW—1 may be considered as repre-
senting respectively a single line, equal in magnitude to
(a? + b?)*, and affected by the sign cos# + /—1sin$@ in
one case, and by the sign cos § — “ — 1 sin@ in the other; or
as denoting the same lines through the medium of the opera-
tions denoted in the one case by +, and in the other by —,
upon the two lines at right angles to each other, which are de-
noted by a and 6b W—1.
We have spoken of the signs of operation + and —, as di-
stinguished from the same signs when used as signs of affection,
and we have also denominated a + 6 W—1, anda —b VW —1,
the sum and difference of a and 6 “ —1, though they can no
longer be considered to be so in the arithmetical or geometrical
sense of those terms; but it is convenient to explain the mean-
ing of the same sign by the same term, though they may be
used in a sense which is not only very remote from, but even
totally opposed to}, their primitive signification; and such a
licence in the use both of signs and of phrases is a necessary
consequence of making their interpretation dependent, not upon
previous and rigorous definitions as is the case in arithmetical
algebra, but upon a combined consideration of their symbolical
conditions, and the specific nature of the quantities represented
by the symbols. It is this necessity of considering all the re-
sults of symbolical algebra as admitting of interpretation sub-
sequently to their formation, and not in consequence of any
previous definitions, which places all those results in the same
relation to the whole, as being equally the creations of the
same general principle: and it is this circumstance which jus-
* The arithmetical quantity ,/(a?+ 6?) has been called the modulus of
a + b,/—1 by Cauchy, in his Cours d’ Analyse, and elsewhere. It is the single
unaffected magnitude which is included in the affected magnitude a+ 6 4/—1:
conversely the affected magnitude (cos 6+ 4/—1 sin 6) 4/a? + 0? is reducible
. 3 Seer 3 a
to the equivalent quantity a + 6 ,/—1, if cos é= VeLe and therefore
sin 6 Vere
+ The sum of a and —4, or a + (— d), is identical with the difference of a
and 6, or with a —b. The term operation, also, which is applied generally to
the fact of the transition from the component members of an expression to the
final symbolical result, will only admit of interpretation when the nature of the
process which it designates can be described and conceived. In all other cases
we must regard the final result alone. Thus, if a and 5 denote lines, we can
readily conceive the process by which we form the results a + 6 and a — 5, at
least when a is greater than b. But when we interpret a + b ,/—1 to mean a
determinate single line with a determinate position, we are incapable of con-
celying any process or operation through the medium of which it is obtained.
Q2
228. THIRD REPORT—1833.
tifies the assertion, which we have made above, that quantities
or their symbols affected by the signs +, —,or cos6+ “%—I.
sin 6, are only distinguished from each other by the greater or
less facility of their interpretation.
The geometrical interpretation of the sign / — 1, when
applied to symbols denoting lines, though more than once
suggested by other authors, was first formally maintained by
M. Buée in a paper in the Philosophical Transactions for 1806*,
which contains many original, though very imperfectly deve-
loped views upon the meaning and application of algebraical
signs. In the course of the same year a small pamphlet was pub-
lished at Paris by M. Argand, entitled Essai sur une Maniére
de représenter les Quantités Imaginaires, dans les Construc-
tions Géométriques, written apparently without any knowledge
of M. Buée’s paper. In this memoir M. Argand arrives at this
proposition, That the algebraical sum { of two lines {, estimated
both according to magnitude and direction, would be the dia-
gonal of the parallelogram which might be constructed upon
them, considered both with respect to direction and magnitude,
which is, in fact, the capital conclusion of this theory. This
memoir of M. Argand seems, however, to have excited very
little attention ; and his views, which were chiefly founded upon
analogy, were too little connected with, or rather dependent
upon, the great fundamental principles of algebra, to entitle
his conclusions to be received at once into the great class
of admitted or demonstrated truths. It would appear that
M. Argand had consulted Legendre upon the subject of his me-
moir, and that a favourable mention of its contents was made
by that great analyst in a letter which he wrote to the brother
of M. J. F. Frangais, a mathematician of no inconsiderable
eminence. It was the inspection of this letter, upon the death
of his brother, which induced M. Frangais to consider this
subject, and he published, in the fourth volume of Gergonne’s
Annales des Mathématiques for 1815, a very curious memoir
upon it, containing views more extensive, and more completely
developed than those of M. Argand, though generally agreeing
with them in their character, and in the conclusions deduced
from them. This publication led to a second memoir upon the
same theory from M. Argand, and to several observations
upon it, in the same Journal, from MM. Servois, Frangais,
and Gergonne, in which some of the most prominent objections
to it were proposed, and partly, though very imperfectly, an-
* This paper was read in 1805. + La somme dirigée.
t Lignes dirigées.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 229
swered. No further notice appears to have been taken of these
researches before the year 1828, when Mr. Warren’s treatise on
the geometrical representation of the square roots of negative
quantities * was published. In this work Mr. Warren proposes
to give a geometrical representation to every species of quan-
tity; and after premising definitions of addition, subtraction,
multiplication and division, involution and evolution, which are
conformable to the more enlarged sense which interpretation
would assign to those operations when applied to lines repre-
sented in position as well as in magnitude; and after showing
in great detail the coincidence of the symbolical results obtained
from such definitions with the ordinary results of arithmetical
and symbolical algebra, he proceeds to determine the meaning
of the different symbolical roots of 1 and — 1, when applied
to symbols denoting lines, under almost every possible circum-
stance. The course which Mr. Warren has followed leads
almost necessarily to very embarrassing details, and perhaps,
also, to the neglect of such comprehensive propositions as can
only derive their authority from principles which make all the
results of algebra which are general in form independent of the
specific values and representation of the symbols: but at the
same time it must be allowed that his conclusions, when viewed
in connexion with his definitions, were demonstrably true; a.
character which could not be given to similar conclusions when
they were attempted to be derived by the mere aid of the arith-
metical definitions of the fundamental operations of algebra.
This objection to the course pursued by Mr. Warren will
more or less apply to all attempts which are made to make the
previous interpretations of algebra govern the symbolical con-
clusions; for though it is always possible to assign a meaning
to algebraical operations, and to pursue the consequences of
that meaning to their necessary conclusions, yet if the laws of
combination which lead to such conclusions are expressed
through the medium of general signs and symbols, they will
cease, when once formed, to convey the necessary limitations
of meaning which the definitions impose upon them. It is for
this reason that we must in all cases consider the laws of com-
bination of general symbols as being arbitrary and independent
in whatever manner suggested, and that we must make our in-
terpretations of the results obtained conformable to those laws,
and not the laws to the interpretations: it is for the same reason,
likewise, that our interpretations will not be necessary, though
: ‘s A Treatise on the Geometrical Representation of the Square Roots of Ne-
gative Quantities, by the Rev.-John-Warren, M.A., Fellow and Tutor of Jesus
College Cambridge. 1828. -
230 THIRD REPORT—1833.
governed by necessary laws, except so far as those interpreta-
tions are dependent upon each other. Thus, if a be taken to
represent a line in magnitude, it is not necessary that (cos 4
+ 4/—1 sin6)ashould represent a line equal in length to the one
represented by a, and also making ,an angle 6 with the line re-
presented by a; but if (cos § + 4/—1 sin 6) a, may, consistently
with the symbolical conditions, represent such a line, without
any restriction in the value of 6, then, if it does represent such
a line for one value of 9, it must represent such a line for every
value of 4 included in the formula. It is only in such a sense
that interpretations can be said in any case to have a necessary
and inevitable existence.
It is this confusion of necessary and contingent truth which
has occasioned much of the difficulty which has attended the
theories of the interpretation of algebraical signs. It has been
supposed that a meaning could be transmitted through a suc-
cession of merely symbolical operations, and that there would
exist at the conclusion an equally necessary connexion between
the primitive definition and the ultimate interpretation, as be-
tween the final symbolical result and the laws which govern it.
So long as the definitions both of the meaning of the symbols
and of the operations to which they are required to be subject
are sufficient to deduce the results, those results will have a
necessary interpretation which will be dependent upon a joint
consideration of all those conditions; but whenever an operation
is required to be performed under circumstances which do not
allow it to be strictly defined or interpreted, the chain of con-
nexion is broken, and the interpretation of the result will be
no longer traceable through its successive steps. This must
take place whenever negative or other affected quantities are
introduced, and whenever operations are to be performed,
either with them, or upon them, even though such quantities
and signs should altogether disappear from the final result.
This principle of interpretation being once established, we
must equally consider —1, /—1, cos# + —1 sin 9, as signs
of impossibility, in those cases in which no consistent meaning
can be assigned to the quantities which are affected by them,
and in those cases only: and it must be kept in mind that the
impossibility which may or may not be thus indicated, has re-
ference to the interpretation only, and not to the symbolical
result, considered as an equivalent form: for all symbolical
results must be considered as equally possible which the signs
and symbols of algebra, whether admitting of interpretation or
not, are competent to express. But there will be found to be
many species of impossibility which will present themselves in
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 231
considering the relations of formule with a view to their equi-
valence, and also under other circumstances, which will be in-
dicated by such means as will destroy all traces of the equiva-
lence which would otherwise exist.
The capacity, therefore, possessed by the signs of affection
involving / —1 of admitting geometrical or other interpreta-
tions under certain circumstances, though it adds greatly to
our power of bringing geometry and other sciences under the
dominion of algebra, does not in any respect affect the general
theory of their introduction or of their relation to other signs:
for, in the first place, it is not an essential or necessary pro-
perty of such signs; and in the second place, it in no respect
affects the form or equivalence of symbolical results, though it
does affect both the extent and mode of their application. It
would be a serious mistake, therefore, to suppose that such inci-
dental properties of quantities affected by such signs constituted
their real essence, though such a mistake has been generally
made by those who have proposed this theory of interpretation,
and has been made the foundation of a charge against them by
others, who have criticised and disputed its correctness*.
* This charge is made by Mr. Dayies Gilbert in a very ingenious paper in
the Philosophical Transactions for 1831, “‘ On the Nature of Negative and Im-
possible Quantities.” He says that those mathematicians take an incorrect
view of ideal quantities,—mistaking, in fact, incidental properties for those
which constitute their real essence,—who suppose them to be principles of
perpendicularity, because they may in some cases indicate extension at right
angles to the directions indicated by the correlative signs + and —; for with
an equal degree of propriety might the actually existing square root of a quan-
tity be taken as the principle of obliquity, in as much as in certain cases it
indicates the hypothenuse of a right-angied triangle. In reply to this last
observation, it may be observed, that I am not aware that in any case the
sign 4/— 1 has had such an interpretation given to it.
It is quite impossible for me to give an abridged, and at the same time a fair
view of Mr. Davies Gilbert’s theory, within a compass much smaller than the
contents of his memoir. But I might venture to say that his proof of the rule
of signs rests upon some properties of ratios or proportions which no arith-
metical or geometrical view of their theory would enable us to deduce. In con-
sidering, also, imaginary quantities as creations of an arbitrary definition, en-
dowed with properties at the pleasure of him who defines them, he ascribes to
them the same character as to all other symbols and operations of algebra;
but in saying “that quantities affected by the sign ,/— 1 possess a potential
existence only, but that they are ready to start into energy whenever that sign
is removed,” he appears to me to assert nothing more than that symbols are
impossible or not, according as they are affected by the sign ,/— 1 or not.
Again, in examining the relation of the terms of the equation
e+ f/®—-1l=(Y4+ fP—1*=y+ny" 1 vP—1
pi fe Aarts tet ;
eee Dp? ge a1) 4 EY. ah => yt 3 ye + &e.,
232 THIRD REPORT—1833.
Signs of transition are those signs which indicate a change
in the nature or form of a function, when considered in the
whole course of its passage through its different states of ex-
istence. Such signs, if they may be so designated, are gene-
rally zero and tnfinity.
Zero and infinity are negative terms, and if applied to desig-
he denies the correctness of the reasoning by which it is inferred that the
second term of the first, and the even terms of the second members of this
equation are equal to one another (when « is less than 1), because they are
the only terms which are homogeneous to each other, in as much as we thus
ascribe real properties to ideal quantities; and he endeavours to make this
equality depend upon an assumed arbitrary relation between x and y, though
it is obvious that if y = cos 6, we shall find « = cos n 6, and that, therefore,
this relation is determinate, and not arbitrary. A little further examination
of this conclusion would show that it did not depend upon any assumed
homogeneity of the parts of the members of this equation to each other, but
upon the double sign of the radical quantity which is involved upon both
sides.
In arithmetical algebra, where no signs of affection are employed or recog-
nised, both negative and imaginary quantities become the limits of operations ;
and when this science is modified by the introduction of the independent
signs + and — and the rule for their incorporation, the occurrence of the
square roots of negative quantities, by presenting an apparent violation of the
rule of the signs, becomes a new limit to the application of this new form of
the science. The same algebraists who have acquiesced in the propriety of
making the first transition in consequence of the facility of assigning a meaning
to negative quantities, at the same time that they retained the definitions and
principles of the first science, were startled and embarrassed when they came
to the second; for it was very clear that no attempt could be made to recon-
cile the existence and use of such quantities, consistently with the main-
tenance of that demonstrative character in our reasonings which exists in
geometry and arithmetic, where the mind readily comprehends the nature of
the quantities employed, and of the operations performed upon them. The
proper conclusion in such a case would be that the operations performed, as
well as the quantities employed, were symbolical, and that the results, though
they might be suggested by the primitive definitions, were not dependent
upon them. If no real conclusions had been obtained by the aid of such
merely symbolical quantities, they would probably have continued to be re-
garded as algebraical monsters, whose reduction under the laws of a regular
system was not merely unnecessary, but altogether impracticable. But it was
soon found that many useful theories were dependent upon them; that any
attempt to guard against their introduction in the course of the progress of
our operations with symbols would not merely produce the most embarrassing
limitations, when such limitations were discoverable, but that they would
present themselves in the expression of real quantities, and would furnish at
the same time the only means by which such quantities could be expressed.
A memorable example of their occurrence under such circumstances presents
itself in what has been called the irreducible case of cubic equations.
In the Philosophical Transactions for 1778 there is a paper by Mr. Playfair
on the arithmetic of impossible quantities, in which the definable nature of
algebraical operations is asserted in the most express terms, and in which
the truth of conclusions deduced by the aid of imaginary symbols is made to
depend upon the analogy which exists between certain geometrical properties
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 283
nate states of quantity, are equally inconceivable. We are ac-
customed, however, to speak of quantities as infinitely great
and infinitely small, as distinguished from jfinéte quantities,
whether great or small, and to represent them by the symbols
co and 0. It is this practice of designating such inconceivable
states of quantity by symbols, which brings them, in some de-
of the circle and the rectangular hyperbola. It is well known that the circle
and rectangular hyperbola are included in the same equation y= »/(1 — 2”),
if we suppose 2 to have
any value between + ©
and — o: let a circle be
described with centre C P I;
and radius CA =1, and
upon the production of
this radius, let a rectan- cM [A
gular hyperbola be de-
scribed whose semiaxis is
1, in a plane at right an-
gles to that of the circle:
if # denote the angle A C P,
then the circular cosine and sine (C M and P M) are expressed by
A, aT se Pb V/A a lie OWS 1
—_____——___ an —
2 2 /—1
respectively; whilst the hyperbolic cosine and sine (to adopt the terms pro-
posed by Lambert) corresponding to the angle 6 ,/—1 (in a plane at right
angles to the former) are expressed by
efpte—é fy pale b+e-o of _--8
and /—1 a , or by 5 and 7
if they be considered as determined by the following conditions; namely,
that (hyp. cosine)? — (hyp. sine)’ = 1, and that hyp. cos 6 = hyp. cos — 4,
and hyp. sine 6 = — hyp. sine — 6. A comparison of these processes in the
circle and hyperbola would show, says Mr. Playfair, that investigations which
are conducted by real symbols, and therefore by real operations, in the hy-
perbola, would present analogous imaginary symbols, and therefore analogous
imaginary operations in the circle, and conversely ; and that the same species
of analogy which connects the geometrical properties of the circle and hyper-
bola, connects the conclusions, of the same symbolical forms, when conducted
by real and imaginary symbols.
This attempt to convert an extremely limited into a very general analogy,
and to make the conclusions of symbolical algebra dependent upon an insu-
lated case of geometrical interpretation, would certainly not justify us in
drawing any genera! conclusions from processes involving imaginary symbols,
unless they could be confirmed by other considerations. The late Professor-
Woodhouse, who was a very acute and able scrutinizer of the logic of ana-
lysis, has criticised this principle of Mr. Playfair with just severity, in a paper
in the Philosophical Transactions for 1802, ‘On the necessary truth of certain
conclusions obtained by means of imaginary expressions.’? The view which he
has taken of algebraical equivalence, in cases where the connexion between
the expressions which were treated as equivalent could not be shown to be
the result of a defined operation, makes a very near approach to the principle
234 THIRD REPORT—1833.
gree, under the ordinary rules of algebra, and which compels us
to consider different orders both of ¢nfinities and of zeros, though
when they are considered without reference to their symbo-
lical connexion, they are necessarily denoted by the same sim-
ple symbols oo and 0; thus there is a necessary symbolical di-
stinction between (00 )3, co and (00 yi and between (0)2, 0 and
(0); though when considered absolutely as denoting infinity
in one case and zero in the other, they are equally designated
by the simple symbols « and 0 respectively.
Though the fundamental properties of 0 and ©, considered
as the representatives of zero and infinity, are suggested by the
ordinary interpretation of those terms, yet their complete in-
terpretation, like that of other signs, must be founded upon the
of the permanence of equivalent forms: thus, supposing, when 2 is a real
quantity, we can show that
a a3
ew =1l+e¢+ 75+ pag t+ kes
but that we cannot show in a similar or any other manner that
VT ayaa . feet
vA TIM! ae Tact are: aes
then the equivalence in the latter case is assumed, by considering 7 dea
as the abridged symbol for the series of terms
— a a3 /— 1
Re Day WD
in other words, the form which is proved to be true for values of the symbols
which are general in form, though particular in value, is assumed to be true
in all other cases.
It is true that such a generalization could not be considered as legitimate,
without much preparatory theory and without considerable modifications of
our views respecting nearly all the fundamental operations and signs of arith-
metical algebra; but I refer with pleasure to this incidental testimony to the
truth and universality of this important law, from an author whose careful
and bold examination of the first principles of analytical calculation entitle
his opinion to the greatest consideration.
Mr. Gompertz published, in 1817 and 1818, two tracts on the Principles and
Application of Imaginary Quantities, containing many ingenious and novel
views both upon the correctness of the conclusions obtained by means of ima-
ginary quantities and also upon their geometrical interpretation. The first
of these tracts is principally devoted to the establishment of the following
position: ‘‘ That wherever the operation by imaginary expressions can be
used, the propriety may be explained from the capability of one arbitrary
quantity or more being introduced into the expressions which are imaginary
previously to the said arbitrary quantity or quantities being introduced, so
as to render them real, without altering the truth they are meant to express ;
and that, in consequence, the operation will proceed on real quantity, the
introduced arbitrary quantity or quantities necessary to render the first steps
of the reasoning arguments on real quantity, vanishing at the conclusion;
+ &c.;
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 235
consideration of all the circumstances under which they pre-
sent themselves in symbolical results. In order, therefore, to
determine some of the principles upon which those interpreta-
tions must be made, it will be proper to examine some of the
more remarkable of their symbolical properties.
and from whence it will follow that the non-introduction of such can pro-
duce nothing wrong.” Thus, 2? + az + b, which is equal to
{VG+4y+VG-9}
«{VG+5Y-VG-)}
is also equal to
(rari VE 18}
x {Vergy te-VG ~o+e)h
whatever be the value of the quantity 6; a conclusion which enables us to
reason upon real quantities and to make 6= 0, when the primitive factors
= =T —% =T
are required. Similarly, if instead of ie ae
%/B=1 —2,/p=1 y/1 —2%,/=1
ee vee =y— R’, and if instead of AAT AMG
2 2V/7—1
e/ p-1 ft os V1 po
2/p—1
éVe-! = y—R!' + /B—1 (z— R), a result which degenerates into
the well known theorem e VAT — y+ V—12,if6=0. Many other ex-
amples are given of this mode of porismatizing expressions, (a term derived by
Mr.Gompertz from the definition of porisms in geometry,) by which operations
are performed upon real quantities which would be otherwise imaginary :
and if it was required to satisfy a scrupulous mind respecting the correctness
_of the real conclusions which are derived by the use of imaginary expressions,
there are few methods which appear to me better calculated for this purpose
than the adoption of this most refined and beautiful expedient.
The second tract of Mr. Gompertz appears ta have been suggested by
M. Buée’s paper in the Philosophical Transactions, to which reference has been
made in the text : it is devoted to the algebraical representation of lines both
in position and in magnitude, as a part of a theory of what he terms func-
tional projections, and embraces the most important of the conclusions obtained
by Argand and Frangais, with whose researches, however, he does not appear
to have been acquainted. I should by no means consider the process of rea-
soning which he has followed for obtaining these results to be such as would
naturally or necessarily follow from the fundamental assumptions of algebra :
but it would be unjust to Mr. Gompertz not to express my admiration of the
skill and ingenuity which he has shown in the treatment of a very novel
subject and in the application of his principles to the solution of many curious
and difficult geometrical problems.
= y, Wwe suppose
=) 4,
we suppose
= « — R, we shall find, whatever 6 may be,
236 THIRD REPORT—1833.
If we assume a to denote a finite quantity, then
(1.) a+O=a,andatwn=to.
o
Consequently 0 does not affect a quantity with which it is
connected by the sign + or —, whilst «, similarly connected
with such a quantity, altogether absorbs it.
a a
2.) ax0=0,ax@ =; 7 =~ and = 0.
It is this reciprocal relation between zero and infinity which
is the foundation of the great analogy which exists between
their analytical properties. ;
(3) If these symbols be considered absolutely by themselves,
without any reference to their symbolical origin, then we must
consider 9 = 1 and =1.
0 00
But if those symbols be considered as the representatives
equally of all orders of zeros and infinities respectively, then
0
ve : -
— and > may represent either | or a or 0 or ©, its final
0
form and value being determined, when capable of determina-
tion, by an examination of the particular circumstances under
which those symbols originated. ‘The whole theory of vanish-
ing fractions will depend upon such considerations.
Having ascertained the principal symbolical conditions which
0 and © are required to satisfy, we shall be prepared to con-
sider likewise the principle of their interpretation. The exami-
nation of a few cases of their occurrence may serve to throw
some light upon this inquiry.
Let us consider, in the first place, the interpretation of the
critical values 0, © and +. in the formule which express the
values of « and y in the simultaneous equations,
ax+by=e
ae Oy =e
In this case we find
8
ll
)
=}
a
S
ll
5 febt b Aaftedinny .0Ge
Biol sept Wep Bilin GAs
Goria yar ty ae sg NON Sect ete
TT Power ;, and therefore pis 7, then @ =
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 237
In this case a! = ma, b! = ma,and c = mc, and the second
equation is deducible from the first, and does not furnish, there-
fore, a new condition: under such circumstances, therefore,
the values of x and y are really indeterminate, and the occur-
0
0
sign, or rather the indication of that indetermination. .
!
If be not equal to a
and y = ©. In this case we have a’ = ma, b/ = mb, but ¢’ is
not equal to mc; and the conditions furnished are inconsistent,
or more properly speaking tmpossible. In this case, the occur-
rence of the sign o in the expressions for 2 and y is the sign
or indication of this inconsistency or impossibility: and it should
be observed that no infinite values of x and y, if the infinities
thus introduced were considered as real existences and ¢denti-
cal in both equations, would satisfy the two equations any more
than any two finite values of x and y which would satisfy one
of them. We may properly interpret 0 in this case by the
term émpossible.
!
If = = ms but if BS be not equal to 4 then wx is zero and y
rence of — in the values of the expressions for x and y is the
!
but if be equal to aa then 2 = o
is finite, and therefore possible. It is in this sense that we
should include zero amongst the possible values of x or y, a
use or rather an abuse of language to which we are somewhat
familiarized, from speaking of the zero of quantity as an exist-
ing state of it in the transition from one affection of quantity to
another.
If we should take the equations of two ellipses, whose semi-
axes are a and J, a’ and Bb’ respectively, which are
2
xv 4
atepa)h
x 2
et peat
and consider them as simultaneous when expressing the co-
ordinates of their points of intersection, then we should find
V{B — 8} V{a@ — a?)
r= BF G2 and y= a? Ce ee
ea? Be Bb?
b
If we suppose any ed or the ellipses to be similar, and at the
same time 6 not equal to 0’, then x = © and y = ©, which
238 THIRD REPORT—1833.
would properly be interpreted to mean that under no cir-
cumstances whatever, whether in the plane of 2 y or in the
plane at right angles to it, in which the hyperbolic portions* of
curves expressed by those equations are included, would a point
of intersection or a simultaneous value of # and y exist: or in
other words, the sign or symbol o would in this case mean
that such intersection was zmpossible. If we supposed s = 4
and also 6 = b’,or the ellipses to be coincident in all their parts,
then we should find « = a and y = 2, indicating that their
values were indeterminate, in as much as every part in the iden-
tical curves would be also a point of intersection, and would fur-
nish therefore simultaneous values. If we should suppose 3
a a
6 we?
greater than 0’, a greater than a’, and then
we should find
not equal to
xw«=aandy = 6 /—I,
or x =a/—1 andy = 8,
according as . is less or greater than > In this case, one
ellipse entirely includes the other, but the hyperbolic portions
at right angles to their planes, which are in the direction of
the major axis in one case and in that of the minor axis in the
other, will intersect each other at points whose coordinates are
the values of 2 and y above given: it would appear, therefore,
that the tmpossible intersection of the curves would be indi-
cated by the sign or symbol o alone, and not by /—1.
The preceding example is full of instruction with respect to
the interpretation of the signs of algebra, when viewed in con-
nexion with the specific values and representations of the sym-
bols; and there are few problems in the application of algebra
to the theory of curve lines which would not furnish the mate-
rials for similar conclusions respecting them: but it is chiefly
with reference to the connexion of those signs with changes in
the nature of quantities, and in the form and constitution of ex-
pressions, that their interpretations will require the most care-
ful study and examination. We shall proceed to notice a few of
such cases.
2 2
* If in the equation <5 “IB a = 1, we suppose y replaced by y W—1,
and the line which it represents when not affected by “—1 to be moved
through 90° at right angles to the plane of x y, we shall find an hyperbola
included in the equation of the ellipse.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 239
- The second member of the equation
1 1 b b?
As a a ak
preserves the same form, whatever be the relation of the values
of a and 5, and the operation, which produces it, is equally prac-
ticable in all cases. As long asa is greater than b, a—b is po-
sitive, and there exists, or may be conceived to exist, a perfect
arithmetical equality between the two members of the equa-
tion. If, however, a = b, we have 7 upon one side and the
sum of an infinite series of units multiplied into | Upon the
other, and both the members are correctly represented by 0;
but if a be less than b, we have a negative and a finite value
upon one side of the equation, and an infinite series of perpe-
tually increasing terms upon the other, forming one of those
quantities to which the older algebraists would have applied
the term plus quam infinitum, and which we shall represent by
the sign or symbol «. It remains to interpret the occurrence
of such a sign under such circumstances.
The first member of this equation z ‘ 3 is said to pass
through infinity when its sign changes from + to —, or con-
versely : its equivalent algebraical form presents itself in a se-
ries which is incapable of indicating the peculiar change in the
nature of the quantity designated by Peay 2 which accompa-
nies its change of sign. The infinite values, therefore, of the
equivalent series (for in its general algebraical form, where no
regard is paid to the specific values of the symbols, it is still
an equivalent form,) is the indication of the impossibility of ex-
hibiting the value of z ul A in a series of such a form under
such circumstances.
Let us, in the second place, consider the more general series
for (a — 6)", or .
D0 (tame De ae
MD psi see? Ue
(abe =ardi—n.% ca
n(n—1)(n—2) B
ge de
The inverse ratio of the successive coefficients of this series
240 ’ THIRD REPORT—1833.
approximates continually to — 1 as a limit, and the terms be-
come all positive or all negative, according as the first negative
coefficient is that of an odd or of an even power of es It follows,
therefore, that if a be greater than 8, the series will be conver-
gent and finite in all cases; if a be equal to 8, it will be 0, |,
or ©, according as x is positive, 0, or negative; and if a be
less than 4, it will be énjinite.
The occurrence of the last of these signs or values is an in-
dication generally that some change has taken place in the na-
ture of the quantity expressed by (a — 6)", in the transition
from a > bto a< b, which is of such a kind that the correspond-
ing series is not competent to express it: thus, if m = 4, then
(a — b)" is affected with the sign 4/—1 when a is less than 6,
whilst no such sign is introduced nor introducible into the equi-
valent series corresponding to such relative values of a and b:
and a similar change will take place, whenever a transition
through zero or infinity takes place.
In this last case (a — 6)" would appear to attain to zero or in-
jfinity, but not to pass through it, and no change would appa-
rently take place in its affection corresponding to the change of
affection of a — 6; but the corresponding series will under the
same circumstances change from being finite to infinite, a cir-
cumstance which we shall afterwards have occasion to notice,
and which we shall endeavour to explain in the course of our
observations upon the subject of diverging and converging
series.
In the preceding examples the sign or symbol «© has not
presented itself immediately, but has replaced an infinite series
of terms, whose sum exceeded any finite magnitude ; and it may
be considered as indicating the zncompetence of such a series
to express the altered state or conditions of the quantity or
fraction to which it was required to be altogether, as well as
algebraically, equivalent. In the examples which follow, it will
present itself immediately and will be found to be the indica-
tion of a change in the algebraical form of the term or terms in
' which it appears, or rather that no terms of the form assigned.
can present themselves in the required equivalent series or
expression.
n+
The integral /a"dax = = it C is said to fail when
n = — 1, in as much as it appears that under such circum-
a—1
stances trey becomes ©, which is an indication that the va-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. P41
riable part of ford xis no longer expressible by a function
grtt
n+1
by independent considerations. A knowledge, however, of the
nature of its form in this particular case has enabled algebraists
to bring it under a general form, by which the sign of failure
or impossibility is replaced by the sign of indetermination
; antl grt — gntl
for if we put — pp C=
under the form » but by one which must be determined
o 5 + C, (borrowing
a the |
a wrt . .
Paro from the arbitrary constant,) we shall get an expression
which becomes iG when x = — 1, and whose value, determined
0
according to the rules which are founded upon the analytical
properties of 0, will be log x + C.
A more general example of the same kind, including the one
which we have just considered, is given in the note to page
211, where it is required to determine the general form of
_ she EI ih
dat ge NO Gar
values of r: a formula is there constructed, from our knowledge
of the form in the excepted case, which is capable of correctly
expressing its value in all cases whatever.
The cases in which the series of Taylor is said to fail are of
a similar nature. Thus, if u =¢(«)=2+ Vx —a, then
aah? Beh he
Pes = pi ical igs Sl Mg alec :
Re het =u + ook to eit duida2 aes
P = (where z is a positive number) for all
and if we suppose x = 4, all the differential coefficients ae
F]
= &c., become infinite, which is an indication that no terms
of such a form exist in its developement, which becomes, under
such circumstances, a + /h. The reasons of this failure in
such cases have been very completely explained by Lagrange
and other writers; but it is possible, by presenting the deve-
lopement which constitutes T'aylor’s series under a somewhat
different and a somewhat more general form, that the series may
be so constructed as to include all the excepted cases.
There are two modes in which the developement of ¢ (a + h)
according to powers of h may be supposed to be effected. In
the first and common mode we begin by excluding all those
Be x the developement whose existence would be incon=
3 R
242 THIRD REPORT—1833.
sistent with general values of the symbols: in the second we
should assume the existence of all the terms which may cor-
respond to values of the symbols, whether general or specific,
and then prescribe the form which they must possess, con-
sistently with the conditions which they are required to satisfy.
If we adopt this second course, and assuming u = ¢ (x) and
u’ = 9(« + h), if we make
w=utAh?+Bh+ Ch + &c.,
the inquiry will then be, if there be such a term as A h*, where
A is a function of x or a constant quantity, and a is any quantity
whatsoever, what are the properties of A by which it may be
determined? For this purpose we shall proceed as follows.
It is very easy to show, from general considerations, that
if «’ be considered successively as a function of x and of h,
dul ,
— = wes for all values of 7, whether whole or fractional,
positive or negative: it will follow, therefore, (adopting the
principles of differentiation to general indices which have been
laid down in the note, p. 211,) that
dtu F(1 + @) een r(1 + bd)
aa TET, Se r(il+6—a)
omitting the arbitrary complementary functions, which will in-
volve powers of k. Ina similar manner we shall get
ia a a ne Coe
dat dat t dat ‘sian dx*
If these results be identical with each other, we shall find
‘BAb-* + @e;
h® + &e.
1 dea. A
and, therefore, A = rato)’ ae since I'(1) = 1, It is easy
to extend the same principle to the determination of the other -
coefficients, and we shall thus find
y dtu, he au : he
u=u+ 7e¢ Pada) da Td+d)
or, in other words, it follows that the coefficient of any power
of h whose index is r will be
1 du
ri +r) da"
+ &e.; (1.)
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 243
The next step is to adapt the series (1) to the different cases
which an examination of the constitution of the function w will
present to us.
If we suppose x to possess a general value, then w! and w
will possess the same number of values, and no fractional
power of / can present itself in the developement. In this case
r(1+a)=1.2... a, and it may be readily proved that
the successive indices a, b, c, &c., are the successive numbers
1, 2, 3, &c., and that consequently,
a du du Bu he
da? 1.2" dw 1.2.3
It will also follow that the series for uw’ can involye no negative
and integral power of 4; for in that case the factorial I'(1 + a),
which appears in its denominator, would become o, and the
term would disappear. If it should appear, also, that for spe-
cific values of 2 any differential coefficient and its successive
values should become infinite, they must be rejected from the
developement, in as much as in that case the equation
d*u
ri+aA= dat
would no longer exist, which is the only condition of the intro-
duction of the corresponding terms. In other words, those
terms in the developement of u' must be equally obliterated,
which, under such circumstances, become either 0 or .
If the general differential coefficient of u could be assigned,
its examination would, generally speaking, enable us to point
out its finite values wherever they exist, for those specific va-
lues of the symbols which make the integral differential coeffi-
cients zero or infinity. For all such values there will be a cor-
responding term in the developement of w’ under those cireum-
stances. Thus, if we suppose wu = « a — x, we shall find
re ce) [re-9-G-yeh
if we make x = a, this expression will be neither zero nor
+ &c.
infinity in two cases only, which are when r = * and when |
a: ae
‘=>: in the first case we get,
244 THIRD REPORT—1833.
and in the second we get,
— 38
1 3 = » oe s
r(5) 4-3
2) dx 21 x0x(@—a)
since '(1) = 1 = 0 F'(O), and the symbol 0 in the denominator
3
= —1;
aa aeag is a stmple zero. The corresponding developement
of u’ under such circumstances is
A eh? tla B*,
a result which is very easily verified.
If we pay a proper regard to the hypotheses which deter-
mine the existence of terms in the series for w for specific
values of the independent variable, we shall be enabled without
difficulty to select the indices of the differential coefficients
which can present themselves amongst the coefficients of the
different powers of / in the developement. For, in the first
place, 4», and the differential coefficient whose index is = will
possess the same number of values, and the same signs of affec-
™m
tion. If there be a term in w which = P (x — a)", where P
neither becomes zero nor infinity, when x = a, and where the
multiple values of P, if any, are independent of those contained
d= .P. (« — aje
d an
which is independent of (a — ayn is P. a and that
dun
in (« — ar, then it will appear that the term of
m™
dn*u
m
dxn
x =a, or, if finite, introducing, through the medium of the
factorial function by which they are multiplied, multiple values
which are greater in number than those contained in w’, must
be rejected, as forming no part of the developement. It will of
- course follow, that the function P will become, under such cir-
cumstances, a function of h, and if we represent it by P’, and
denote its values, and those of its successive differential coeffi-
cients, when h = 0, by p, p’, p", pl”, &c., we shall find
P= 7 1 h* mw he
=ptph+ pap" 7-9-3 + ke.
all the other terms of ,» being either zero or infinity when
REPORT ON CERTAIN BRANCHES OF ANALYSIS, 245
none of which become zero or infinity, in as much as P does not
vanish when x = a.
If there exist other terms in zu of a similar kind, such as
, mm"
m
Q (x — 5)", R (w — c)””, &c., the same observations will apply
to them. Such terms will correspond to values of x, which
make radical expressions of any kind zero or infinity, and the
form of the function « must be modified when necessary, so
that such radicals may present themselves in single terms of
‘ ™ ;
the form P (« — a)". The same observations will apply to ne-
gative as well as positive values of Fe unless we suppose a
negative whole number. The principle of the exception in this
last case may be readily inferred from the remarks in the note,
p- 211, on the subject of the values of ae a = when 7 isa
whole number. If we suppose, therefore, « to involve terms
m m!
such as P (x — a)", Q (n — 5)”, &c., the most general form
under which its developement can be put, supposing all terms
which become zero or infinity for specific values of x to be
rejected, will be as follows:
fu hh d? u h3
Bi wick ~du La ie tra
Bar Mitigate rene ue 10a. i
eae meee
Wee r(i+”
n
pale ane ae -
+ .Q). — — ¢ &e. :
za«—b oy ate ‘agent ;
or,
du d?u_ h? Bu .h
‘a pers 6 Sent Ape aaa ae es
int ga iaet 1 oae Te a ree
ig ee 2
a ' h m
+ “(pt phtp. 5+ Sic.)
tI—
b—b h? feed
+ Fos (gt gata’ + Se. ) he
+ &e.
-s s ! u i 4 a=
We have introduced the discontinuous signs or factors .
cm &
246 THIRD REPORT—1833.
b6—b
zx~b’
but which are zero for all other values of 2, to show that the
terms into which they are multiplied disappear from the deve-
lopement in all cases except for such specific values of a.
The existence of the terms of the series for w’ is hypothetical
only, and the equation which must be satisfied, as the essential
condition of the existence of any assigned hypothetical term, at
once directs us to reject those terms which would lead to infi-
nite values of the differential coefficients, as well as those which
possess multiple values which are incompatible with those con-
tained in w’. It is quite obvious that upon no other principle
could we either reject such infinite values, or justify the con-
nexion of a series of terms with the general form of a’, which
have no existence except for specific values of 2 The con-
clusion obtained is of considerable importance, in as much as it
shows that the series of Taylor, if considered and investigated
as having a contingent, and not a necessary existence, may be
so exhibited as to comprehend all those cases in which it is
commonly said to fail: and it will thus enable us to bring under
the dominion of the differential calculus many peculiar cases in
its different applications which have hitherto required to be
treated by independent methods.
Thus, if it was required to determine the value of the fraction
( pe all a’)?
&c., which become equal to 1 when 2 = a or a = 8, &e.,
, when x = a, we should find it to be,
x? (a — a)?
dt
oo cae Lae a’)?
d x?
di Ms
++ 2? (a2 — a)?
"0 ( )
or,
dz
(# + a)?- (« — a)?
+ a
a = @a? 4/20;
di? a?
a conclusion which would be justified by the developement of
the numerator and denominator of this fraction by the complete
form of Taylor’s series, when 2 = a.
Many delicate and rather obscure questions in the theory of
maxima and minima, particularly those which Euler has deno-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. Q47
minated maxima and minima of the second species, and others
also relating to the singular or critical points of curve lines,
must depend for their dilucidation upon this more general view
of Taylor’s series, as connected with the consideration of ge-
neral differential coefficients *.
* Euler has devoted an entire chapter of his Calculus Differentialis to the
examination of what he terms the differentials of funciions in certain peculiar
cases. It is well known that he adopted Leibnitz’s original view of the prin-
ciples of the differential calculus, and considered differentials of the first and
higher orders as infinitesimal values of differences of the first and higher orders.
uch a principle necessarily excludes the consideration of differential coefficients
as essentially connected with determinate powers of the increment of the inde-
pendent variable, which may be said to constitute the essence of Taylor's
theorem, and which must be the foundation of all theories of the differential
calculus, which make its results depend upon the relation of forms, and not
upon the relation of values. As long, however, as the independent variable
continues indeterminate, the symbolical values of the differentials are the same
upon both hypotheses. But when we come to the consideration of specific va-
lues of the independent variable which make differential coefficients above or
below a certain order, infinite or zero, then such a view of the nature of dif-
ferentials necessarily confounds those of different orders with each other. Thus,
if y= a? + (« — a), Euler makes, when r=a, dy=(d x)=, instead of
dy ay ‘
(f/9\= 8 , = (a)?. fy=2axr— 2 + a (a — 2%), he makes,
MG) a”
when « = a, dy = a ./— 2a. da, instead of
a? (d a) {* /2 L. =1\
pe a +av
These examples are quite sufficient to make manifest the inadequacy of
merely arithmetical views of the principles of the differential calculus to ex-
hibit the correct relation which exists between different orders of differentials,
and, @ fortiori, therefore, between different orders of differential coefficients.
M. Cauchy, in his Legons sur le Calcul Infinitesimal (published in 1823), has
attempted to conciliate the direct consideration of infinitesimals with the purely
algebraical views of the principles of this calculus, which Lagrange first securely
established; and it may be very easily conceded that no attempt of this able
analyst, however much at variance with ordinary notions or ordinary practice,
would fail from want of a sufficient command over all the resources of analysis.
He considers ail infinite series as fallacious which are not convergent, and that,
consequently, the series of Taylor, when it takes the form of an indefinite series,
is not generally true. It is for this reason that he has transferred it from the
differential to the integral calculus, and exhibits it as a series with a finite
number of terms completed by a definite integral. It is very true that M. Cauchy
has perfectly succeeded in dispensing with the consideration of infinite series in
the establishment of most of the great principles of the differential and integral
calculus; but I should by no means feel disposed to consider his success in over-
coming difficulties which such a course presents as a decisive proof of the expe-
diency of following in his footsteps. The fact is, that if the operations of algebra
be general, we must necessarily obtain indefinite series, and if the symbols we
employ are general likewise, it will be impossible to determine, in most cases,
dty=
248 THIRD REPORT—1833.
Signs of discontinuity are those signs which, in conformity
with the general laws of algebra, are equal to 1 between given
limits of one or more of the symbols involved, and are equal to
zero for all their other values. If merely conventional signs
were required, we might assume arbitrary symbols for this
purpose, attaching to them far greater clearness as diventical
marks, the limits of the symbol or symbols between which the
sign of discontinuity was supposed to be applied. Thus, we
might suppose 7D,” to denote 1, when x was taken between
0 and a, to denote zero for all other values; 7D, ,%, to denote 1,
when x was taken between a and a + 3, and zero for all other
values ; and similarly in other cases.
Thus, if y= a+ Band y = a’ x + 6! were the equations
of two lines, and if we supposed that the generating point whose
coordinates are x and y was taken in the first line between the
limits 0 and a, and in the second line between the limits a and 8,
then we should have generally,
y= "D,; (ax + B) ph °T),” (a! x + B’) (1.)
the convergency or divergency of the series which result. It is only, therefore,
when we come to specific values that a question will arise generally respecting
the character of the series: and it is only when we are compelled to deduce the
function which generates the series from the application of the theory of limits
to the aggregate of a finite number of its terms, that its convergency or diver-
gency becomes important as affecting the practicability of the inquiry : in short,
it must be an erroneous view of the principles of algebra which makes the result
of any general operation dependent upon the fundamental laws of algebra to be
fallacious. The deficiency should in all such cases be charged upon our power
of interpretation of such results, and not upon the results themselves, or upon the
certainty and generality of the operations which produce them: in short, the
rejection of diverging series from analysis, or of such series as may become
divergent, is altogether inconsistent with the spirit and principles of symbolical
algebra, and would necessarily bring us back again to that tedious multipli-
cation of cases which characterized the infancy of the science. A very instruc-
tive example of the consequences of adopting such a system may be seen in the
researches of M. Liouville, which have been noticed in the note at p. 217.
Lagrange in his Théorie des Fonctions Analytiques, and in his Calcul des
Fonctions, has given theorems for determining the limits between which the
remainder of Taylor’s series, after a finite number of terms, is situated: and
the same subject has been very fully discussed in a memoir by Ampére, in the
sixth volume of the Journal de Ecole Polytechnique. Such theorems are ex-
tremely important in the practical applications of this series, but they in no
respect affect either the existence or the derivation of the series itself. Itisa
very common error to confound the order in which the conclusions of algebra
present themselves, and to connect difficulties in the interpretation and appli-
cation of results with the existence of the results themselves: and it is the in-
fluence of this prejudice which has induced some of the greatest modern ana-
lysts, not merely to deny the use, but to dispute the correctness of diverging
series.
Messrs. Swinburne and Tylecote, the joint authors of a Treatise on the true
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 249
_ Thus, if in the triangle A C B, we
draw C D, a perpendicular from the
ms a
vertex to the base, and if we suppose et
AD=a, AB= 4, A the origin of a
the coordinates, A B the axis of 2, yan beni
o 1 ‘
4 ’
y = a x the equation of the line AC, Ke
and y = a! « + 6! the equation of the 4 B
line B C, then we should find that the value of y represented
by the equation
y= “D,°.ax2 + °D;" (a! a + B')* (2.)
would be confined to the two sides A C and B C of the triangle
A BC, excepting only the point C, which corresponds to the
common limit of the discontinuous signs, For if we suppose
*D,” and *D,’ to be true up to their limits, we shall find, when
& = a, that 7D,’ + 7D," = 2. If we replace, however,
2 £ a 2T)y.2 avT).@ b—5
D, by ..— aa and D; by D; aienet
a=
ta
Developement of the Binomial Theorem, which was) published in 1827, have
contended vigorously for the restriction of the meaning of the sign = to simple
arithmetical equality, and would reject its use when placed between a function
and its developement, unless its complete remainder, after a finite number of
terms, should replace the remaining terms of the series; or unless, when the
indefinite series was supposed to be retained, the value or the generating func-
tion of this remainder could be assigned. In conformity with this principle
they have assigned the remainder in the series for (a + x)", which they exhibit
under the following form :
“(a+ a)*=a%®+na"-le+.... nie LL chelate cute Wan +) gn-r ge
1 (r + 1) a
1 Om cas Sens, wala Pil ey Aenea EP doy
Fat ©) @int ja) aaa 1 ‘(@+part2
(r+) (7% +2)...(2—1) a®-7-1) |
the remainder being (a + 2)" 27 +1 multiplied into x — r terms of the deve-
1 1
{@+a)— ape t 8 ear
The method which they have employed for this purpose, which is extremely
ingenious, succeeds for integral values of m, whether positive or negative, but
fails to assign the law when the index is fractional. But my own views of the
principles of symbolical algebra would, of course, induce me to attach very little
value to results which were exhibited in such a form as to be incapable of being
generalized, a defect under which the formula given above evidently labours.
_ * The conventional sign 7D,7 might be replaced, though not with perfect
sre 4 1
propriety, by the definite integral -—> S, "de.
lopement of
250 THIRD REPORT—1833.
and if we make, therefore,
4 i ot gray ‘,
y=}ps— Sars }p, —Jaih@e +e) (3.)
the equation will be true for the ordinate of every point of the
sides A C and CB of the triangle A BC.
More generally, if we suppose y = 9, 7, ¥ = 22, ¥ = $34,
y = 9, x, &c., to be the equations of a series of curves, then the
equation of a polylateral curve composed of the several portions
of the separate curves corresponding to values of «, included
between the limits a and b, b and c, ¢ and d, &c., would be,
a b—b r oe
y= \7D: — 2S) ee + (*DP-2=*) ge
r
a. (De a g = ‘) Q,2 + &e.; (4.)
the value of the ordinate at each successive limit being replaced
by that of the succeeding curve. In this manner, if we should
grant the existence of the sign of discontinuity, we should be
enabled to represent the equations of polygons, and of poly-
lateral curves of every description.
It remains to consider the nature of the expressions which
are competent to express 7D;".
The expressions which have been generally proposed for this
purpose are either infinite series, or their equivalent definite
integrals. Le Comte de Libri, however, a Florentine analyst
of distinguished genius, has proposed * a finite exponential ex-
pression which will answer this purpose. The examination of
the expression
ellog 0) log 0) (v — a)
would readily show that its value is 1 when z is greater than
a, and that it is 0 when 2 is equal to or less than a. It will
therefore follow that the product
e (log 0) 2098 (#~ a) ye log 0) 2080) 0-2)
is equal to 1 between the limits @ and 4, and is equal to 0 at
those limits, and for all other values. And, in as much as
* Mémoires de Mathématigue et de Physique, p. 44. Florence 1829. The
author has since been naturalized in France, and has been chosen to succeed
Legendre as a member of the Institute: he has made most important additions
to the mathematical theory of numbers.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 251
208°) = 0, we may replace the preceding product by the equi-
valent expression
(v= a) (6 = 2)
QS eravhaxo8 avout
a—a b—b
t—a «—b’
has been applied by Libri to the expression of many important
theorems in the theory of numbers*.
G0
The definite integral BA nae sin r has been shown by
This expression, which is equivalent to 7D,” —
Euler} and many other writers, to be equal to = when ~ is
when z is negative. It
— 7
positive, to 0 when 2 is 0, and to 3
follows, therefore, that
2 fdr. (b—a) f G+9 |
=f a ee oe rT COS fev lniagial Tr
) = 1 war. 1 Qdr.
| =~, Taine — art — J = sin (@ — b)r
is equal to 1, when z is between the limits a and 8, to = when ats
at those limits, and to zero, for all other values. If we denote the
eae 2 f®dr . (b—a) { (a + b)
definite integral oy os sin —3— r cos4 a = est ?
by C;”, we shall get,
nae ey a—@ Saye
ihe to vides toe CL -amt) Bws EBLE
and consequently the equation of a polylateral curve, suchas
that which is expressed by equation (4), will be,
y=Cr. 92+ C.. Ge+Ci. a2 4+&e.,
in as much as at the limits we have $, (b) = 9, (6), @2 (c) = 95 (¢),
and consequently for such limits Cy” 9, (2) + C,? 9, (b) = 9, (6
= 9, (b), and not 2 ¢, (5). a ie
All definite integrals which have determinate values within
given limits of a variable not involved in the integral sign, may
be converted into formule which will be equal to { within those
* Creile’s Journal for 1830, p. 67.
+ Inst. Calc. Integ., tom. iv.; Fourier, Théorie de la Chaleur, p.442.; Frul-
loni, Méemorie della Societé Italiana, tom. xx. p. 448, ; Libri, Mémoires de Ma=
thématique et de Physique, p. 40. HB OO y
252 THIRD REPORT—1833.
limits and also including the limits, and to zero for all other
values *. But the expressions which thence arise, though fur-
nishing their results in strict conformity with the laws of sym-
bolical combinations, possess no advantage in the business of
calculation beyond the conventional and arbitrary signs of dis-
continuity which we first adopted for this purpose: but though
it is frequently useful and necessary to express such signs ea-
plicitly, and to construct formule which may answer any as-
signed conditions of discontinuity, yet such conditions will be
also very commonly involved implicitly, and their existence and
character must be ascertained from an examination of the pro-
perties of the discontinuous formule themselves. We shall now
proceed to notice some examples of such formule.
The well known series +
© é {Vs ee bey
seth een Pa srentyhl ot
ret>= sing 5g singe + 3 sind a q sin 4a + &e. (1.)
is limited to integral values of r, whether positive or negative,
and to such values of ra + = as are included between *. and
— = the value of r, therefore, is not arbitrary but condi-
* If a definite integral (C) has determinate values @,, a, .. - én, within
the limits of the variable a and b, and no others, the values at those limits
being included, and if C be equal to zero for all values beyond those limits,
then we shall find
apy tie Cra Ee a): oc Se 2g
a, X tg XK. an
thus in the case considered in the text, we get
*p,? = —2(C—1) (c— +) pl = aCe ee
+ The principle of the introduction of r x in equation (1.) by which it is ge-
neralized, will be sufficiently obvious from the following mode of deducing it:
2 Vai * we
log {tere fome hee} ta 4 ee
e
Oe reat et oem /Leae senda aa
—s{eev ingoaenoth $i pe Vay seat in ad
and, therefore, dividing by 2 ./—1, and replacing the exponential expressions
by their equivalent values, we get
e : a. In. ‘a
vr. — =sinz — — sin 22+ — sin3«—— sin42+ &c.,
’ a 2 2 a 3 4 +
where a upon the second side of the equation may have any value between
+ © and —o,
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 258
tional. If we successively replace, therefore, x by e + x and
Fi x, we shall get
-
* . Zz Th. 1
Ae Sy rs gt ostt se sin2v — 3 cos 3 #
— sin da + &e.
“~ iy 1
ran+——-—=cosr— > sn2r — > cos3r
412 2 3
-. = sin 4a + &c.
Adding these two series together and dividing by 2, we get
CF) + Zs cose— | cos 324 pe ean (2.)
4 3 3
If x be included between + and — = then r = 0 and x’ = 0,
and we get
og 1 1
q = cose — gcosda + — cos 5a — &e, (3.)
If z be included between + and oe) thenr = — 1 andr’ = 0,
and we get
sew J cos 82 + + cos 52 —& 4.
BP gh ES ap ene e+ — cos Sax Cc. (4.)
tan 37 5a Of it —7
If the limits of z be a and Ta and ae ree and
=i a — _ and — a we shall obtain values of the series
(2.), which are alternately *- and — A, f
~ Again, if in equation (1.), or ra + s = sing — a sin2 x
+ ania PF toa fs sin 4.2 + &c., we replace « by r — 2, we
shall get
Ee | OL) ae
ee + 5 = sing + g sin2a + 3g sind.2 + qsindae + &e,
Adding these equations together and dividing by 2, we get
254 THIRD REPORT—1833.
(x + 7’) a Pe Te Te We
a t+ 7 = sine + 3 sind2 + = sind x + &e. (5.)
which may be easily shown to be equal to = and — = alter-
4 4
nately, in the passage of x from 0 to 7, from 7 to 27, from 27
to 3 7, &c., or from 0 to— 7, from — ¢ to —27, &e.: its
values at those limits are zero.
The series (2.) and (5.) have been investigated by Fourier, in
his Théorie de la Chaleur *, by a very elaborate analysis, which
fails, however, in showing the dependence of these series upon
each other and upon the principles involved in the deduction
of the fundamental series: and they present, as we shall now
proceed to show, very curious and instructive examples of dis-
continuous functions.
x
2
Q A P, making an angle with the axis of x, whose tangent is
The equation y = — is that of an indefinite straight line,
io
1 Phy. ;
@? and which passes through the origin of the coordinates :
whilst the equation
y = sine — 3 sind zt + + sine = os sin 42 + &c.
is that of a series of terminated straight lines, d'c, dC, DC,
&e., passing through points a, A, A’, &c., whieh are distant
27 from each other: the portion d C alone coincides with the
primitive line, whose equation is y = 3
- Again, the line whose equation is y = is parallel to the
|
|
>
a
ea
es
ar
Ls)
* From page 167 to 190; also 267 and 346.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 255
axis of x at the distance 7 above it: the line whose equation is
eg a is also parallel to the axis of x, at the distance * below
4
it: the line whose equation is
1 4 1
y= cost — 3 cos 3a + — cos 5a — &e.
consists of discontinuous portions of the first and second of
those lines, whose lengths are severally equal to. The values
as
2
are equal to zero, since the equidistant points D and C, ¢ and d,
are common to both equations at those points.
* It would appear, therefore, in the cases just examined, that
the conversion of one member of the equation of a line into a
series of sines and cosines would change the character of that
equation from being continuous to discontinuous, the coinci-
dence of the two equations only existing throughout the ex-
tent of one complete period of circulation of the trigonometrieal
series: and more generally, if, in any other case, we could ef-
fect this conversion of one member of the equation of a curve
into a series of sines or cosines, it is obvious that the second
equation must be discontinuous, and that the coincidence
would take place only throughout one period of circulation,
whether from 0 to z or from — z to > It remains therefore
of y at the points B and 8, corresponding to z = — and — oy
to consider whether such a conversion is generally practicable.
Let us take equidistant points in the axis of the curve
whose equation is y = ¢ 2, between the limits 0 and, those
limits being excluded: if we denominate the correspondin
values of the ordinate by y;, Ya, +++» Yn and if it be ee
to express the values of these ordinates by means of a series
of sines (of z terms) such as
a, sinz+a,sin2r4+a;,sn3a+....+a,snuez,
then we shall get the following z equations to determine the
coefficients @,, Ao, 3. +--+» An
T SOME . oT Sli he
ioe apes rg Pile yo ae neha ere noe telat
5 res . Ag bh ,.2n
ola ne aa Pe a ar st Oe aren
eit S pki: 5 aaa EN . Ont.
Y¥3 >= a, ro | ae eau IEE | +.» Oy sine a,
If any assigned coefficient a, be required to be determined
from this system of equations, we must multiply * them seve-
rally by
Qma . dm
——_ in ——.,.
n+l
when all the coefficients except a,, will disappear from the sum
of the resulting equations: and we shall thus find
nme
n+’
_ mn :
2sin 74 -. 2sin
Be pad { eam sin 2m _ nme
OF Apa Qa ab iF meds 5a Bice | -
It would thus appear that it is always possible to determine a
series of sines of m terms with finite and determinate coeffi-
cients, which shall be the equation of a curve which shall have
m points in common with the curve whose equation is y = ¢ 2,
within the limits corresponding to values of x between 0 and 7;
and it is obvious that the greater the number of those points,
the more intimate would be the contact of these two curves
throughout the finite space corresponding to those limits. If
we should further suppose the number of those points to be-
come infinitely great, then the number of terms of the trigono-
metrical series would be infinite likewise, and the coincidence of
the curve which it expresses with the curve whose equation is
y = > x, would be complete within those limits only, producing
a species of contact to which the term finite osculation has been
applied by Fourier +. Beyond those limits the curves would
have no necessary relation to each other.
It would follow, also, from the preceding view of the theory of
finite osculations, that the curve expressed by y = $ x might be
perfectly arbitrary, continuous, or discontinuous. Thus, it might
express the sides of a triangle, or of a polygon, or of a multi-
lateral curve, or of any succession of points connected by any
conceivable law ; for in all cases when the corresponding or-
dinates of equidistant points are finite, we shall be enabled to
determine values of the coefficients a,, which are finite or zero
by the process which has been pointed out above.
* This is the process proposed by Lagrange in his ‘‘ Théorie du Son,” in
the third volume of the Turin Memoirs, as stated by Poisson in his memoir
on Periodic Series, &c., in the 19th cahier of the Journal de l’ Ecole Polytech-
nique.
t Théorie dela Chaleur, page 250.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 257
__ The hypothesis of » being infinite would convert the series
for a, into the definite integral *
4
er eae te
=f, gxsinmxrdx,
a
Mm 7 ; : . «
= 2 and =: d x: or otherwise if we
n+ 1 n+l
assume the existence of the series
if we make
Px =a,snz+az,sin2xrx+...admsinmn + &e.,
it may be readily shown, by multiplying both sides of the equa-
tion by sin m «x d x, that
2
= — x“sinm«xdx:
An JT ()
and in a similar manner, if we should assume
$x =a,cosOxr + a,cosxr +...d,cosmax + &e.,
that
2 0 ;
On = =f; gxcosmaxdxt.
Thus, if we should suppose ¢z = cos x, we should find
sin 6 a + &e.|
bs
6
1.3 3.5 5.7
a very singular result, which is of course only true between the
limits 0 and z, excluding those limits {.
cose = {7 gsin 2 + cs sin 4a -+
If we should suppose ¢ z = a constant quantity = between
the limits 0 and a, and that it is equal to sero between « and 7,
we should find
| (= Cosa). 50> (1 —'cos 22) «. © cos 3 2)
oe a oe a ee + ag ae
sn32r+ &e,
excluding the limiting value «, when the value of the series is
only = §.
If we should suppose ¢ 2 = *D,’. ax + *D,”. (ex + 6),
which is the equation of the sides of a triangle (excluding the
-* Poisson, Journal de I’ Ecole Polytechnique, cahier xix. p. 447.
_*+ Fourier, Théorie de la Chaleur, pp.235 & 240.
} Ibid., p. 238 ; Poisson, Journal de ’ Ecole Polytechnique, cahier xix. p. 418.
§ Fourier, Théorie de /a Chaleur, p. 244.
1833. s
258 THIRD REPORT—1833.
limit 2 = 4), whose base is represented by 7, then we shall
find * ;
bi r ; sn22 sn3z _
gu = — {ax + (a—a!) d} {sine — behing se. }
rs kd Cony) — ‘i win ace n aos 9 we. |,
The trigonometrical series, in this last case, would represent a
series of triangles placed alternately in an inverse position with
respect to each other; and a similar observation would apply
to the discontinuous curves which are represented by any series
of sines and cosines. Thus, if y = ¢ x be the equation of the
curve PC C’Q, and if we suppose
y=?ex=a,snze + agsin22+a,sn32+ &e.,
between the limits 0 and 7; and if we make AB =a, A A’
= 27, AB'=3rn, &c., we shall get a discontinuous curve,
consisting of a series of similar arcs, C D, aC", C’ D', &c.,
placed successively in an inverse relation with respect to each
other upon each side of the axis of x, of which one are C D
alone coincides with the primitive curve.
If we should suppose the same curve to be expressed be-
tween the limits 0 and a bya series of cosines or
y= Gx =a + a, cosx + a,cos22 + &e.,
and if we make A B=7, Ab = —7, AA’ = 27, AB =3z,
&c., then the trigonometrical equation will represent a discon-
tinuous curve dC D C’ D’, of which the portions C D and Cd,
* Fourier has given a particular case of this series, p. 246.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 259
C! D! and C' D will be symmetrical by pairs; but one portion
only, C D, will necessarily coincide with the primitive curve.
The theory of discontinuous functions has recently received
considerable additions from a young analyst of the highest pro-
mise, Mr. Murphy, of Caius College, Cambridge. In an admi-
rable memoir on the Inverse Method of Definite Integrals *, he
has given general methods for representing discontinuous func-
tions, of one or a greater number of breaks, by means which are
more directly applicable to the circumstances under which they
present themselves in physical problems than those which have
been proposed by Fourier, Poisson, and Libri. Mr. Murphy
had already, in a previous memoir }, given a most remarkable
extension to the theory of the application of Lagrange’s theo-
rem to the expression of the least root of an equation, which
we shall have occasion to notice hereafter; and he has shown
that if g (x) be an integral function of z then the coefficient of
= in the developement of — log = will represent the least
root of the equation ¢2 = 0. We thus find that the least
of the two quantities « and will be represented by the coeffi-
cient of = in the series for log saat te | which is
(« 8) (« 6)?
JPat ed : (7 u By) a ~igae ‘ (058) + &e. (I.)
and if we replace « and B by es and $ the feast of the two
sila: ty 1 : as
quantities — and ae the greatest of the two quantities # and
B, will be represented by
2
a ee ee
axptaa (2+* * ke ct ae (ctf) + Be (2.)¢
Zz
&
~
* Transactions of the Philosophical Society of Cambridge, vol. iv. p. 374.
t+ Ibid. p. 125.
t+ If we represent the series (2.) by S, we shall get
dr-1§s 1
oe Sor Oy
(—1)"-1T(n) da™-! ~ an os
dea
traction within and without a spherical shell, which is 0 or Li where « is
oe
the distance from the centre.
= would represent the at-
according as @ is greater or less than 8: thus
s2
260 THIRD REPORT—1833.
Thus, ify — «7 — 6B = Oand y — @’ x — 6’ = 0 be the equa-
AB P oD
tions of two lines B C and DC, forming a triangle with a por-
tion B D of the axis of x, then the system of lines which they
form will be expressed by the product
(y—ax—B) (y—avax—f)=0. (3.)
Now it is obvious that if common ordinates P M, PM’ be
drawn to the two lines, the /east of them will belong to the sides
of the triangle B C D; if we denote, therefore, P M and P M!
by y, and yo, the equation
(Yi Yo)” Og)
oo Shas: a ; in: aaa ee ok
ete eee) +0 14.6 (TES mao
will become the equation of the sides of the triangle BC D,
when y, and y are replaced by their values; for y will denote
P M for one side and p ™ for the other.
In order to express a discontinuous function ¢, which as-
sumes the successive forms ¢,, $5, $3, &c., for different values
of a variable which it involves between the limits a and 6, 6
and y, y and 8, &c., Mr. Murphy assumes 8 (4% 2), 8 (6, 2),
S (y, 2), &c., to denote the coefficient of 3 in the several series
for
ere Ae OE a8), es
&
and supposes
Se Mo”
If « be less than x or 2 greater than a, then S (a, x) = a,
a8 2) = 1: if p be less than 2, ‘hen oe ds (B, 9)
wane Bake
dS (y, 2)
dy
dS (8, s
neg 6 Saeeru errs rae
and Peet rore
= 1: if y be less thane, then = |, and so on; con-
-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 261
‘sequently, in the first case we have ¢ = f, = ¢,:
in the second,
@=f, + fo = %, and therefore f, = ¢, — ¢,:
in the third,
9=f, + fo + fs = 3, and therefore f; = $3 — $2.
It appears therefore that }
dS (a,z LSB; 8 dS (y, 2
9= 9, te) + 0) e+ @s— 9) + &e
is a formula which is competent to express all the required
conditions of discontinuity *.
Equivalent forms may. be considered as permanent within
the limits of continuity, and no further, unless the requisite
signs of discontinuity, whether implicit or explicit, exist upon
both sides of the sign =: thus, the equation
*D,cosx = “ire Zat+ zinta + son sin6a + we.
is permanent within the limits indicated by the sign 7D and
no further, and similarly in most of the cases which have been
considered above. The imprudent extension of such equivalent
forms, which has arisen from the omission of the necessary
signs of discontinuity, has frequently led to very erroneous
conclusions; thus, the equation
es _ 12-1 1 Lin ee a — 1 Ae par
ee ere eet 2° (@@+12" 8° (@41) te.
which is true for all values of 2 between 0 and «, has been
extended to all values of « between — 0 and + «, and has
thus been made the foundation of an argument for the identity
of the logarithms of the same number, both when positive and
negative.
There are two species of discontinuity which we have consi-
dered above, one of which may be called instantaneous and the
other finite: the first generally accompanies such changes of
form as are consequent upon the introduction of critical values
* These formule would require generally a correction at their limits, in
order to render them symbolically general. The nature of these corrections
may in most cases be easily applied from the observations which we have
made above. E
_ + This series is given by M. Bouvier in tke 14th volume of Gergonne’s
Annales des Mathématiques. The conclusion referred to in the text assumes
the identity of the logarithms of 2? and of (— 2)*, which is in fact the whole
_guestion in dispute. vii
262 THIRD KEPORT—1833.
of the variables, when the corresponding equivalent form no
longer exists, or when the conditions which determined its exist-
ence no longer apply ; the second restricts the existence of the
equivalent form to limits of the variable which have a finite dif-
ference from each other. In neither case, if we suppose the con-
ditions of the discontinuity to be implicitly involved, or if we
suppose the explicit signs of discontinuity to be assumed con-
formably to the general laws of algebra, can we consider the
law of the permanence of equivalent forms to be violated. It is
only when a continuous formula is assumed to be equivalent to
a discontinuous formula, without the introduction of the requi-
site sign of discontinuity to limit the extent of the continuous
formula, that we can suppose this fundamental law to be vio-
lated or the asserted equation between such expressions to be
false. Many important errors have been introduced into ana-
lysis from the neglect of those conditions.
The identity of the values of powers of 1, whose indices
are general whole numbers, and also of the sines and cosines
of angles which differ from each other by integral multiples of
360°, is a frequent source of error in the generalization of equi-
valent forms, when the symbols which express those indices or
multiples are no longer whole numbers. . X + con X!,
which is the form which has been erroneously assigned by La-
grange * and Lacroix} as generally true for all values of x.
Many other examples of similar wndulating functions, ex-
* Calcul des Fonctions, chap. xi.
+ Traité du Calcul Diff. et Intég., tom. i. p. 264.
264 ‘ THIRD REPORT—1833.
pressing the various relations between the cosines and sines of
multiple arcs and the powers of simple ares, whether ascending
or descending, have been given by Lagrange * and other writers
as general, which are either degenerate forms of the correct
and more comprehensive equations, or altogether erroneous.
Poisson had pointed out some of the inconsistencies to which
some of these imperfect equations lead, and had slightly hinted
at their cause and their explanation ; and the discussion of such
cases became soon.afterwards a favourite subject of speculation
with many writers in the Mathematical Journals of France + and
Germany {; but the complete theory and correction of these
expressions was first given by M. Poinsot in an admirable me-
moir which was read to the Academy of Sciences of Paris in
1823, and published in 1825. They form a most remarkable
example of expressions extremely simple and elementary in
their nature, which have escaped from the review and analysis
of the greatest of modern analysts, in forms which were not
merely imperfect, but in some cases absolutely erroneous.
The difficulties which have presented themselves in the
theory of the logarithms of negative numbers, as compared with
those of the same numbers with a positive sign, have had a
very similar origin. If we consider the signs ‘of quantities as ©
factors of their arithmetical values, and if we trace them through-
out the whole course of the changes which they undergo, we
shall find many examples of results which are identical when
considered in their final equivalent forms, but which are not
in every respect identical when considered with respect to their
derivation: thus (+ a)? is identical with (— @)*, when consi-
dered in their common result + a*, but not when considered
with respect to their derivation. Let us now consider their se-
veral logarithms, the common arithmetical value of the logarithm
of a being denoted by p:
log (+ a)? = log (12 a2 =4r0 /—1 + 2p (1.)
log (— a)? = log (— 1? a2 = (27 +1) 24 YW —1 4+ 2p~ (2.)
log a =log1.a®@ =2r%rV7—1+4 2p (3.)
It thus appears that the values of log (+ a)? and log (— a)? are
included amongst those of log a”, but not conver sely; and also
that the values of log (+ a) and log(— a)’, the arithmetical
value being excepted, are not included in each other.
> Correspondence sur ? Ecole Polytechnique, tom. ii. p. 212.
+ In Gergonne’s-dnnales des Mathématiques, tom. Xiv. XV. XVI. XVii.
{ In Crelle’s Journal fiir die reine und angewandte Mathematik, Berlin.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 265.
Again, if we consider — a” as originating from (— 1) (+ a)”,
we shall get
log — a” = (2r + Qmr +1)rV—l + mp*:
if we suppose m = a y = 0 andr! = — 1, we shall get
log — Vaate = Flog a = log ¥ a3
or the logarithm of a negative quantity will be identical with
the logarithm of the same quantity with a positive sign. Ina
similar manner, if we suppose ™ = me where p is prime to 7,
pi ~nandr =25+, then 2r +2 me’ + 1 = 0, and the
corresponding logarithm of — a” will coincide with the arith-
metical logarithm of a”. We should thus obtain possible loga-
rithms of negative numbers in those cases in which we should
be prepared to expect them from the ordinary definition} of
logarithms.
In the absence of all knowledge of the specific process of de-
rivation of quantities, such as a” and — a”, we should consider
their logarithms as ‘dentical with those of 1”. A and (—1) 1”. 4
where A is the arithmetical value of a”: and in considering
the different orders of logarithms which correspond to the same
value of a” or of — a”, they will be found to differ from each
other by the logarithms of 1” and (— 1) 1” only, which are
Omrt f—land 2r+2mr' + lyrv—l respectively. The
logarithms in question are Napierian logarithms whose base is é.
If we should suppose the logarithms to be calculated to any
other base, we should replace the Napierian logarithms of 1”
and (— 1) 1” by the logarithms of those quantities (or signs)
multiplied by the modulus M: the same remarks will apply to
such logarithms which have been made with respect to Na-
-pierian logarithms.
The question of the identity of the logarithms of the same
number, whether positive or negative, was agitated between
Leibnitz and Bernoulli, between Euler and D’Alembert, and
has been frequently resumed in later times. The arguments in
~ * Peacock’s Algebra, p. 569.
+ The logarithm being defined to be the index of the power of a given base
which is equal to a given number, it would follow, since at = ++ n, that—
is equally the logarithm of + and — n. The same remark ay plies to all in-
dices or logarithms which are rational fractions with éven dencminatars.
266 THIRD REPORT—1833.
favour of the affirmative of this proposition, which were for the
most part founded upon the analytical interpretation of the pro-
perties of the hyperbola and logarithmic curve, were not en-
titled to much consideration, inas much as they were not drawn
from an analysis of the course followed in the derivation of the
symbolical expressions themselves and from the principles of
interpretation which those laws of derivation authorized. A
very slight examination of those principles, combined with a re-
ference to those upon which algebraical signs of affection are in-
troduced, will readily show the whole of the very limited num-
ber of cases in which such a proposition can be considered to
be true *.
_ * In the 15th volume of the Annales des Muthématiques of Gergonne, there
is an ingenious paper by M. Vincent on the construction of the logarithmic
and other congenerous transcendental curves. Thus, if y = e” there willbe in
the plane of x y a continuous branch such as is commonly considered, and a
discontinuous branch corresponding to those negative values of y which arise
from values of x, which are expressible by rational fractions with even deno-
minators: thus, if we suppose the line between « = 0 and xz = 1 to be di-
vided into an even number 2p of parts, (where p is an odd number,) the
values of x will form a series of fractions,
yet. Bin 2p—1
2p p 2p p 2p
which have alternately odd and even denominators, and which correspond
therefore to values of y which are alternately single and double. If we may
suppose, therefore, a curve to be composed of the successive apposition of
points, the complete logarithmic curve will consist of two symmetrical
branches, one above and the other below the axis of x, one of which, in cor-
responding parts of the curve, will have double the number of points with the
other. The inferior curve, therefore, may in this sense be considered as dis-
continuous, being composed of an infinite number of conjugate points, forming,
in the language of M. Vincent, une branche pointillée. ‘lhe same remark ap-
plies to other exponential curves, such as the catenary, &c.
It was objected to this theory of M. Vincent by M. Stein, another writer
in the same journal, that every fractional index in this interval might be con-
verted into an equivalent fraction with an even denominator, which would
give a double possible value of the ordinate, which would be different from
that given by the fractional index in its lowest terms; and that consequently
there would necessarily be a double ordinate for every point of the axis, and
therefore also a double number, cne positive and the other negative, corre-
sponding to every logarithm. In reply to this objection, it is merely neces-
we 2.2 oe rae
sary to observe that the values of a” and a”? or of 1” and 1”? are in every
respect identical with each other, the m p values in the second case consisting
merely of p periodical repetitions of those in the first.
In a paper in the Philosophical Transactions for 1829, Mr. Graves has given
a very elaborate analysis of logarithmic formule, and has arrived at some
conclusions of great generality which it is difficult to reconcile with those
which have been commonly received. Amongst some others may be men-
tioned the formula which he has given for the Napierian logarithms of 1,
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 267
Convergency and Divergency of Series.—The subject of di-
vergent series, their origin, their interpretation and their use
in analysis, is one of great importance and great difficulty, and
has been and continues to be the occasion of much controversy
and doubt. I shall feel it necessary, for such reasons, to notice
it somewhat in detail.
If the operations of algebra be considered as general, and
the symbols which are subject to them as unlimited in value,
it will be impossible to avoid the formation of divergent as
well as of convergent series: and if such series be consi-
dered as the results of operations which are definable, apart
from the series themselves, then it will not be very important
to enter into such an examination of the relation of the arith-
metical values of the successive terms as may be necessary to
ascertain their convergency or divergency; for, under such
circumstances, they must be considered as equivalent forms
representing their generating function, and as possessing, for
the purposes of such operations, equivalent properties. ‘Thus,
if they result from the division of the numerator of an alge-
braical fraction by its denominator, then they will produce the
numerator when multiplied into the denominator or divisor: if
they result from the extraction of the square or cube root of
an algebraical expression, then their square or cube will pro-
duce that expression; and similarly in other cases, no regard
2rea
which is not 2r* V. —1, but i Pip which, though it includes the
former, is not included by it. It appears to me, however, that there exists a
fundamental error in the attempt which has been made by Mr. Graves to
generalize the ordinary logarithmic formule upon the same principles which
have been applied by Poinsot to the generalization of the trigonometrical series
which have been noticed in the text. He assumes f (4) = cos + V—1 sin@
— ef aoe and makes the series for f (4) and f —1 (), combined with the equa-
tion f (« 4) = a value of f (6)”, and therefore f—' f 6 = 2r x + 6, the foun-
dation of his logarithmic developements: in other words, he makes e afeat
periodic quantity the base of his system of logarithms, an assumption which
is essential to the truth of the formula f~' f 6= 27 x + @ and to the gene-
ralization of the series for f—~' @ by means of it; an hypothesis which is al-
together at variance with our notions of logarithms as ascertained by the ordi-
nary definition. The logarithms of + 1 and of (+ 1)” alone, for very obvious
reasons, can be considered as possessing such a character.
Though I have felt myself called upon to state my objections to the fun-
damental principle assumed in this memoir of Mr. Graves, and consequently
to many of the conclusions which are founded upon it, yet I think it right at
the same time to observe that it displays great skill and ingenuity in the con-
duct of the investigations, and is accompanied by many valuable and ori-
ginal observations upon the general principles of analysis.
268 THIRD REPORT—1833.
being paid in such cases to terms which are at an infinite di-
stance from the origin.
It is this last condition, which, though quite indispensable,
is rather calculated to offend our popular notions of the values
of series as exhibited in their sums. We speak of series as
having swms when the arithmetical values of their terms are
considered, and when the actual expression for the sum of n
terms does not become infinite when z is infinite, or when, in
the absence of such an explicit expression, we can show from
other considerations that its value is finite. In all other cases
the series, arithmetically speaking, may be considered as di-
vergent, and therefore as having no sum *, if the word sum be
used in an arithmetical sense only, as distinguished from gene-
rating function.
We are in the habit of considering quantities which are én-
finitely great and infinitely little as very differently circum-
stanced with respect to their relation to finite magnitude. We
at once identify the latter with zero, of which we are accus-
tomed to speak as if it had a real existence ; but if we subject
our ideas of zero and infinity to a more accurate analysis, we
shall find that it is equally impossible for us to conceive either
one or the other as a real state of existence to which a mag-
nitude can attain or through which it can pass. But it is the
relation which magnitudes in their finite and conceivable state
still bear to other magnitudes in their course of continued in-
crease or continued diminution, which enables us to consider
their symbolical relations when they cease to fe finite ; and
whilst quantities infinitely little are neglected as being absorbed
in a finite magnitude, so likewise finite magnitudes are consi-
dered as being absorbed in infinity, and therefore neglected
when considered with relation to it. The principle, therefore,
of neglecting terms beyond a finite distance from the origin, in
converging series, is both safe and intelligible, whilst the case is
very different with respect to the neglect of similar terms in a
diverging series. Of such series it is said that they have no
arithmetical sum; but it may be said in the same sense of all
algebraical series involving general symbols that they have no
sum. But it is not the business of symbolical algebra to deal
with arithmetical values, but with symbolical results only ; and
such series must be considered with reference to the functions
which generate them, and the laws of the operations employed
for that purpose. The neglect, therefore, of terms beyond a
* This would appear Cauchy’s view of the subject: see the 6th chapter
of his Cours d’ Analyse,
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 269
a ;
finite distance from the origin would be perfectly safe as far as
it does not influence the determination of the series from the
generating function, or the generating function from the series ;
and it is upon this principle that the practice is both founded
and justified. A few examples may make this reasoning more
plain.
Let it be required to determine the function which generates
the series
ataxr+ax*?+ ax+ &e. * (L.)
Let s be taken to represent this function, and therefore
s=atax+ax?+ax*+ &e.
=atue{atar+ax?+ax+ &e.}.
a+2£s: consequently
a
dui ee.
If the arithmetical values of the terms of this series be con-
sidered, and if z be less than 1, then
oS
is the sum of the
l—wz
series: in all other cases it is its generating function.
We may consider, however, s (whether it expresses a swm or
a generating function) as identical with s,, s,,s3, &c., in the
seyeral expressions
§&=@425, ;
S=at ax wx 5,
s=a+art+azr+ xs,
s=atart+az*4+...a2" 4 x5,,:
for if the number of terms of the series s be expressed by x
and if » be infinite, we must consider 5), Sg, 53, @... Sm as abso-
lutely zdentical expressions ; for otherwise we must consider an
infinite as possessing the properties of an absolute number, and
must cease to regard énfinities with finite differences as iden
tical quantities when compared with each other. It is for this
reason that we assume it as a principle that no regard must be
paid to terms at an infinite distance from the origin, whatever
their arithmetical values may be.
The sum of the series
a—-ata—a-+t &e.
was assigned by Leibnitz, upon very singular metaphysical
; : a of eee
considerations, to be Zz? the principle just stated would allow
us to put
270 THIRD REPORT—1833.
s=a—(a—ata—a+ &c.)
a
= a —s; and therefore s = Pat
* The same principle would show that the equation
z=at+f(atsf(atsfaat...))
is identical with the equation
ex=at+f(a);
and that
e=af(af(as(..)))
is identical with
ie = aefa(m).
The example in the text is the most simple case of a class of periodic series,
the determination of whose sums to infinity has been the occasion of much
controversy and of many curious researches. The general property of such
series is the perpetual recurrence of the same group of terms whose sum is
equal to zero: thus, if there should be p terms in each group, and if the num-
ber of terms n = m p + i, their sum would be identical with that of the 7 first
terms of the series; and if we should denote those terms by a, do,... a,,
and if we should take the successive values of this sum for all the values of ¢
between 1 and p inclusive, their aggregate value would be represented by
pa + (p—1) a+ (p—2) as+--- ay
of which the average (A) or mean would be represented by
P
If this periodic series was continued to infinity, it was contended by Daniel
Bernoulli, in memoirs in the 17th and 18th volumes of Novi Commentarii
Petropolitani, for 1772 and 1773, that its sum would be correctly represented
by the average (A), in as much as it was equally probable that any one of
the p values would be the true one. Upon this principle it would follow,
that of the apparently identical series
1—1+1—1+4+1—&c....
DENS Say 6 a ed oe eee ne
14+0+0—1+4+1+4+0+4+0—1+4 &c.
the first would be equal to a the second to = and the third to
=. In the
same manner we should find
1+1—1—1+1+4+1—1—14, &.
equal to 1, and
1+1+0—1—14+1+4+1+4+0—1—141+4+1+4&c.
equal to = The same observations would apply to the series
1+ cosz+ cos2x+ cos3x+ cos4z + &e.
and
1+ cosz +0+4 cos2a2+ cos3x%+0+4cos4x+ &c.
where x is commensurable with 2 x.
These conclusions, however, though curious and probable, rested upon no
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 271
If we consider this principle of the identity of series, whose
terms within a finite distance from the origin are identical, as
established, we shall experience no difficulty in admitting the
perfect algebraical equivalence of such series, and their gene-
secure basis founded upon the general principles of analysis, and their truth
was not, therefore, generally admitted amongst mathematicians. In the year
1798, Callet, the author of the logarithmic tables which go by his name, pre-
sented a memoir to the Institute for the purpose of showing that the sums
of such periodic series were really indeterminate: thus, if we divide 1 by
1+ wand subsequently make x= 1, we get
P— 7 i WE ie, (1.)
the value of which is = In a similar manner, if we divide 1 + x by
1+ 2+ 22, we get for the quotient
1— a+ 23 — 25 + x — a8 4+ &e.,
which becomes the same series (1.), though the value of the generating func-
tion under the same circumstances becomes os The same remark applies
to the result of the division of 1 + «+ a? + ..2” byl +2+a2?4+..2",
which produces the same series (1.) when « = 1, though under such circum-
stances its generating function becomes fy
This memoir of Callet gave occasion to a most elegant Report upon this
delicate point of analysis by Lagrange, who justified upon very simple prin-
ciples the conclusion of Daniel Bernoulli. The series which results from the
division of 1 + 2 by 1+ + 2%, if the deficient terms be replaced, becomes
14+0.¢2—24 040. at— ao + of + 0.07 — 2 4 &e.,
which degenerates, when « = 1, into the series
Gh A de Orme ied obs Bee
and not into the series (1.). The same remark applies to the series which
arises from the divisionof 1+ 2+ ..a”byl+ae+....2°..n7m;
which becomes, when x = 1,
14+0+4+0+4+0+&. —1+0+0+4&. +1404 &e,
- which is equal, by Bernoulli’s rule, to =.
But it is not necessary to resort to this expedient for the purpose of deter-
mining the sums of such series ; for the series
Q, + dg2 + ay a? + 2G 2P! ea, oP + &e.
is a recurring series resulting from the developement of
a, + do2+a,2274+ .. Ce ne
we EE eas ae
1— a?
which becomes > when «= 1. If we replace « by ~, this fraction will
become
272 THIRD REPORT—1833.
rating functions. For the same principle would justify us in
rejecting remainders after an infinite number of terms, whatever
their arithmetical values may be; for such remainders can in-
fluence no terms at a finite distance from the origin, and there-
fore can in no respect affect any reverse operation, by which
it may be required to pass from the series to any expression
dependent upon the generating function. Thus, if
& ynie 24% 1s
BE ata Si Ce MMs Pe sy ets og ae ee
we shall get
Bi i 12). 8: =, 08,
if we reject remainders after an infinite number of terms; and
similarly in other cases. It would thus appear that algebraical
equivalence is not necessarily dependent upon the arithmetical
equality of the series and its generating function.
It is, however, an inquiry of the utmost importance to be able
to ascertain when this arithmetical equality exists; or, in other
words, to ascertain under what circumstances we can determine
the sum of the series, either from our knowledge of the law of
formation of its successive terms, or approximate, to any required
nye oe age? Ths, a, z
ti ;
which becomes by the application of the ordinary rule of the differential cal-
culus, when s = 1 or2z = 1,
pyA+t p—VDat.. 4,
Pp >
which is the average or mean value determined by Bernoulli’s rule.
The discussion of the values of these periodic series has-been resumed by
Poisson in the twelfth volume of the Journal de l’ Ecole Polytechnique. He
considers them as the limits of these series when considered as converging
series, a view of their origin and meaning which is almost entirely coincident
with that of Lagrange. Thus, the sum of the series
sing + psin (x + q) + p’ sin (2a + q) + &e.
is equal to
sin g + p sin (2 — q)
1—2pcosa +p?’
when p is less than 1, an expression which degenerates, when p = 1, into
1 gen il fis
i sin g + cy cos g cot >»
which may be considered, therefore, as the limit of the sum of the series
sin g + sin (a + g) + sin (2% + ¢) + &e, in infin.
#
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 273
degree of accuracy; to its value by the aggregation of a finite
number of those terms. Many tests of the summability of series
(considered as different from the determination of their gene-
rating functions,) have been proposed, possessing very different
degrees of certainty and applicability. The geometrical series
which we have just been considering is convergent or divergent,
that is, semmable or not, according as z is greater or less than 1;
and it is convenient, for this and for other reasons, to assume it
as the measure of the convergency or divergency of other series.
If it can be shown that a converging geometrical series can be
formed whose terms within a finite and assignable distance from
the origin become severally greater than those corresponding
to them of the assigned series, then that series is convergent.
And if it can be shown that a divergent geometric series can be
formed whose terms within a finite and assignable distance from
the origin are severally less than those corresponding to them
of the assigned series, then that series is divergent*. Such
tests are certain, as far as they are applicable; but there may
be many cases, both of divergent and convergent series, which
they are not sufficiently delicate to comprehend.
It would appear from the preceding observations that. di-
verging series have no arithmetical sums, and consequently
* Peacock’s Algebra, Art. 824, and following. Cauchy, Cours d’ Analyse
Algébrique, chap. vi. This last work contains the most complete examination
of the tests of convergency with which I am acquainted.
The measure of convergency mentioned in the text, which was first sug-
gested and applied by D’Alembert, will immediately lead to the following :
“If w, represent the n‘* term of a series, it is convergent (or will become so)
1
if the superior limit of (w,,)” be less than 1, when x is infinite; divergent in
the contrary case.”
“Tf the limit of the ratio w, , , to u, be less than 1, the series is convergent,
and divergent in the contrary case.”
Many other consequences of these and other tests are mentioned by Cauchy
in the work above referred to.
M. Louis Olivier, in the second volume of Crelle’s Journal, has proposed th
following test of convergency. ‘If the limit of the value of the product nu,
be finite or zero when 7 is infinite, then the series is divergent in the first case,
and convergent in the second.” This principle, however, though apparently
very simple and elementary, has been shown by Abel, in the same Journal, to
be not universally true. Thus, the series
1 1 af 1
2 log 2 + 3 log 3 G 4 log 4 mr preci 9 n log n ar
may be shown to be infinite, though the product x 7, is equal to xero when n is
infinite. The same acute and original analyst has shown that there is no func-
tion of n whatever which multiplied into w, will produce a result which is zero
or finite when n is infinite, according as the series is convergent or divergent. -
1833. : T
Q74 THIRD REPORT—1833.
admit of no arithmetical interpretation. And it will be after-
wards made to appear that such series do not include in their
expression, at least in many cases, all the algebraical conditions
of their generating functions. Before we proceed, however, to
draw any inferences from this fact, it may be expedient in the
first instance to give a short analysis of some of the cireum-
stances in which such series originate.
The series
1 1 aia
ene Hy a + af + &c.
is convergent or divergent according as a is greater or less
than 6. As this series is incapable, from its form, of receiving
a change of sign corresponding to a change in the relation of
a and b to each other, it would evidently be erroneous in the
latter case if it admitted of any arithmetical value, in as much
as it would then be equivalent to a quantity which is no longer
arithmetical. In this case, therefore, the series may be replaced
by the symbol ©, which is the proper sign of transition, (see
page 237,) which indicates a change in the constitution of the
generating function, of such a kind as to be incapable of being
expressed by the series which is otherwise equivalent to it.
The same observations apply to the equation
Bi eid 6b n(n—1)
(a — bp sardine + a Tale DR
n(n —1)(n—2) B
zs 1 ' 2 3 + beh
as we have already stated in our remarks upon signs of transition,
in page 237. It will be extremely important, however, to examine,
both in this and in other cases, the circumstances which attend
the transition from generating functions to their equivalent
series, in as much as they will serve to explain some difficulties
which have caused considerable embarrassment.
The two series
1 1 2b 3b 468
=e{it+ yt Jorn + &e.}
(a — b)? a?
and
1 1 2a 8ar 4a
(b Tu ay = 2 41 a5 Bh 55 ob) a5 ee at &e. }
will be divergent in one case, and convergent in the other,
whatever be the relation of a and 8, though they both equally
REPORT ON- CERTAIN BRANCHES OF ANALYSIS. 275
vigil 1 1
Represent Tse ab + geand &-—2ab+a
braically, as well as arithmetically, equivalent to each other. It
might be contended, therefore, that in this instance the signo,
which replaces one of the two series, is no indication of a change
in the constitution of the generating function which is conse-
quent upon a change of the sign of a— bor b—a. But
though a? — 2a 6 + 6b? is equal to (a — b)?, and 6? — 2ab + a?
to (6 — a)?; and though a’ — 2a 6 + 8? is identical in value
and signification with 6°? — 2a 6 + a® when they are considered
without reference to their origin, yet we should not, on that
account, be justified in considering (a — 6)? and (6 — a)? as
algebraically identical with each other. The first is equal to
(+ 1)? (a — 6)*, and the second to (— 1)? (a — 6); or the first
to (— 1)? (6 — a)’, and the second to (+ 1)? (6 — a)?. But the
signs (+ 1)? and (— 1)? are not algebraically identical with each
other, though identical when considered in their common result,
in as much as their square and other roots and logarithms are
different from each other*. It follows, therefore, that there is
, which are alge-
a symbolical change in the quantity denoted by sartroiig in its
passage through infinity, which is indicated by the infinite value
of the equivalent series, in as much as it is not competent to ex-
press, in its developed form, the algebraical change which its
generating function has undergone. The same remarks will
apply to the series for (a — 6)" and (6 — a)", in all cases in
which x is a negative even number. When 2 is a negative odd
number, the change of constitution of the generating function
is manifest, and requires no explanation.
The two series
1 1 b Fn Baiy
eran etei stake}
1 a @ a. at
— = — 1 | ati 75>. 0C~C*”«C—SS= oF .
b+a at i ii: ay we. }
correspond to the same generating function, though one of
them is divergent, and the other convergent. But the divergent
series, whose terms are alternately positive and negative, cannot
be replaced by the symbol oo , in as much as it does not indicate
., " Thus, if @ denote a line, (+ a)? and (— a)? can only be considered as
identical in their common result a2. When (-+ a)? and (— a)? are considered
with reference to each other, they are not identical quantities, though equal te
each other.
T2
276 THIRD REPORT—1833.
any change in the constitution of the generating function. They
may both of them, therefore, be considered as representing the
value of this function, though in one case only can we approxi-
mate to its arithmetical value by the aggregation of any number
of its terms *.
Similar observations would apply to the series
aw”, nb n(n—1) 6B
(a+b =a He 2 a ost — ee + &e.\
when z is not a positive whole number. In all such cases, the
developement will sooner or later become a series, whose terms
are alternately negative and positive, and which will be di-
vergent or convergent, according to the relation of a and b to
each other. More generally we might assume it as a general
proposition, “ that divergent series which correspond to no
change in the constitution of the generating function, will have
their terms or groups of terms alternately positive and nega-
tive :” and conversely, ‘that divergent series which correspond
to a change in the constitution of the generating function, will
have all their terms or groups of terms affected with the same
sign, whether + or —, and the whole series may be replaced
by the symbol «.”
In both these propositions the change of which we speak is
that which corresponds to those values of the symbols which
convert the equivalent series from convergency to divergency,
and conversely.
I am not aware of any proof of the truth of these important
propositions which is more general than that which is derived
from an induction founded upon an examination of particular
cases. But such or similar conclusions might be naturally ex-
pected to follow from the fundamental principles and assump-
tions of symbolical algebra. If the rules of algebra be perfectly
general, all symbolical conclusions which follow from them must
be equally true: and those rules have been so assumed, that
when the symbols of algebra represent arithmetical quantities,
the operations with the same names represent arithmetical
operations, and become symbolical only when the correspond-
ing arithmetical operations are no longer possible. It will be
essential, therefore, to the perfection of algebraical language
that it should be competent to express fully its own limitations.
1 bs 1 as *, :
i =— — =) — —— ]
* The equations s = Z - and s 7 5 will equally give us
t= :: b in one case, and s = an in the other, whatever be Lae relation
of and b.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. O77
Such limitations will be conveyed by the introduction of signs
of affection, of signs of transition, or of signs of discontinuity,
which may be involved either implicitly or explicitly. It is for
such reasons that all those signs must be considered in the
interpretation of algebraical formule, and their occurrence will
at once suggest the necessity of such an examination of the
circumstances of their introduction as may be required for their
correct explanation*.
We thus recognise two classes of diverging series, which are
distinct in their origin and in their representation. The first
may be considered as involving the symbol or sign oo implicitly,
and as capable, therefore, of the same interpretation as we give
to the sign when it presents itself explicitly. The second re-
presents finite magnitudes, which in their existing form are
incapable of calculation by the aggregation of any number of
their terms. Such series are in many cases capable of trans-
formations of form, which convert them into equivalent con-
verging series; and in some cases, where such a transformation
is not practicable, or is not effected, the approximate values of
the generating functions may be determined, from indirect con-
siderations, supplied by very various expedients.
The well known transformation of the series
az—b2#4+cx#—dat+ex—f2'+ &e.,
which Euler has given}, into the equivalent series
r 2
a as FY
Tta”"” (+a""
would be competent to convert a great number of divergent
series of the second class into equivalent convergent series, or
into such as would become so. In this manner the Leibnitzian
series
2 ae Se Aa pee ee a &
1—1+4+1—1+4 &c.
may be shown to be equal to = The series
1—3+6—10+4+15—21 + &e.
* The essential character of arithmetical division is that the quotient should
approximate continually to its true value, and that the terms of the quotient
which are introduced by each successive operation should be less and less con-
. . : 1 1
tinually. In the formation, therefore, of the quotient of = ma and Pai
the analogy between the arithmetical and algebraical operation would cease to
exist, unless @ was greater than 8, or unless the several terms in the quotient
went on diminishing continually. oer a
+ Institutiones Calculi Differentialis, Pars posterior, cap. i.
278 _— REPORT—1833.
of triangular numbers to as The series
1—44+9-—16 +4 25 — &e.
of square numbers to 0. The series of tabular logarithms
log 2 — log 3 + log 4 — log 5 + &c.,
would be found to be equal to ‘0980601 nearly. If we should
suppose x negative and greater than 1, the original and the
transformed series would become divergent series of the first
class.
The series
aS evils ap ers (a—1 (a—1)
log a = (a — 1) Tat oe car eh ge + &c.
is divergent when a is greater than 2, and convertible by Euler’s
formula into the convergent series
@-1) , 1 @-1F, 1 @-1, 1@-H
a 2 a? 3 a 4 a‘
+ &c.;
or by the method of Lagrange into the series
n (Wa —1)— 5 (Wa —1P + 5 (= 1) — &e.,
which may be made to possess any required degree of con-
vergency. But it is not necessary to produce further examples
of such transformations, which embrace a very great part of the
most refined artifices which have been employed in analysis.
One of the most remarkable of these artifices presents itself
in a series to which Legendre has given the name of demicon-
vergent*, The factorial function (1 + «) is expressed by the
continuous expression
(=) (29 a)? R,
e
where R is a quantity whose Napierian logarithm is expressed
by
A B c
122 Weeds ao oat cine
where A, B, C, &c., are the numbers of Bernoulli. The law of
formation of these numbers, as is well known, is extremely
* Fonctions Elliptiques, tom. il. chap. ix. p. 425.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 279.
irregular, and after the third term they increase with great
rapidity. The series under consideration, therefore, even for
considerable values of x, becomes divergent after a certain
number of terms. But an approximate value of the series will
be obtained from the aggregation of the convergent terms only:
and it has been proved by a German analyst* that the error
which is thus made in the value of the generating function will
in this case be less than the last of the convergent, or the first
of the divergent, terms.
It has been usual amongst some later mathematicians of the
highest rank to denominate diverging series, without any di-
stinction of their class, as false, not merely when arithmetical
values are considered, but also when employed as equivalent
forms, in purely symbolical processes. ‘The view of their ori-
gin and nature which we have taken above would explain the
sense in which they might be so considered in relation both to
arithmetical processes and to the calculation of arithmetical
values. It seems, however, an abuse of terms to apply the term
false to any results which necessarily follow from the laws of
algebra. M. Poisson, perhaps the most illustrious of living
analysts, has referred, in confirmation of this opinion, to some
examples of erroneous conclusions produced through the me-
dium of divergent series}; and as the question is one of great
importance and of great difficulty, I shall venture to notice them
in detail.
Let it be required to express the value of
5 ioe dx
y" =f. {(l1— 2azx + a*) (1—2b62 + B*)}#
by means of series.
Assuming K = (1 — 2a + a®)-*and K’ = (1 — 2b + 0?)-4,
let us suppose K and K’ developed according to ascending and
descending powers of a and 6 respectively ; or,
e =1l+aX,+a°X,+ aX,+ &e.
K’=1+6X,+ #X,+ &X, + &e.
1 1 1 1
K= 7+ exit pret airst &c.
; 1 1 1 1
Kazt pit pXet pXst &e.
* Erchinger in Schrader’s Commentatio de Summatione Seriei, &c. Weimar
1818. 4
+ Journal de l Ecole Polytechnique, tom. xii.
280. THIRD REPORT—1833.
The coefficients X,, X,, X3, &c., are reciprocal* functions, pos-
1
sessing the following remarkable property, that /” : Xm Xn de
=k
= 0, in all cases, unless » = m, in which case ue X,X,d x
1 -1
~On+1
The knowledge of this property will readily enable us to de-
termine the following four different values of =:
ab ab? @&@b
mpsieeey Oe OE, we.
1 a a a
ha Div ok BUT Botot es:
1 b b? b?
: ogee tget+zatrat ke.
1 1 1 1
“= Got see + sae t Tat t
Whatever be the relation of @ and 6 to each other and to 1,
two of these four series are convergent, and two of them di-
vergent. But it appears from the examination of the finite in- _
+1 :
tegral /_ K K! da, that one only of these two convergent
-1
series gives the correct value of z, being that which arises from
the combination of the two convergent developements of K and
K’, whilst the incorrect value arises from the combination of a
convergent developement of K with a divergent developement
of K’, or conversely. The conclusion which is drawn from this
fact is, that the introduction of the divergent developement of
K or of K’ vitiates the corresponding value of z, even though
that value is expressed by a convergent series. Let us now
+1
examine how far the definite integral of f K K’ dz will jus-
tify such an inference. e
If we denote K K’ by - we shall easily find,
* Functions which possess this property have been denominated reciprocal
functions by Mr. Murphy, in a second memoir on the Inverse Method of Defi-
nite Integrals, in the fifth volume of the 7ransactions of the Philosophical Society
of Cambridge, in which general methods are given for discovering all species of
such functions, and where one very remarkable form of them is assigned. The
functions referred to in the text were first noticed by Legendre, in his first me-
moir on the Attraction of Ellipsoids, and subsequently, at great length, in the
Fifth Part of his Exercices du Calcul Intégral. Cauchy has used the term recipro-
eal function in a different sense; see Exercices des Mathématiques, tom. ii. p. 141.
REPORT ON ‘CERTAIN BRANCHES OF ANALYSIS. 281
ere (eee bg g a) + const. ;
ie, P 35 log zi ¥ ae
and if we denote by r and 7’ the extreme values of p, when x
= —1 and x = +1, we shall find,
‘ ee ed et Srvuh tab ale see
J-1 p 4V7ab 2 lar Jab —4ab— (a+ b)(1+ab)8?
inasmuch as POP is 4a 6 — (a + b) (1 + @b) in one case, and
—4ab—(at+ + 8) (1 + wb) inthe other. It will appear like-
wise that r and 7’ will have the same sign, whether + or —,
in as much as p will preserve the same sign ‘thr oughout the whole
course of the integration. If, therefore, Hh a + a)(1+ a),
then r = + (1 — a) (1 — 8); and if r’ = — (1 + a) (1 4+ 3B),
then r = — (1 — a) (1 — 6). It thus appears that (1 — a) (1— 6)
must have the same sign with (1 + a) (1 + 0), and consequently
ifa 7 1, and b 7 1, we shall have,
_? (a—1) (6-1) Vab +406 — (a+b) (1+ad)
4 “ie ‘(a+1) (641) fab — 4ab6 — (a +b) (1 +45)
; 1 _(4ab +19
Aad ~ (Wab—1)
(striking out the common divisor
| be Meme e
BFE BOe Wa beet ee
If a Z1 and 6 21, we shall find r = (1 — a) (1 — 6), and
1+ Vab
svat” \L— Vab
If a Z1 and 6 71, we shall find r = (1 — a) (1 — 5), and
1 vb + xii)
laa iY | SS = + °
2Vab °\Wb— Va)?
_Ifa@ 71 and 6 21, we shall find r = (a — 1) (1 — 8), and
1 a Vat Wvb
== eaiiie Wat
Lien api ave + ibh cata
It would thus appear that the definite integral would furnish
erroneous values of = if no attention was paid to those values
of the factors of r and r’, which the circumstances of the inte-
gration require: and it may be very easily shown that an atten-
tion to the developements of K and K’ will, with equal certainty,
enable us s to select the proper developement forz. T hus, ifa 7 1
Bi 8 sa b=
z=
= + 28.
s: =>
282 THIRD REPORT—1833.
1
f(a — 2b — IE
and the value of x (z,) is determined by the combination of the
two last developements. In a similar manner, if a Z1 and bZ1,
(z,) will be formed by the combination of the two first. If
1
a Z\and 6 71, thenr = (1—a)(b—1) (=a? (bby
and the value of z (z,) is formed by the combination of the first
and third developement. And if a 71 and 6 2 1, then the value
of = (z3) will be formed by the combination of the second and
third developements: in other words, the selection of the de-
velopements is not arbitrary, in as much as {(1 — a)?}7* and
{(a@ — 1)?}-* ought not to be considered, as we have already
shown, as identical quantities,
These combinations of the convergent and divergent series
form all the four values of z, of which it appears that one value
alone is correct for any assigned relation of a and 6 to 1, being
that which arises from the combination of the convergent series
for K and K’ only. The considerations, however, which deter-
mine the selection of the correct developement of z are as de-
finite and certain when the general series are employed as when
that value is determined directly from the definite integral
which expresses the value of z. It would appear to me, there-
fore, that not only was the employment of divergent series
necessary for the determination of a// the values of z, but that
when the theory of their origin is perfectly understood they
are perfectly competent to express all the limitations which are
essential to their usage. The attempt to exclude the use of
divergent series in symbolical operations would necessarily im-
pose a limit upon the universality of algebraical formule and
operations which is altogether contrary to the spirit of the
science, considered as a science of symbols and their combina-
tions. It would necessarily lead to a great and embarrassing
multiplication of cases; it would deprive almost all algebraical
operations of much of their certainty and simplicity; and it
would altogether change the order of the investigation of results
when obtained, and of their interpretation, to which I have so fre-
quently referred in former parts of this Report, and upon which
so many important conclusions have been made to depend.
Elementary Works on Algebra.—There are few tasks the
execution of which is so difficult as the composition of an ele-
mentary work ; and very few in which, considering the immense
number of such works, complete success is so rare. They re-
quire, indeed, a union of qualities which the class of writers
who usually undertake such works are not often competent to
and 6 7 1, we have r = (a — 1) (6 — 1)
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 283
furnish. Great simplicity in the exposition and exemplification
of first principles, a perfect knowledge of the consequences to
which they lead, and great forbearance in not making them an
occasion for the display of the peculiar opinions or original re-
searches of their authors.
There is, in fact, only one elementary work which is entitled
to be considered as having made a very near approach to per-
fection. ‘The Elements of Euclid have been the text-book of
geometers for two thousand years; and though they labour
under some defects, which may or may not admit of remedy,
without injury to the body of the work, yet they have not re-
ceived any fundamental change, either in the propositions them-
selves, or in their order of succession, or in the principles of
their demonstrations, in the propriety of which geometers of
any age or country have been found to acquiesce. It is true that
both the objects and limits of the science of geometry are per-
fectly defined and understood, and that systems of geometry
must, more or less, necessarily approach to a common arrange-
ment, in the order of their propositions, and to common prin-
ciples as the bases of their demonstrations. But even if we
should make every allowance for the superior simplicity of the
truths to be demonstrated, and for the superior definiteness of
the objects of the science to be taught, and also for the superior
sanction and authority which time and the respect and accept-
ance of all ages have assigned to this remarkable work, we may
well despair of ever seeing any elementary exposition of the prin-
ciples of algebra, or of any other science, which will be entitled to
claim an equal authority, or which will equally become a model to
which all other systems must, more or less, nearly approximate.
There are great difficulties in the elementary exposition of
the principles of algebra. As long as we confine our attention
to the principles of arithmetical algebra, we have to deal with
a science all whose objects are distinctly defined and clearly un-
derstood, and all whose processes may be justified by demon-
strative evidence. If we pass, however, beyond the limits which
the principles of arithmetical algebra impose, both upon the re-
presentation of the symbols, and upon the extent of the opera-
tions to which they are subject, we are obliged to abandon the
aid which is afforded by an immediate reference to the sensible
objects of our reasoning. In the preceding parts of this Report
we have endeavoured to explain the true connexion between
arithmetical and symbolical algebra, and also the course which
must be followed in order to give to the principles of the latter
in their most general form such a character as may be adequate
to justify all its conclusions. But the necessity which is thus
284 THIRD REPORT—1833.
imposed upon us of dealing with abstractions of a nature so
complete and comprehensive, renders it extremely difficult to
give to the principles of this science such a form as may bring
them perfectly within the reach of a student of ordinary powers,
and which have not hitherto been invigorated by the severe dis-
cipline of a course of mathematical study.
The range of the science of algebra is so vast, and its appli-
cations are so various, both in their objects and in their degrees
of difficulty, that it is quite impossible to fix absolutely the
proper proportion of space which should be assigned to the
developement of its different departments. If a system of al-
gebra could be confined to the statement of fundamental prin-
ciples, and to the establishment of fundamental propositions
only, it might be possible to approximate to a fixed standard,
which should possess the requisite union of simplicity and of
sufficient generality. But it is a science which cannot be taught
by an exposition of principles and their general consequences
only, but requires a more or less lengthened institution of ex-
amples of many of its different applications, in order to produce
in the student mechanical habits of dealing with symbols and
their combinations. The extent also to which such develope-
ments are necessary will vary greatly with the capacities of dif-
ferent students, and it would be quite impossible to determine
any just mean between diffuseness and compression which shall
be best adapted to the wants of the general average of students,
or to the systems of instruction followed by the general average
of teachers.
In the early part of the last century the Algebra of Maclaurin
was almost exclusively used in the public education of this
country. It is unduly compressed in many of its most essential
elementary parts, and is also unduly expanded in others which
have reference to his own discoveries. It was written, however,
in a simple and pure taste, and derived no small part of its
authority as a text-book from the great and well-merited repu-
tation of its author. It was subsequently, ina great measure,
superseded, in the English Universities at least, by the large
work of Sanderson, which was composed by this celebrated
teacher to meet the wants of his numerous pupils. It was, in
consequence, swelled out to a very unwieldy size by a vast
number of examples worked out at great length; and it laboured
under the very serious defect of teaching almost ‘exclusively
arithmetical algebra, being far behind the work of Maclaurin
in the exposition of general views of the science. At the latter
end of the last century Dr. Wood, the present learned and
venerable master of St. John’s College Cambridge, in conjunc-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 285
tion with the late Professor Vince, undertook the publication
of a series of elementary works on analysis, and on the appli-
cation of mathematics to different branches of natural philo-
sophy, principally with a view to the benefit of students at the
Universities. The works of the latter of these two writers have
already fallen into very general neglect, in consequence partly
of their want of elegance, and partly in consequence of their
total unfitness to teach the more modern and improved forms
of those different branches of science. But the works of his
colleague in this undertaking have continued to increase in
circulation, and are likely to exercise for many years a consi-
derable influence upon our national system of education; for
they possess in a very eminent degree the great requisites of
simplicity and elegance, both in their composition and in their
design. ‘The propositions are clearly stated and demonstrated,
and are not incumbered with unnecessary explanations and
illustrations. There is no attempt to bring prominently forward
the peculiar views and researches of the author, and the dif-
ferent parts of the subjects discussed are made to bear a proper
subordination to each other. It is the union of all these qua-
lities which has given to his works, and particularly to his
Algebra, so great a degree of popularity, and which has se-
cured, and is likely to continue to secure, their adoption as
text-books for lectures and instruction, notwithstanding the
absence of very profound and philosophical views of the first
principles, and their want of adaptation, in many important
particulars, to the methods which have been followed by the
great continental writers.
In later times a great number of elementary works on algebra,
possessing various degrees of merit, have been published.
Those, however, which have been written for purposes of in-
struction only, without any reference to the advancement of
new views, either of the principles of the science, or to the ex-
tension of its applications, have generally failed in those great
and essential requisites of simplicity, and of adequate, but not
excessive, illustration, for which the work of Dr. Wood is so
remarkably distinguished ; whilst other works, which have pos-
sessed a more ambitious character, have been generally devoted
too exclusively to the developement of some peculiar views of
their authors, and have consequently not been entitled to be
generally adopted as text-books in a system of academical or
national education. There are, however, many private reasons
which should prevent the author of this Report from enlarging
upon this part of his subject, who is too conscious that there
are few defects which he could presume to charge upon the |
286 THIRD REPORT—1833.
works of other authors from which he could venture to exempt
his own.
The elementary works on algebra and on all other branches
of analytical and physical science which have been published
in France since the period of the Revolution, have been very
extensively used, not merely in this country, but in almost
every part of the continent of Europe where the French lan-
guage is known and understood. The great number of illus-
trious men who took part in the lectures at the Normal and
Polytechnic Schools at the time of their first institution, and
the enlarged views which were consequently taken of the prin-
ciples of elementary instruction and of their adaptation to the
highest developement of the several sciences to which they
lead, combined with the powerful stimulus given to the human
mind in all ranks of life, in consequence of the stirring events
which were taking place around them, at once placed the scien-
tific education of France immensely in advance of that of the
rest of Europe. The works of Lagrange, particularly his Caleul
des Fonctions and his Théorie des Fonctions Analytiques, which
formed the substance of lectures given at the Ecole Polytech-
nique, exhibited the principles of the differential and integral
calculus in a new light, and contributed, in connexion with his
numerous other works and memoirs, which are unrivalled for
their general elegance and fine philosophical views, to fami-
liarize the French student with the most perfect forms and
with the most correct and at the same time most general prin-
ciples of analytical science. The labours of Monge also, upon
the application of algebra to geometry, succeeded in bringing
all the relations of space, with which every department of na-
tural philosophy is concerned, completely under the dominion
of analysis *, and thus enabled their elementary and other
writers to exhibit the mathematical principles of every branch
of natural philosophy under analytical and symmetrical forms.
Laplace himself gave lectures on the principles of arithmetic
and of algebra, which appear in the Séances de l’Ecole Nor-
male and in the Journal de l’ Ecole Polytechnique; and there are
very few of the illustrious men of science, of that or of a subse-
quent period, who have done so much honour to France, who
have not been more or less intimately associated with carrying
* The developement of the details of this most important branch of analy-
tical science, which has been so extensively and successfully cultivated in
France, is greatly indebted to Monge’s pupils in the Polytechnic School,
many of whom have subsequently attained to great scientific eminence: their
results are chiefly contained in the three volumes of Correspondance sur
U Ecole Polytechnique.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 287
on the business of national education in its highest departments.
The influence of such men has been felt not merely in the very
general diffusion of scientific knowledge in that great nation,
but also in the form and character of their elementary books,
which are generally remarkable for their precision and clear-
ness of statement, for their symmetry of form, and for their
adaptation to the most extensive developement of the several
sciences upon which they treat. ;
The elementary works of M. Lacroix upon almost every de-
partment of analytical science have been deservedly celebrated :
they possess nearly all the excellences above enumerated as
characteristic of French elementary writers, and they are also
remarkable for the purity and simplicity of the style in which
they are written*. The Cours des Mathématiques Pures of
M. Francceur possesses merits of a similar kind, being too
much compressed, however, for the purposes of self-instruction,
though well adapted to form a basis for the lectures of a teacher.
The works of M. Garnier are chiefly valuable for their careful
illustration of, and judicious selection from, the writings of
Lagrange, and are well calculated to make the general views
and principles of that great analyst and philosopher familiar
to the mind of a student. The Arithmetic, Algebra}, and Appli-
cation of Algebra to Geometry, of M. Bourdon are works of
more than ordinary merit, and present a very clear and fully
developed view of the elements of those sciences. Many other
works have been published of the same kind and with similar
views by Reynaud, Boucharlat and other writers.
I am too little acquainted with the elementary works which
are used in the different Universities of Germany to be able to
express any opinion of their character. Those which I have seen
have been wanting in that precise and symmetrical form which
constitutes the distinguishing merit of the French elementary
writers ; but they are generally copious, even to excess, in their
examples and illustrations. The immense developement which
public instruction, in all its departments, has received in that
country would lead us to conclude that they possess elementary
mathematical works, which are at least not inferior to those which
* Before the Revolution, the Cours des Mathématiques Pures et Appliquées
of Bezout, in six volumes, was generally used in public education in France :
it is a work much superior to any other publication of that period of a simi-
lar kind which was to be found in any European language.
_+ A part of the Algebra of Bourdon has been translated and highly com-
mended by Mr. De Morgan, a gentleman whose philosophical work on Arith-
“metic and whose various publications on the elementary and higher parts of
mathematics, and particularly those which have reference to mathematical
education, entitle his opinion to the greatest consideration.
288 THIRD REPORT—1833.
exist in other languages : and the labours of Gauss, Bessel, and
Jacobi, and the numerous and important memoirs which appear
in their public Journals and Transactions upon the most difficult
questions of analysis and the physical sciences, sufficiently show
that the mathematical literature of this most learned nation is
not less diligently and successfully cultivated than that which
belongs to every other department of human knowledge.
The combinatorial analysis, which Hindenburg first intro-
duced, has been cultivated in Germany with a singular and
perfectly national predilection *; and it must be allowed that it
is well calculated to compress into the smallest possible space
the greatest possible quantity of meaning. In the doctrine of
series it is also frequently of great use, and enables us to ex-
hibit and to perceive relations which would not otherwise be
easily discoverable. Without denying, however, the advantages
which may attend either the study or the use of the notation of
the combinatorial analysis, it may be very reasonably doubted
whether those advantages form a sufficient compensation for
the labour of acquiring an habitual command over the use and
interpretation of a conventional symbolical language, which is
necessarily more or less at variance with the ordinary usage and
meaning of the symbols employed and of the laws of their com-
binations. These objections would apply, if such a conven-
tional use of symbolical language was universally adopted and
understood; but they acquire a double force and authority,
when it appears that they are only partially used in the only
country | in which the combinatorial analysis is extensively
cultivated, and that, consequently, those works in which it is
adopted are excluded from general perusal, in consequence
of their not being written in that peculiar form of symbolical
language with which our mathematical associations are indis-
solubly connected.
Trigonometry.—The term Trigonometry sufficiently indicates
the primitive object of this science, which was the determina-
tion, from the requisite data, of the sides and angles of trian-
gles: it was in fact considered in a great degree as an inde-
* See Eytelwein’s Grundlehre der hohern Analysis, a very voluminous work,
which contains the principal results of modern analysis and of the theory of
series exhibited in the language and notation of this analysis.
+ Professor Jarrett, of Catherine Hall, Cambridge, in some papers in the
Transactions of the Philosophical Society of Cambridge, and in a Treatise on
Algebraical Developement, has attempted to introduce the use of the lan-
guage of the combinatorial analysis. The great neglect, however, which has
attended those speculations, which are very general and in some respects
extremely ingenious, is a sufficient proof of the difficulty of overcoming those
mathematical habits which a long practice has generated and confirmed.
;
.
q
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 289
pendent science, and not as auxiliary to the application of al-
gebra to geometry. It is to Euler* that we are indebted for
the emancipation of this most important branch of analytical
science from this very limited application, who first introduced
the functional designations sin x, cos z, tan z, &c., to denote the
sine, cosine, tangent, &c., of an are x, whose radius is 1, which
had previously been designated by words at length, or by simple
and independent symbols, such as a, b, s, c, t, &c. The intro-
duction of this new algorithm speedily changed the whole form
and character of symbolical language, and greatly extended
and simplified its applications to analysis, and to every branch
of natural philosophy.
The angles which enter into consideration in trigonometry
are generally assumed to be measured by the arcs of a circle
of a given radius, and their sines and cosines are commonly de-
fined with reference to the determination of these arcs, and not
with reference to the determination of the angles which they
measure. It is in consequence of this defined connexion of
sines and cosines with the arcs, and not immediately with the
angles which they measure, that the radius of the circle upon
which those ares are taken must necessarily enter as an element
in the comparison of the sines and cosines of the same angle
determined by different measures: and though they were ge-
nerally, at least in later writers, reduced to a common standard,
by assuming the radius of this circle to be 1, yet formule were
considered as not perfectly general unless they were expressed
with reference to any radius whatsoever}. In the application,
likewise, of such formule to the business of calculation, the
consideration of the radius was generally introduced, producing
no small degree of confusion and embarrassment; and even in
the construction of logarithmic tables of sines and cosines the
* Introductio in Analysim Infinitorum, vol. i. cap. viii. ‘Quemadmodum
logarithmi peculiarem algorithmum requirunt, cujus in universa analysi summus
extat usus, ita quantitates circulares ad certam quoque algorithmi normam
perduxi: ut in caleulo eque commode ac logarithmi et ipsze quantitates alge-
braicee tractari possent.’’—Extract from Preface.
+ We may refer to Vince’s Trigonometry, a work in general use in this
country less than a quarter of a century ago, and to other earlier as well as
contemporary writers on this subject, for examples of formule, which are uni-
formly embarrassed by the introduction of this extraneous element. Later writers
have assumed the radius of the circle to be 1, and have contented themselves
with giving rules for the conversion of the resulting formulz to those which
would arise from the use of any other radius. It is somewhat remarkable that
the elementary writers on this subject should have continued to encumber their
formule with this element Jong after its use had been abandoned by Euler,
Lagrange, Laplace, and all the other great and classical mathematical writers
on the Continent.
1833. U
290 THIRD REPORT—1833.
occurrence of negative logarithms was avoided by a fiction,
which supposed them to be the sines and cosines of arcs of a
circle whose radius was 10”,
A very slight modification of the definition of the sine and
cosine would enable us to get rid of this element altogether.
In a right-angled triangle, the ratio of any two of its sides will
determine its species, and conse- ©
quently the magnitude of its angles. P
If we suppose, therefore, a point P
to be taken in one (A C) of the two
lines A C and A B containing the
angle B A C (6), and P M to be
drawn perpendicular to the other
line (A B), then we may define the A M
sine of 6 to be the ratio aos and the cosine of 6 to be the
By such definitions we shall make the sine and
ti AM
ratio |p:
cosine of an angle depend upon the angle itself, and not upon
its measure, or upon the radius of the circle in which it is taken:
and upon this foundation all the formule of trigonometry may
be established, and their applications made, without the neces-
sity of mentioning the word radius*.
If we likewise assume the ratio of the are which subtends an
angle to the radius of the circle in which it is taken, and not
the arc itself, for the measure of an angle, we shall obtain a
quantity which is independent of this radius. In assuming,
therefore, the angle @ to be not only measured, but also repre-
sented by this ratio, we shall be enabled to compare sin # and
cos 6 directly with 6, and thus to express one of them in terms
of the other. It is this hypothesis which is made in deducing
the exponential expressions for the sine and cosine, and the
series which result immediately from them f.
* See A Syllabus of a Course of Lectures upon Trigonometry, and the Appli-
cation of Algebra to Geometry, published at Cambridge in 1833, in which all
the formulz of trigonometry are deduced in conformity with these definitions.
+ If we should attempt to deduce the exponential expressions for sin @ and
cos 6 from the system of fundamental equations, Re
cos? § + sin? @= 1 (1.)
cos § = cos (— @) (2.)
sin §@ = — sin (— @) (3.)
we should find,
pAdV—1 4 .—Abv—1 hal AOSD abl
cos § = + ah eracear WARP aaa and sin §@= Mets ee
in which the quantity A, in the absence of any deferminate measure of the
aie
— se
————- =!
’ of the equation
Jaen See ae eee ee eee
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 291
The sines and cosines and the measures of angles defined
and determined as above, are the only essential elements in a
system of trigonometry, and are sufficient for the deduction of
all the important formule which are required either in algebra
angle 6, would be perfectly indeterminate. It is the assumption of the measure
of an angle which is mentioned in the text which makes it necessary to re-
place A by 1.
The knowledge of the exponential expressions for the sine and cosine would
furnish us immediately with all the other properties of these transcendents.
Thus, if the sines and cosines of two angles be given, we can find the sines
and cosines of their sum and difference; and from hence, also, we can find
the sine and cosine of any multiple of an angle from the values of the sine
and cosine of the simple angle; and also through the medium of the solution
of equations the sine and cosine of its submultiples. In fact, as far as the
symbolical properties of those transcendents are concerned, it is altogether
indifferent whether we consider them to be deduced primarily from the
assumed functional equations (1.), (2.), (3.), or from the primitive geome-
trical definitions of which those equations are the immediate symbolical con-
sequences.
¢ x dex y dy
If we should denote the integrals and >=, (com-
0 0 vl—y
a/1 — 22
mencing from 0 respectively) by @ and 6’ respectively, then the integral of
the equation
dx Oya
/1 — 2 Ji —y2 (a.)
would furnish us with the fundamental equation
sin (9 + 6’) = sin 4 cos 6’ + cos 6sin 6’, (B.)
if we should replace x by sin 6, /1 — x by cos 6, y by sin 6’, and 1 — y
by cos @’. If the formulz of trigonometry were founded upon such a basis,
they would require no previous knowledge either of circular arcs considered
as the measures of angles, or of the geometrical definitions of the sines and
cosines, except so far as they may be ascertained from the examination of the
values and properties of the transcendents which enter into the equation (a.).
In a similar manner, if we should suppose 4 and 6! to represent the integrals
d
1
ie
of the transcendents , ot and if, Wie ey then the integral
y
Tt
dx dy
: ——*__ =9 :
vate) * Ja+ey ce
would be expressed by the equation
hsin (6 + 6’) =hsin 6 X hcos 6’ + hcos 6 X Asin #, (8.)
if we should make « = h sin 6 (the hyperbolic sine of 4), and 4/(1 + 2?)
=h cos 4 (the hyperbolic cosine of 6), y= h sin 6’, and V1 + y? = hos 6’,
adopting the terms which Lambert introduced, and which have been noticed
in the note in p. 231; and it is evident that it would be possible from equa-
tion (0.), combined with the assumptions made in deducing it, to frame a
system of hyperbolic trigonometry (having reference to the sectors, and not
u2
292 THIRD REPORT—1833.
or in its applications to geometry. The terms tangent, co-
tangent, secant and cosecant, and versed sine, which denote
very simple functions of the sine and cosine, may be defined by
those functions and will be merely used when they enable us to
exhibit formule involving sines and cosines, in a more simple
form. By adopting such a view of the meaning and origin of
the transcendental functions, the relations and properties of
which constitute the science of trigonometry, we are at once
freed from the necessity of considering those functions as lines
described in and about a circle, and as jointly dependent upon
the magnitude of the angles to which they correspond and of the
radius of the circle itself. It is this last element, which is thus
introduced, which is not merely superfluous, but calculated to
give erroneous views of the origin and constitution of trigono-
metrical formule and greatly to embarrass all their applications.
to the arcs of the equilateral hyperbola), whose formule would bear a very
striking analogy to the formule of trigonometry, properly so called.
Abel, in the second volume of Crelle’s Journal, has laid the foundation, of
a species of elliptic trigonometry, (if such a term may be used,) in connexion
with a remarkable extension of the theory of elliptic integrals. If we denote
the elliptic integral of the first species
oldie
Be / (1 — & sin? )
by 4, and replace sin W by «, we shall get
dx
0 if { a _ a) — a a) }
=
or more generally
dx
= STATE GPa GaRTTa eT ata
« v {0 +ea%) (1— 2 a}
If we now suppose «= 96, ./(1 — c? a?) > f band / (1+ 22?) = F 8, it
may be demonstrated that
n — 9Osf 0. Fe +08. fH). FA
COT 14 ee ee.ge’
rn _f4-f4'—20b.00.F).F#
fO+ “= Ite ee. es ,
FO.FV+29060.900.fO.f 0
1+ec¢?s.g f
or if, for the sake of more distinct and immediate reference to these peculiar
transcendents, we denote
Q 4 by sin 4 (elliptic sine of 4),
F6@+@%)=
f 4 by cos 6 (elliptic cosine of 4), and
F é by (sur 4 (elliptic sursine of @),
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 293
The primitive signs + and —, when applied to symbols de-
noting lines, are only competent to express the relation of lines
which are parallel to each other when drawn or estimated in dif-
ferent directions; but the more general sign cos + “—1 sin 4,
which has been noticed in the former part of this Report, when
applied to such symbols, is competent to express all the rela-
tions of position of lines in the same plane with respect to each
other. It is the use of this sign which enables us to subject
the properties of rectilinear figures to the dominion of algebra:
thus, a series of lines represented in magnitude and position by
Mp, (cos 6, + VW —1 sin 6,) ay, {cos (6, + 6) + VW —1 sin (6, + 45) } ata,
w+ {cos (6, + 65+... On1) + YW = sin (0,4 05+... Oni) } Qos
will be competent to form a closed figure, if the following equa-
tions be satisfied :
then these fundamental equations will become
sin 6 cos 4' surs 6! + sin 6’ cos 6 surs 6
. e e e e e e€
sin (6+ 6')= : -
2 SAPP fl 1+ e ¢? sin? 6 sin? 6’ ’
e e
cos 6 cos 6’ — c2 sin @ sin 6’ surs 4 surs 6'
Aappetany e ile aa Re na Nat oat
cos (6+64= 1 + & c2 sin? 6 sin? 6’
e e
surs @ surs 6! + e2 sin 6 sin 6’ cos 6 cos 6!
8 nyt e € e é 4 e
Piaaly ld dic 1 + e2 c2 sin? @ sin? 6!
e €
If we add, subtract and multiply, the elliptic sines, cosines and sursines of
the sum and difference of 4 and 4! respectively, reducing them, when necessary,
by the aid of the fundamental relations which exist amongst these three tran-
scendents, we shall obtain a series of formulz, some of which are very remark-
able, and which degenerate into the ordinary formule of trigonometry, when
e= 0 and c= 1: we shall thus likewise be enabled to express sin » 6, cos n 6,
é
surs n6, in terms of sin 6, cos 6, sursé. The inverse problem, however, to express
e e é e
sin 8, cos 6, surs 6, in terms of sin n 6, cos n 4, surs n 6, is one of much greater
e é e 4 e e
difficulty, requiring the consideration of equations of high orders, but whose
ultimate solution can be made to depend upon that of an equation of (m + 1)
dimensions only. It is in the discussion of these equations that Abel has dis-
played all the resources of his extraordinary genius.
It would be altogether out of place to enter upon a lengthened statement
of the various properties of these elliptic sines, cosines, and sursines ; their
periodicity, their limits, their roots, and their extraordinary use in the trans-
formation of elliptic functions. My object has been merely to notice the ru-
diments of a species of elliptic trigonometry, the cultivation of which, even
without the aid of a distinct algorithm, has already contributed so greatly to
the enlargement of the domains of analysis.
294 THIRD REPORT—1833.
dy +a, cos 6, + aq cos (6; +03) +. - An, COS (6, + 4+.» On—1)= 0 (1.)
a, sin 6; +a sin (6, +45) +... @p_; sin (6,4 6)+.. 6,1) =0 (2.)
6 t+b+..-41.=(n—Q2r)e (3.)
The first two of these equations may be called equations of
figure, and the last the equation of angles, and all of them must
be satisfied in order that the lines in question may be capable
of being formed into a figure, along the sides of which if a point
be moved it will circulate continually. If the values of 4,,
6, — 9), 6; — 95. » bn-1 — 4n—2 be all positive, and if r = 1, then
the equation of angles will correspond to those rectilineal figures
to which the corollaries to the thirty-second proposition of the
first book of Euclid are applicable, and which are contemplated
by the ordinary definitions of rectilineal figures in geometry.
If we should suppose r = 2 or 3 or any other whole number
different from 1, the equation would correspond to stellated
figures, where the sum of the exterior angles shall be 8, 12, or
4 r right angles. The properties of such stellated figures were
first noticed by Poinsot in the fourth volume of the Journal
de 1 Ecole Polytechnique, in a very interesting memoir on the
Geometry of Situation*.
All equal and parallel lines drawn or estimated in the same
direction are expressed by the same symbol affected by the
same sign, whatever it may be: and it is this infinity of lines,
geometrically different from each other, which have the same
algebraical representation, which renders it necessary to con-
sider the position of lines, not merely with respect to each other,
but also with respect to fived lines or axes, through the medium
of the equations of their generating points. In other words, it
is not possible to supersede even rectilineal geometry by means
of affected symbols only. We are thus led to the consideration
of a new branch of analytical science, which is specifically de-
nominated the Application of Algebra to Geometry, and which
enables us to consider every relation of points in space and the
laws of their connexion with each other, whatever those laws
may be. It is not our intention, however, to enter upon the
discussion of the general principles of this science, or to notice
its present state or recent progress.
A great number of elementary works on trigonometry have
been published of late years in this country, many of which are
remarkable for the great simplicity of form to which they have
reduced the investigation of the fundamental formule. Such
works are admirably calculated to promote the extension of
® See also Peacock’s A/gebra, p. 448.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 295
mathematical education, by placing this most important branch
of analytical science, the very key-stone of all the applications
of mathematics to natural philosophy, within the reach of every
student who has mastered the elements of geometry and the
first principles of algebra.
We have before had occasion to notice the work of the late
Professor Vince upon this subject, which was generally used
in the Universities of England for some years after the com-
mencement of the present century. Its author was a mathema-
tician of no inconsiderable powers, and of very extensive know-
ledge, but who was totally destitute of all feeling for elegance
‘in the selection and construction of his formule, and who had
no acquaintance with, or rather no proper power of appreciating,
those beautiful models of symmetry and of correct taste which
were presented by the works of Euler and Lagrange. But
though this treatise was singularly rude and barbarous in its
form, and altogether inadequate to introduce the student to a
proper knowledge either of the objects or of the powers of this
science, yet it was greatly in advance of other treatises which
were used and studied in this country at the period of its pub-
lication. Amongst these may be mentioned the treatise on Tri-
gonometry which is appended to Simson’s Euclid, which was
more adapted to the state of the science in the age of Ptolemy
than at the close of the eighteenth century *.
The Plane and Spherical Trigonometry of the late Professor
Woodhouse appeared in 1810, and more than any other work
contributed to revolutionize the mathematical studies of this
country. It was a work, independently of its singularly oppor-
tune appearance, of great merit, and such as is not likely, not-
withstanding the crowd of similar publications in the present
day, to be speedily superseded in the business of education.
The fundamental formule are demonstrated with considerable
elegance and simplicity ; the examples of their application, both
in plane and spherical trigonometry, are well selected and very
carefully worked out; the uses of trigonometrical formule, in
some of their highest applications, are exhibited and pointed
* Similar remarks might be applied to treatises upon trigonometry which
were published both before and after the appearance of Professor Wood-
house’s Trigonometry. The author of this Report well recollects a treatise of
this kind which was extensively used when he was a student at the Univer-
sity, in which the proposition for expressing the sine of an angle in terms of
the sides of a triangle, was familiarly denominated the black triangle, in con-
sequence of the use of thick and dark lines to distinguish the primitive tri-
angle amidst the confused mass of other lines in which it was enveloped, for
the purpose of obtaining the required result by means of an incongruous
combination of geometry and algebra.
296 THIRD REPORT—1833.
out in a very clear and striking form; and, like all other
works of this author, it is written in a manner well calculated
to fix strongly the attention of the student, and to make him
reflect attentively upon the particular processes which are fol-
lowed, and upon the reasons which lead to their adoption.
The circumstances attending the publication and reception of
this work in the University of Cambridge were sufficiently re-
markable. It was opposed and stigmatized by many of the older
members, as tending to produce a dangerous innovation in the
existing course of academical studies, and to subvert the pre-
valent taste for the geometrical form of conducting investiga-
tions and of exhibiting results which had been adopted by -
Newton in the greatest of his works, and which it became us,
therefore, from a regard to the national honour and our awn,
to maintain unaltered. It was contended, also, that the primary
object of academical education, namely, the severe cultivation
and discipline of the mind, was more effectually attained by
geometrical than by analytical studies, in which the objects of
our reasoning are less definite and tangible, and where the
processes of demonstration are much less logical and complete.
The opposition, however, to this change, though urged with
considerable violence, experienced the ordinary fate of attempts
made to resist the inevitable progress of knowledge and the
increased wants and improving spirit of the age. In the course
of a few years the work in question was universally adopted.
The antiquated fluxional notation which interfered so greatly
with the familiar study of the works of Euler, Lagrange, La-
place, and the other great records of analytical and philoso-
phical knowledge, was abandoned*; the works of the best
mathematical writers on the continent of Europe were rapidly
introduced into the course of the studies of the University; and
the secure foundations were laid of a system of mathematical
and philosophical education at once severe and comprehensive,
which is now producing, and is likely to continue to produce,
the most important effects upon the scientific character of the
nation.
Theory of Equations. 1. Composition of Equations.—The
first and one of the most difficult propositions which presents
itself in the theory of equations is to prove “that all equations
under a rational form, and arranged according to the method
* The continental notation of the differential calculus was first publicly
introduced into the Senate House examinations in 1817. Though the change
was strongly deprecated at the time, it was very speedily adopted, and in
less than two years from that time the fluxional notation had altogether dis-
appeared.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 297
of Harriott, the significant terms forming one member, and
zero the other, are said to be resolvible into simple or quadratic
factors.” It is only another form of the same proposition to
say, ‘that every equation has as many roots as it has dimen-
sions, and no more; those roots being either real* or ima-
ginary ;” that is, being quantities which are expressible by
symbols denoting real magnitudes affected by such signs as
are recognised in algebra.
We have before said that it is impossible to assign before-
hand an absolute limit to the possible existence of signs of
affection different from those which are involved in the sym-
bolical values of (1)” and (—1)"; and when it is said that every
equation is resolvable into factors of the form x — a, we presume
that a is either a real magnitude, or of the form « + 6 Woah)
where « and # are real magnitudes. If we should fail in esta-
blishing this proposition, it would by no means necessarily fol-
low that there might not exist other forms of factors like x — a,
where a denoted a real magnitude affected by some wnknown
sign different from +, —, or cos 6+ “—1 sin 8, which might
satisfy the required conditions: at the same time its demonstra-
tion will show that our recognised signs are competent to de-
note all the affections of magnitude which are subject to any
conditions which are reducible to the form of an equation.
If we assume in the first instance the composition of equa-
tions to be such as we have stated in the enunciation of the
fundamental proposition, we can at once ascertain the composi-
tion of the several coefficients of the powers of « in the equa-
tion
x — pw 4+ poem -3— 2... + py = 0;
and we can complete the investigation of all those general pro-
perties of equations which such an hypothesis would lead to.
All such conclusions, when established upon such a foundation,
are conditional only. It is not expedient, however, to make
the fate of any number of propositions, however consistent with
each other, and however unquestionable their truth may appear
to be from indirect or from a posteriori considerations, depend-
ent upon an hypothesis, when it is possible to convert this hypo-
thesis into a necessary symbolical truth. Using such an hypo-
thesis, therefore, as a suggestion merely, let us propose the
* It is convenient in the theory of equations, for the purpose of avoiding
repetition, to consider symbols denoting arithmetical magnitudes and affected
with the signs + or —, as real; and quantities denoted by symbols affected
with the sign cos 6 + “—1 sin 6, as imaginary.
298 THIRD REPORT—1833.
following problem, and examine all the consequences to which
its solution will lead.
“To find n quantities x, 21, 2, ... %,_,, such that their sum
shall be equal to p,, the sum of all their products two and two
shall be equal to p,, the sum of all their products three and
three shall be equal to p,, and so on, until we arrive at their
continued product, which shall be equal to py.”
The quantities x, x,,... a,-1, are supposed to be any quan-
tities whatever, whether real or affected by any signs of affec-
tion whether known or unknown. It is our object to show that
the only sign of affection required is cos @ + “—1 sin 4, taken
in its most general sense.
It is very easy to show that the solution of this problem will
lead to a general equation, whose coefficients are p, Po, +++ Pn:
for if we suppose the first of these quantities a to be omitted,
and P,, P.,... P,_, to be the quantities corresponding to p,,
Po, » ++ fn when there are (n — 1) quantities instead of m, then
we shall get
z+P,=p,,
xP, + Po = pa,
xP, + P3= ps,
x Py_5 ar PR) = Pn-1s
ax ier = Pn
If we multiply these equations from the first downwards by the
terms of the series #"~!, 2"-?,... x?, x, 1, and add the first,
third, fifth, &c., of the results together, and subtract the second,
fourth, sixth, &c., we shall get the general equation
a — p, a" 4+ pa? —... + (— 1) pp = 9. (1.)
In as much as p,, po, --- Pn May represent any real magni-
tudes whatever, zero included, it is obvious that we may consi-
der this equation as the result of the solution of the problem in
its most general form. And in as much as # may represent any
one of the » quantities involved in the problem, we must equally
obtain the same equation for all those m quantities: it also fol-
lows that every general solution of this equation must compre-
hend the expression of all the roots.
By this mode of presenting the question we are authorized in
considering the symbolical composition of the coefficients of
every equation as known, though the ultimate symbolical form
of the roots is not known ; and our inquiry will now be properly
limited to the question of ascertaining whether symbols repre-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 299
senting real magnitudes affected by the recognised and known
signs of affection only, are competent, under all circumstances,
to answer the required conditions of the problem.
If the value of one root can be ascertained, and that root be
real, the problem can be simplified, and the dimensions of the
equation depressed by unity; for the coefficients of the reduced
equation P,. P,. Pa-1, which are also real, can be successively
determined. If more real roots than one can be found, the
dimensions of the equation can be depressed by as many wnities
as there are real roots. If the root determined be not real, and if
a similar process for depressing the dimensions of the equation
be adopted, the coefficients of the new equation would not be
real, and the conditions of the problem with respect to the re-
maining roots would be changed. But if we could ascertain a
pair of such roots, such that their sum = x + x, and their pro-
duct = 2 x, should be real, then the dimensions of the equation
might be depressed by two unities, without changing the con-
ditions of the problem with respect to the remaining roots; for
if we supposed Q,, Q,, Q;, &c., to represent the coefficients of
the reduced equation, we should find,
e+a,+Q,= p
XX, + (x + x,)Q, + Q2 = pa
x t,Q) + (@ + a) Q, + Qs = ps;
xX, Q,-4 => (x + 2) Qn-3 + Q,-2 = Pn-1s
x Ly Qn-2 = Pn
from which equations we can determine successively rational
values of Q,, Q,, . - - Qr-s It remains to show, therefore,
that in all cases we can find pairs of roots which will answer
these conditions.
If the number of quantities x, 2,,. . . ,, be odd, it is very
easy to prove that there is always a real value of one of them, «,
which will satisfy the conditions of the general equation (1.) *,
and that consequently the dimensions of the equation may be
depressed by unity, and our attention confined therefore to
the case where the dimensions of the equation are even. If m,
therefore, be any odd number, the form of x may be either 2 m,
2? m, 22 m, 2" m, and so on. Let us consider, in the first place,
the first of these cases.
~ The number of combinations of 2 m, things taken two and two
together, is m (2 m — 1,) and therefore an odd number: these
* This may be easily proved without the necessity of making any hypothesis
respecting the composition of the equation. See the Article ‘ Equarions’ in
the Supplement to the Encyclopedia Britannica, written by Mr. Ivory.
300 THIRD REPORT—1833.
combinations may be either the swms of every two of the quanti-
ties, @, @,...X,_1, Such as x + 2, x + X29, &c., or their products,
such as w 2, or other rational linear functions of those quanti-
ties, involving two of them only, such as « + a, + ra,,2 + 2,
+2xx,,0rx+ 2, +x x, where k may be any given num-
ber whatsoever. If we take any one of these sets of combina-
tions, we can form rational expressions for their sum, for the
sum of their products, two and two, three and three, and so on,
in terms of the coefficients p,, 2, ..- Pn, of the original equa-
tion (1.), by means of the common theory of symmetrical func-
tions *, and consequently, we can form the corresponding equa-
tions of m (2m— 1) dimensions which will have rational and
known coefficients. - Such equations being of odd dimensions
must have at least one real roct ; or, in other words, there must
exist at least one real value of one of the sums of two roots,
such as # + x,, of one of the products, such as x 2, of one
of the functions, x + 2, + «a,orx +a,+hkeau,. If the
symbols which form the real sum 2 + 2, are the same with those
which form the real value of the product x x,, then, under such
circumstances, x and x, are expressible by real magnitudes af-
fected with the ordinary signs of algebra. We shall now pro-
ceed to show that this must be the case.
If we form the equations successively whose roots are x + 2,
+ kx x,, corresponding to different values of 4, we shall have
one real root at least in each of them. If we form more than
m (2m — 1), such equations for different values of 4, we must
at least have amongst them the same combination of x and a,
forming the real root, in as much as there are only m (2 m — 1)
such combinations which are different from each other. Let &
and #, be the values of * which give such combinations, and
let a! and 6! be the values of the real roots corresponding ; then
we must have
r+a,+khea =e’
eee a a, ay Se
* The formation of symmetrical combinations of any number of symbolical
quantities 2, 2,,...#n—1, and the determination of their symbolical values
in terms of their sums (p,), their products two and two (pg), three and three
(ps), and so on, involves no principle which is not contained in the direct
processes of algebra, and is altogether independent of the theory of equations.
The theorems for this purpose may be found in the first chapter of Waring’s
Meditationes Algebraice, in Lagrange’s Traité sur la Résolution des Equations
Numériques, chap. i. and notes 3 and 10, and with more or less detail in
nearly all treatises on Algebra.
+ Ife+a,=aandxex,=8., where wand Aare real magnitudes, then
= 4/ { os — af the values of which are either real or of the form
(cos 6+ VST sin 6) /B, where the modulus /f is real.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 301
and therefore
haba
ices
he —kB
diddul ia dane a
There are therefore necessarily two roots of the equation or two
values of the symbols x, 2}, %o,-.- 1, Such that x + x, and
x x, are real; and therefore it is always possible, in an equation
whose dimensions are impariter par, to depress them by two
unities, so that the reduced equation may still possess rational
coefficients.
If the number of symbols involved in the original problem be
22m, then the number of their binary combinations must be
2 m (2? m — 1) or impariter par. It will immediately follow, from
what we have already proved, that there are two values of the
sum and product of the same symbols, which are either real or
of the forma + 6 “—1; and consequently the symbols them-
selves will admit of expression under a similar form *.
If the dimensions of the original equation be 2? m or 24 m, or
any one in an ascending series of orders of parity, it may be re-
duced down to the next order of parity ina similar manner: and
under all circumstances it may be shown that there must be two
roots which are reducible to the forma + 6 / —1, where «and 6
real or zero; and also in any equation of even dimensions, we
can reduce its dimensions successively by two unities, thus pro-
ducing a series of equations of successive or decreasing orders of
parity, in which we can demonstrate the existence of successive
pairs of roots of the required form until they are all exhausted.
This mode of proving the composition of equations differs
chiefly from that which was noticed by Laplace, in his lectures
to the Ecole Normale in 1795}, in the form in which the ques-
tion is proposed. A certain number of symbols, representing
magnitudes with unknown affections, are required to satisfy
~ * Let vt a2! =r (cosé+ /—1 sin 6)
x x' = e(cos@+ V.— 1sinQ)
x + al? —4e2' = R?(cos2y + V/—T sin 2)
orz— x'=R (cos + V—1 sin)
oa neon tS Cad aye
= r' (cos % + V1 sin x)
x' =r! (cosy — VW —I1sinx).
+ Legons de l’Ecole Normale, tom. ii.
302 THIRD REPORT—1833.
certain real conditions: those conditions are found to be iden-
tical with those which the unknown quantity, or, in other words,
the root in an equation of m dimensions, is required to satisfy.
The object of the proof above given is to show that it is always
possible to find ” real magnitudes with known affections which
are competent to satisfy these conditions ; and those quantities,
therefore, are of such a kind that the equation, whose roots
they are, is always resolvible into real quadratic factors ; a most
important conclusion, which the greatest analysts have laboured
to deduce by methods which have not been, in most cases at
least, free from very serious objections.
There are two classes of demonstrations which have been
given of this fundamental proposition in the theory of equations.
The first class comprehends those in which the form of the
roots is determined from the conditions which they are required
to satisfy; the second class, those in which the form of the
roots is assumed to be comprehended under different values of
p and 4 in the expression p (cos § + “—1 sin 6), and it is shown
that they are competent to satisfy the conditions of the equa-
tion. To the first class belongs the demonstration given above;
those given by Lagrange in notes ix. and x. to his Résolution des
Equations Numériques; the first of those given by Gauss in the
Gottingen Transactions for 1816*; and by Mr. Ivory in his
article on Equations in the Supplement to the Encyclopedia
Britannica. 'To the second class belongs the second demon-
stration given by Gauss in the same volume of the Gottingen
Transactions; by Legendre in the 14th section of the first
Part of his Théorie des Nombres; by Cauchy in the 18th
cahier of the Journal de Ecole Polytechnique; and subse-
quently under a slightly different form in his Cours d’ Analyse
Algébrique.
The first of the demonstrations given by Gauss, like many
other writings of that great analyst, is extremely difficult to
follow, in consequence of the want of distinct enunciations of
the propositions to be proved, and still more from their not
always succeeding each other in the natural order of investi-
gation. It requires the aid likewise of principles, or rather of
processes, which are too far advanced in the order of the re-
sults of algebra to be properly employed in the establishment
of a proposition which is elementary in the order of truths,
though it may not be so in the order of difficulty. If we may
* There is another demonstration by Gauss, published in 1799, which I
have never seen. In his Preface to his Demonstratio Nova Altera he speaks
of its being founded partly on geometrical considerations, and in other re-
spects as involving very different principles from the second.
y
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 303
be allowed, however, to consider it apart from such considera-
tions, it would appear to be complete and satisfactory, and
very carefully guarded against any approach to an assumption
of the proposition to be proved, a defect to which most of the
demonstrations of this class are more or less liable*. It extends
to equations whose dimensions involve different or successive
orders of parities, nearly in the same manner as in the demon-
stration which we have given above.
The demonstration given by Mr. Ivory is different from any
other, and the principles involved in it are such as naturally
present themselves in such an investigation; and it will be re-
commended to many persons by its not involving directly the
use, or supposing the necessary existence of, imaginary quan-
tities. It is not, however, altogether free from some very serious
defects in the form under which it at present appears, though
most of them admit of being remedied without any injury to
the general scheme of the demonstration, which is framed with
great skill, and which exhibits throughout a perfect command
over the most refined and difficult artifices of analysis.
Lagrange has devoted two notes to his great work on the
Resolution of Numerical Equations to the discussion of the
forms of the roots of equations. In the first of these notes,
after examining the very remarkable observations of D’Alem-
bert on the forms of imaginary quantities, he proceeds to con-
sider the case of an equation such as f (x) + V = 0, where
J (x) is a rational function of x; if for different values a and }
of the last term of this equation, where a 2 6, we may suppose
a root which is not real for values of V between those limits, to
become real at those limits, he then shows that for values
of V between those limits, and indefinitely near to them, the
corresponding root of the equation must involve “—1, or
=1, or Y—1, and so on; or, in other words, that the roots
of the equation in the transition of their values from. real
to imaginary (whatever may be the affection of magnitude
which renders them imaginary), will change in form from « to
m +n —1. He subsequently shows that the same result will
follow for any values of V between a and 6, and consequently,
* I do not yenture to speak more decidedly; for though I have read it en-
tirely through several times with great care, I do not retain that distinct and
clear conviction of the essential connexion of all its parts which is necessary
to compel assent to the truth of a demonstration. It is unfortunately fre-
quently the character of many of the higher and more difficult investigations
connected with the general theory of the composition and solution of equa-
tions to leave a vague and imperfect impression of their truth and correctness
even upon the minds of the most laborious and best instructed readers.
304. THIRD REPORT—1833.
that in every instance, when roots of equations cease to be real, |
they will assume the form m + n VW —1.
This demonstration is not merely indirect, but it does not _
arise naturally from the question to be investigated. It seems
likewise to assume the existence of some algebraical form which
expresses the value of the root in terms of the coefficients of
the equation, an assumption which, as will afterwards be seen,
it would be difficult to justify by any & priori considerations.
The illustrious author himself seems to have felt the full force
of these objections, and he proceeds therefore in the following
Note to prove that every polynomial of a rational form will ad-
mit of rational divisors of the first or second degree. The de-
monstration which he has given is founded upon the theory of
symmetrical functions, and shows that the coefficients of such
a divisor may be made to depend severally upon equations all
whose coefficients are rational functions of the coefficients of
the polynomial dividend. Whatever be the degree of parity of
the number which expresses the dimensions of this polynome,
he shows the possibility of the coefficients of this quadratic di-
visor, which is the capital conclusion in the theory. It ought
to be observed, however, that the whole theory of the compo-
sition of equations is so much involved in the different steps of
this investigation, or, at all events, that so little provision is
made in conducting it to guard against the assumption of
this truth, that we should not be justified in considering this
demonstration as perfectly independent or as furnishing an
adequate foundation for so important a conclusion. If we view
it, however, simply with reference to the problem for exhibiting
the nature of the law of dependence which connects the coefli-
cients of the polynomial factor with those of the original poly-
nomial dividend, it must still be considered as an investigation
of no inconsiderable importance, as bearing upon the general
theory of the solution and depression of equations.
The second of the proofs given by Gauss, the proof of Le-
gendre, and both of those which have been given by Cauchy,
belong to the second class of demonstrations to which we
have referred above. Assuming the root to be represented
by p (cos 6 + “—1 sin), the equation is reduced to the form
P + QV-=1, or /(P? + Q?). (cos¢ + “—1 sin 9); and the
object of the demonstration is to show that there exist neces-
sarily real values of p and 6, which make P? + Q* =0. This
is effected by Gauss by processes which are somewhat syn-
thetical in their form, and such as do not arise very natu-
rally or directly from the problem to be investigated ; and the
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 305
essential part of the demonstration requires a double integra-
tion between assigned limits, a process against which serious
objections may in this instance be raised, independently of its
involving analytical truths and principles of too advanced an
order.
_ The demonstration of Legendre depends upon the possible
discovery, by tentative or other means, of values of @ and 4,
which render P and Q very small; and subsequently requires
us, by the application of the ordinary processes of approxima-
tion, to find other values of e and 4, subject to repeated correc-
tion, which may render P and Q smaller and smaller, and ulti-
mately equal to zero. The objection to this demonstration, if
so it may be called, is the absence of any proof of the necessary
existence of values of e and 4; and if they should be shown to
exist, it seems to fail in showing that the subsequent correc-
tions of their values which this process would assign would really
and necessarily increase thé required approximations.
The demonstrations of Cauchy are formed upon the general
scheme of that which is given by Legendre, at the same time
that they seem to avoid the very serious defects under which
that demonstration labours: he shows that (P* + Q*) must ad-
mit of a minimum, and that this minimum value must be zero.
_ The second of the demonstrations differs from the first merely
in the manner of establishing the existence and value of this
minimum: they both of them appear to me to be quite com-
plete and satisfactory.
It is not very difficult to establish this fundamental propo-
sition by reasonings derived from the geometrical representa-
tion of impossible quantities. This was done, though imper-
fectly, by M. Argand, in the fifth volume of Gergonne’s An-
nales des Mathématiques*, and has been since reconsidered by
M. Murey, in a very fanciful work upon the geometrical in-
terpretation of imaginary quantities, which was published in
1827. It seems to me, however, to be a violation of propriety
to make such interpretations which are conventional merely,
and not necessary, the foundation of a most important symbo-
lical truth, which should be considered as a necessary result of
the first principles of algebra, and which ought to admit of de-
monstration by the aid of those principles alone.
General Solution of Equations.—The solution of equations
in its most general sense would require the expression of its
roots by such functions of their coefficients as were competent
i In the fourth volume of the same collection there are demonstrations of
this fundamental proposition, given by M. Dubourguet and M. Encontre,
which do not appear, however, to merit a more particular notice.
. x
306 THIRD REPORT—1833.
to express them, when those coefficients were general symbols,
though representing rational numbers. Such functions also
must equally express all the roots, in as much as they are all of
them equally dependent upon the coefficients for their value ;
and they must express likewise the values of no quantities which
are not roots of the equation.
The problem, in fact, is the inverse of that for the formation
of the equation which is required to satisfy assigned condi-
tions. And as we have shown that there always exist quanti-
ties expressible by the ordinary signs of algebra which will fulfil
the conditions of any equation with rational coefficients, so like-
wise we might appear to be justified in concluding that there
must exist explicable functions of those coefficients which in all
cases would be competent to represent those roots.
A very little consideration, however, would show that sucha
conclusion was premature. In the first place, such a function
must be irrational, in as much as all rational functions of the
coefficients admit but of one value; and they must be such ir-
rational functions of the coefficients as will successively insulate
the several roots of the equation,—for they must be equally ca-
pable of expressing all the roots,—and they must be capable
likewise of effecting this insulation without any reference to the
specific values of the symbols involved, or to the relation of the
values of the roots themselves; for otherwise they could not be
said to represent the general solution of any equation whatever
of a given degree. ‘The question which naturally presents it-
self, after the enumeration of such conditions, is, whether we
could conclude that any succession of operations which are, pro-
perly speaking, algebraical, would be competent to fulfil them.
If it be further considered that those successive operations
must be assigned beforehand for every general equation of an
assigned degree; that every one of these operations can give
one real value only, or at the most two; and that the result of
these operations, which must embrace all the coefficients, must
express the » roots of the equation and those roots only; it
will readily be conceded that the solution of this great pro-
blem is probably one which will be found to transcend the
powers of analysis.
The solutions of cubic and biquadratic equations have been
known for nearly three centuries; and all the attempts which
have hitherto been made to proceed beyond them, at least in
equations in which there exists no relation of dependence
amongst the several coefficients, and no presumed or presuma-
ble relation amongst the roots, have altogether failed of success:
and if we consider that this great problem has been subjected to
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 307
the most scrutinizing and laborious examination by nearly all
the greatest analysts who have lived in that period, we may be
justified in concluding that this failure is rather to be attributed
to the essential impossibility of the problem itself than to the
want of skill or perseverance on the part of those ho have
made the attempt. But in the absence of any compete and
uncontrovertible proof of this impossibility, the question cannot
be considered as concluded, and will still remain open to spe-
culations upon the part of those with whom extensive and well-
matured knowledge, and a deep conviction founded upon it, have
not altogether extinguished hope.
The different methods which have been proposed for the
resolution of cubic and biquadratic equations, and the conse-
quences of the extension of their principles to the solution of
equations of higher orders, have been subjected to a very de-
tailed analysis by Lagrange, in the Berlin Memoirs for 1770
and 1771, and in the Notes xiii. and xiv. of his Traité sur la
Résolution des Equations Numériques ; and it would be diffi-
cult to refer to any investigations of this great analyst which are
better calculated to show the extraordinary power which he
possessed of referring methods apparently the most distinct to.
a common principle of a much higher and more comprehensive
generality. In the subsequent remarks which we shall make,
we shall rarely have occasion to proceed beyond a notice of the
general conclusions to which he has arrived, and to show their
bearing upon some later speculations upon the same subject.
A very slight examination of the principles involved in the
solution of the equations of the third and fourth degrees will
show them to be inapplicable to those of higher orders.. A no-
tice of a very few of such methods will be quite sufficient for
our purpose.
Thus, the ordinary solution of the cubic equation
e—3qae+2r=0* |
is made to depend upon that of the following problem: __.
_ “To find two numbers or quantities such that the sum of
their cubes shall be equal to 2 r and their product equal to g.”
If we represent the required numbers by wu and », we readily
obtain the equation of reduction
w&—2ruv4+q=0,
* This equation may be considered as equally general’ with
e&—Asxv®+Ba—C=0, .
in as much as we can pass from one to the other by a very easy transforma-
tion; and the same remark may be extended to equations, of higher orders.
Such a change of form, however, will determine the applicability or inappli-
cability of many of the methods which are proposed for their solution.
x2
308 THIRD REPORT—1833.
which gives, when solved as a quadratic equation,
War + 7 (r= 9g),
and consequently,
wa {rt VP @¥8,
and therefore
ih Wifi ee Sates
ua {r+ v—¢ys
If we call 1, a, a, the three cube roots of 1, or the roots of
the equation =? — 1 = 0, and if we assume a to represent the
arithmetical value of uw, we shall obtain the following three
values of w + v, which are
v=
at Lae La bit pe
a a aa
These values, though derived from the solution of an equation
of six dimensions *, are only three in number, and form, there-
fore, the roots of a cubic equation. A little further inquiry will
show that they are the roots of the cubic equation
w—S8qx+2r=0:
for it may readily be shown, in the first place, that their sum
= 0; that the sum of their products two and two = — 3 q; and
that their continued product = 27; or in other words, that
they are the roots of an equation which is in every respect iden-
tical with the equation in question +.
* There are siz values of vu, in as much as the values of w and v are inter-
changeable, from the form in which the problem was proposed ; but there are
only three values of u + v.
+ Since qd
{r 2b A (9? — q3) }3
it is usual to express the roots of the equation 28 —~3qz+2r=0, by the
formula . :
:= {r+ A (r? — 3) }3 + {r— V (1? — 8) }3, (1.)
which is in a certain sense incorrect, in as much as it admits of nine values
instead of three. The six additional values are the roots of the two equations
w—3agx+2r=—0,
we—3e2¢x+2r=0,
and the formula (1.) expresses the complete solution of the equation
(a8 — 27r)? — 27 a? = 0,
which is of 9 dimensions. It is the formula
+ ~~, where u= {r+ V(r q) }3,
and has the same value in both terms of the expression, which corresponds to
the equation a—3qx+2r=0.
= {r— V(?— 9},
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 309
This mode of effecting the solution of a cubic equation would
altogether fail if the original equation possessed all its terms:
and though the absence of the second term of a cubic equation
cannot be said, in a certain sense at least, to affect the gene-
rality of its character, yet it would lead us to expect that the
method which we had followed was of so limited a nature as not
to be applicable to general equations of a higher order. ‘Thus,
if it was proposed to find two quantities, w and v, the sum of
whose x‘ powers was equal to 2 r, and whose product was equal
to g, we should find
ua {r+ V2 —Q}r;
. le Se ee
Prev e——}*
where uw + v is the root of the equation
n(n—3 if n(n — 3) (n—4) 4
“Sera e: amas girs,
utov={rt flee Higa ob
a —ng ar? +
Hh yeecs S08 HF.
The form of this equation is of such a kind as to prevent its
being identified with any general equation whatever, beyond a
cubic equation wanting the second term; a circumstance which
precludes all further attempts, therefore, to exhibit the roots of
higher equations by radicals + of this very simple order: but
it is possible that there may exist determinate functions of the
roots of higher equations (not symmetrical functions of all of
them, which are invariable as far as the permutations of the roots
amongst each other are concerned,) which may admit of triple
values only, and which will be expressible, therefore, by means
of a cubic equation, and consequently by the general formula
for its solution. —
Thus, if 2, 2, 3, %4, were assumed to represent the roots of
a biquadratic equation
* This equation was first solved by Demoivre in the Philosophical Trans-
actions for 1737, and it was readily derived from the theorem which goes by
his name. It was afterwards shown to betrue, by a process, however, not al-
together general, by Euler, in the sixth volume of the Comment. Acad. Petrop.,
. 226. See also Abel’s ‘‘ Mémoire sur une Classe particuliére d’Equations
résolubles algébriquement,”’ in Crelle’s Journal, vol. iv.
+ Abel has used the term radicality to designate such expressions. To
say, therefore, that the root of an equation is expressible by radicalities, is
the same thing as to say that the equation is solvable algebraically. It is
used in contradistinction to such transcendental functions, whether of a known
or unknown nature, as may, possibly, be competent to express those roots,
when all general algebraical methods fail to determine them.
310 THIRD REPORT—1833.
v—prPigx—rx«+s=0, (1.)
such functions would be 2, x, + 23x, and (a, + xv, — x3 — 24),
which admit but of three different values, and which may seve-
rally form, therefore, the roots of cubic equations, whose coeffi-
cients are expressible in terms of the coefficients of the original
equation. Such a function also would be (a, + «,)°, if we should _
suppose p or the coefficient of the second term of equation (i.)
to be zero*. The function (x, + x9) (x3 + 24) would give
three values only under all circumstances. The functions x,
+ # + #3, and 2, xx; are capable of four different values,
and therefore do not admit of being expressed by a determina-
ble equation of lower dimensions than the primitive equation.
Functions of the form 2, x, admit of six values, and require for
their expression equations of six dimensions, which are reduci-
ble to three, in consequence of being quasi recurring equations +.
Innumerable functions may be formed which admit of 12 and of
24 values, and one alternate function which admits of two values
only f.
The success of such transformations m reducing the dimen-
sions of the equation to be solved, would naturally direct us to
the research of similar functions of the roots of higher equa-
tions than the fourth, which admit of values whose number is
inferior to the dimensions of the equation. We may presume
that, if such functions exist, they are rational functions, for
if not, their érrationality would increase the dimensions of
the reducing equation, and would tend to distribute its roots
into cyclical periods; and what is more, it has been very
clearly proved that if equations admit of algebraical solution,
all the algebraical functions which are jointly or separately in-
volved in the expression of their roots, will be equal to rational
* The first of these transformations involves the principles of Ferrari’s, some-
times called Waring’s, solution of biquadratic equations ; the second that of
Euler; and the third that of Des Cartes. See the third chapter of Meyer
Hirsch’s Sammlung von Aufgaben aus der Theorie der algebraischen Gleichungen,
which contains the most complete collection of formule and of propositions
relating to symmetrical and other functions of the roots of equations with
which I am acquainted. The combinatory analysis receives its most advan-
tageous and immediate applications in investigations connected with the
theory of such functions. See also Peacock’s Algebra, note, p. 619.
+ The form of its roots being « and =, they are reducible by the same me-
thods as are applied to recurring equations.
t See Cauchy, Cours d’ Analyse, chap. iii. and noteiv. The use of such al-
ternate functions in the elimination of the several unknown quantities from
simultaneous equations of the first order, involving » unknown quantities,
will be noticed hereafter.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. $11
functions of these roots; and consequently, if irrational func-
tions of those roots are employed in the formation of the re-
ducing equation, the roots of the equation must enter into the
final expression of the required roots, in a form where that ir-
rationality has altogether disappeared *. If we assume, there-
fore, that such functions are in all cases rational, the next ques-
tion will be, whether they are discoverable in higher equations
than the fourth.
This inquiry was undertaken by Paolo Ruffini, of Modena,
in his Teoria delle Equazione Algebraiche, published at Bo-
logna in 1799, and subsequently in the tenth volume of the
Memorie della Societa Italiana, in a memoir on the impossibi-
lity of solving equations of higher degrees than the fourth.
He has demonstrated that the number of values of such func-
tions of the roots of an equation of” dimensions must be either
equal to1.2.3...m, or to some submultiple of it; and that
when z = 5, there is no such function, the alternate function
being excluded, which possesses less than 5 values. The pro-
cess of reasoning which is employed by the author for this pur-
* This proposition has been proved by Abel, in his Beweis der Unméglich-
keit algebraische Gleichungen von hoheren Graden als dem vierten allgemein
Aufzulésen, in the first volume of Crelle’s Journal: the same demonstration
was printed at Paris, in a less perfectly developed form, during his residence
in that capital. This proof applies to algebraical solutions only, excluding
the consideration of the possibility of expressing such roots by the aid of un-
known transcendents. After defining the most general form of algebraical
functions of any assigned degree and order ; and after demonstrating the pro-
position referred to in the text, and analysing the demonstrations of Ruffini and
Cauchy, and showing their precise bearing upon the theory of the solution
of equations, he proceeds to show that the hypothesis of the existence of
such a solution in an equation of five dimensions will necessarily lead to an
equation, one member of which has 120 values and the other only 10; an ab-
surd conclusion. It is quite impossible to exhibit this demonstration in
a very abridged form so as to make it intelligible ; and though some parts of
it are obscure and not perfectly conclusive, yet it is, perhaps, as satisfactory,
upon the whole, as the nature of the subject will allow us to expect.
It is impossible to mention the name of M. Abel in connexion with this
subject, without expressing our sense of the great loss which the mathematical
sciences have sustained by his death. Like other ardent young men, he com-
menced his career in analysis by attempting the general solution of an equa-
tion of five dimensions, and was for some time seduced by glimpses of an
imagined success ; but he nobly compensated for his error by furnishing the
most able sketch of a demonstration of its impossibility which has hitherto
appeared. His subsequent discoveries in the theory of elliptic functions,
which were almost simultaneous with those of Jacobi, have contributed most
materially to change the whole aspect of one of the most difficult branches of
analytical science, and furnish everywhere proofs of a most vigorous and in-
ventive genius. He died of consumption, at Christiania in Norway, in 1827,
in the 27th year of his age.
312 THIRD REPORT—1833.
pose is exceedingly difficult to follow, being unnecessarily en-
cumbered with vast multitudes of forms of combination, and
requiring a very tedious and minute examination of different
classes of cases; and it was, perhaps, as much owing to the
necessary obscurity of this very difficult inquiry as to any im-
perfection in the demonstration itself, that doubts were ex-
pressed of its correctness by Malfatti * and other contemporary
writers. The subject, however, has been resumed by Cauchy in
the tenth volume of the Journal de l’ Ecole Polytechnique, who
has fully and clearly demonstrated the following proposition,
which is somewhat more general than that of Ruffini: “ That
the number of different values of any rational function of x
quantities, is a submultiple of 1 . 2.3... ,and cannot be re-
duced below the greatest prime number contained in n, without
becoming equal to 2 or to 1.” Ifwe grant, therefore, the truth
of this proposition, it will be in vain to seek for the reduction
of equations of higher dimensions than the fourth, by transfor-
mations dependent upon rational functions of the roots.
The establishment of this proposition forms an epoch in the
history of the progress of our knowledge of the theory of equa-~
tions, in as much as it so greatly limits the objects of research
in attempts to discover the general methods for their solution.
And if the demonstration of Abel should be likewise admitted,
there would be an end of any further prosecution of such in-
quiries, at least with the views with which they are commonly
undertaken.
Lagrange, in his incomparable analysis of the different me-
thods which have been proposed for the solution of biquadratic
and higher equations, has shown their common relation to each
other, and that they all of them equally tend to the formation o
a reducing equation, whose root is
ty +4%+ex,+ ex,+ &e.
where 2, %, %3, &c., are the roots of the primitive equation,
and where «¢ is a root of the equation
Eien Gai 78 tpt tae si Oy
where z expresses the dimensions of the equation to be solved.
He then reverses the inquiry, and assuming this form as
correctly representing the root of the reducing equation, he
seeks to determine its dimensions. The beautiful process which
he has employed for this purpose is so well known { that it is
quite unnecessary to describe it in this place; and the result,
* Memorie della Soc. Ital., tom. xi.
t+ Resolution des Equations Numériques, Note xiii.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 3138
as might be expected, perfectly agrees with the conclusions
which are derived from more direct, and, perhaps, more ge-
neral considerations. If nm, or the number of roots x,, Xo, gy
&c., be a prime number, then the dimensions of the final re-
ducing equation will be 1.2... (m — 2); and ifn be a compo-
site number = mp, then the dimensions of the final reducing
equation will be :
ee ria 12 fim
(m— 1)m.(1 -2...pr (p —1)p.(1.2...m)?’
according as we arrive at it, by grouping the terms of the ex-
pression
H, +a%,+ oe 4,+ &e.
into m periods of p terms, or into p periods of m terms. It thus
appears, that for an equation of 5 dimensions, the final reducing
equation is of 6 dimensions; for an equation of 6 dimensions,
the final reducing equation is of 10 dimensions in one mode of
derivation and 15 in the other ; and the higher the dimensions
of the equation are, the greater will be the excess of the dimen-
sions of the final reducing equation. And in as much as there
exist no periodical or other relations amongst the roots of these
reducing equations, it is obvious that the application of this
process, and therefore also of any of those primary methods
which lead to the assumption of the form of the roots of the
reducing equation, must increase instead of diminishing the
difficulties of the solution which was required to be found.
It was the imagined discovery of a cyclical period amongst
the roots of this reducing equation which induced Meyer Hirsch,
a mathematician of very considerable attainments, to believe
that he had discovered methods for the general solution of equa-
tions of the fifth and higher degrees. Amongst the different
methods which Lagrange has analysed in the Berlin Memoirs
is that which Tschirnhausen proposed in the Acta Eruditorum
for 1683. It proposed to exterminate, by means of an auxiliary
equation, all the terms of the original equation except the first
and the last, and thus to reduce it to a binomial equation.
Thus, in order to exterminate the second term of x? + ax
+ 6=0, we must employ the auxiliary equation y + A +a
= 0, and then eliminate x. To exterminate simultaneously
the second and third terms of the cubic equation 2° + aa?
+ bx + ¢c=0, we must employ the auxiliary equation y +A
+ Bez + «? = 0, and then eliminate x; and more generally, to
destroy all the intermediate terms of an equation of » dimen-
sions,
Bt Ay 0) 4 dg, BOA bo on An = 0,
314 ; _ THIRD REPORT—1833.
we must employ the auxiliary equation
y+tA+A 27+ Aga?+...a*'=0,
whose dimensions are less by | than those of the given equation.
Such a process is apparently very simple and uniform and
equally applicable to all equations; and so it appeared to its
author. But it wili be found that the equations upon which
the determination of A, A,, A,, depend, in an equation of the
fourth degree, will rise to the sixth degree, which are subse-
quently reducible to others of the third degree; and that for
an equation of the fifth degree, it will be impossible to reduce
them below the sixth degree. Such was the decision of La-
grange, who has subjected this process to a most laborious
analysis, and who has actually calculated one of the coefficients
of the final reducing equation, and shown the mode in which
the others may be determined *.
Meyer Hirsch, however, though fully adopting the conclu-
sions of Lagrange to this extent, attempted to proceed further;
and, deceived by the form which he gave to his types of combina-
tion, imagined that he had discovered cyclical periods amongst
the roots of this final equation, by which it might be resolved
into two equations of the third degree. If such a distribution
of the roots was practicable in the case of the final equation cor-
responding to equations of the fifth degree, it would be practi-
cable in that corresponding to equations of higher degrees.
But some consequences of this discovery, and particularly the
multiplicity of solutions which it gave, would have startled an
analyst whose prudence was not laid asleep by the excitement
consequent upon the expected attainment of a memorable ad-
vancement in analysis, which had eluded the grasp even of
Lagrange. Its author, however, was too profound an analyst
to continue long ignorant at once of the consequences of his
error and of the source from which it sprung. In the Preface
to his Integraltafeln, an excellent work, which was published
in 1810, within two years of the announcement of his discovery,
he acknowledges with great modesty and propriety, that he
had not succeeded in effecting general solutions of equations
in the sense in which the problem was understood by Euler,
Lagrange, and the greatest analysts.
The well known Hoéne de Wronski, in a short pamphlet pub-
lished in 1811, announced a method for the general resolution of
equations. He assumes hypothetical expressions for the roots of
the given equation in terms of the z roots of 1, and of the (m—1)
* Inthe Berlin Memoirs for 1771, p. 170: it forms a work of prodigious
labour, such as few persons would venture to undertake or to repeat.
—_—
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 315
roots of a reduced equation of (x — 1) dimensions, and employs
in the determination of the coefficients of this reduced equation
n"-! fundamental equations, designated by the Hebrew letter x,
and n"-? others designated by the Greek letter 2. It is un-
necessary, however, to enter upon an examination of the truth
of processes which the author who proposes them has left un-
demonstrated ; and in as much as the application of his method
to an equation of 5 dimensions would require the formation of
625 fundamental equations of the class Aleph and 125 of the
class Omega, and the determination of the greatest common
measure of 2 polynomials of 24 and 30 dimensions respectively,
it was quite clear that M. Wronski might in perfect safety retire
behind an intrenchment of equations and operations of this
formidable nature. And this was the position which he took
in answer to M. Gergonne, who, in the third volume of the An-
nales de Mathématiques, in the modest form of doubts, showed
that the form of the roots which he had assumed was not essen-
tially different from those which Waring, Bezout, and Euler,
had assumed, and which Lagrange had shown to be incompa-
tible with the existence of a final reducing equation of the di-
mensions assigned to it*.
The process given by Lagrange for determining the dimen-
sions and nature of the final reducing equation has been the
touchstone by which all the methods which have been hitherto
proposed for the solution of equations have been tried, and will
probably continue to serve the same purpose for all similar at-
tempts which may be hereafter made. Its illustrious author,
however, hesitated to pronounce a decisive opinion respecting
the possibility of the problem, contenting himself with demon-
strating it to be so, with reference to every method which had
been suggested, or which could be shown to arise naturally out
* The works of Hoéne de Wronski were received with extraordinary favour
in Portugal, where the Baron Stockler, a mathematician of considerable at-
tainments, and other members of the Academy of Sciences became converts
to his opinions. There is, in fact, a bold and imposing generality, and appa~
rent comprehensiveness of views in his speculations, which are well calculated
to deceive a reader whose mind is not fortified by the possession of an extensive
. and well digested knowledge of analysis. In the year 1817, the Academy of
Sciences at Lisbon proposed as a prize, ‘‘ The demonstration of Wronski’s
formule for the general resolution of equations,’’ which was adjudged in the
following year to an excellent refutation of their truth by the academician
Evangelista Torriani: it chiefly consists-in showing, and that very clearly,
that the coefficients of the reducing equation of (n — 1) dimensions, assuming
the form of the roots of the equation which Wronski assigned to them, can-
not be symmetrical functions of those roots, and therefore cannot be expressed
by the coefficients of the primitive equation, whatever be the number, nature
and derivation of the fundamental equations & and © which are interposed.
316 THIRD REPORT—1833.
of the conditions of the problem itself. But even if we should
assume the impossibility of the problem, to the full extent of
Abel’s demonstration, it is still possible that there may exist
solutions by means of undiscovered transcendents. It is, in fact,
quite impossible to attempt to limit the resources of analysis, or
to demonstrate the nonexistence of symbolical forms which may
be competent to fulfil every condition which the solution of this
problem may require. In conformity with such views, we may
consider the numerical roots of equations as the only discover-
able values of such transcendental functions; but it is quite
obvious that such values will in no respect assist us in deter-
mining their nature or symbolical form, in the absence of any
knowledge of the course of successive operations upon all the
coefficients of the equation which were required for their de-
termination.
Though we may venture to despair, at least in the present
limited state of our knowledge of transcendental functions, of
ever effecting the general resolution of equations, in the large
sense in which that problem is commonly proposed and under-
stood, yet there are large classes of equations of all orders
which admit of perfect algebraical solution. ‘The principal pro-
perties of the roots of the binomial equation #* — 1 = 0, had
long been ascertained by the researches of Waring and La-
grange, and its general transcendental solution had been com-
pletely effected. Its algebraical solution, however, had been
limited to values of » not exceeding 10; and though Vander-
monde in some very remarkable researches *, which were con-
temporary with those of Lagrange, had given the solution of
the equation «” — 1 = 0, as a consequence of his general me-
thod for the solution of equations, and had asserted that it
could be extended to those of higher dimensions, yet his solu-
tion contained no developement of the peculiar theory of such
binomial equations, and was so little understood, that his dis-
covery, if such it may be termed, remained a barren fact, which
in no way contributed to the advancement of our analytical
knowledge.
The appearance of the Disquisitiones Arithmetice of the
* Mémoires de l Académie de Paris for 1771. The result only of this solu-
tion was given, the steps of the process by which it was obtained being omitted.
This result has been verified by Lagrange in Note xiv. to his Traité sur la
Résolution des Equations Numériques. Poinsot, in a memoir on the solution
of the congruence a” — 1 = M (p), which will be noticed in the text, has at-
tempted to set up a prior claim in favour of Vandermonde for Gauss’s memo-
rable discovery ; in doing so, however, he appears to have been more influ-
enced by his national predilections in favour of his countrymen, than by a
strict regard to historical truth and justice.
a“
REPORT ON CERTAIN BRANCHES OF ANALYSIS, 317.
celebrated Gauss, in 1801, gave an immense extension to our
knowledge of the theory and solution of such binomial equa-
: . ae—1
tions. It was well known that the roots of the equation chy =0,
where » is a prime number, could be expressed by the terms of
the series ~
Pp? ap Po rt};
where r represented any root whatever of the equation, and
where, consequently, the first term 7 might be replaced by any
term of the series. But in this form of the roots there is pre-
sented no means of distributing them into cyclical periods, nor
even of ascertaining the existence of such periods or of determin-
ing their laws. It was the happy substitution of a geometrical
series formed by the successive powers of a primitive root * of x,
in place of the arithmetical series of natural numbers, as the in-
dices of r, which enabled him to exhibit not merely all the dif-
Le
ferent roots of the equation - - = 0, but which also made
manifest the cyclical periods which existed amongst them.
Thus, if a was a primitive root of n, and nm — 1 = mf, then in
the series ‘
2 3 k—-1 mk—1
Ma aN am CaS RE EENY Mo, cule oe
é]
the m successive series which are formed by the selection of
every i term, beginning with the first, the second, the third,
and so on successively, or the % successive series which are
formed in a similar manner by the selection of every m™ term,
are periodical; and if the number m or £ of terms in one of
those periods be a composite number, they will further admit of
resolutions into periods in the same manner with the complete
series of roots of the equation. The terms of such periods will
be reproduced in the same order, if they are produced to any
extent according to the same law, it being understood that the
multiples of » which are included in the indices which succes-
sively arise, are rejected, for the purpose of exhibiting their
values and their laws of formation in the most simple and ob-
vious form. If two or more periods also are multiplied together,
the product will be composed of complete periods or of 1, or of
multiples of them, the rules for whose determination are easily
* There are as many primitive roots of as there are numbers less than
m—1 which are prime to it. Euler, who first noticed such primitive roots
as determined by Fermat’s theorem, determined them by an empirical pro-
cess. Mr. Ivory, in his admirable article on Equations, in the Supplement
to the Encyclopedia Britannica, has given a rule for finding them directly.
318 . THIRD REPORT—1833.
framed * ; and it arises from the application of such rules that
we are enabled to determine the coefficients of an equation of
which those periods are the roots, and thus to depress the
original binomial equation to one whose dimensions are the
greatest prime number, which is a divisor of m — 1.
It follows, therefore, that if the highest prime factor of m — 1
be 2, the resolution of the binomial equation 2 — 1 = 0 will
be made to depend upon the solution of quadratic equations
only, and consequently to depend upon constructions which
can be effected by combinations of straight lines and circles,
and therefore within the strict province of plane geometry :
this will take place whenever m is equal to 2* + 1 and is also
a prime number. Thus, if k = 4 we have nm = 17, a prime
number, and therefore the solution of the equation «” —1=0
will be reducible to that of four quadratic equations. Similar
observations apply to the equations
Px | gern ene and iA pe
The same principles which enable us to solve algebraically
binomial equations, under the circumstances above noticed, will
admit of extension to other classes of equations, whose roots
admit of analogous relations amongst each other. Gauss} has
stated that the principles of his theory were applicable to func-
tions dependent upon the transcendent f°", which de-
fines the arcs of the lemniscata, as well as to various species of
congruencies ; and he has also partially applied them to certain
classes of equations dependent upon angular sections, though
in a form which is very imperfectly and very obscurely deve-
loped. Abel, however, in a memoir} which is remarkable for
the generality of its views and for its minute and careful ana-
lysis, has not merely completed Gauss’s theory, but made most
important additions to it, particularly in the solution of exten-
sive classes of equations which present themselves in the theory
of elliptic transcendents §. Thus he has given the complete
* Symmetrical functions of these periods will be multiples of the sum (—1)
of these periods and of 1. This conclusion follows immediately from the re-
placement of the arithmetical by the geometrical series of indices, according
to the general process of Lagrange, without any antecedent distribution of
the roots into periods. See Note xiv. to the Résolution des Equations Numé-
riques. It follows from thence that the coefficients of the reducing equations
will be whole numbers.
+ Disquisitiones Arithmetice, pp. 595, 645.
{ “Sur une Classe particuliére d’Equations résolubles algébriquement,”—
Crelle’s Journal, vol. iv. p. 131.
§ Crelle’s Journal, vol. iv. p. 314, and elsewhere.
Sous
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 319
algebraical resolution of an equation whose roots can be repre-
sented by
we, bay Peen eer me,
where 6” x = x, and where @ is a rational function of “x and of
known quantities; and also of an equation where all the roots
can be expressed rationally in terms of one of them, and where,
if x and 6, x express any other two of the roots, we have like-
wise
Go,7 = 6,0 2,
It is impossible, however, within a space much less than that
of the memoir itself, to give any intelligible account of the pro-
cess followed in the demonstration of these propositions, and
of many others which are connected with them. We shall con-
tent ourselves, therefore, with a slight notice of their applica-
tion to circular functions.
2 ;
If we suppose a = a the equation whose roots are cos a,
cos 2a, cos3a,... coswais
ee a ne ee
J. rae 2 eats CN 4 ——
x qe + 76: ito @ isha 0 (1.)
which may be easily shown to possess the required form and
properties ;—for, in the first place, cos m a = 4 (cos a), where @
is, as is well known, a rational function of cos a or x; and,
in the second place, if 9 = cos ma and 4, x = cos m, a, then
likewise 66, 2 = cosmm,a = cosm,ma = 6,6 x, which is the
second condition which was required to. be fulfilled.
Let us suppose » = 2” + 1, when the roots of the equation
(1.) will be
Qa 7 4na 9
Int cos On+ 1 « « « COS Qn+l’ COS a7,
of which the last is 1, and the x first of the remainder equal to
the v last. The equation (1.) may be depressed, therefore, to
one of z dimensions, which is
cos
n 1 n—1 1 n—2 1 n—3
1 @—2)(»—3) 94, 1 @—-3)(@—4) sg
er 2 ee ie, eee
whose roots are
Qa 4 x za Qnn
3820 THIRD REPORT—18353.
Qu 2m
= x = cos a, and Cos = = 6x =cosma,
2Qn+1 2Q2n+1
then these roots are reducible to the form
If cos
5.0 yO &3. 0). OF aes
or,
COs @, COS ma, cos m2 a,... cos ma:
and if we suppose m to be a primitive root to the modulus
2n + 1, then all the roots
COs a, COS Ma, COS mM? a, ... Cosma
will be different from each other, and cos m" a = cos a; con-
sequently it will follow, since the roots of the equation (2.) are
of the form
Co, ean a «On
where 6" x = x, they will admit, in conformity with the preceding
theorems, of algebraical expression.
Abel has given the general form of the expression for these
roots, which in this case are all real; and their determination
will involve the division of a circle into 2” equal parts, the
division of an assigned or assignable arc into 2 equal parts,
and the extraction of the square root of 2m + 1; a conclusion
to which Gauss had also arrived, though he has not given the
steps of the process which he followed for obtaining it*. If we
suppose 2 = 2%, we shall get the case of regular polygons of
2+! + 1 sides, which admit of indefinite inscription in circles
by purely geometrical means. It will follow from the same re-
sult that the inscription of a heptagon will depend upon that
of a hexagon, the trisection of a given angle, and the extraction
of the square root of 7.
Poinsot + has given a very remarkable extension to the theory
of the solution of the binomial equation 2” — 1 = 0, by showing
that its imaginary roots may be considered in a certain sense
as the analytical representation of the whole numbers which
satisfy the congruence or equation
a” —1=M(p),
whose modulus (a prime number) is p: thus, the imaginary
cube roots of 1, or the imaginary roots of «7 —1=0, are
ae Wf 8: — 1 = OS
2 ; 2
‘
, and the whole numbers 4 and 2,
* Disquisitiones Arithmetice, p. 651. ,
+ Journal de l’ Ecole Polytechnique, cahier 18.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 321
which satisfy the congruence
2—l1=M x 7,
whose modulus is 7; are expressed by patel Ms Sukd
and pedis -innerah <2: which arise from adding 7 to the
parts without and beneath the radical sign.
The principle of this transition from the root of the equation
to that of the congruence is sufficiently simple. We consider
the roots of 2” — 1 = 0 as resulting from the expression for
those of the congruence 2” — 1 = M (p), when M = 0; and
we thus are enabled to infer, in as muchas M (p), its multiples
‘and powers, are involved in those formule, whether without
‘or beneath the radicals, and disappear, therefore, when M = 0,
‘that some such multiples, to be determined by trial, or other-
wise, are to be added when M (p) is restored, or when 1 is
replaced by 1 + M(p). When the congruence admits of in-
‘tegral values of x, which are less than p, then they can be found
by trial: when no such integral values exist, then, amongst the
irrational values which thus arise, those values will present them-
selves which will satisfy the congruence algebraically, though
they can only be ascertained by a tentative process.
The equation of Fermat,
2? —]|=M (p)s
where p is a prime number, will be satisfied by all the natural
numbers 1, 2, 3,.. as far as (pv — 1): and it follows, therefore,
that all the rational roots of the equation
a” — 1 = M (p)
will be common to the equation
1 =M(p),
the number of them being equal to (d), the greatest common
divisor of m and of p—1. If d be 1, then all the roots except
1 are irrational. If we suppose the equation to be
a —1 = M(p),
then all the roots will be equal to each other and to 1. It is
unnecessary, however, to enter upon the further examination
of such cases, which are developed with great care and sin-
gular ingenuity in the memoir referred to.
These views of Poinsot are chiefly interesting and valuable as
ily ai the theory of indeterminate with that of ordmary
3. Y
322 THIRD REPORT—1833.
equations. It has, in fact, been too much the custom of analysts
to consider the theory of numbers as altogether separated from
that of ordinary algebra. The methods employed have generally
been confined to the specific problem under consideration, and
have been altogether incapable of application when the known
quantities employed were expressed by general symbols and not
by specific numbers. It is to this cause that we may chiefly attri-
bute the want of continuity in the methods of investigation
which have been pursued, and the great confusion which has
been occasioned by the multiplication of insulated facts and
propositions which were not referable to, nor deducible from,
any general and comprehensive theory.
Libri, in his Teoria det Numeri, and in his Mémoires de
Mathématique et de Physique, has not merely extended the
views of Poinsot, but has endeavoured to comprehend all those
conditions in the theory of numbers, by means of algebraical or
transcendental equations, which were previously understood
merely, and not symbolically expressed. He has shown that
problems which have been usually considered as éndeter-
minate are really more than determinate, and he has thus been
enabled to explain many anomalies which had formerly embar-
rassed analysts, by showing the necessary existence of an equa-
tion of condition, which must be satisfied, in order that the
problem required to be solved may be possible. By the aid of
such principles the solutions of indeterminate equations, at
least within finite limits, may be found directly, and without
the necessity of resorting to merely tentative processes.
A great multitude of new and interesting conclusions result
from such views of the theory of numbers; but the limits and
object of this Report will not allow me to discuss them in de-
tail, or to point out their connexion with the general theory of
equations, and with the properties of circular and other func-
tions. The reader, however, will find, in the second of the
memoirs of Libri above referred to, a general sketch of the
nature and consequences of these researches, which is unfor-
tunately, however, too rapid and too imperfectly developed to
put him in full and satisfactory possession of all the bases of
this most important theory.
On the Solution of Numerical Equations.—The resolution
of numerical equations formed the subject of a truly classical
work by Lagrange, in which this problem, one of the most im-
portant in algebra, is not only completely solved, but the imper-
fections of all the methods which had been proposed for this
purpose by other authors are pointed out with that singular
distinctness and elegance which always distinguish his reviews
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 823
of the progress and existing state of the different branches of
the mathematical sciences. In the following report we shall
commence by a general account of the state in which the pro-
blem was left by him, and of the practical difficulties which
attend the use of his methods, and we shall then proceed to
notice the important labours of Fourier and other authors, with
a view to bring its solution within the reach of arithmetical
processes which are at once general and easy of application.
The resolution of numerical equations involves two principal
objects of research: the first of them concerns the separation
of the roots into real and imaginary, positive and negative, and
the determination of the limits between which the real roots
are severally placed; the second regards the actual numerical
approximation to their values, when their limits and nature have
been previously ascertained. Many different methods have been
proposed for both these objects, which differ greatly from each
other, both in their theoretical perfection and in their practical
applicability. We shall begin with a notice of the first class of me-
thods, which have been proposed for the separation of the roots.
If the coefficients of an equation be whole numbers or rational
fractions, their real roots will be either whole numbers or ra-
tional fractions, or otherwise irrational quantities, which will be
generally conjugate* to each other and which will generally pre-
sent themselves, therefore, in pairs. The method of divisors
which Newton proposed, and which Maclaurin perfected, will
enable us to determine roots of the first class, and they are also
determined immediately and completely by nearly all methods
of approximation. It will be to roots of the second class, there-
fore, that our methods of approximation will require to be ap-
plied, though such methods will never enable us to assign them
under their finite irrational form, nor would our knowledge of
their existence under such a form in any way aid us, unless in a
very small number of cases, in the determination of their ap-
proximate numerical values. '
The equal roots of equations, if any exist, may be detected
by general methods; and the factors corresponding to them
may be completely determined, and the dimensions of the equa-
* An irrational real root may be conjugate to the modulus of a pair of im-
possible roots; and there-may exist, therefore, as many irrational real roots
which have no corresponding conjugate real roots as there are pairs of im-
possible roots in the equation. It is not true, therefore, generally, as is some-
times asserted, that such irrational roots enter equations by pairs. It would
not be very difficult to investigate the different circumstances under which
roots present themselves, and the different conditions under which they can
be conjugate to each other; but the inquiry is not very important, in as much
as the knowledge of their form would not materially influence the application
of methods for approximating to their values.
Y¥2
824. THIRD REPORT—1833.
tion depressed by a number of units equal to the number of
such factors. We might suppose, therefore, in all cases, that
the roots of the equation to be solved were unequal to each
other; but if it should not be considered necessary to perform
the previous operations which are required for the detection
and separation of the equal roots, the failure of the methods of
approximation or other peculiar circumstances connected with
the determination of the limits of the roots, would indicate their
existence, and at once direct us to the specific operations upon
which their determination depends.
If we suppose, therefore, the equal roots to be thus separated
from the equation to be solved, and if we assume a quantity
A which is less than the least difference of the unequal roots,
then the substitution of the terms of the series
Ay (k — TAs. 2, a, 0, — A, 2 oy ee ee me a,
where k 4is greater than the greatest root, and — /, 4 less than
the least root*, will give a series of results, amongst which the
number of changes of sign from + to — and from — to + will
be as many as the number of real roots, and no more ; and where
the pairs of consecutive terms of the series of multiples of 4
which correspond to each change of sign are limits to the seve-
ral real roots of the equation. ‘This is the principle of the me-
thod of determining the limits of the real roots which was first
proposed by Waring, and which has been brought into practical
operation by Lagrange and Cauchy. It remains to explain the
different methods which have been proposed for the purpose of
determining the value of 4.
Waring first, and subsequently Lagrange, proposed for this
purpose the formation of the equation whose roots are the
squares of the differences of the roots of the given equation. If
we subsequently transform this equation into one whose roots
are the reciprocals of its roots, and determine a limit / greater
than the greatest root of this transformed equation}, then —,
Vo
* A negative root is always considered as less than a positive root, unless
the consideration of the signs of affection is expressly excluded.
+ Newton proposed for this purpose the formation of the equation whose
roots are x — e, and where e is determined by trial of such a magnitude that
all the coefficients of the equation may become positive. In sucha case e is the
limit required. Maclaurin proved that the same property would belong to the
greatest negative coefficient of the equation increased by 1. Cauchy, in his
Cours d’ Analyse, Note iii., and in his Exercices des Mathématiques, has shown
that if the coefficients of the equation, without reference to their sign, be
A, As, .. Am, and if x be the number of such coefficients which are different
from zero, then that the greatest of the quantities
1
n Aj, (n A,)?, (n As)", .. (a Am)”
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 325
will be less than the least difference of any two of the real roots
of the primitive equation, and will consequently furnish us with
such a value of 4 as will enable us to assign their limits. The
extreme difficulty, however, of forming the equation of dif-
ferences, which becomes nearly impracticable in the case of
equations beyond the fourth degree*, renders it nearly, if not
altogether, useless for the purposes for which this transforma-
tion was intended by the illustrious analysts who first proposed
it; in other words, it is only ina theoretical sense that it can be
said to furnish the solution of the problem of determining the
limits of the real roots of an equation.
Cauchy has succeeded in avoiding the necessity of forming
the equation of the squares of the differences of the roots, by
showing that a value of 4 may be determined from the last term
of this transformed equation, combined with a value of a limit
greater than the greatest root of the primitive equation. If we
suppose H to represent this term, & to be the superior limit
required, and a and 6 to represent any two roots of the equa-
tion, whether real or imaginary, then he has shown that their
difference a — 6, or the modulus of their difference, will be
will be a superior limit to the roots. An inferior limit (without reference to
algebraical sign) may be readily found by the same process by the formation
of the equation whose roots are the reciprocals of the former.
M. Bret, in the sixth volume of Gergonne’s Annales des Mathématiques, has
investigated other superior limits of the roots of equations, which admit of
very easy application, and which likewise give results which are generally not
very remote from the truth. One of these limits is furnished by the following
theorem : ‘‘If we add to wnity a series of fractions whose numerators are the
‘successive negative coefficients, taken positively, and whose denominators
are the sums of the positive coefficients, including that of the first term, the
greatest of the resulting values will be a superior limit of the roots of the
equation.” Thus, in the equation
2 a7 + 11 «7° — 10 a — 26 at + 31 a3 + 72 a — 2304 — 348 = O,
the number 4, which is equal to the at sa of the Dian:
10
Le
iF iz} += hia ~~ Bisposs —
is a superior limit required ; and re we change the signs of the alternate terms,
we shall have 1 + cat or 7, a superior limit of the roots of the resulting
oer : it will follow, therefore, that all the real roots of the first equation
will be included between 4 and — 7.. Other methods are proposed in the
same memoir which are not equally new or equally simple with the one just
given, and which I do not think it necessary to notice.
* Waring, as is well known, gave the transformed equation of the 10th de-
gree, whose roots were the squares of the differences of the roots of a general
equation of the fifth degree, wanting its second term: it involves 94 different
combinations of the coefficients of the original equation, many of them ‘eee
large numerical coefficients.
326 THIRD REPORT—1833.
Hi
greater than ap? if nm denote the dimensions of the
2
equation; and in as much as H is necessarily, when the coeffi-
cients are whole numbers, either equal to or greater than 1, it
will follow that ipightala will furnish a proper value of 4,
2
where / has been determined by the methods described above,
or in any other manner. The chief objection to the use of a
value of 4 thus determined arises from its being generally much
too small, and from the consequent necessity of making a much
greater number of trials for the discovery of the limits of the
roots than would otherwise be necessary.
Lagrange has proposed different methods of determining the
value of 4, which, though much less laborious, at least for
equations of high orders, than the equation of the squares of
the differences, are still liable to great objections, in conse-
quence of their being indirect, difficult of application, and likely
to give values of 4 so small and so uncertain as greatly to mul-
tiply the number of trials which are necessary to be made*. It
is for this and other reasons that such methods have never been
reduced to such a form as to be competent to furnish the re-
quired limits by means of processes which are expressible in
the form of arithmetical rules, like those which are given for the
extraction of the square and cube root in numbers. In this re-
spect, therefore, they have failed altogether in satisfying the
great object proposed to be attained by their author, who con-
sidered the resolution of numerical equations as properly consti-
tuting a department of common arithmetic, the demonstration
of whose rules of operation must be subsequently sought for in
the general theory of algebraical equations +.
The basis of all methods of solution of numerical equations
must be found in the previous separation of the roots; and the
efforts of algebraists for the last two centuries and a half have
been directed to the discovery of rules for this purpose. The
methods, however, which have been proposed have been chiefly
directed to the separation of the roots into classes, as positive
and negative, real and imaginary, and not to the determination
of the successive limits between which they are severally placed.
The celebrated theorem of Des Cartest gave a limit to the
number of positive and negative roots, but failed in deter-
* Résolution des Equations Numériques, Note iv.
+ Ibid., Introduction.
+ The proper enunciation of this theorem is the following: “ Every equa-
tion has at /east as many changes of sign from + to — and from — to +
as it has real and positive roots, and at Jeas¢t as many continuations of sign
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 327
mining the absolute number either of one class or of the other,
in the absence of any means of ascertaining the number of ima-
ginary roots. If the roots of the equation were all of them real,
and could be shown to be so by any independent test, it would
be easy to determine the limits between which the roots were
severally placed; for the number of changes of sign which are
lost upon the substitution of 2 + ¢ for 2 would show the number
of roots which are included between 0 and e; and if, therefore,
we should assume a succession of values of e, whether positive
or negative, such as to destroy one change of signs and no more,
upon the substitution of any two of these successive values, we
should be enabled to obtain the limits of every root of the
equation.
It was chiefly with a view to this consequence of Des Cartes’s
theorem that De Gua investigated and assigned the conditions
of the reality of all the roots of an equation. If we suppose
X = 0 to be the equation, and Xi, X"/, Xili, Xiv, Xv, &c., to
denote the successive differential coefficients of X, then, if all
the roots of X = 0 be real, the roots of the several derivative
equations Xi= 0, Xii'=0, X#i# = 0, &c., must be real like-
wise; and if the roots of any one of these equations X = 0
be substituted in X°-” and X°*”, it will give results affected
with different signs. If we form, therefore, a succession of
equations in y by eliminating successively x from the equations
y= X™ . XX) and X—) = 0,
y= Xe | Xe ) and X*-) = 0,0... .°.
y = Xi Xiliand Xi = 0, y = X Xl and X'=0,
the coefficients of all these equations must be positive, forming
from + to + and from — to — as it has real and negative roots.’”’ It is very
doubtful, notwithstanding the assertions of some authors, whether Des Cartes
himself was aware of the necessary limitation of the application of this theorem,
which is required by the possible or ascertained existence of imaginary roots.
The demonstration which was given by De Gua of this theorem in the Mé-
moires de l’ Académie des Sciences for 1741, founded upon the properties of the
limiting equation or equations, has been completed by Lagrange with his
usual fullness and elegance, in Note viii. to his Résolution des Equations Nu-
mérigues. 'The most simple and elementary, however, of all the demonstra-
tions which have been given of it, and the one, likewise, which arises most
naturally and immediately from the theory of the composition of equations, is
that which was given by Segner in the Berlin Memoirs for 1756, The few im-
perfections which attach to this demonstration, as far as the classification of
the forms which algebraical products may assume is concerned, have been
completely removed in a demonstration which Gauss has published in the
third volume of Credle’s Journal.
_ This theorem is included as a corollary to Fourier’s more general theorem
for the separation of the roots, as we shall have occasion to notice hereafter.
328 THIRD REPORT—1883.
a collection of conditions of the reality of the roots of an equa-
i i : ‘ n(n—1).
tion of x dimensions which are segs in number~*.
These speculations of De Gua were well calculated to show
the importance of examining the succession of signs of these
derivative equations, with a view to the discovery of their con-
nexion with the nature of the roots of the primitive equation.
The changes in the succession of signs of the coefficients of the
equations which resulted from the substitution of 2 + a and
x + b, gave no certain indications of the nature and number of
the roots included between a and 8, unless it could be shown
that all the roots of the primitive equation were real, a case of
comparatively rare occurrence, and which left the general pro-
blem of the separation of the roots, as preparatory to their
actual calculation, nearly untouched. It was the conviction that
all attempts to effect the solution of this problem by the aid of
Des Cartes’s theorem would necessarily fail, which led Fourier,
one of the most profound and philosophical writers on analysis
and physical science in modern times, to the examination of the
* Résolution des Equations Numériques, Note viii. The equation of the
squares of the differences of the roots of an equation will indicate the reality
n(n — 1)
2
nately positive and negative. The succession of signs of the coefficients very
readily furnishes the indications of the number of impossible roots in all equa-.
tions as far as five dimensions, as has been shown by Waring and Lagrange.
The number of conditions of the reality of the roots of an equation of five
dimensions would appear from the formula in the text to be 10; but some of
these conditions, as Lagrange has intimated, may, and indeed are, included
in the system of the others, so as to reduce them to a smaller number. La-
grange has assigned two conditions (not three) of the reality of the roots of
a cubic equation ; but the first of these is necessarily included in that of the
second, so as to reduce the essential conditions to one. Similar consequences
are found to present themselves in the examination of these conditions for
an equation of the fourth degree, which are three in number, and not six, as
the formula would appear to indicate.
Cauchy, in the 17th cahier of the Journal de l’ Ecole Polytechnique, has suc-
ceeded, by a combined examination of the geometrical properties of the curve
whose equation is y = X (where X is a rational function of x of the form
am + p,am-1 + ... . pn), and of their corresponding analytical charac-
ters, in the discovery of general methods, not merely for the determination of
the number of real roots, but likewise of the number of positive and negative
roots, as distinguished from each other. These methods are equally appli-
cable to literal and numerical equations. He has applied his method to ge-
neral equations of the first five degrees, and the results are in every respect,
as far at least as they have been examined in common, equivalent to those
which are derived from the equation of the squares of the differences. It is
impossible, however, in the space which is allowed to me in this Report, to
give any intelligible account of this most elaborate and able memoir, and I
must content myself, therefore, with this general reference to it.
of all the roots, if its coefficients have changes of sign, or be alter-
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 329.
succession of signs of the function X and its derivatives, upon
the substitution of different values of 2. The conclusions
which have resulted from this examination, which we shall now
proceed to state, have completely succeeded in effecting the
practical solution of this most difficult and important problem,
as far, at least, as real roots are concerned.
If we suppose
X = 2" 4+ 4,27 + a,x"? +...a,=9,
and if we write X and its derivatives in the following order,
ee a te Oe a. ie
alts L, © sseagl gers ‘
then the substitution of he and — —,, will give two series of re-
0 0
sults, the terms of the first series being all of them positive,
and those of the second being alternately positive and negative.
The same will be the case if, in the place of 9: We put any
limit («) greater than the greatest root of the equation X = 0,and
if in the place of —>o we substitute any negative value of
x (— P) (to be determined by trial or otherwise) which will
make the first terms of X, X', X¥, &c., considered with regard
to numerical value only, severally greater than the sum of all
those which follow them. In the course of the substitution of
values of x intermediate to those extreme values — 6 and a, all
the m changes of sign of X and its derivatives, from + to —
and from — to +, will disappear, in conformity with the fol-
lowing theorems, which are capable of strict demonstration.
Ist. If, upon the substitution of any value of 2, one or more
changes of signs disappear, those changes are not recoverable
by the substitution of any greater value of x. é
2nd. If upon the substitution of two values a and 6 of x,
_ one change of signs disappears, there is one real root and no
more included between a and 6. If under the same circum-
stances an odd number 2 p + 1 of changes of sign have disap-
eared, there must be at least one, and there may be 2p! + 1
where p’ is not greater than p) real roots between @ and 6;
but if an even number 2 p of signs have disappeared in the in-
terval, there may be 2p — 2p! real roots, and p! pairs of ima-
ginary roots corresponding to it, where p’ is not greater than p.
If no change of sign disappears, upon the successive substi-
tution of a and 6, then no root whatever of the equation X = 0
can be found between the limits @ and 0b.
drd. If the substitution of a value a of a makes X = 0, then
a isa root of the equation. If the substitution of the same
value of « makes at the same time X = 0 and X' = 0, then
330 THIRD REPORT—1833.
there are two real roots equal to a; and generally, as many of
the final functions X, X', X", &c., will disappear, under the same
circumstances, as there are roots equal to a.
4th. If the substitution of a value of a makes one intermediate
function X equal to 0, and one only, and if the result 0 be placed
between two signs of the same kind, whether + and + or — and
—, then there will be one pair of imaginary roots corresponding to
this occurrence ; but if 0 be placed between two unlike signs, +
and — or — and +, then there will be no root corresponding to it,
unless at the same time X = 0. Ifthe substitution of a makes any
number of consecutive derivative functions equal to 0, then, if
there be an even number 2 p of consecutive zeros, there will be p
or (p — 1) pairs of imaginary roots corresponding, according as
they are placed between the same or different signs; and if there
be an odd number 2p + | of consecutive zeros, then there will
be p + 1 or p pairs of imaginary roots corresponding, according
as they are placed between the same or different signs *.
The preceding propositions may be easily shown to include
the theorem of Des Cartes ; for it is obvious that the substitution
of 0 for x in X and its derivatives will give a succession of signs
identical with those of the successive coefficients of X, deficient
terms being replaced by 0. If the extreme values « and — 6
be substituted, there will be m permanences in one case and m
changes in the second ; it will follow therefore that the number
of real and therefore positive roots between « and 0 cannot ex-
ceed the number of changes of sign corresponding to « = 0, or
amongst the successive coefficients of the equation ; and that the
number of real and therefore negative roots between — 6 and 0
cannot exceed the number of permanences corresponding to
x = 0, or of changes between 0 and — 8, which is also identical
with the number of successive permanences of sign amongst the
coefficients of the equation.
* | have stated this rule differently from Fourier, whose rule of the double
sign appears to me to be superfluous. If we consider the zeros as possessing
arbitrary signs, the nature and extent of the ambiguity which they produce
will always be determined by the circumstances of their position with respect
to the preceding and succeeding sign.
The rule of the double sign, when one of the derivative functions Xi, Xi, Xi,
&c., becomes equal to zero, is made use of in a memoir by Mr. W. G. Horner,
in the Philosophical Transactions for 1819, upon a new method of solving nu-
merical equations. This memoir, though very imperfectly developed, and in
many parts of it very awkwardly and obscurely expressed, contains many
original views, and also a very valuable arithmetical method of extracting the
roots of affected equations. It makes also a very near approach to Fourier’s
method of separating the roots of equations. It is proper to state that
Fourier’s proposition was known to him as early as 1796 or 1797, as very
clearly appears from M. Navier’s Preface to his Analyse des Equations Déter-
minées, a posthumous work, which appeared in 1831.
REPORT ON CERTAIN BRANCHES OF ANALYSIS. 331
In order to render the preceding propositions more easily in-
telligible, we will apply them to two examples.
Let X = 24 — 423 —32 + 23=0, and underneath X”,
Xiii, Xi, Xi, X, let us write down the signs of the results of the
substitution of 0, 1, 2, 3, 10, in the place of x, in conformity
with the following scheme:
be ee b, tah X', XxX,
(0) radon pont): Dx sosmie snk
(1) epsom wh caghee g
(2) ae 0 — +
(3) Fabs cries lt wngic ict
(10) eel Ws bae te
For x = 0, there is a result 0 placed between two similar
signs; there is therefore a pair of imaginary roots correspond-
ing to it. Every value of z less than 0 will give results alter-
nately + and —, and there is therefore no real negative root.
For x = 1, there is a result 0 placed between two dissimilar
signs: there is therefore no pair of imaginary roots corre-
sponding ; and since there is no loss of changes of sign in pass-
ing from 0 to 1, there is no real root between those values.
For x = 2, there is a result 0 placed between two dissimilar
signs ; there is therefore no pair of imaginary roots correspond-
ing, and there is no root between | and 2.
For z = 8, there is a loss of one change of sign, and there is
therefore one real root between 2 and 3.
For x = 10, there is a loss of one change of signs and all the
resulting signs are positive; there is therefore one real root
between 3 and 10.
The limits of the real roots are thus completely determined,
and the substitution of the successive whole numbers, from 3
upwards, will show the nearest whole numbers 3 and 4, between
which the greatest root is situated.
Let X = «®— 122° + 6024 + 123.2% + 4567 x — 89012 = 0
xX", » oa , GP Bi bd Xi, ».¢
(—10) apy be Mored baerechp he asia
(—1) 2 Spihiite o2 Dye we einbniceat Se =
(0) Ep eer ae
Cee
TRANSACTIONS OF THE SECTIONS. 399.
natural results due to the influence of the chemical affinity,
modified by the current. The refusal of elements or substances
present to collect at the poles unless they are in relation by
solution or chemical affinity with the substances present, also
finds its natural reason in the theory.
The fact that an element will sometimes go to one pole and
sometimes to the other, according to the substances with which
it is in association at the time, is an immediate result-of the
theory. Nitrogen is said to do this: it will go freely to the po-
sitive pole, and doubtfully to the negative pole. Water will go
either to the positive or negative pole, and sulphur will also do
so: from oxygen it will go to the negative pole, from silver to
the positive pole.
Want of time and apparatus prevented a further develop-
ment of this view and its consequences, but it will appear in de-
tail in the next Part of the Philosophical Transactions.
Experiments on Atomic Weights. By Dr. Turner.
Dr. Turner reported to the Meeting that he had continued
his researches into atomic weights, and had to his own convic-
tion determined the points which had induced him to undertake
the inquiry. ‘These were, first, to form an opinion of the re-
lative accuracy of the tables of equivalents employed in this
country and on the continent; and, secondly, to ascertain whe-
ther there existed any trustworthy evidence in proof of the
hypothesis that the equivalents of bodies are multiples by whole
numbers of the equivalent of hydrogen. To examine these
questions he endeavoured to ascertain by careful and often-
repeated experiments the equivalents of silver, chlorine, lead,
barium, thercury, and nitrogen, in relation to oxygen. These
were selected in consequence of their frequent use in analysis.
An error in these could not exist without affecting the equiva-
lents of nearly all the other elementary substances. The re-
searches on this subject had been lately read before the Royal
Society, and would probably, ere long, be published in some
form or other. The general result is, that the atomic weights
current in this country are much less exact than those given
by Berzelius; that though they had been recommended to
British chemists as rigidly correct, they were often very inexact,
and had been determined by methods which in some important
cases were defective. Further, he finds that as far as experi-
mental evidence at present goes, the hypothesis above alluded
to is unsupported. In some instances the equivalents are so
nearly simple multiples of that of hydrogen that they may be
taken as such without appreciable error; but in many other
400 THIRD REPORT—1833.
cases the numbers given by experiment cannot. be reconciled
with the hypothesis. The following are the numbers which he
is disposed to believe very nearly correct :—lead, 103-6; silver,
108 ; chlorine, 35°42; barium, 68-7; mercury, 202, perhaps
slightly higher, but not higher than 202°3; nitrogen, 14-2. Dr.
Turner states that his methods for ascertaining nitrogen were
not so advisable as that in which Dr. Prout is occupied by
weighing the gases. This weight should be kept in abeyance
for the present. He conceives that it does not fall below 14,
nor exceed 14°2. During these researches he incidentally ob-
tained some facts for inferring the equivalent of silver; and.
from these it appears that the equivalent of sulphur is nearer
16:1 than 16. He would not venture, however, to make a
positive statement without further inquiry.
He then mentioned that Dr. Prout had kindly informed him
of a fact which he conceived analytical chemists in general to be
ignorant of, and which he thought might have had an influence
on these researches. The fact is, that chloride of silver, however
white and well washed, gives out a little muriatic acid at the
moment of fusing: This fact Dr. Turner has examined, and can
confirm. It especially ensues when fusion takes place before
the chloride has been well dried ; but in the event of the chloride
of silver being first well dried at 300° (when no acid is given
out), and then, without exposure to the atmosphere while cold,
fused, the loss of acid is not appreciable in weight, though it is
still sufficient to redden delicate litmus paper. In two experi-
ments about fifty grains of chloride of silver were fused, (pre-
viously dried at 300°, introduced while hot into a dry bottle
furnished with a tight cork, and weighed in that state,) and the
loss was inappreciable. From this circumstance, taken in con-
junction with the mode in which he habitually weighs the
chloride of silver, he is satisfied that the fact observed by Dr.
Prout does not necessarily produce any error in the determi-
nation of chlorine by means of silver.
Notice of a Method of analysing Carbonaceous Iron. By
Professor JOHNSTON.
Professor Johnston gave an account of a new mode of deter-
mining the amount of charcoal in the carbonaceous irons, by »
which he hopes to obtain results more precise and trustworthy
than those arrived at by any former mode. This method con-
sists essentially in reducing the iron to fine powder in a steel
mortar, and burning it with oxide of copper. Mr. Johnston
expects to be able to lay a series of results before the next
Meeting of the Association.
‘ews eS re
TRANSACTIONS OF THE SECTIONS. 401
‘Communication respecting an Arch of the Aurora Borealis. .
By R. Porter, Jun.*
A very luminous arch of an aurora borealis was observed at
Edinburgh by Professor Forbes on the evening of the 21st of
March 1833. It was observed at Athboy in Ireland by the
Earl of Darnley, by Dr. Robinson at Armagh, and also by a
correspondent of one of the Carlisle newspapers.
‘The observations demonstrate the view of the symmetrical
arches being similar to parallels of latitude round the magnetic
axis, the arch being seen in those positions at Edinburgh,
Armagh, and Athboy which such a direction requires.
Report of Experiments on the Quantities of Rain falling at dif-
ferent Elevations above the Surface of the Ground at York,
undertaken at the request of the Association, by Wiua1aAM
Gray, Jun., and Joun Puttuirs, F.R.S. G.S., Secretaries of
the Yorkshire Philosophical Society ; with Remarks on the
Results of these Experiments, by Joun Putuutrs, F.R.S. G.S.
I. Report of the Experiments.—York, the site of these
experiments, stands in the centre of perhaps the most uniform
and extensive vale in England, reaching from the mouth of the
Tees to the estuary of the Humber, a length of 70 miles, with
a breadth of from 15 to 25 miles. In this vast space no ground
rises more than 100 or 150 feet above the level of York ; and
the Minster, elevated 200 feet from the ground, looks down upon
an area of above 1000 square miles, in which hardly any object,
whether of nature or art, rises to within 100 feet of its summit.
On the east the vale is bordered by the range of the Wolds,
whose extreme height is 805 feet, and the escarpments of the
oolitic system, which swell to 1485 feet. On the west, the
distant hilly regions of the coal and limestone tract appear
above the low plateau of magnesian limestone.
- These circumstances of situation give an importance to the
moderate height of York Minster which is denied to many
loftier buildings in England. From its summit the course of a
aed storm may be well traced from even the distant hills of
ichmond ; and the deflections occasioned by the attraction of
the sides of the vale, the rushing of the air, the sudden fall
of temperature, and many other curious phznomena accom-
panying the precipitation of rain, may be well observed.
_ It is, probably, to the peculiarity of its geographical situation
that we are to attribute the remarkable general regularity of the
curves of mean temperature at York; for the deviation of the
* See Lond. and Edinb. Philosophical Magazine, Third Series, vol. iii. p. 422.
1833. 2D
402 THIRD REPORT—1833.
daily mean temperature at this place from the annual mean is
pretty exactly proportional to the sines of the sun’s declination
25 days before the day of observation. The mean temperature
of the year is 48°-2; of July 62°, of January 34°°5. Average
quantity of rain 24 inches. Prevalent winds W. and S.W.:
about the vernal equinox N.E. winds are frequent.
The Yorkshire Museum lies nearly west of the Minster, en-
tirely beyond the city, which here encircles the Minster by a
narrow belt of houses. Its roof is the highest in the immediate
vicinity: it stands free from other buildings, and is surrounded
on every side by the grounds of the institution.
In these grounds, south-west of the Museum, the third sta-
tion is taken, in the midst of a large grass-plat. ‘The second
and third stations are nearly equidistant from the Minster:
the intervening distances are, Pace
Between the Minster and the Museum gauges . 1100 ©
the Museum and garden gauges ... 186
Elevation of the gauges above the river, which is nearly
level with high water in the Humber: PE a.
Minster top gauge, raised on 9 ft. pole . . . 241 104
Museum top Bade Vy.) ceil ee oY 72 8
Gauge in grounds ...... Ve? Ae ee 29° 0
From these data it will appear that it would be difficult to
select three points more remarkably embracing the desired
conditions of gradation of altitude, openness of sky, and con-
tiguity of position. :
The gauges employed are of the simplest construction. A
cubical box of strong tin, exactly 10 inches by the side, open
above, receives, at an inch below its edge, a funnel sloping to
a small hole in the centre. On one of the lateral edges of the
box, close to the top of the cavity, is soldered a short pipe,
in which a cork is fitted. The whole is well painted. This is
the gauge. The water which enters it is poured through the
short tube into a cylindrical glass vessel graduated to cubic
inches and fifths of cubic inches. Hence one inch depth of
rain in the gauge will be measured by 100 inches of the gra-
duated vessel, and +,!5;th of an inch of rain may be very easily
read off. All the gauges were made on the same mould, and
the same glass jar has been used in every observation.
The gauge in the ground has its edge nearly level with the
grass ; that on the Museum projects 11 inches above the stone-
work; and the Minster gauge is supported on a pole nine feet
above the level of the battlements of the great tower, whose
top is 70 feet square. ;
TRANSACTIONS OF THE SECTIONS.
Table of Results for Twelve Months.
1832, 1833.
Feb. 4 to Feb. 13.
September
October .
November
December .
January .
February .
Total of 12 months} 15-910
Ditto, exclusive of
snow in Feb. 1833
Minster.
Inches,
‘060
20. -010
27. 017
5. 174
12. *198
19. 052
041
2. “005
9. ‘701
16. 013
23. “249
30. 1-113
ve 375
14. 133
21. 088
002
5. 557
12. "958
2. “908
9. +351
16. “999
113
6. ‘711
13. 033
27. 1-639
3. 1:388
17. *376
8. 439
12. 1°459
30. 1:019
17. “708
14. “836
1, Snow *195
} 15715
Museum.
Inches.
7119
010
7020
“251
273
062
116
-006
756
“015
"353
1:574
442
203
141
010
“719
1-138
1-166
397
1-115
133 |
*785
*050
1911
1:747
500
*605
2-080
1308
1:012
1165
Snow'279
20°461
20°182
Ground.
Inches.
"147
-008
018
+366
*386
093
*238
004
Snow ‘616 drift- {
ed.
24:401
23°785
Q2p2
Abundance of Aphodii
in the Minster gauge.
Remarks.
Violent gales.
{ Perpendicular
without a trace of
wind, in large drops.
Thunder storm.
Abundance of small
Hymenoptera in the
Minster gauge, but
not in the others.
ditto.
(This occurrence has
been frequently noticed
in the summer and au-
Ditto
tumn.)
Drifted snow on the top
of the ground gauge.
403
rain,
404 THIRD REPORT—1833.
II. Remarks on the Results of the Experiments.—The pre-
ceding table of results appears sufficient, when combined with
some other data which I have obtained, to authorize some in-
teresting inductions concerning the law and the cause of the
remarkable inequality of the quantities of rain at different ele-
vations above the ground.
1. The notion which is most generally entertained of the
cause of this inequality is, that wind, blowing horizontally,
causes fewer drops of rain to fall upon the more elevated
gauges. That this notion is a mere fallacy, the least acquaint-
ance with mechanics is sufficient to prove; for certainly the
number of drops of rain which fall, under the joint influence
of gravitation and ordinary wind, upon horizontal surfaces,
will be, ceteris paribus, exactly the same at all elevations be-
low the point from which the rain descends.
2. It is supposed by some that eddy winds, produced by
the sides of buildings and rising upwards, may deflect the rain
so as to prevent much of it from falling on those buildings. It
is certainly conceivable that this irregular action against gra-
vity may, when very violent, under particular circumstances,
produce a sensible effect, and such appears to be recognised
by our experiments, in one instance, during the equinoctial
period of March 1832.
But it is evident that in the majority of cases the effect of
the eddying wind is quite unimportant. I have noticed in se-
veral instances the fact, that the wind which accompanies the
fall of rain takes the line of the rain-drops themselves ; and
on the Minster, in particular, this was very strikingly illus-
trated, when, with my friends Mr. Jonathan Gray and Mr.
William Gray, junior, I watched the progress of a storm for 30
miles down the vale of York. The wind was insensible except
during the fall of rain, and then it came downward with the
drops. There is no need of further remarks on this subject,
because the results recorded are too regular, considerable, and
consistent with known properties of the atmosphere, to be
explained by such fluctuating and inadequate agency.
3. With respect to the observations on the ground, I have
procured several registers of the rain which fell in and about
York, for comparison with the observations in the Museum
garden. By this comparison it is abundantly evident that the
situation of the gauge, its exposure to eddy winds, and other
irregularities, have very little influence upon the mean results.
While the gauge in the Museum garden is remarkably open on
all sides, and set devel with the ground, Mr. J. Gray’s is raised
three feet above, and placed ina small garden, surrounded by
TRANSACTIONS OF THE SECTIONS. 405
high walls and buildings. Yet in the Museum garden we have
for 12 months 23°785 inches of rain, and Mr. J. Gray’s results
for the same period are 23:020. (The snow which fell in this
period is excluded from both these numerical statements.) ‘The
depth of rain appears pretty nearly uniform over the broad
vale of York, and even beyond it. Thus at Ackworth, 25
miles S.W., the quantity collected in 1832 .... . =24°94
At Brandsby, 12-miles N. (station nearly level with the
top of York Minster) .. 1... + +++ ee ee + 25°69
a ere CE CO ow ne ai a lan i se LOT
4. I shall now proceed to arrange the numerical results of
the experiments, in relation to mean temperature and the
season of the year, and thence to énfer the ratios of quantity
at the several stations. The quantity of snow which fell is
always deducted, because it was found to drift into the lower
auge. This quantity was, however, very small and only sen-
sible in February 1833. =
On On On
Periods. Mean Minster. Museum. Ground. Ratios,
Temp. | In. of Rain.| In. of Rain.| In. of Rain.
Whole year... . . | 48:20| 15°715 | 20-182 | 23-785
7 coldest months,
Oct., Nov., Dec., j : y :
Jan., Feb., Mar., 40°8 7:089 9-725 | 12:079
April
7 warmest months,
April, May, June,
July, Aug., Sept.,
October ....
5 coldest months,
Nov., Dec., Jan.,,
Feb., March
5 warmest months,
May, June, July,
Aug., September
Winter quarter,
Dec., Jan., Feb.
Spring quarter,
Mar., April, May
Summer quarter,
June, July, Aug.
Autumn quarter,
Sept., Oct., Nov.
* In 1833, The Museum gauge gave. . . - + - 22959 inches.
Mr. J. Gray’s 23-060
Dr. Wasse, at Moat Hall, (10 miles from
York)... 23-895
406 THIRD REPORT—1833.
5. The first remark which I shall make on these results is,
that the diminution of the quantity of rain received at different
heights above the ground, as compared with that received on
the ground, is very accurately represented by a simple formula
involving one constant, viz. the square root of the height of
the station above the ground, and one variable coefficient.
Thus, m / h = the diminution of rain at the given height.
In these experiments
WV h for the Minster gauge =° / 212°833 = 14°5885
for the Museum gauge = / 43°666 = 6°6080
Taking m = 2°29, we have for the whole year,
: By calculation . . .. 66°5 84°97)
Ratios :
By observation .. 66:1 we
For the 7 coldest months (m = 2°88,)
By calculation ... 58 81
By observation .. 58°6 80°5
For the 7 warmest months (m = 1:97,)
By calculation ... 71°3 87-0 . +, 100
By observation .. 71:2 SS ORE Aer
For the 5 coldest months (m = 3:06,)
By calculation... 55°4 — 79°8
By observation .. 562 79
For the 5 warmest months (m = 1°75,)
By calculation... 745 88:4
By observation .. 73°7 89°2 J
In these, which are the longest averages attainable from the
experiments, there is an almost exact agreement between
the calculated and the observed results, the greatest error
being +3,th.
‘In shorter averages of three months, and, indeed, though
less exactly, in every single month when much rain fell, we
may recognise the same constant relation. Thus we have
For the summer quarter (m = 1°43,) 7
By calculation . . . 79-0 90°5
By observation .. 771 92°5
For the winter quarter (m = 3°79,) tel
By calculation... 446 747
By observation .. 49°3 70°5 ‘ to 100
For the spring quarter (m = 2°84,) ;
By calculation... 58°6 811
By observation .. 59°8 80:0
For the autumn quarter (m = 2°19,)
By calculation ... 68:1 85°4:
By observation .. 65°8 87°7 J
TRANSACTIONS OF THE SECTIONS. 407
The three most rainy months of the year 1832 were June,
August, and November.
For June we have, 7
By calculation... 77°6 90:1
By observation .. 74° 5 93°2
For August,
By calculation ... 77°6 90:1
By observation .. 77:9 89:8 |
For November,
By calculation .. . 70°2 86°8
By observation .. 663 90°7
6. From these comparisons it appears to follow, that though
the exact relation between the diminution of rain and the
height of the station can hardly be considered as satisfactorily
determined by the experiments of twelve months, the nature
of this relation is so far ascertained that we may conclude it
to be constant for all periods of the year, and that the form
WV h is a good first approximation.
7. The account of Dr. Heberden’s experiments on West-
minster Abbey does not state the elevation of the stations ;
yet if we take the height of the square part of the roof at
about 120 feet, and from this infer, according to the formula,
the height of the house-top which was the middle station above
the point below the house-top which was the lowest station,
we shall still be able to use those experiments as a check upon
the law of the ratio now given. In this case, fA = 11:0
and 4°6, and we have :
For the whole year, qoin
By calculation (m = 4°23)... 53°5 80°5
By observation... ..... 53°5 80:5
For the 7 coldest months,
By calculation (m = 4°26) . 53:1 80:4
By observation ....... 53 80°5
For the 7 warmest months,
By calculation (m = 3:90) . 57:1 is D
By observation ....... 57
For the 5 coldest months,
By calculation (m= 4°70) . 48:3 78°53
By observation ....... 48°6 78°0
For the 5 warmest months,
By calculation (m = 4:19) 53°9 ms °|
By observation ...... 54°5
to 100.
CH
408 THIRD REPORT—1833.
For the winter quarter, 7
By calculation (m = 4°42) . 51°4 79°6
By observation ....... 51°5 79°5
For the summer quarter,
By calculation (m = 4°14) . 55°5 808
By observation ¢ it! sa. Wee 52°7 82°6
For the spring quarter, Mee
By calculation (m = 4°92) . 45:9 17:2 |
*By observation. ;... 00°20. 48 75°1
For the autumn quarter,
By calculation (m = 3°71) . 59:2 82:9
By observation ....... 57°8 84°3 J
It is therefore probable that the Westminster results obey the
-same constant relation to height as those of York.
8. But it is evident that the values of the variable coefficient
are very different ; that its maxima and minima are perhaps
not quite in the same periods of the year as at York; and
that ‘the range of variation in its value is very much less.
From M. Arago’s determination of the relative quantities of
rain falling on the Observatory at Paris and in the court 28
metres below, as given by Professor Forbes, in his Report on
Meteorology, 50:47 : 56°37, the relative mean value of m at
Paris = 1°24, while at Westminster it was 4°23, at York 2°29.
It must be owned that these discrepancies with other obser-
vations as respects the quantity of the diminution of rain up-
wards are somewhat discouraging, and probably will, for a
considerable time, deprive the most exact local determinations
of this quantity of a general application. This, indeed, could
hardly be expected, since the whole quantity of rain is so va-
riously dependent on circumstances of physical geography,
that centuries have been found insufficient to determine the
general law and ascertain the numerical constants of local
climate. Yet, on account of the remarkable regularity of the
progress of monthly temperature at York, and some very ob-
vious relations between the quantities of rain collected and
the mean temperature of the period, I will venture to state
what seem unavoidably to suggest themselves as probable in-
ferences.
9. First, it is obvious that the diminution at the upper sta-
tions is greatest in the cold season, and least in the warm
season, and therefore the coefficient is in some way znversely
dependent on the temperature, or on some effect of this tem-
* March very anomalous.
ee ee ee ee eee
TRANSACTIONS OF THE SECTIONS. 409
perature. If we consider it in relation to the mean tempera-
ture, we shall find a near coincidence between the following
t i
; —~ta-,
formula, and observation: m =* 7 ik ¢*, where a = the
ascertained value of m, for the whole year, ¢ the mean tempe-
rature of the year, and ?¢' that of the particular period under
consideration.
Value of m| Value of m Difference:
For the 7 colder months .. 40'S |= 2°98
7 warmer months..| 55°5 1°87
5 colder months ..| 39:3 3°16
5 warmer months..| 58°5 1:74
Winter quarter....| 363 3°57
Spring quarter....| 47°6 2°35
Summer quarter ..| 60°8 1-64
Autumn quarter ..| 48:3 2°30
10. Secondly, it is obvious that the relation between the
values of m and the dryness of the air is inverse. This dry-
ness is usually expressed by the difference between the mean
temperature and the mean dew point, and where the latter is
erfectly determined, no better plan perhaps can be suggested.
But this is the case for very few places in Great Britain. There
is, however, another mode of expressing the dryness of the air,
which is fortunately applicable to the present purpose; the
mean range of daily temperature, or mean difference of maxima
and minima, is a good approximation to an accurate expression
of the relative dryness of the air. The following table of the
mean ranges of temperature near York has been determined
with the greatest nicety, by long averages, from the careful
and continued observations of Francis Cholmeley, Esq., of
Brandsby.
January mean range.... 8°0 July: mean range ....:. 19°6
BEDURAIRe js \<:- 30s apnteyl ae 10-1 AME USbic wiped «AF di 218 17-7
ES an re es 13°1 Senter Ber oy. a uicisadetieds 16:0
To nahin sean 16:2 9 Fee) 17 a ee nT 118
Ea 19°7 INOVEMIDER ws. nicsnteg ass, « 9:0
Nr ct cin nin 20°1 DE CARA DEE pies non crac ion
General mean Tage... ws os 14:08
On comparing these numbers with Mr. Daniell’s estimates of
the dryness of the air in London, they will be found analogous
410 THIRD REPORT—1833.
in general proportions. ‘They may also be compared with an
excellent series of dew point observations in the Manchester
Memoirs by my triend Mr. John Blackwall, whose results in
other respects | have found remarkably in accordance with my
own inferences concerning the climate of York.
Now, let m be taken inversely as the mean range of tempe-
= we shall have the following
rature, (r) orm=a
comparison between the calculated and observed values.
(a = 2°29.)
Value of m | Value of m
Pet es ae | Difference.
For the 7 coldest months...... = 2°98 = 2°88 0:10
7 warmest months .... 1°86 1:97 O11
5 coldest months...... 3°36 3°06 0°30
5 warmest months .... 1°73 L- 73 0-00
Winter quarter ...... 3°74 3°79 0:05
Spring quarter........ 2°48 2°84 0°36
Summer quarter ...... 1°68 1°43 0°25
Autumn quarter ...... 2°63 2°19 0:44
Na a a
So remarkable and continued an accordance between the co-
efficients fixed by observation and those derived by two methods
from a very simple view of the condition of the air as to heat
and moisture, appears to me decisive of the question as to
the general cause of the variation of the quantity of diminution
of rain at any one height above the ground. It has already
been shown how strictly the observations warrant the con-
clusion that the ratio of diminution at different heights is con-
stant through the whole year. It is therefore rather as a
matter of very probable inference than a plausible speculation
that I offer the hypothesis, that the whole difference in the
quantity of rain, at different heights above the surface of the
neighbouring ground, is caused by the continual augmentation
of each drop of rain from the commencement to the end of its
descent, as it traverses successively the humid strata of air at
a temperature so much lower than that of the surrounding me-
dium as to cause the deposition of moisture upon its surface.
This hypothesis takes account of the length of descent, because
in passing through more air more moisture would be gathered ;
it agrees with the fact that the augmentation for given lengths
of descent is greatest in the most humid seasons of the year ;
it accounts to us for the greater absolute size of rain-drops in
ee)
TRANSACTIONS OF THE SECTIONS. 411
the hottest months and near the ground, as compared with
those in the winter and on mountains; finally, it is almost an
inevitable consequence from what is known of the gradation of
temperature in the atmosphere, that some effect of this kind
must necessarily take place. The very common observation
of the cooling of the air at the instant of the fall of rain, the
fact of small hail or snow whitening the mountains, while the
very same precipitations fall as cold rain in the valleys where
the dew point may be many degrees above freezing, is enough
to prove this. A converse proof of the dependence of the
quantity of rain at different heights on the state of the air at
those heights, is found in the rarer occurrence of a shower
falling from a cloud, but dissolving into the air without reaching
the ground. Lastly, I cannot forbear remarking, that this hy-
pothesis of augmentation of size of the elementary drops
agrees with the result that the increase of quantity of rain for
equal lengths of descent is greatest near the ground; for
whether the augmentation of each drop be in proportion to its
surface or its bulk, the consequence must be an increasing
rate of augmentation of its quantity as it approaches the
ground.
The direct mathematical solution of this problem, now that
the laws of cooling and of the distribution of temperature have
undergone such repeated scrutiny, may perhaps be attempted
with success; but for the purpose of eliminating the effects of
periodical or local modifying causes, it is desirable that obser-
vations on the same plan should be instituted at many and di-
stant places,—both along the coasts and in the interior,—in the
humid atmosphere of Cornwall and in the drier air of the mid-
land counties. Always, at least three stations should be chosen,
as open as possible, one of them very near to the ground:
their relative heights, the mean temperatures, the mean
ranges of temperature, and the mean dew point for each
month should be ascertained. It would be useful to measure
‘the size of the rain-drops, and, if possible, their own tempe-
rature. The height of clouds, according to the plan of Mr.
Dalton, in his Meteorological Essays, and the direction and
force of wind should be noted, and distinctions made between
snow; hail, and rain. Some of these data I have not yet found
the means of procuring, partly in consequence of the great
labour and time required, and partly from the difficulty of well
arranging the experiments themselves. But since it is now
ascertained that the general results follow some settled laws,
and that the effects may be very well appreciated at moderate
_ heights, I hope not only to procure these, but also several
412 THIRD REPORT—1833.
other data towards the completion of the theory of this curious
subject, the patient investigation of which cannot fail to give
us new and penetrating views into the constitution of the at-
mosphere.
II. PHILOSOPHICAL INSTRUMENTS AND
MECHANICAL ARTS.
On a peculiar Source of Error in Experiments with the Dip-
ping Needle, By the Rev. Wituiam Scoressy, F.R.S.
Certain discrepancies, at the time apparently unaccountable,
in observations made with a beautiful dipping-needle, by Dol-
lond, entrusted to Mr. Scoresby’s care by the Board of Lon-
gitude, in an arctic voyage, led him, after a considerable interval
of time, to reflect upon the cause. Whatever might be the
apparent consistency of any particular series of observations
in the ordinary use of the instrument, the differences perceived
when the poles of the needle were changed indicated that
the preceding results were not accurate. But as the different
results thus obtained were capable of being combined for ob-
taining the true position of the needle, the formula of Professor
J. Tobias Meyer, given in his treatise De Usu accuratiori
Acts Inclinatorie Magnetice, was adopted for this purpose.
To verify the position thus obtained, another series of obser-
vations on the same spot was then made, with one of the arms
of the needle weighted, so as to render its position more de-
cisive from being the resultant of two forces, gravity and
magnetic attraction. The results, however, of the different
series were again anomalous ; but the cause of the discrepancies
thus observed not being fully apprehended at the time, the
consequence was that the observations were set aside for want
of consistency.
Subsequently, however, it occurred to the author that the
cause of the discrepancies was to be found in the alteration of
the magnetic intensity of the needle when the polarity was
changed; a circumstance furnishing a new element in these
calculations, not hitherto, he believes, taken into account. For
when the poles of the dipping needle are changed, (unless
magnetized with extraordinary care and some perseverance in
repeating the process,) the magnetic intensity of both positions
will not be the same. It is indeed a fact which the author fre-
quently observed, that the capacity of a properly tempered
steel bar for the magnetic power (provided it have been kept a
considerable time in the same magnetic condition,) is the great-
TRANSACTIONS OF THE SECTIONS. 413
est when the polarity is preserved in the usual way, and of
consequence loses in intensity of directive force whenever the
polarity is changed. This effect, then, if the needle be not
perfectly balanced and suspended,—which, strictly speaking, it
scarcely can be expected to be,—must necessarily follow, that
the calculated position, by the usual formule, derived from
observations made with the needle in opposite conditions of
polarity, will not give the true direction of the magnetic force.
For wherever there is any defect in accuracy of suspension,
balancing, or adjustment, then the needle being acted upon
by two forces,—that of magnetic direction, depending on its
magnetic intensity, and gravitation, depending on the horizontal
leverage of the centre of gravity of the needle in respect to the
axis,—its position will, of course, be the resultant of the two
operating influences. But if with one direction of the poles
the magnetic intensity be less than in the other, then the re-
sultant of the combined forces must change its direction from
the preponderating of gravitation there; and, consequently,
the effect of gravitation will not be neutralized by the ordinary
mode of mutual correction, because of the relations of that
force to the directive being changed. Of this, an example
taken from arithmetical means will be sufficient for illustration.
Suppose the dip, as determined by the mean of various ob-
servations in the usual position of the needle, to be, say 70°,
and the result on inversion of poles be 72°, then the actual
dip will evidently not be the arithmetical mean of 71°, neither
the mean of the tangents of 70° and 72°, thatis, 71° 3!, unless
the magnetic intensity be in both cases precisely the same. But
as the intensity in the original direction of the polarity would,
probably, be very considerably greater than the other*, the
real dip might be 70° 50’, or even 70° 40’, rather than 71°!
Hence, for accuracy of result in such cases, a new element
seems to be requisite—that of the relative magnetic intensities
or powers of the poles of the needle under each condition of
polarity—and by observing the number of vibrations of the
needle in a given time, in each state of polarity, these reduced
to actual intensities would afford an element as a corrective for
the source of error herein under consideration.
* The difference of intensity on changing the poles will be the most consider-
able in the hardest-tempered needles, or in cases where the fixedness of the axis
renders the best modes of magnetizing impracticable. In soft bars, or where
very powerful magnets are used, the differences from this cause become com-
paratively trifling, and sometimes altogether disappear; but still there is no
security without verification, that in any case the intensities of the changed
poles will be the same. '
414 THIRD REPORT—1833.
On the Construction of a New Barometer. By the Rev. W.H.
Mutter, F.G.S., Professor of Mineralogy, Cambridge.
This barometer consists of two tubes, of equal diameter, a
little longer than the greatest height and greatest range of the
barometric column respectively, terminating in a small cistern,
the bottom of which can be elevated or depressed by a screw.
The long tube is bent so that the upper part of it, which is
closed at the end and has a fine point of glass or steel fixed
in its axis, may coincide with the prolongation of the short
tube, which is open at the end. A graduated scale slides along
a vernier attached to the frame of the instrument, in such a
manner that a steel point fixed to the lower end of the scale
may move in the axis of the short tube.
In making an observation with this instrument, the bottom
of the cistern must be elevated or depressed till the surface of
the mercury in the long tube touches the fixed point therein :
the moveable point on the scale being then brought down till
it touches the surface of the mercury in the short tube, the
height of the barometric column is indicated by the division of
the scale opposite to zero on the vernier. The barometer may
be rendered portable by placing a stopcock between the short
tube and the cistern.
On a Barometer with an enlarged Scale. By Wiuu1am L.
WuartTon.
In this barometer a light fluid is introduced upon the top of
the mercurial column of the common barometer, the tube of
the instrument being enlarged at the point of junction of the
two fluids, by which device an instrument of equal or superior
extent of scale may be obtained, without the expense and dif-
ficulty attendant upon the construction and erection of a baro-
meter of which the whole tube is occupied by the light fluid.
Mr. Wharton has employed an instrument of this construction
for twelve years without perceiving that its sensibility is at all
impaired. ,
On the Construction of a new Wheel Barometer. By
Wii1aMm Snow Harris, F.R.S., §e.
The tube of this instrument is 0°5 of an inch in diameter
within, bent in a siphon form at one end, and at the other ex-
panded into a flattened spheroidal bulb, whose diameter is
four inches, and axis, in the direction of the tube, two inches.
eo
a
TRANSACTIONS OF THE SECTIONS. 415
The straight part of the tube, exclusive of the bulb, is 32
inches ; inclusive of the bulb, 34; the recurved end is bent
twice at right angles, so as to project from the tube 3
inches, and rise parallel thereto 7°5 inches. The tube is at-
tached to a mahogany support, the spheroidal bulb being up-
wards; and the quantity of mercury is so adjusted in the tube
that at mean pressures the upper level is nearly coincident
with the greatest diameter of the spheroid, and the lower is
near the middle of the shorter leg.
There is a circle of brass, divided into 1000 parts, fixed to
the front of a light copper drum or case, having a glass front
and back, the centre of which circle is placed just over the
orifice of the glass tube: a small frame of brass is fixed to the
circle behind, so as to carry a light horizontal axis bearing two
small pulleys. The extremities of this axis are turned to ex-
tremely fine pivots, and are set in small jewels: the front one
projects forward so as to carry a light index of straw, which is
sustained on a small brass ring, placed by means of a socket on
the extremity of the axis, in the manner of the hand of a watch.
The two small pulleys above mentioned carry, by means. of
fine untwisted silk threads, two small cones of glass or wood,
one of which rests on the surface of the mercury in the recurved
tube, the other hangs freely on the outside of the tube. These
cones are nearly equal in weight, that resting on the mercury
being rather the heavier of the two. ‘This slight difference of
weight, setting aside the inertia and friction of the axis, is the
amount of the resistance which the rising or falling of the mer-
cury in the tube has to contend with; and this is all extremely
little, so little that the index moves by the unequal action of
the wind during a light gale, and is put into a state of oscil-
‘lation of some considerable duration by the mere opening of
the door of a room. These pulleys measure very nearly one
inch in circumference, so that if the mercury moves an inch
the index is carried once round the brass circle, and hence one
division thereon corresponds to ath of an inch, a correction
being made on the pulley according to the relative capacity of
the tube and the bulb.
The index is made in three parts, of light straws, a centre
piece and two extreme pieces inserted into it: one extremity
is cut after the manner of a pen to a somewhat short and very
fine point, which is turned edgeways. The whole is carefully
equipoised by a short piece of straw sliding on one of the ex-
treme pieces, so that when attached to the axis it takes indif-
ferently any position in the circle, and, consequently, follows
exactly the movement of the mercury.
416 THIRD REPORT—~1833.
A varnished paper is pasted on the front of the tube, marked
27, 28, 29, 30, &c., to denote the height of the mercurial co-
lumn in inches ; these measures being taken with care from the
surface of mercury in the bulb to that in the tube. The index
is set as nearly as possible when the altitude corresponds to
fixed divisions of the scale or measure.
There is a thermometer close to the mercurial column, the
bulb of which is placed in a small cistern of mercury, to indi-
cate the temperature, and a hygrometer to measure the change
which may be supposed to happen in the silk line, to which
the cone resting on the mercury is attached; but the author
has found that by employing fine unspun silk the changes are
quite unimportant.
The quantity of mercury in the instrument is about 15 lbs.
In order to fill the tube clear of air, the following process was
adopted as a substitute for boiling. A small iron cap, polished,
was first cemented air-tight upon the end of the tube, and into
this was screwed an iron stopcock: a long glass tube was then
cemented to the stopcock, furnished with iron caps, &c., so
that by reverting the instrument and steadying the tubes by
cross-bars of wood, tied with silk-ribbon band, the whole may
be screwed into the plate of a good air-pump.
The air being withdrawn as completely as a good air-pump
will effect, the cock is closed, the whole is detached from the
pump, the long tube removed, and the barometer tube trans-
ferred to a cistern of mercury, under the surface of which the
stopcock is fairly immersed, whilst the tube is inclined as much
as possible. The operator, being placed in a convenient position,
supports the ball of the tube in his hand, and turns the cock
gradually, so as to allow the mercury to be pressed up in an
extremely small stream into the tube, and to flow down without
violence into the ball. During this process the ball is gently
moved about with an easy circular motion, which allows of the
more speedy union of the mercury and displacement of the air.
An assistant should be ready to close the cock occasionally, for
the purpose of examining the state of the mercurial mass
within the tube.
In this way the barometer tube may be filled with great
nicety, so as to show a most resplendent surface, equal in ap-
pearance to that produced by boiling even under a powerful
magnifying glass.
When the tube is complete to the point required, the stop-
cock is again closed, the whole is reverted, and the tube is
placed in its intended place; the cock is then opened by de-
grees, and the mercury will gradually descend to the level of
pe
TRANSACTIONS OF THE SECTIONS. 417
the atmospheric pressure. The iron stopcock and cap may
now be removed, by cautious application of first a warm and
then a hot iron rod to the cement.
The mercury intended for the purpose of the barometer
should be first distilled, and then well agitated, about an ounce
or less at a time, in phials capable of holding one ounce and a
half. Previously to introducing the mercury into the tube it
should be well boiled in a crucible, of porcelain or Wedgwood
ware, and should be used just before getting cold, at a tempe-
rature of 90° or 100°, the tube of the barometer being also
made a little warm by careful exposure to a charcoal fire.
The process now described is believed by the author to be,
when carefully performed, in every respect equal to that of
boiling. The wheel-barometer made in this way has been com-
pared with other instruments with boiled tubes and of un-
doubted excellence, amongst others with a fine mountain baro-
meter on Gay-Lussac and Renard’s principle, which had been
compared with the standard of the Royal Society in Somerset
House, and with that in the observatory at Paris. The dif-
ferences from this instrument, when both were placed in the
same room, were very minute. It is found to be more sensible
than a very finely boiled tube, carefully prepared by that emi-
nent maker Mr. Cox, of Plymouth, with a scale and vernier
divided to awth of an inch, set up in an adjoining room.
On a new Method of Constructing a Portable Barometer.
By Joun Newman, Mathematical Instrument Maker.
The object of this construction is to make barometers port-
able without the use of a leather bag, which has always been
a defective part of the instrument.
The method adopted is to have a cylindrical cistern of iron
in two parts, rather longer than usual, the upper part, or
chamber, or that to which the cap is fastened, which connects
to the tube, being about three times the length of the lower
part, of the same diameter, moving round upon a pin, and
secured by a screw and collar. The two chambers thus formed
communicate internally in one situation by means of holes in
the divisions, through which the mercury flows upon invert-
ing the instrument. The vacant space, or that intended to
receive the mercury from the tube when the barometer falls, is;
when the instrument is in use, in the upper part of the upper
cistern, the lower one being full. Upon inverting the instru-
ante mercury flows from the latter into the former, which
418 THIRD REPORT—1833.
becoming filled, is by a quarter turn of the one now upper-
most cut off from communication with it, and the instrument
is rendered portable with the end of the tube dipping into a
cistern of mercury, which is perfectly secure.
By this method Mr. Newman is enabled to make portable
mountain barometers with very large tubes, for sufficient room
can be left in the cistern to receive the mercury which flows
from the tube into the cistern in high situations, notwithstand-
ing the increased diameter of the tube. Barometers, therefore,
can be made and transported, which when put up may be de-
pended upon as standard instruments with perfect security.
On an Instrument for measuring the total heating Effect of
the Sun’s Rays for a given time. By the Rev. James
Cummine, V.P.R.S., F.G.S., Professor of Chemistry,
Cambridge.
It has appeared to Professor Cumming that the information
conveyed to us by the ordinary instruments for measuring the
heating power of the sun’s rays is, in one respect, imperfect,
in as much as these instruments indicate only the momentary
energy of the rays: he was therefore led to devise a process
which should measure the total result of their action in a given
time. The process employed is to expose to the sun a retort
with a blackened bulb containing ether, and to note the quan-
tities of this liquid distilled over in different days. In some
cases, a second bulb of plain glass has been used to increase
the condensing surface, and the apparatus has been otherwise
modified. With instruments on this plan Professor Cumming
has registered the daily effects of the sun’s radiation for more
than two years, and he hopes soon to publish his results in a
connected form.
On some Electro-magnetic Instruments. By the Rev. James
Cummine, V.P.R.S., Professor of Chemistry, Cambridge.
The instruments exhibited and explained by Professor Cum-
ming consisted of: ;
1. A galvanometer of four spirals, similar to that described
in his translation of Demonferrand, (pl. v. fig. 86,) but formed
of flattened copper wire with silk ribbon interposed, each spiral
being fixed upon a graduated slide.
2. A Breguet’s thermometer, with a conducting wire passed
through its axis, for the purpose of measuring either the heat
evolved by different galvanic arrangements in passing through
a given wire, or that evolved in different wires by the same
battery.
TRANSACTIONS OF THE SECTIONS, 419
On the Thermostat, or Heat-governor, a self-acting physical
Apparatus for regulating Temperature. By ANDREW
Ure, M.D., F.R.S., &c.
This instrument acts by the unequal expansion of different
metals in combination: it admits of many modifications of ex-
ternal form, but, im all, the metallic bars must possess such force
of flexure in heating or cooling as to enable their working rods
or levers to open or shut valves, stopcocks, and ventilating
orifices.
»- Steel and zinc are the two metals employed: they possess a
great difference of expansiveness, nearly as two to five, and
are sufficiently cheap to enter into the composition of 'ther-
mostatic apparatus; but zinc has in reference to the present
object one property which should be corrected. After being
many times heated and cooled, a rod of that metal remains
permanently elongated. This property may, however, be in
a great measure destroyed, and considerable rigidity acquired
by alloying it with four or five per cent. of copper and one of
tin. Such an alloy is hard, close-grained, elastic, and very
expansible, and therefore suits pretty well for making the more
expansible bar of a thermostat.
-» Let a bar of zine or of this alloy be cast, about an inch in
breadth, one quarter of an inch thick, and two feet long, and
let it be firmly and closely riveted along its face to the face of
a similar bar of steel of about one third the thickness. The
product of the rigidity and strength of each bar should be
nearly the same, so that the texture of each may pretty equally
resist the strains of flexure. Having provided a dozen such
compound bars, let them be united in pairs by a hinge-joint at
each of their ends, having the steel bars inwards. At ordinary
temperatures the steel plates of such a pair of compound bars
will be parallel and nearly in contact, but when heated they
will bend outwards, receding from each other at their middle
parts, like two bows tied together at their ends. Supposing
this recession to be one inch for 180° Fahrenheit, then six such
pairs of bows, connected together in an open frame with
rabbeted end plates, and with a guide rod playing through a
hole in'the centre of each, will produce an effective aggregate
motion of six inches, being half an inch for every 15° Fahr.,
or 843° C.\ ‘Instead of limiting ourselves to half a dozen such
pairs of compound bars, we may readily lodge in a slender iron
frame a score or two of them, so as to furnish as great a range
of motion as can be desired for most purposes of heat regu-
2E2
420 THIRD REPORT—1833.
lation; and the power of pressure or impulsion may be in-
creased, if necessary, by increasing somewhat the thickness of
each component lamina. One extremity of the series must
obviously be firmly abutted against a solid fulerum or bearing,
while the opposite extremity gives motion to a working-rod of
a suitable kind.
The author of the communication then describes in detail
the various mechanical adjustments by which the apparatus
may be applied to maintain any determined rate of ventilation
through the casements of church windows; to give alarm and
open yalves in water-cisterns in case of fire; to preserve a cer-
tain rate of combustion in furnaces, a uniform temperature in
baths and stills, and to act as a safety-valve for a steam-
engine.
Ona Reflecting Telescope. By Tuomas Davison, of Low
Brunton, near Alnwick.
The author of the invention described in this communication
is a weaver of linen, who has devoted himself with great per-
severance and ingenuity to the construction of telescopes and
other instruments. ‘The modification of the ordinary con-
struction of a reflecting telescope which Thomas Davison has
executed is intended to improve the performance of the in-
strument by diminishing the false or aberrant light which in-
terferes with the distinctness of the image.
From the nature of its construction, the Gregorian telescope
is most exposed to this defect, and it is, therefore, to that form
of the instrument that the invention more particularly applies.
To each reflector tubes are adapted, having their axes coin-
cident with that of the mirrors, and their free ends directed
towards each other. The tube connected to the great speculum
enters the hole of that speculum, and is of a slightly conical
form, diminishing cuban; and prolonged to such a degree as,
without stopping many of the rays which should meet in the
image, to prevent nearly all the false light from entering the
eye-tube. The tube connected with the small mirror is pro-
longed so as to meet the extreme rays which converge from
the great speculum towards the ibaa Constructed in this
manner, Thomas Davison’s telescope was found more effective
than one upon the ordinary plan. By simple contrivances the
instrument can be converted to the Cassegrainian or Newtonian
form.
TRANSACTIONS OF THE SECTIONS. 421
On a Steam-engine for pumping Water. ByW.L.Wuarton.
In this engine the steam is admitted from the boiler upon a
deep float, occupying the top of a column of water contained in
a metallic cylinder, placed in the flue of the boiler fire. The
lower part of the column of water is connected by pipes to the
under side of a piston, moving water-tight in a much smaller
cylinder, fixed immediately above the pumps of any mine, to
the rods of which is affixed the piston rod. By this arrange-
ment the steam always acts upon a heated surface, and its
power is applied to the pump rods without the intervention of a
main beam, parallel motion, &c., and, consequently, without any
expense for frame-work and buildings requisite for their support
in other engines. The friction of this engine, moreover, is very
trifling, a stratum of oil being introduced both above and be-
low the piston. A rod or wire is attached to the float, and,
passing through a stuffing box in the top of the large cylinder,
works the hand gear at the proper periods after the admission
and escape of the steam, and consequent depression and ele-
vation of the water and float, within that cylinder. A condensing
apparatus may be added, by which the atmosphere may be
rendered available, in addition to the weight of the pump rods,
to force down the piston in the small cylinder, and, conse-
quently, the water and float to the top of the large cylinder,
after each stroke of the engine.
On the Application of a glass Balance-spring to Chrono-
meters. By Enwarp Joun Dent.
Mr. Dent described the various difficulties in the con-
struction of chronometers dependent on the imperfection of
metallic balance-springs, whether made of gold, or of soft or
hardened steel; and explained the advantages which may be
expected to arise from the substitution of some substance pos-
sessed of greater and more regular elasticity. Glass appeared
a substance likely to answer this condition, and when formed
into a cylindrical spring, it promised, from the trials that had
been made, to be both accurate and durable. An instrument
was exhibited with the glass spring in movement.
ost
On the Effect of Impact on Beams. By Karon Hopexinson.
The author gave the results of some inquiries into the power
of beams to resist impulsive forces. The experiments were
422 THIRD REPORT—1833.
made by means of a cast-iron ball, 44 Ibs. weight, suspended
by a cord from the top of a room with a radius of 16 feet. The
ball, when hanging freely, just touched laterally an uniform
bar of cast-iron, sustained at its ends in a horizontal position
by supports under it and behind it, four feet asunder. The
intention was to strike the bar, sometimes in the middle and
sometimes half-way between the middle and one end, with im-
pacts obtained by drawing the ball and letting it fall through
given arcs, shifting the bar when the place of impact was to
be changed, and obtaining the deflections of the bar at that
lace by measuring the depth which a long peg, touching the
back of the bar, had been driven by the blow into a mass of
clay placed there. The results were:
1. The deflections were nearly as the chords of the arcs
through which the weight was drawn, that is, as the velocities
of impact.
2. ‘The same impact was required to break the beam, whe-
ther it was struck in the middle, or half-way between the middle
and one end.
3. When the impacts in the middle and half-way between
that and the end were the same, the deflection at the latter
place was to that at the former nearly as three to four, which
would be the case if the locus of ultimate curvature, from suc-
cessive impacts in every part, was a parabola.
The preceding deductions the author had found to agree
with theoretical conclusions, depending on the suppositions,
(1.) that the form of a beam bent by small impacts was the
same as if it had been bent by pressure through equal spaces ;
and (2.) that the ball and beam, where struck, proceeded to-
gether after impact as one mass. ‘These suppositions likewise
gave as below:
4, The power of a heavy beam to resist impact is to the
power of a very light one, as the sum of the inertias of the
striking body and of the beam is to the inertia of the striking
body.
rag The time required to produce a deflection, and conse-
quently the time of an impact, between the same bodies, is
always the same, whether the impact be great or small. The
time, moreover, is inversely as the square root of the stiffness
of the beam.
6. The results of calculations, comparing pressure with im-
pact, gave deflections agreeing with the observed ones, within
an error of about one eighth or one ninth of the results.
TRANSACTIONS OF THE SECTIONS. 428.
On the direct tensile Strength of Cast Iron. By
E. Hopexinson.
The absolute strength of this metal, notwithstanding the
extensive use made of it in the arts, is still a matter of doubt.
If we turn for information to authors, we find Mr. Tredgold
and Dr. Robison making it nearly three times as great as Mr.
Rennie or Captain Brown, and the advocate of the greater
strength (Tredgold) attributing the less strength, as found by.
the others, to the straining force not having been kept in the
centre of the prism. For supposing the extensions and com-
pressions to continue always equal from equal forces (which they
are under slight strains), a small deviation from a central strain
would make a great reduction in the strength; and if the force
were applied along the side of a square piece, the strength
would be reduced to one fourth. (Tredgold, Art. 61, 62. 234.)
The above contrariety of opinion was the cause of the fol-
lowing experiments, in which the utmost care was taken to _
keep the straining force along the centre of the castings, which
had their transverse sections of the form +, except in the
last two experiments, in which the section of the castings was
rectangular, and the force applied exactly along the side. The
iron was of a strong kind, the same as in the author’s expe-
riments on beams(Manchester Memoirs, vol. v.), and was broken
— machine on Captain Brown’s principle for testing iron
cables.
Force up the middle.
Area of section
— in parts of an i 7 int Strength per square inch in tons. ©
inch.
1 3:012 22°5 747 Tons.
2 2°97 21:0 7:07 -mean 7°65.
3 3031 25°5 8°41
4 2:95 19°5 6:59 Different quality of iron.
Force along the side.
». Experi-
ents. Area of section. | Breaking weight.
Strength per inch.
|
4°83 11°5 2°38
2°855
Tons.
4-815 13°75 } mean 2°62.
424 THIRD REPORT—1833.
Whence the strength of a rectangular piece of cast iron
drawn along the side is rather more than one third of 73
tons, its strength, as above found, to bear a central strain
2°62
( for G5 s) ; but from the preceding. remarks it ought
only to be one fourth; and, therefore, it would appear that a
shifting of the neutral line had made the pieces capable of
bearing a greater force along the side than in their natural
state.
An Investigation of the Principle of Mr. Saxton’s locomotive
differential Pulley, and a Description of a Mode of pro-
ducing rapid and uninterrupted Travelling, by means of a
Succession of such Pulleys, set in Motion by Horses or by
stationary Steam-engines. By Joun Isaac Hawkins.
In order to a clear understanding of the operation of this
differential pulley, in the propelling of carriages or vessels, it
will be convenient to view the principle under three cases.
Case Ist. Let the bottom spoke or radius of a wheel, rolling
on a horizontal plane, be considered as a lever.
Let the point of contact of the wheel with the plane be the
fulcrum of the lever.
If a cord be fastened at one fourth of the length of the
lever above the fulcrum, and it be pulled a given distance, (say
one inch,) then the top of the lever or axis of the wheel will
be moved in the same direction four times the distance, or four
inches, agreeably with the common doctrine of the lever.
If now a pulley be concentrically affixed to the wheel, and
the circumference made to meet the point in the lever where
the cord is fastened ; in other words, if the pulley be three
fourths of the diameter of the wheel, and the cord be wound
around the pulley, and be drawn horizontally in the vertical
plane of the pulley, then the wheel will run along the hori-
zontal plane in the direction of the pull with a velocity equal
to four times the speed of the cord, because every point of
the circumference of the wheel as it comes in centact with the
plane becomes a new fulcrum, and the perpendicular line from
that point to the axis becomes a new lever, upon which the
cord acts at one fourth of the length of the lever above the
fulcrum, and thus a repetition of such leverage is continually
brought into action as the cord is drawn along.
Case 2nd. Let the point where the periphery of the pulley
meets the spoke or lever, and where the cord of Case 1. was
attached, be considered the fulcrum; and let another cord be
TRANSACTIONS OF THE SECTIONS. 425
applied to the bottom end of the lever. If this lower cord be
drawn horizontally in the same vertical plane, but in the op-
posite direction to that in which the former one was pulled,
then the top of the lever or axis of the wheel will be moved
in the same direction as before, three times the distance that
the cord passes through: thus, if the cord be pulled one inch,
the axis will be moved three inches, because the leverage is
in this case as three to one. Let the pulley be made to roll
along a horizontal plane, and the cord be passed around a
wheel concentrically attached to the pulley by the side of the
plane, the radius of which wheel is equal to the whole lever,
as was the wheel of Case 1.; then the cord being passed around
that wheel, and pulled, the pulley will run along the plane with
three times the velocity of the cord that draws the wheel, but
the motion will be in a direction opposite to the pull.
Case 3rd. Let both the cords of Case 1. and Case 2. be
pulled at the same time, (say each one inch,) then the fulcrum
will necessarily be removed to a point exactly half-way between
the two cords, which fulcrum will be at one eighth of the length
of the lever from the bottom end; and the top of the lever or
common axis of the wheel and pulley will, in this case, be
moved seven inches, being seven times the distance through
which the cords pass. The ratio of the velocity of the axis to
the cord is as the sum of the two radii of the pulley and wheel
divided by their difference.
Now fix a spindle in the axis, and support it on a four-
wheeled travelling carriage, or on a vessel afloat upon water,
and make a groove in the wheel to constitute it a pulley, and
pass a cord around each pulley in opposite directions, and
pull both cords with equal speed, then the carriage or floating
vessel will be propelled with seven times the velocity of the
cords, in the direction in which the cord of the smaller pulley
is drawn, because the axis of the pulleys or top of the lever
is seven eighths of the whole length of the lever above the
fulcrum, and the two cords act at one eighth of the length of the
lever above and below the fulcrum, which, in every part of the
revolution of the pulleys, remains perpendicularly under the axis;
at a height half-way between the bottom ends of the radii of
the two pulleys. But if instead of the two cords being at-
tached to the pulleys, an endless cord be stretched around two
riggers, placed at some considerable distance from each other,
and one side of the cord be made to take one turn around one
pulley, and the other side of the cord one turn also around the
other pulley, then the cord being drawn at either side or either
end will cause the pulleys to revolve, and the carriage or vessel
426 . THIRD REPORT—1833.
in which they are hung to be propelled the whole length of the:
space between the riggers, with a speed seven times greater
than the motion of the cords.
In applying this admirable invention of Mr. Saxton to the
propelling of carriages to great distances, Mr. Hawkins pro-
poses to place a number of endless ropes in a line, each rope
stretched between two riggers, from a quarter of a mile to four
miles apart, the rope lying upon several rollers to keep it off
the ground, and passing around a pair of differential pulleys,
supported on a light four-wheeled truck, running upon a pair of
slight rails about 30 inches apart; the diameter of one pulley
to be about 22 inches, and of the other about 26 inches, giving
a velocity of 12 to 1: the diameter of the wheels on which
the truck runs to be about 30 inches. Each rope to be set in
motion from one of the two riggers being placed on a shaft
passing under the rails and extending a few feet outside the
railway, where the shaft may be turned either by a horse or
horses, by an ox or oxen, or by a stationary steam-engine, ac-
cording to the quantity of travelling or traffic on the road, or
to other circumstances.. The coach for passengers, or wagon
for goods, to be placed upon four wheels, of about four feet
diameter, running upon a pair of rails, placed five feet apart,
parallel with and lying on each side the pair of truck rails, and
also a little above their level; so that the axletrees of the coach
and wagon wheels shall pass over the rims of the truck
wheels; or the same effect may be produced by placing the
four rails on a level, and cranking the axletrees to raise them
over the truck wheels. A pawl in the frame of the carriage
or wagon being let fall upon a post arising from the frame of
the truck, will enable the truck to draw or drive the carriage
the length of its rope; but on the truck being stopped near
the end of its rope, the momentum of the carriage will continue
its motion until it pass over and beyond the truck of the next
rope, which truck being set in motion, its post catches against
the pawl of the carriage, and drives or draws it on until
it reach the third truck, which again operates in the same
manner.
In this way 388 horses, each acting, at their most effective
or walking pace of two miles and a half per hour, on a mile of
rope, might easily drive a coach containing eight persons from
London to Edinburgh in 13 hours, at the rate of 30 miles an
hour, the coach passing from truck to truck without stopping,
and the truck returning to take another coach every five
minutes: 500 passengers a day for the whole distance would
be very moderate labour for that number of horses.
TRANSACTIONS OF THE SECTIONS. ; 427
Account of the Depths of Mines. By Joun Taytor, F.R.S.,
Se.
Mr. Taylor exhibited a section, showing the depths of shafts
of the deepest mines in the world, and their position in relation
to the level of the sea.
The absolute depths of the principal ones were :
eet.
1. The shaft called Roehrobichel, at the Kitspuhl mine
inithé: Byvolctoara goin in oes hs bas «e1 RIG
. At the Sampson mine, at Andreasberg in the Harz 2230
. At the Valenciana mine, at Guanaxuato, Mexico 1770
. Pearce’s shaft, at the Consolidated mines, Cornwall 1464
. At Wheal Abraham mine, Cornwall... . . . .. 1452
. At Dolcoath mine, Cornwall . . . . . . . 1410
. At Ecton mine, Staffordshire . . . . . . ~ 1880
. Woolf’s shaft, at the Consolidated mines .. . 1350
These mines are, however, very differently situated with re-
gard to their distance from the centre of the earth, as the last
on the list, Woolf’s shaft, at the Consolidated mines, has 1230
feet of its depth below the surface of the sea, while the bottom
of the shaft of Valenciana in Mexico is near 6000 feet in abso-
lute height above the tops of the shafts in Cornwall. The bot-
tom of the shaft at the Sampson mine in the Harz is but a few
fathoms under the level of the ocean; and this and the deep
mine of Kitspthl form, therefore, intermediate links between
those of Mexico and Cornwall.
Mr. Taylor stated, that taking the diameter of the earth at
8000 miles, and the greatest depth under the surface of the sea
being 1230 feet, or about 3th of a mile, it follows that we
have only penetrated to the extent of 35355 part of the earth’s
diameter.
_ Some:account was then given of the mines to which the shafts
referred to belong. 2
~ Of the deepest, at Kitspiihl, as it has long ceased to work,
we donot know much. Villefosse, in his great work on the
Richesse Minérale de l’ Europe, states that this was a copper
mine, which passed for being the deepest in Europe ; and that
in 1759, it was reported on, amongst other mines, by MM. Jars
and Duhamel, and it was then proposed to abandon the work-
ing, the water having been already suffered to rise near 200
fathoms.
The Sampson mine in the Harz is one of the most celebrated
in that district: it has been working since the middle of the
00 ID Orb 5 2
428 THIRD REPORT—1833.
sixteenth century, and produces silver ores of superior quality.
The principal shaft is sunk about 6 feet deeper every year, by
which ground enough is drained for a regular extraction of the
ores. The mine is one of the oldest in Germany, and has al-
ways been profitable : it employs from 400 to 500 men. It is
the property of shareholders, who are very numerous, the in-
terest having been much subdivided in the course of time.
The mine of Valenciana at Guanaxuato was one of the most
renowned in Mexico. It produced annually, about the end of
the last century, 360,000 ounces of silver, worth about £600,000
sterling, and then employed 3100 persons. The shaft referred
to in the section was commenced in 1791, the mine having been
long previously worked by other shafts: it had attained its pre-
sent depth in 1809, when the mine was stopped by the Revo-
lution. It is octagonal, and more than 30 feet in diameter, a
great part of its depth being walled with beautiful masonry, and
is probably the most magnificent work of the kind. The ex-
pense of forming this shaft is estimated by Humboldt at the
enormous sum of £220,000. The mine was so little troubled
with water that it was considered almost a dry one: during the
suspension of the works it, however, gradually filled. In 1825
one of the English companies undertook to drain it, which
was, after great labour and expense, accomplished; but the
mine has not been sufficiently productive since to make it worth
while to continue the working.
The Consolidated mines form the most extensive concern in
Cornwall, embracing what were formerly several distinct mines,
which, as the name indicates, were connected in one under-
taking. ,
This was arranged in 1818, and the mines which had remained
unwrought for many years were drained by very powerful steam-
engines, and were put into a state of active working. The ma-
nagement was confided to Mr. Taylor and the late Captain
William Davey : an outlay of £73,000 was incurred, which has
since been repaid with ample profit. The present produce is
20,000 tons of ore a-year, yielding about 1920 tons of fine cop-
per, being one seventh of the whole quantity raised in Great
Britain. The mines employ about 2400 persons, of whom about
1400 are miners working underground. The water raised to
the adit level is about 2000 gallons per minute: the height to
which this is lifted is more than 220 fathoms, or 1320 feet; the
aggregate weight of the columns of water in the pumps being
512,000 pounds, or about 230 tons, and the whole is put in
motion by eight immense steam-engines, four of which are the
largest ever made.
TRANSACTIONS OF THE SECTIONS. 429
The depth of the mines has been increased 100 fathoms
since the period of the drainage being completed, being at the
rate of about 8 fathoms a year.
There are, in the whole concern, 95 shafts, besides other
perpendicular communications’ from level to level underground
called winzes. The depths of the whole added together make up
‘about 22,000 fathoms, or 25 miles ; and the levels, or galleries,
will make up, in horizontal distance, a length of 38,000 fathoms,
or about 45 miles.
Wheal Abraham is an old copper mine, the working of which
was abandoned a few years since, the vein having ceased to be
productive in depth. It was, until very lately, the deepest
mine from the surface in Cornwall, but is now surpassed by
the Consolidated mines.
Dolcoath mine was formerly called Bullen Garden, and a
section of it as it was at that time will be found in Dr. Pryce’s
work, Mineralogia Cornubiensis, published in 1778. It wasthen
rather more than 90 fathoms deep, and probably one of the
deepest mines at that time. It has, therefore, been sunk 140
fathoms since; but, like all the great mines, it has not been in
constant work. It has now been actively prosecuted for many
years, and at present stands third in the list of copper mines in
Cornwall, arranging them according to the value of their pro-
duce. That of Dolcoath, however, does not amount to one half
of that of the Consolidated mines.
Ecton mine is celebrated in most books on mineralogy as one
of the principal copper mines in England ; and it was so at one
period, though the produce is now inconsiderable. It is situ-
ated in Staffordshire, on the borders of Derbyshire, and is
very curious, from being in limestone and having no regular
vein. The ore has been found in large masses, irregularly de-
posited, and is generally taken to be an example of contempo-
raneous formation. ‘The mine has been regularly worked for a
long series of years, and is now nearly exhausted. It is the
property of the Duke of Devonshire, and very large profits
were given by it in the latter part of the last century, some of
which, it is said, were applied by the late Duke to the erection
of the beautiful Crescent at Buxton. The mine is not far di-—
stant from this place, and is in a very picturesque situation on
the banks ‘of the river Manifold.
_ Mr. Taylor gave some account of the extent to which steam
power is at present employed in Cornwall in draining the mines
which penetrate so far beneath the level of the sea, showing
the influence that the great improvements, which have from time
430 THIRD REPORT—1833,
to time been made, and many of them even recently, must have
upon the production of some of the most useful metals.
The number of steam-engines used in pumping water from
the mines in Cornwall in December 1882 was altogether 64.
Some of these are of immense size and power: there are five
in the county, of which the diameter of the cylinder is 90 inches,
the pistons making a stroke of 10 feet. Four of these are at
the Consolidated mines, and the first constructed of this size
was planned and erected there by Mr. Woolf. The beam of
such an engine weighs 27 tons; the pump rods are of mast
timber, 16 inches square, connected by iron strapping plates of
enormous weight. ‘The column of water lifted, the rods and
beam, make up a weight of more than 100 tons, and this is kept
in motion at the rate of from 5 to 10 strokes per minute.
The quantity of coal consumed in drawing water in the same
month in all the mines of Cornwall was 84,034 bushels, and the
quantity of water delivered, about 19,279 gallons per minute.
‘The weight of water actually poised by all these engines to
produce this effect amounts to about 1137 tons.
From calculations carefully made in Mexico as to horse power
employed in draining mines, and deduced from a large scale of
operations, it is found that the performance is equal to 19,000
Ibs. raised one foot high per minute for each horse.
According to this rate, the coal consumed in Cornwall in a
month being 84,000 bushels, or 2800 per day, and taking the
duty of the engines at 55,000,000 pounds lifted 1 foot by each
bushel, which is very nearly the fact, it will be found that the
sixteenth part of a bushel does as much in raising water in
Cornwall as a horse does in Mexico, (working 3 hours out of
24,) and that thus the number of horses required to drain the
mines of Cornwall would be 44,800.
On Naval Architecture. By JEREMIAH OWEN,
A great deal has been done by mathematicians towards at-
tempting to establish a general theory of resistances, and con-
siderable expense has been incurred in conducting experiments,
some of which have been made on the Continent under the su-
perintendence of eminently scientific men. D’Alembert, Bos-
sut, Romme, and several others were employed at different
times in experiments of this nature. Don Juan in Spain, and
Chapman, the great Swedish naval architect, also made several
experiments on the same subject; as did also the Society for
the improvement of Naval Architecture, which was established
in England some years ago, but which has now ceased to exist,
These experiments have always been made upon models, the
SR a are ee
TRANSACTIONS OF THE SECTIONS. 431
largest of which, it is believed, have never exceeded 14 feet in
length. They were generally much smaller. The results which
have been thus obtained on small bodies have not been found
to agree with results similarly obtained on larger bodies; and
not only has this been the case, but experiments conducted ap-
parently with equal care by different individuals have even led
to different results.
Naval architecture has, consequently, gained but little from
the labour that has been bestowed upon these experiments,
and the forms which have been given by different individuals
to ships have depended rather upon the fancy and general ex-
perience of those individuals than upon any facts which this
branch of experimental science has furnished.
In order to discover that form of the body of a ship which
shall oppose the least resistance to its passage through the
water, the author recommends that experiments be made on
ships themselves, under all the ordinary circumstances of
sailing.
These experiments must be conducted, not in the mode in
which experimental squadrons have hitherto been, viz. by
comparing together the sailing qualities of ships that have va-
ried in every particular. We are no more justified in saying
that results obtained in this way have proved which form of
body is best calculated for velocity, than we are in saying which
ship has been the best managed.
~ If it be desirable to discover by experiment which of two or
more forms is best adapted for velocity, it is, of course, neces-
sary that the form shall be the only variable element ; the ships
in every other respect must be exactly similar.
By the aid which the mathematics afford, we shall be able
_ most completely to accomplish this. Let a ship be given which
sails well, and which is in all other respects an efficient man-of-
war as regards capacity, stability, &c. &c. Let this ship be
docked, and let the most complete drawings of her form be
made, from which we shall be able to calculate exactly every
necessary element, such as displacement, area of midship sec-
tion, of load water section, stability, &c.; and let the surface
of sail, the position and rake of masts be also acertained.
‘Then let one or more ships be constructed, having exactly
the same principal elements as the given one, with whatever
difference of form it may be thought proper to select, and let
the same surface of sail be given to them all. We shall thus
have the same weights to be moved, and the same propelling
force to move them; the result will, of course, show which form
is best calculated for velocity.
432 THIRD REPORT—1833.
These ships may be made to sail against each other under
ever possible circumstance of sailing, taking care always to ap-
ply the propelling force in the same way, that is, by bracing the ©
corresponding yards of all the ships to the same angle with a fore
and aft line, during every comparison, and by raking the masts
to the same degree. 3
It is of importance that during the experiments the surface
of sail in each ship should be presented as nearly as possible
at the same angle to the action of the wind ; and this is perfectly
practicable, for it is easy to measure the angles of the yards by
an instrument for that purpose; and the officer who commands
the squadron can take care, by means of frequent signals, to
have the yards of all the ships braced to the same angle at the
same time.
These experiments would not be: limited in their result to the
discovery merely of that form of a ship which is best calculated
for velocity, although this of itself is so important as to justify
almost any expense, but we might also be able to discover how
far the angle of leeway is affected by the form, -which is also a
very important question connected with the sailing of ships ;
and after having, by repeated and careful trials, discovered the
order of superiority of ships in respect of velocity, we might
then, by varying the angle of bracing the yards, discover also
the trim of the sails and the course of the ship by which to gain
most on a wind, a question which is not by any means satisfac-
torily settled, in as much as it involves all the uncertainty of our
present knowledge of the resistance of fluids.
Experiments to determine this latter question might, however,
be made immediately on sister ships, of which there are several
at present in His Majesty’s service.
Let two ships be selected of the same form, and let the ut-
most pains be taken to make the position and rake of the
masts, the seat in the water, the stowage of the ballast, and of
all the heavy weights, exactly the same in both ships, and let
them be compared together in sailing both on the wind and at
various points off the wind; the angles of bracing the yards
being constantly varied, we should doubtless, from a series of
experiments of this nature, succeed in discovering the best trim
of the sails for every direction of the wind on every course.
It may, perhaps, be urged against a series of experiments like
those which have been here recommended, that the expense of
building a ship is so great as to render it advisable not to run
the risk of building a bad one for the sake of experiment merely.
But the author suggests that our knowledge of naval architec-
ture is such as to enable us to construct ships which we can
ae
TRANSACTIONS OF THE SECTIONS. 433
certainly predict will be good, notwithstanding they may not
be the best that might be produced ; and the ships which would
be included in the experiments proposed would have all the
essential qualities of a man-of-war, except, that by differing in
- form, some would be superior to others in respect of velocity.
Naval architecture is a branch of science which depends so
essentially upon experiment for its advancement, and the ex-
periments are necessarily upon so large and expensive a scale,
as to place it out of the power of individuals, or even of socie-
ties of individuals, to conduct them. It is, therefore, one of
those enterprises in science which none but a nation can un-
dertake ; and it is worthy of so great a maritime nation as En-
gland to endeavour to advance, at whatever reasonable cost, a
subject so important to its defence.
HI. NATURAL HISTORY—ANATOMY—
PHYSIOLOGY.
On the originary Structure of the Flower, and the mutual De-
pendency of its Parts. By Professor AGARDH.
_TuE observations in this paper were generally directed against
the commonly adopted view, that the flower is formed of several
verticils independent of each other. The author remarked the
difference between the appearance of the verticillated parts and
their real and originary situations. Adopting the view, that
the flower is nothing more than a branch, which has been re-
duced to a mere point whilst its subordinate parts have been
transformed, he concluded that the different parts of each yer-
ticillus formed an originary spiral, and are really of unequal
order, age, and situation, which, in many cases, is still evident
during the inflorescence ; and imagining the branch shortened
to a point, it will be found that the upper, later, and weaker
parts must be the inner ones of the apparent verticillus.
. The second point of Professor Agardh’s view is, that the.
stamens are not transformations of petals but of buds. This
view is consistent with the whole theory of the development of
plants, as laid downinaseparate work (Organography of Plants),
_and founded on the principle, that the several appendicular
parts of the plant are not all transformed leaves, but only one
part of them are transformed leaves, and others are transformed
buds, so that to every part which is a transformed leaf be-
1833. QF
434 THIRD REPORT—1833.
longs another part, which is a transformed bud. The stamens
are now, according to Professor Agardh, the buds of the leaves
of the flower, or of the petals and sepals. ‘They are therefore
situated in their axillz, and each stamen belongs to a certain
petal or sepal, and both organs together form a little flosculus
as part of the whole flower, in the same way as the carpella are
parts of the fruit. Thus a Decandrous plant, for example a Ce-
rastium, consists of 10 floscules, each consisting of a leaflet and
of astamen. A Pentandrous plant, for example a Borago,
consists also of 10 floscules ; but 5 of them, those of the interior
verticillus, are incomplete, bearing no stamens in their axille.
The observations made on the situation of the parts of the
flower were collected by Professor Agardh into the following
general laws or views. ' .
1. The number of stamens, in all cases where this num-
ber is determinate, depends upon the number of sepals and
petals ; and when there seems to be a different normal num-
ber for the leaves of the flower and for the stamens, it is an
aberration arising from abortion.
2. The difference between the flowers which have the same
number of stamens as of leaflets, and those where their num-
ber is only the half of the leaflets, is caused by the abor-
tion of the stamens of a whole verticillus of floscules ; and ge-
nerally of the corolline floscules. The reason is, that the corol-
line verticillus is constituted of later parts, which do not arrive
at complete development.
3. The same reason is to be assigned to the general fact that
the petaline stamens are generally the weaker, smaller, and
later.
4, The determinate stamens are either 1, 3, or 5 in num-
ber, belonging to each leaflet, because the buds, according to
Professor Agardh’s theory laid down in his above-mentioned
work, originate properly in the axille of two deviating fasciculi
of spiral vessels, which fasciculi in the leaf (being no other
than the nerve) are always 1, 3, or 5, &c., and the buds must
therefore have the same symmetry and number. This is the
reason of the determinate number of stamens in several Polyan-
drous families, as, for example, in Rosacee, in which the sepals
have each 3 stamens, and the petals each 1; and in Phila-
delphie, in which the sepals have 5 stamens, and the petals
1: whence the former family must have 20 stamens, and the
latter 24. ny
- 5. Some Polyandrous plants have not a determined number
of stamens. In these Professor Agardh distinguished two cases.
-
TRANSACTIONS OF THE SECTIONS. 435
In some, as in the Ranunculaceae, the buds of the flower are in
a vascillating state between the form of stamens and flower-buds,
and even the sepals are in a vascillating state between bractez
and sepals. In Helleborus, Nigella, &c., the inferior buds are
nearly like flowers, and also in Ranunculus the buds are only
to be regarded in the same state of transition to petals, as
the sterile flowers of Synantheree approach the form of
petals. By this is explained, not only why the nectaria of
Helleborus are axillary to the sepals, which they could not be
if they were originary petals or leaves, but also why the nec-
taria of Berberidee, which are so nearly allied to Ranunculaceae,
are axillary to the sepals; and finally, why there is an evident
transition between stamens and petals in Nympheacee, and
in all the families allied to Ranunculacee, the buds in the
flower having an equal tendency to form flowers, petals, and
stamens. a
» The other case of Polyandrous plants is where no relation at
all is observable between the flowers, leaves, and the number
of stamens. This is to be explained by the analogous case,
wheré the flowers in capitula, as, for example, of some Synan-
theree, are without distinct bractez to each single flower ; and
it is not more singular, that the stamens should be in some
cases without their respective flower-leaves, than that the
flowers in some cases should be without determinate bractez.
6. When some floscules in the same verticillus are sterile or
without stamens, they are frequently those which are younger
or later than the others. The same reason is to be assigned
for the inequality of the stamens in the same verticillus. Ex.
Personate, Labiate,.in which the two younger stamens are
smaller, and the youngest stamen fails.
7. The ternary number in Monocotyledonous plants is de-
rived from a leaf-bud, in which two outer leaves, or squame,
turn their back to the stem, and form two sepals; and the
third sepal is the leaf, in the axilla of which the bud is situated.
This is evident in Carex (in which the two leaves coalesce into
the utriculus,) and in the Graminee.
8. Dicotyledonous plants have their flowers formed on two
different plans.
“9. One group of them has originally opposite leaves; on
these the floscules are naturally in pairs, and when a fifth flos-
cule exists, it-is to be regarded as the last, and the only one of
the third pair which has found sufficient room to develop. (See
Calyx of Dianthus.)
-°10. The other portion of Dicotyledonous plants has alternate
leaves, and, in consequence, impair and unequal floscules; but:
ZE2
436 THIRD REPORT—1833.
the floscules have a tendency to take a symmetrical form on both
sides, so that in this case a floscule exists which is especially
to be regarded as impair, and which is the first or the last in
the spiral: This impair floscule is commonly placed either near-
est to the axis of the racemus (axilis), or outermost in the peri-
phery (periphericus) of the racemus.
11. ‘The petaline floscules have a contrary progression to the
sepaline, so that if the odd or impair sepal is placed nearest
to the axis of the racemus, the odd or impair petal i is placed
outermost in its periphery.
12. The situation of the impair floscule is different in dif-
ferent families, for example, the odd sepal, (the first or last sepal,)
is axilis in Labiate, Personate, Umbellifere, and periphericus
in Leguminose, Rutacee, &ce.
13. By the situation of the carpella two cases are to be di-
stinguished.
14. In some cases the carpella are commensurable with the
number of floscules. They are then placed either parallel to
the sepals, as in the Liliaceae, Primulacee, Geraniacee,; Cru-
cifere, or parallel to the petals, as in the Rutacee, Philadelphus,
Onagrarie.
15. In other families, and by far the greatest part, the car-
pella are two, (complete and incomplete,) and thence not com-
mensurable with the five divided flowers. In this case one
carpellum is parallel with the impair sepal, and the other
with the impair petal. The fruit of the Boraginee and Labiate
is to be referred to this case, two carpella taken together being
placed parallel to the impair sepal, and the two others parallel
to the impair petal, the fifth carpellum having vanished.
Notice of Researches on the Action of Light upon Plants.
By Professor DavBeny.
The author communicated a notice of certain researches
which he is at present pursuing concerning the action of light
upon plants, and that of plants upon the atmosphere.
He considers that he has established, by experiments on
plants immersed sometimes in water impregnated with carbonic
acid gas, and at others in atmospheric air, containing a notable
proportion of the same, that the action of light.in promoting
the discharge of certain of their functions, and especially that
of the decomposition of carbonic acid, is dependent neither
upon the heating nor yet upon the chemical energy of the se-
veral rays, but upon their illuminating power.
TRANSACTIONS OF THE SECTIONS. 437
He regards light as operating upon the green parts of plants
in the character of a specific stimulus, calling into action and
keeping alive those functions from which the assimilation of
carbon and the evolution of oxygen result, and that the de-
scription of rays which are proportionally more abundant in
solar than in artificial light are those most instrumental to the
above purposes.
With regard to the second branch of the inquiry, Professor
Daubeny has only proceeded in it so far as to have satisfied
himself, that in fine weather a plant consisting chiefly of leaves
and stem will, if confined in the same portion of air night and
day, and duly supplied with carbonic acid during the sunshine,
go on adding to the proportion of oxygen present, so long as
it continues healthy, at least up to a certain point, the slight
diminution of oxygen and increase of carbonic acid which
takes place during the night bearing no considerable pro-
portion to the degree in which the contrary effect is observable
by day.
He accounts for the discrepancy between his own results
and those reported by Mr. Ellis in his work on Respiration, by
his having taken care to remove the plant from the jar imme-
diately upon its beginning to suffer from the heat or confine-
ment, and from his having carried on the experiments upon a
larger and more suitable scale.
Considering the quantity of oxygen generated by a very
small portion of a tree or shrub so introduced, he sees no
reason to doubt that the influence of the vegetable may serve
as a complete compensation for that of the animal kingdom,
especially since this same function appears to belong to every
plant which has come under his review, whatever may be its
structure or organization.
On some symmetrical Relations of the Bones of the Mega-
therium. By Waiter Apam, M.D
The author, having examined the bones of the megatherium
which are preserved in the Museum of the College of Surgeons,
was led to observe their forms according to their symmetrical
relations. For this purpose, the coronal breadth of the cra-
nium is taken as a common term of reference. It measures
8-75 inches, but in the following scale of proportions its breadth
is denoted by 10, and all the other measures are altered in the
same ratio, and expressed by the nearest integers. Dr. Bar-
clay’s nomenclature is employed.
438 THIRD REPORT—1833.
Heap. 620%! Coronal breadth of cranium............ 10
Mesial thickness of the bony plate form-
ing the palate and the basilar surface of
the nasal passage). 32. sc) stele mre teed Jord 2
Mesial height from the surface of the palate
to the concavity of the coronal surface,
about the rostral margin of the rostral
ELS ge ee IR RE 8
Greatest height of the fragment of the
head from the palatal surface in the di-
rection of the socket of the third molar 12
VeERTEBRA. . . Breadth of the transverse process of the atlas 14
of the fifth cervical............ 9
of one of the largest dorsal .... 12
of a caudal vertebra, supposed to
be that next the sacrum...... 25
of the seventh of the 12 caudal
which remain.......4....%...% 10
of the smallest caudal.......... 4
Length of the body of the atlas........ 3—
of the fifth cervical............ 3—
of one of the largest of the dorsal . ae
of one of the lumbar............
Of SixvCHnUAlS Gee ee ee ee
of the smallest caudal .......... 3
In the first three vertebrz of the tail in which the length is
diminished, that dimension is greatest on the upper or dorsal
aspect, indicating that about the middle the tail had a ten-
dency to curvature downwards and forwards.
Longest spinal process of a dorsal vertebra............ 16
Srrnat Cana, . Width in atlas ......0.....0.000.000. 3
in fifth conyieal: +s! bateieht . w:tes 3+
at She mel visi. :.96- sii wnae mains 4
The ribs of the megatherium were connected to the sternum
by osseous attachments.
Length of the longest rib which has been found (without
its sternal attachment)... . 00+ « ecisinies rieieeesefe 36
of the shortest rib found (probably the first). . 15+
Greatest breadth of the shortest rib ............+4-- 5
of the longer ribs........... ao ae 3°5
Thickness of the longer ribs ...-..........seecceees 1°8
Srernum .... Breadth of the rostral portion.......... 8
Mesial length of the same ..... SR 40
et a. eee ee ee
He
PELvis
Scapuba ,...
TRANSACTIONS OF THE SECTIONS.
Greatest transverse extent of the iliac bones 75
Width of pelvic aperture.............. 16
Depth: of ditto; .. 9 -alkibiqew apreeisei2 zis |- 28
Breadth at the mesial margins of the ace-
ST Bie er at uh oxauddhy oicksileiheg och ater she 18
between the acetabula and the
ischial tuberosities .......... 28
at the ischial tuberosities ...... 24
Thickness of bone at the ischial tuberosities 3
Symphysis pubis, its rostro-caudal extent 11
From the sternal surface of the symphysis
pubis to the sternal surface of the spinal
canal, the mesial distance is.......... 39
Length of the thyroid foramina ........ 12
Breadth of the same...........0...... 6
From the lateral extremity of. the left iliac
bone to the right ischial tuberosity.... 58 .
Breadth from the acromico-glenoid sinuosity 17
from the caudal margin of the gle-
ADU RTI i hn ad ati ige hin mm a 20
Length of the glenoid cavity............ 7
Extent of dorsal margin of scapula...... 31
from the dorso-caudal angle to the
extremity of the acromion .... 33
From the acromion to the glenoid cavity,
Kerentest brewdth)y ies fired oes iene 14
Thickness of scapula at the dorso-caudal
alien .sneitisds sl th dS GE A. . 3
Craviciz,... This strikingly resembles that of man.
Ptsubeastlins inci shaages. diay Bia tote stasis 17
Harel: Boma tiv eias gues Ws ww retewo 7
Rapivs...... Dteribeteetdaand cerv rye slenar lS. latsseed i te aiaia 28
, Its greatest breadth near the os humeri ee)
; Its ginpllest printer costes wes ches boo me lee 10
Aernaganwe: > Bread@edags 9, (ewaamnys oi ioe ese 11
Length be) eaccyc +i. bts steno bagte)-relsdnatigd> 10
_ Catcanevo .. Digital breadth.........-.0.. 0.0200 ee © 18
Greatest dene thts. n:..» .-.-. 0am whybsl 20
PGE TO oases», psalm rere, *' Sys « 12
Smallest girth ...... CR ene 9 20
BOATS Fie...» 5.0 Da PON g ooo wy ony a 28a apa hee 13
Proximal reat’. fcige 80 Poa. Je eee 14
Fibular length 22 ypask OS PN st al 24
Tibial length 2 > teapindee. tO) OTT 85 25
Tibia, smallest’ girth. +. “Miedetk).2 ae. 16
Femur ...... Breadthe.< wae. terest he teenie... 18
Smallest pinky 6) HOW -AWL MIUE A... 30
Greaheoteleme tly, © ci wivoniieiy lek Mads. alee 32
439
440 THIRD REPORT—1833.
Dr. Adam observes, that by the completion of Mr. Clift’s
labours in adapting and mounting the remains of this animal,
some peculiarities now visible in the internal structure of the
bones will be concealed, and on this account he directs the
attention of zoologists to the following observations :
‘© Tn the thicker parts of the ribs as well as of the bones of
the limbs where broken, there are dispersed and conglomerated
in the reticulated texture, like the spherules in some crypto-
gamous plants, numerous round bodies from one tenth to two
tenths of an inch in diameter. These bodies are hard, but of
a steatomatous appearance: they seem to have resulted from
the same exuberance of ossification so conspicuous in the ex-
ternal surface. The external surface of the thicker parts of
the bones looks as if formed by a conflict of the osseous spi-
cule, which are of the size of coarse needles.”
Dr. Adam is of opinion, that probably the nails of the me-
gatherium might have been doubled under the foot in the same
manner as those of a living cognate species, the short-tailed
manis, the feet of which living species had hitherto been incor-
rectly figured in zoological works.
On some new Species of Fossil Saurians found in America.
By R. Harran, M.D., of Philadelphia.
The species of saurians mentioned in this communication
had been all examined by Dr. Harlan, and a full account of
them is preparing for publication. The following extracts will
make known the names and localities of these fossils.
1. Ichthyosaurus Missouriensis.—A fragment of the head
has been found in a hard bluish grey limestone, near the junc-
tion of the Yellow-stone and Missouri rivers.
2. A dorsal vertebra, analogous to those of plesiosaurus,
except that its length is remarkably greater in proportion to its
breadth. Found in marl on the banks of the Arkansaw river :
supposed to belong to a very large individual. The marl con-
tains many bivalve shells.
Remains of crocodiles, geosauri, &c., were also mentioned
by Dr. Harlan as occurring in West New Jersey in marls. _
Remarks on Genera and Subgenera, and on the Principles on
which they should be established. By the Rev. Leonard
Jenyns, 4.M., F.L.S.
The object of this paper was to make some remarks on the
great multiplication of genera at the present day, and to show
-—
TRANSACTIONS OF THE SECTIONS. 441
that in constructing them sufficient attention had not always
been paid to the true principles of classification. It was par-
ticularly stated that in this country zoologists had very much
overlooked the principle which determines that all groups bear-
ing the same title should be groups of the same value; and
that in raising to the rank of genera the subgenera of the
French, they put these last on the same footing with groups of
a higher denomination, to which in strict reality they were
subordinate. Instances were brought forward from amongst
the genera of British birds, in which this disregard to a due
subordination of groups was particularly manifest. It was
mentioned that in this way Plectrophanes was made a group of
equal value with Emberiza, Lagopus with Tetrao, Coturnix with
Perdix,and Botaurus with Ardea, although it might be clearly
seen, that in each of these instances the first group rested on
characters far less important and less numerous than those
which were common to the two considered as one genus.
Some remarks were then made on the method of ascertaining
the value of any new group that presents itself. It was ob-
served, that to fix this with certainty required a previous ac-
quaintance with all the other existing groups belonging to the
same family, and that therefore it can only be determined so
far as the present state of our knowledge of that family will
allow. If it be found on comparison that its characters are of
equal value with those of other acknowledged genera in that
family, the group in question may be considered as a genus
also ; but if of less, it is clear that the group itself is one of
less importance, and must occupy a subordinate station.
The author concluded with pointing out the impropriety of
splitting up natural genera, as had been done in some cases,
merely because they contained a large number of species. He
stated that the value of a group was not affected by such a
circumstance ; furthermore, that no groups should exist in our
systems but such as exist in nature; and that for the mere
purpose of abridging labour in the search after particular spe-
cies, it was quite sufficient in the case of extensive genera to
institute sectional divisions, indicating such sections by signs.
On some parts of the Natural History of the Common Toad.
¢ By James Macartney, M.D., F.R.S.
After commenting upon the unfounded prejudices against the
whole class of reptiles, and the toad in particular, the author
corrects an error concerning the mode of feeding of the toad—
into which even Linnzus had fallen—that the flies are attracted
442 THIRD REPORT—1833.
into its mouth by a power of fascination. ‘‘ The toad takes
its prey in the same manner as the chameleon and many
other lizards, by projecting its tongue, striking the insect, and
drawing it back into the mouth, and this it does so rapidly that
the action cannot be seen; but if a fly alights on the outside of
a glass vessel in which a toad is inclosed, the creature, thinking
its prey is within its reach, performs the usual act, and the
stroke of the tongue is very distinctly heard against the inside
of the glass opposite to the fly.”
Stories are very frequently published of living toads being
found encased in solid rocks and in the trunks of trees, and
these accounts receive very general credit. To ascertain how
far this is probable, Dr. Macartney made the following experi-
ments.
He placed a toad ina glass vessel covered loosely with a
piece of slate, and buried the vessel containing the toad about a
foot deep in a garden; on digging it up a fortnight afterwards,
the animal was in perfect health, and had recovered from a
wound it had previously received in the thigh. He then took
the same toad, and having secured the top of the vessel in such
a way that no air nor moisture could be admitted, he buried it
in the same place, and on raising it a week afterwards found
the animal dead and putrid: from hence he concluded that the
toad cannot live if moisture and atmospheric air be perfectly
excluded. It is very probable that toads have been often found
alive in chasms of rocks, or in hollow trees having a small aper-
ture through which the air and also insects might enter; but
that any animal possessing lungs should live for an indefinite
time without some communication with the atmosphere appears
quite incredible.
Cuvier has stated that the toad, although not venomous, yet
when provoked ejects a liquor from two glands placed on its
head, which is capable of irritating the skin. Dr. Macartney
has often had toads in his possession, but never observed any-
thing of the kind; nor does he believe that the animal has any
disposition to injure others: on the contrary, the toad is very
gentle, capable of being domesticated, and of becoming attached
to those who treat it well.
It is a popular notion that toads cannot live in Ireland, which
opinion is in some degree countenanced by the fact of there
being no reptiles in that country except the water-newt and the
frog, and the latter was introduced within the last century. It
is also understood that there are no reptiles in the Isle of Man.
The climate of both these islands being more moist than that
of England would be particularly suitable to frogs and toads,
—
TRANSACTIONS OF THE SECTIONS. 443
although it would probably be unfavourable to serpents and
many kinds of lizards.
Some years ago the author brought eleven toads from this
country to Ireland, and as he did not wish them to be propa-
gated, on account of the alarm and disgust which many weak
people feel towards them, he buried them in a flower-pot co-
vered loosely with a slate, to prevent the earth falling in upon
them. In this situation he kept them for two years, occasionally
digging them up, for the purpose of exhibiting them and making
them the subject of experiments. They at length all died during
a very hot summer, the ground in which they were buried
having become so dry that the animals could no longer receive
any moisture; for although the toad eats many insects when
it is at liberty, it will live and increase in size by imbibing
moisture alone, for which purpose its skin is provided with nu-
merous pores.
The toad possesses greater powers of repairing the effects
of injuries than most other animals. One of the toads which
has been mentioned as living beneath the surface of the earth
for two years had been subjected to the experiment of having
the upper part of the skull removed, and a portion of the brain
scooped out. The wound rapidly healed, leaving a depression
corresponding to the quantity of bone and brain taken away.
The only effect which remained from this injury was that the
animal afterwards did not walk in a direct line, but in curves
to the one side, a fact which has been observed in other in-
stances consequent to injuries of the brain. Dr. Macartney has
seen one instance of the same kind in the human subject, the
person being incapable of locomotion, except in circles, as if
he were waltzing.
There is one fact in the natural history of the toad which the
author believes to be quite unknown,—the utterance by the
animal of a musical sound, consisting of one note, so clear and
pure that it perfectly resembles that which is produced by
striking a piece of glass or some sonorous metal. The season
of the year in which this was heard was the latter part of au-
tumn. Dr. Macartney concludes by observing that ‘‘ One ob-
ject in studying zoology, and that not an unimportant one, is,
by closely investigating the habits of animals, to remove the
prejudices and apprehensions which are traditionally handed
down to us from those ages in which fable took the place of
knowledge. Many of these errors and prejudices with respect
to animals exist in the present day, even amongst well informed
persons, to an extent that would scarcely be believed unless
our attention had been directed to the subject. In selecting
444. THIRD REPORT—18398.
the history of the toad, I have merely employed a remarkable
example of the fact.”
Observations relative to the Structure and Functions of
Spiders. By Joun Buacxwatt, F.L.S.
During the last three years the author has been engaged
occasionally in conducting experiments having for their object
the determination of a highly interesting question in physiology,
namely, what are the true nature and functions of the remark-
able organs connected with the fifth or terminal joint of the
palpi of male spiders? The opinion advanced by M. 'Treviranus,
and adopted by M. Savigny, that those parts are instruments
employed for the purpose of excitation merely, preparatory to
the actual union of the sexes by means of appropriate organs
situated near the anterior extremity of the inferior region of the
abdomen, is in direct opposition to the views of Dr. Lister and
the earlier systematic writers on arachnology, who regarded
them as strictly sexual; and the results of the author’s investi-
gations clearly demonstrate the accuracy of the conclusion
arrived at by our celebrated countryman.
In the spring of 1831 Mr. Blackwall procured young female
spiders of the following species, Epeira diadema, Epeira apo-
clisa, Epeira calophylla, Epeira cucurbitina, Theridion ner-
vosum, Theridion denticulatum, Agelena labyrinthica, &c., and
having placed them in glass jars, fed them with insects till they
had completed their moulting and attained maturity, which is
easily ascertained in most instances by the perfect development
of the sexual organs. He then introduced to them adult males,
taking care to remove the latter as soon as a connexion had
been consummated in the usual manner, by the application of
the palpal apparatus to the orifice situated between the plates
of the spiracles in the females. He never in any instance suf-
fered the sexes to remain together any longer than he found it
convenient to continue his observations, and remarks that their
union, however prolonged and undisturbed, was invariably ac-
complished in the manner stated above. After a lapse of se-
veral weeks the females thus impregnated respectively fabricated
their cocoons, and deposited their eggs in them, all of which
proved to be prolific; affording a complete refutation of the
opinion promulgated by M. Treviranus.
That there might not remain the slightest doubt, however,
on the mind of the most fastidious inquirer, in the summer of
1832 the author brought up from the egg young females of the
species Epeira calophylla and Epeira cucurbitina, which, when
TRANSACTIONS OF THE SECTIONS. 4A
they had arrived at maturity, he treated in the manner de-
scribed in the preceding cases. In the autumn of the same
year these spiders deposited their eggs in cocoons spun for
their reception, out of which the young issued in the ensuing
spring, having undergone their final metamorphosis in the
cocoons.
These experiments, besides effecting the purpose for which
they were instituted, served also to supply collateral evidence
of the correctness of M. Audebert’s observations relative to
the capability of the House-spider, Aranea domestica, to pro-
duce several sets of prolific eggs in succession, without renew-
ing its intercourse with the male; for three females of the spe-
cies Agelena labyrinthica deposited each a second set of eggs,
and a female, Epeira cucurbitina, laid four consecutive sets,
intervals of fifteen or sixteen days intervening, all of which pro-
duced young, though these females had not associated with
males of their species for a considerable period antecedent to
the deposition of the first set of eggs.
MM. Lyonnet and Treviranus, with other skilful zootomists,
have fallen into the error of mistaking the superior spinning
mammule of spiders, when triarticulate and considerably elon-
gated, for anal palpi (palpes de l’anus), denying that they per-
form the office of spinners, in consequence of their having failed
to detect the papilla from which the silk proceeds; and in this
opinion they are followed by the most distinguished arachno-
logists of the present day. The author is inclined to attribute
this singular oversight to the peculiar disposition and structure
which the papillae or spinning tubes connected with the su-
perior mammule, when greatly elongated, frequently exhibit.
Arranged along the under side of the terminal joint, they pre-
sent the appearance of fine hairs projecting from it at right
angles ; but if the spinners when they are in operation be care-
fully examined with a powerful magnifier, the function of the
hair-like tubes may be ascertained without difficulty, as the fine
lines of silk proceeding from them will be distinctly perceived. |
In conducting this observation Mr. Blackwall usually employs
the Agelena labyrinthica of M. Walckenaer: its size, the length
of-its superior mammule, and its habits of industry, afford a
combination of advantages comprised by no other British spider.
_ The purpose subserved by the superior mammulz, when very
prominent and composed of several joints, is the binding down
with transverse lines, distributed by means of an extensive la-
teral motion, the threads emitted from the inferior mammule ;
by which process a compact tissue is speedily fabricated.
The foregoing facts supply a striking exemplification of the
446 THIRD REPORT—1833.
importance of connecting physiological researches with anato-
mical details.
In attempting to drown a small spider, new to naturalists,
(which the author has named Erigone atra,) for the purpose of
taking its dimensions accurately by measurement, he was asto-
nished to find that at the expiration of two days, though it had
remained under water the whole of the time, it was as lively
and vigorous as ever. This extraordinary circumstance induced
him to submerge numerous specimens of both sexes in cold
water contained in a glass vessel with perpendicular sides, on
the 21st of October 1832, in which situation they continued till
the 22nd of November, an interval of 768 hours, without having
their vital energies suspended.
. He has tried the same experiment with individuals of other
species, and some of them have preserved an active state of
existence for six, fourteen, or twenty-eight days, spinning their
lines and exercising their functions as if in air, while others
have not survived for a single hour. It is evident, therefore,
from these curious facts, that some spiders possess the power
of abstracting respirable air from water; for though in the act
of submersion the spiracles are generally enveloped in a bubble
of air, yet so small a supply is speedily exhausted, and, indeed,
soon disappears.
The external and internal organization of such species of
Araneide as can exist for along period of time under water
deserves to be attentively examined ; but those species which
the author has observed hitherto are minute, and it would re-
quire the hand and eye of an accomplished anatomist, assisted
by the most delicate instruments and powerful magnifiers, to
effect this desirable object satisfactorily.
On the Reproductionofthe Eel. By Wiiu1aM Y ARRELL, F.L.S.
Sir Humphry Davy, in his “ Salmonia,” considered the
mode in which eels produced their young as a problem in na-
tural history not then solved, the more general opinion being
that they were viviparous.
The paper commences with a recital of the opinions of various
writers on this subject, from Aristotle and Pliny to the time of
Bloch and Lacépéde, and the author states his belief that the
viviparous nature of eels had been inferred from the circum-
stance of their being subject to numerous intestinal worms, three
species of which are named and described as of frequent occur-
rence.
The sexes are distinct ; the females oviparous. The situation,
Spee Oe he
TRANSACTIONS OF THE SECTIONS. 447
structure, and peculiarities of the sexual organs are described,
and the author gives a statement, from his own examinations,
of the dates at which eels in various ponds and riyers in
different southern counties deposited their ova and _milt, all
et which occurred between the 15th of April and the 7th of
ay.
The migration of adult eels in autumn, in tide rivers, is con-
sidered as extending to the brackish water only, and believed
to be induced by the higher degree of temperature there exist-
ing. The mixed water is shown by experiment to maintain a
temperature two degrees higher than the pure sea or fresh
water, from the combination of two fluids of different densities.
Eels pass the winter imbedded in mud.
The return of adult eels is shown by the habits and success
of the basket fishermen in rivers within the tide-way, who place
the mouths of their eel-pots up stream in autumn, and down
stream in the spring.
The ascent of the fry is described as it occurs in the Thames,
the Dee, the Severn, and the Parret.
Sea water contains a much larger proportion of earthy mat-
ter, and in consequence less air, than the water of rivers, and
fresh water also yields its oxygen much more rapidly than that
of the sea; the author states his belief that no instance of a
freshwater fish going to the sea todeposit its spawn will be
found, while more than twenty species of truly marine fishes
ascend rivers to deposit their spawn, obtaining thereby, for the
vivification of the ova, the assistance afforded by a larger quan-
tity of oxygen. .
. The restlessness of eels during thunder-storms, when enor-
mous quantities are taken, is referred by the author to the high
degree of muscular irritability known to exist in all animals pos-
sessing a low degree of respiration, with which coexist. the
power of sustaining privation of air and food, a low animal tem-
perature, and great tenacity of life, all of which eels are well
known to possess. ) pow
Fishes that swim and take their food near the surface die
soon when taken from the water, having a higher degree of re-
spiration and less muscular irritability, compared with those that
swim near the bottom; and vice versd. . :
» The paper concludes with descriptions of the characters
— distinguish three different species of British freshwater
. ; pPNe
448 THIRD REPORT—1833.
On the Naturalization in England of the Mytilus crenatus, a
native of India, and the Acematicherus Heros, a native of
Africa. By Cuaries Witticox, Curator of the Museum of
the Portsmouth and Portsea Literary and Philosophical So-
ciety.
Mr. Willcox states that when His Majesty’s ship Wellesley
was docked at Portsmouth in July 1824, he discovered on the
lead of the cutwater and under the keel a great number of My-
tili, which, on examination, proved to belong to the species
named M. crenatus. ‘The Wellesley was launched at Bombay
about February 1815, and came into this harbour in May 1816,
where she remained for upwards of eight years previously to her
being taken into dock.
The same species of Mytilus has, however, within the last
twelve months, been found by Mr. Willcox among groups of
Mytilus edulis, on the fore part of the keel of several ships on
being taken into dock, which proves their naturalization in a
climate apparently uncongenial to their nature.
The Acematicherus Heros has been found in many parts of
His Majesty’s dockyard at Portsmouth for some years past.
Several specimens are in the possession of Mr. Willcox, and al-
though it was generally supposed that they were bred in African
timber, imported for the building and repairs of the navy, yet
it was not until the following circumstance occurred that this
fact was proved. With the intention of determining this ques-
tion, Mr. Willcox had for a considerable time been in the habit
of examining every piece of African timber which came under
his inspection: at length, whilst a piece of this timber was be-
ing cut, several small holes, the size of a pea, were discovered
running in a direction more or less oblique to the fibres of the
wood, and generally increasing to six or seven times their dia-
meter at the orifice, the inside surface being perfectly smooth.
Shortly after, a larva was found surrounded by the dust of the
wood, and it was carefully extracted from one of these holes.
This circumstance encouraged Mr. Willcox to make further
search, and he at length succeeded in finding in another hole
the pupa, which was taken out alive, and he found it to be that
of the insect before mentioned. 3
The perfect insect was kept alive by Mr. Willcox nine weeks,
by feeding it on sopped bread sweetened with sugar. Several
of these insects have of late been found in an apparent healthy
state, at different parts of the island of Portsea; two of them
(male and female) Mr. Willcox has now alive. It may be, per-
TRANSACTIONS OF THE SECTIONS. 449
‘haps, concluded from this circumstance that this species of in-
sect will ultimately become naturalized in this climate.
Abstract of Observations on the Structure and Functions of the
Nervous System. By James Macartney, M.D., Professor
of Anatomy and Surgery in the University of Dublin.
The author begins by stating the received opinion respecting
the structure of the brain, as consisting of two substances; the
one an opake white pulp, which is considered to be the nervous
matter; the other a coloured substance, in some places inclosing
the white, and at other places being imbedded in it.
It has been long known, he adds, that the white substance in
many parts assumes the shape of bands or bundles of fibres.
Dr. Spurzheim did not hesitate to call these fibres nerves, and
was more successful in tracing their course in some parts of the
brain than his predecessors had been.
But the author has employed a method of dissecting the brain,
which has enabled him to discover that all our former ideas with
respect to the structure of the cerebral organ fall far short of
the intricacy with which its several parts are combined.
In order to perceive the real structure of the brain, recent
specimens are necessary. The sight should be aided by spec-
tacles of a very high magnifying power; and as the different
parts are exposed in the dissection, they should be wetted with
a solution of alum in water, or some other coagulating fluid. B
these means it will be observed that all the white substance,
whether appearing in the form of bands, cords, or filaments, or
simply pulp, are composed of still finer fibres, which have a
plexiform arrangement, and that all those fibres, to the finest
that can be seen, are sustained and clothed by a most delicate
membrane. By the same mode of dissection, also, it is possible
to make apparent the existence of still finer interwoven white
fibres in all the coloured substances of the brain, in many of
which the nervous filaments are so delicate and transparent that
they are not visible until in some degree coagulated by the so-
lution of alum or by spirits.
Dr. Macartney has thus been enabled to see twenty-six
plexuses not hitherto described in the brain, the fibres com-
posing which assume two arrangements, the one reticular, the
other arborescent.
The membrane mentioned as pervading the entire substance
of the brain, and supporting its delicate organization in every
part, has heretofore escaped the observation of anatomists, and
yet when the fact is declared, we at once perceive that such a
1833. 26
450 THIRD REPORT —1833.
membrane must exist. It cannot be supposed that a mass of
the magnitude of the brain, and possessing so definite an or-
ganization, should form an exception to the fabric of all the
other parts of the body, and be left unprovided with a mem-
branous support. ‘This membrane is analogous to the cellular
membrane; and if we admit that the filaments of the brain are
similar to the fibres in other parts of the nervous system, we
may consider the membrane which sustains and connects the
cerebral plexuses as their proper musclema.
The pia mater, or vascular integument of the brain, is com-
posed of two layers; the external of which passes over the
convolutions of the cerebrum and the gyri of the cerebellum,
and the internal is reflected between these forms, and gives all
their exterior surface an intimate covering. The blood-vessels
seen on the brain are inclosed between these layers, and are
conducted on the inner layer to the substance of the organ. The
inner portion of the pia mater is continuous with the membrane
of the substance of the brain, but becomes so delicate on enter-
ing the structure of the organ that it is readily detached from
the brain without apparently injuring the integrity of its sur-
faces. When the inner layer of the pia mater is obtained in
connexion with a portion of the vessels and membrane which
penetrate the brain, it has the appearance of tufts or shreds,
and as such has been described by Ruisch and Alkenus under
the name of tomentum cerebri.
- The musclema of the brain appears in the adult to be only
furnished with colourless vessels, except in those places where
red vessels are seen to pass into the substance of the organ;
but in the foetus, the coloured substance of the convolutions
may be injected so as to appear quite red. ‘This fact is con-
sistent with the structure of many other organs during feetal
life, which in that period of existence receives red injection,
yet only admits afterwards colourless fluids. ‘The great degree
of vascularity in the foetus is particularly remarkable in the eye,
the lining of the labyrinth of the ear, the periosteum, &c.
The author has ascertained that the actual quantity of the
sentient substance existing in the brain and other parts of the
nervous system is extremely small. The bulk of these parts is
not materially diminished by removing their nervous matter,
provided their membranous structure be left behind; and
whenever we meet with the sentient substance in connexion with
a highly attenuated membrane, as in the retina and in several
of the cerebral plexuses contained in the coloured matter of the
brain, it is absolutely invisible until it has undergone some de-
gree of coagulation. It is, perhaps, not assuming too much
TRANSACTIONS OF THE SECTIONS. 45]
from these facts, to suppose that the whole nervous system, if suf-
ficiently expanded, and divested of all coverings, would be found
too tender to give any resistance to the touch, too transparent
to be seen, and probably would entirely escape the cognizance
of all oursenses. Consistently with this view of the matter, the
author thinks that we can hardly take upon us to say that the
simplest animals, and even plants, may not have some modifi-
cation of sentient substances incorporated in their structure, m-
stead of being collected, as in the higher classes of animals, into
palpable membranous cords and filaments.
The term plexus has been generally employed to signify an
interweaving or crossing of filaments; but Dr. Macartney is
satisfied that there is an actual union or intermixture of sub-
stance in both the plexuses of the brain and of the other parts
of the nervous system. He has discovered that the roots of
the spinal nerves, instead of being connected with the medulla
by mere contact or insertion, as hitherto supposed, actually
enter into the composition of the filaments of the spinal marrow,
and that these roots of nerves (as they are called) form com-
munications with each other within the substance of the me-
dulla. With regard to the cerebral nerves also, it can be
shown that they are continuous with the cerebral plexuses in
their immediate neighbourhood.
Many of the communications formed between the right and
left sides of the nervous system are well known, such as the
commissures of the brain, the crossing white filaments of the
spinal marrow, the decussation of the pyramids, and the inter-
change of the two optic nerves in fishes. The author has
found so many communications to exist between the origins of
the nerves on the right and left sides of the body, that he is
‘disposed to believe it to be a general fact. The optic nerves
in the human subject do not decussate, as some have supposed,
but form a very intricate plexus where they come into contact.
This mode of conjunction accounts for atrophy of the tractus
opticus being in some instances found on the same side, and at
others on the opposite side to that of the eye affected with
blindness.
The facts already observed would justify the opinion that
the sentient substance is in no place distant or isolated; that
it is essentially one and indivisible; and consequently the ner-
vous system differs from all the other systematic arrangements
in nature. oF
It appears to the author that this view of the sentient system
will alone serve to explain the numerous sympathies which
exist in animal bodies, the occurrence of disease in the higher
262
452 THIRD REPORT—1833.
orders of animals from indirect or remote impression, and the
operation of all remedies which act through the medium of the
sensibility.
The mode in which the sentient substance is arranged, its
more or less minute subdivision, and the degree of arterial
vascularity, determine the phanomena of sensibility as they
come under our observation. Hence, we find that the brain,
even different parts of it, the spinal marrow, the trunks of the
nerves, and their sentient extremities, are so differently en-
dowed, that we might be almost led into the error of supposing
them all composed of different materials.
It is well known to surgeons and to experimental physiolo-
gists, that the brain is not endowed with any feeling, in the
common meaning of the word. It may be wounded without
any sense of pain to the individual.
The trunks of the nerves not possessing the arrangement of
the sentient substance suitable to common sensation can only
transmit the feeling of pain. Thus, patients after amputation
often complain of pain in the part that has been removed ; but
the author believes that in no instance have they experienced
natural or agreeable sensations, or have expressed a conscious-
ness of the presence of the removed limb unattended with
ain.
3 The sentient extremities of nerves are alone capable of being
affected by narcotic poisons. Half a tea-spoonful of the es-
sential oil of almonds introduced into the substance of the
brain of a rabbit did not produce the least effect on the ani-
mal, nor was any effect produced by placing the end of the
sciatic nerve in a spoonful of the essential oil of almonds
during half an hour, although the animal was afterwards killed
in the usual manner by a few drops of this liquid on the
tongue.
Impressions on the extremities of nerves sent to the organs
of sense and to the external surfaces of the body are attended
with consciousness in the individual, whilst those naturally
made on the interior surfaces cause no perception. ‘These
surfaces, however, are amply supplied with nerves, and possess
a high degree of local sensibility, by which they not only
discern mechanic forms, but qualities in food and medicines
that the perceptive powers of the individual cannot distinguish.
These internal and unperceived sensations are continually
though secretly influencing the condition of the whole nervous
system, and are often the cause of remote morbid actions.
Under some circumstances movement follows impression made
on the external parts of the body after consciousness has be-
TRANSACTIONS OF THE SECTIONS. 453
come extinct. It is known that the ordinary actions of the iris
correspond with the impressions of light on the retina; and
the author has observed that the iris continues to move under
the same law after the animal’s head has been cut off, or the
eye taken out, as long as the retina retains its local sensibility :
similar effects take place in other parts of the body.
The mutual influence of the nerves and spinal marrow seems
to be all that is necessary during foetal life, as the absence of
the brain in the acephalous foetus does not interfere with any
of the functions of the creature until the moment of birth.
The offices which the coloured substance performs in the
nervous system have been matter of speculation with anatomists.
One obvious purpose of its existence is to give support and
security to the finest subdivisions of the sentient substance ;
we therefore find that it affords such protection in proportion
to the necessity: hence, in the brain, the coloured substance is
soft and tender, while in the ganglia of the nerves it is gene-
rally dense and firm. Besides, however, forming a nidus for
the ultimate plexuses of the sentient matter, the coloured sub-
stance would seem to fulfill some other use not yet ascertained,
as wherever it exists it exhibits the same character with respect
to colour, varying from yellow to green or brown. Dr. Mac-
artney considers the yellow spot in the retina of the human
eye, and in that of the monkey and lemur, as a ganglion, having
discovered that it contains a more intricate reticulation of the
nervous filaments than exists in the other parts of the retina.
The coloured substances of the nervous system in no degree
derive their peculiar tints from the blood that circulates in
them, since the colours are palest in the foetus, and grow
darker as the nervous system approaches its perfect organi-
zation. ;
It is a generally received opinion that the ventricles of the
brain are cavities or hollow spaces containing some liquid.
This error has arisen from the common modes of dissecting the
brain, which necessarily separate the surfaces of the ventricles
from each other. If, however, the dissection be performed
without disturbing the natural position of the parts, not the
slightest appearance of cavity or interspace presents itself.
The sole use of the ventricles, therefore, seems to be, merely
to gain an extent of surface necessary to the development of
the peculiar organization of the brain. Apparently there is
less superficies in proportion to the magnitude of the mass of
the brain in man than in that of animals; but if we calculate
the depth of the surfaces between the convolutions of the cere-
brum and on the branches of the arbor vita in the cerebellum,
454 THIRD REPORT—1833.
together with the internal surfaces, we shall find that the su-
perficies of the human brain is greater in relation to its bulk
than that of any other animal. In addition to the surfaces
already known, Dr. Macartney has ascertained the existence
of ventricles (so called) in the bulb of the olfactory nerves, and
in the optic thalami of the human adult brain. In the thalami
the distinction of surface is obscure, but in the olfactory tu-
bercles it is sufficiently plain.
The author concludes with stating his belief that every as-
semblage of the nervous filaments in the form of plexus is
destined to fulfill an especial purpose, and with the anticipation
that at no distant period we shall be able to understand many
of the phznomena of sensation which have been hitherto
veiled in the utmost obscurity.
Abstract of Observations on the Motions and Sounds of the
Heart. By Hveu Care, A.B., Demonstrator in the
School of Anatomy in the University of Dublin.
The circumstances in the history of the heart’s action which
have been most the subject of controversy within late years
may be enumerated as follow:—Ilst, the expansion and con-
traction of the auricles and ventricles, commonly called their
‘systole’ and ‘diastole’; 2nd, the beat of the heart against
the side of the chest; 3rd, the arterial pulse; and 4th, the
sounds perceptible during the heart’s motion. With a view to
the explanation of these phenomena the author has made some
experiments on living animals, the results of which he was
desirous of communicating to the Association.
In experiments of this kind it is desirable, as well for ensuring
the means of accurate observation as for the sake of humanity,
to diminish as much as possible the suffering of the animal.
This can be accomplished by the use of the artificial respiratory
apparatus, the animal having been suddenly deprived of sensa-
tion without shedding its blood. But the author has found
that the application of this apparatus causes the heart to con-
tinue and terminate its motions in an unusual manner, and is
therefore liable on some points to mislead the observer. In
those cases in which the employment of artificial respiration is
not expedient, there is much advantage in using very young
animals for experiment. In this stage of life, as well as in ani-
mals of the inferior classes, the different organs appear to haye
a comparatively independent existence; and as their functions
are in many instances performed with little disturbance under
—— oe
aC ths
Se eee rere rr rrr
TRANSACTIONS OF THE SECTIONS. 455
serious injury to the individual, they also retain their vitality
long after their separation from the rest of the system. From
the same causes very young animals appear to suffer less pain
during experiment than those of mature age.
After discussing the methods of experimenting, the author
proceeds to describe the opinions which have been held by
other persons on the subjects in question, and to compare them
with the conclusions to which his experiments have led.
Ist. It has been asserted by Bichat, and his celebrity has
induced many to adopt the opinion, that the ventricles possess
a power of active dilatation, by means of which, when their
systole has terminated, they are enabled to invite into their
cavities the blood from the neighbouring auricles. The author,
however, has ascertained by experiment that there is no such
dilating power in the ventricles, but that these muscles, when
their state of contraction has ceased, become perfectly soft and
flaccid, like all other muscles in their state of repose, and thus
readily admit the blood from their respective auricles, which
had become distended during the systole of the ventricles. The
feeling of resistance which was mistaken by Bichat for a dilating
power, and was supposed by him to accompany the diastole of
the ventricles, the author has ascertained to be caused by the
swelling of their muscular fibres during their systole.
The auricles contract but little upon their contents in man
and in the higher classes of animals, the small quantity of blood
which the ventricles discharge at each contraction being com-
pensated by the frequency of their movement; while in the
cold-blooded animals, in which the heart acts with less fre-
quency, the degree of expansion and contraction of both au-
ricle and ventricle is much greater than in the former classes,
and the quantity of blood sent through the heart at each move-
ment is much larger. sind
2nd. The impulse of the heart against the side of the chest,
commonly called its beat, has been explained by different
writers in various ways. Mr. Hunter supposed it to have been
caused by the straightening of the curve of the aorta during
the systole of the ventricles, whereby the apex of the heart was
thrown forwards. Meckel refers it, in part, to the elongation
of the arterial tubes during the ventricular contraction, and
partly to the swollen state of the auricles at that time, by which
the ventricles are pushed forward against the side of the chest.
Harvey mentions an opinion held by some in his time, and which
has been lately revived, namely, that the beat is caused, not by
any active power in the ventricles, but by the muscular con-
traction of the auricles during their systole, by which the blood
456 THIRD REPORT—1833.
being sent with force into the ventricles, distends their cavities,
and causes them to strike against the chest. This opinion,
therefore, supposes the beat of the heart to coincide with the
ventricular diastole. Various other suppositions have been put
forward upon this subject by different authors.
The author’s experiments show that the beat of the heart is
coincident with the systole of the ventricles, and is caused by
the peculiar shape which these parts acquire in their contracted
and hardened state, their middle part becoming globular and
prominent, and their apex being, as Hunter expressed it, ‘ tilted’
forward. During their systole the ventricles, like other muscles
in a state of contraction, become swollen and hard to the touch,
as was observed long since by Harvey. The greatest quantity
of muscular fibre being situated about their middle part, where
the ‘ musculi papillares’ are placed, this part during the systole
assumes a globular and prominent form, projecting in front,
and by its protuberance behind pushing forward the body of
the ventricles. The apex is ‘ ¢é/ted’ forward for the following
reason. The author has ascertained, by unravelling the struc-
ture of hearts prepared by boiling, that the fibres which pass
from the base to the apex, on the front of the ventricles, are
considerably longer than those similarly placed behind. In
some human hearts he has found them in the ratio of five to
three; the shape of the ventricles being nearly that of an ob-
lique cone, whose base is applied to the auricles, and whose
longest side is in front. Now it is a law of muscular action
that fibres are shortened during their contraction in proportion
to their length when relaxed. For instance, if a fibre one inch
long lose by contraction one fourth of its length, or one quarter
of an inch, a fibre two inches in length will lose one inch by a
contraction of equal intensity. We have seen that the fibres
which by their contraction cause the apex to approach the base
of the ventricles, are much longer on the front than on the back
part, and, consequently, the former are more shortened during
their contraction than the latter. The apex, then, does not ap-
proach the base in the line of the axis of the ventricles, but is
drawn more to the side of the longer fibres, that is, towards
the front, thus producing the ‘tilting’ forward.
This conclusion is strengthened by the fact that the forward
motion of the apex of the ventricles is always proportioned to
the obliquity of the form of these cavities in different classes of
animals. In the heart of some reptiles, the frog for example,
in which the lengths of the fibres of the ventricle before and
behind are nearly equal, the tilting of the apex is scarcely dis-
_ cernible. The obliquity is greater, as far as the author has
TRANSACTIONS OF THE SECTIONS. 457
been able to observe, in the human heart than in that of any
other animal.
Mr. Carlile has ascertained, also, that the ventricles assume
this form during their contraction, after they have been sepa-
rated from the auricles by a ligature, and even after they have
been removed from the body, and placed in a vessel of tepid
water, or keld upon the hand, the auricles having been pre-
viously cut off; in all which cases the peculiar motions which
accompany their contraction and relaxation were observed to
recur as long as their power of moving remained ; proving that
the beat of the heart is produced altogether by the action of
the ventricles during their systole, and that in these, as in all
other muscles, the peculiar forms assumed during their con-
traction depend upon the relation, as to length and position, of
the fibres of which they are composed.
ord. The arterial pulse, which is produced by the jet of
blood sent from the left ventricle into the aorta during its
systole, has been stated by Bichat and many other writers to
be synchronous throughout the whole arterial system. But
the experimenter can ascertain in his own person that the pulse
is successive at different distances from the heart. If the hand
be placed over the region of the heart, and the radial artery be
felt at the same time, an interval will be distinctly perceptible
between the beat and the pulse ; and if the anterior tibial artery
be substituted for the radial, the interval will be found still
greater. Repeated observations of this kind show that the in-
tervals of time between each beat of the heart and the corre-
sponding pulse in different parts of the body are proportioned
to the distances measured along the arteries, from the heart to
_ the respective parts; and a knowledge of this fact leads, without
further anatomical inquiry, to the conclusion that the beat of
the heart is coincident with the ventricular systole. For, as
the intervals of time between the beat and pulse are propor-
tioned to the distances from the heart to those parts where the
pulses are felt, it follows that when the distances become eva-
nescent the intervals of time will also vanish. Consequently, at
the origin of the aorta the pulse will coincide as to time with
the beat of the heart; but the pulse at the origin of the aorta
isnecessarily synchronous with the ventricular systole, by which
the blood is driven into that artery; and therefore the beat
_of the heart will coincide with the ventricular systole, a conclu-
sion which agrees with that drawn from positive experiment.
The proportion which exists in the pulse between the in-
tervals and distances is dependent upon the elasticity of the
arteries. |
458 THIRD REPORT—1833.
4th. An explanation of the sounds of the heart has become
necessary since the employment of the stethoscope in ascer-
taining the state of internal parts. Laennec has well described
these sounds, and properly refers the first to the rush of blood
from the ventricles during their systole. But, in supposing
that the second sound is produced by the auricular systole, he
has fallen into an extraordinary error, as the second sound
follows immediately after the first one, whereas the auricular
systole precedes the ventricular. This mistake has been no-
ticed by different writers since Laennec’s time, who have re-
jected his explanation, and substituted others in its place.
From the observations which the author has made, he has
no doubt that the second sound is caused by the obstacle which
the semilunar valves present to the passage of the blood from
the arteries back into the heart, at the termination of the ven-
tricular systole.
At each contraction of the ventricles a quantity of blood is
driven by them into the trunks of the arteries, which, being
already full, accommodate the addition to their contents by a
lateral expansion of their parts nearest to the heart. When
the systole of the ventricles is at an end, the elastic force of the
arteries, acting upon their contained blood, drives it towards
the heart, its entrance into which is prevented by the sudden
closing of the semilunar valves: and thus a shock is communi-
cated to the front and upper part of the ventricles, and to the
adjacent trunks of the arteries, which may be heard by the
ear placed over the region of the heart. ‘The relation, as to
time, which the second sound has to the first, its abrupt cha-
racter, and its coincidence with the end of the ventricular systole,
have led the author to adopt the foregoing opinion.
Mr. Carlile then described the experiments from which the
greater number of the preceding conclusions have been drawn,
and having detailed the circumstances of some made upon living
subjects, proceeded to relate those which follow.
1. Artificial respiration having been established in a rabbit
which had been strangled, and the heart having been exposed,
the following observations were made.
The finger being applied successively to the front, back, and
each side of the ventricles, conveyed the sensation of hardness
and impulse when the ventricles assumed the globular form, and
of softness and flaccidity when they became flattened and ex-
panded. The end of a probe being laid on the front surface
of the ventricles, was raised nearly a quarter of an inch during
the former of these states, and sank, causing a slight depression
on the surface, in the latter. The probe was more elevated
TRANSACTIONS OF THE SECTIONS. 459
when‘placed on the middle point of the surface, or on the front
of the apex, than when placed elsewhere.
The right wing being held aside, so as to admit of the right
auricle being’ seen, this was observed to swell during the con-
tinuance of the ventricles in their hardened state, and to dimi-
nish its size from the instant in which their flaccidity commenced,
its degree of contraction being, however, inconsiderable. _ The
contraction of the appendix was preceded by that of the rest of
the auricle, and followed by the instantaneous movement and
hardening of the ventricles... The contraction of the different
parts of the auricle was successive, commencing at the venz
cave, and terminating at the appendix, of which last the con-
traction was much more sudden and distinguishable than that of
any other part.
The heart in this subject continued to beat for an hour, when
the motions in all its parts ceased, and nearly at the same time ;
both auricles and both ventricles remaining distended, soft, and
full of blood. The heart, separated from the body, was thrown
into tepid water, where it remained, soft, and without motion,
and had lost the power of contracting itself.
2. A rabbit having been strangled, the heart was exposed
while still beating. In about 10 minutes the left ventricle
ceased to move, and had contracted itself firmly. In a minute
or two afterwards all motion was at an end in the left auricle,
which was also contracted. The right ventricle continued. its
movements for 45 minutes, and during its contraction the apex
of the heart was drawn a little to the right side. The right,
auricle continued to possess motion for an hour and three quar-
ters; and for the last 20 minutes its contraction proceeded
slowly, and with a motion apparently vermicular, over its sur-
face ; always commencing at the part contiguous to the venz
cave, and ending at the appendix. The right auricle and ven-
tricle contained each some blood when their motions ceased ;
but, the heart having been thrown into tepid water, they gra-
dually expelled their contents, assuming, as those of the left
side had done, a firm and contracted state.
The difference of the states in which the hearts were found,
after their motions had ceased, in the last two experiments, is
remarkable, and appears to admit of the following explanation.
In the last experiment, in which no means were employed to
continue respiration, the left side of the heart soon ceased to
move; because a continuance of the functions of the lungs, as
proved by the experiments of Bichat, is necessary to the main-
taining of its actions. The firmness of its contraction shows,
that although its ordinary motions had ceased, it still retained
460 THIRD REPORT—1833,
a considerable share of organic life, as it is known that muscles,
whose vitality is quite extinct, have no power of contraction.
In the experiment in which respiration was artificially main-
tained, the left side of the heart continued to beat for an hour,
the sustained function of the lungs affording to it a motive for
prolonged action ; but having been deprived of the influence
which the central parts of the nervous system extend to organs
in vital connexion with them, its powers of life were exhausted
by the long continuance of its motions, and when these ceased,
it was quite dead, and incapable of a vital contraction. The
right side of the heart in the last experiment seems to have
participated in the exhausted state of the left side, because its
motions had been performed with much more energy during
their continuance than would have been the case had not re-
spiration been artificially maintained.
On the Mechanism and Physiology of the Urethra. By
Henry Earte, F.R.S., Professor of Anatomy and Surgery
to the Royal College of Surgeons.
The author, having been lately engaged in delivering a course
of lectures on the anatomy and diseases of the urinary organs,
was led to prosecute his inquiries into the minute structure of
the urethra, and to avail himself of the aid of comparative ana-
tomy to elucidate the subject. The results of this inquiry he
related briefly to the Section, with a view of reconciling some
of the discordances of opinion at present existing, and of ex-
plaining the double functions of the organ.
On the Nomenclature of Clouds. By —— Burr.
In the course of some meteorological observations, Mr. Burt
found the variations in the forms of clouds to be so numerous,
that it was difficult, by the use of Mr. Howard’s nomenclature,
to describe them with sufficient accuracy.
In consequence, he suggests the propriety of defining the
leading sections of clouds by peculiarities of their external con-
stitution, and of characterizing the minor divisions by the ex-
ternal forms of the masses.
TRANSACTIONS OF THE SECTIONS. 46]
On the peculiar Atmospherical Phenomena, as observed at Hull
during April and May 1833, in relation to the prevalence of
Influenza. By G. H. Frevpine, M.R.C.S.L.
. The author observes, that the true causes of epidemic dis-
eases being for the most part unknown, all the unusual circum-
stances which occur during their prévalence, especially if these
be capable of estimation by exact comparative measurements,
should be carefully recorded. ‘The value of meteorological ob-
servations, as tending to determine the most important of the
variable conditions of this interesting problem, is insisted on,
and the results of his own observations are presented as prov-
ing that the state of the atmosphere during the period of the
prevalence of influenza at Hull in 1833 was extraordinary.
The following are the numerical results.
- 1832, 1833.
Gia at We ee Ca
April. May. Diff. April. | May. Diff.
Mean pressure of the air. | 30°063 | 29-989 | 0-08 29°799 | 30°177 | 038
dew point ..... 40°006 40°808 0°80 37°823 | 45°253 | 7:48
temperature in shade | 46°674 | 49°767 | 3-09 44-706 | 55°393 | 10°69
temperature in sun. | 68°348 | 72:865 | 4°52 7:251 | 84:122 | 16-97
max. temp. in shade | 53°933 | 57°809 | 3°87 51°310 | 63-690 | 12°38
min. temp...... 39°416 41°725 2°31 387103 | 47-096 | 8:99
Quantity of rain in inches 3°820 2-240 { 1°58 4530 0-600 |} 3:93
From the columns of differences it will be seen how much
more sudden and violent in all respects was the transition from
‘April to May in 1833 than in 1832. The number of hours in
which the sun thermometer, which has a blackened bulb,
could be used was, in April, 81; in May, 158. ‘The winds in
April were easterly at the beginning and end, W., S.W., and
N.W. in the middle ; in March generally S., varying to the E.
and W. Rainy days in April, 23; in March, only 2.
The 16th of May is particularly mentioned as affording a
remarkable instance of contrast between the years 1832 and
1833. In 1833, during 14 hours, the thermometer in the shade
averaged upwards of 70°; during 8 hours nearly 75°; from 2
tod p.m. 77°. The thermometer in the sun for 19 successive
hours was upwards of 90°. Minimum temperature of the fol-
lowing night 49°. Range of temperature in the sun 47°°5; in
‘the shade 28°. In 1832, during 13 hours, the thermometer in
the shade averaged rather more than 48°; in the sun at 3 P.M.
the thermometer reached 62°°8; at 2 and 3 in the shade 50°°8
and 51°, which was the maximum. Minimum of the following
night 33°.
462 THIRD REPORT—1833.
In conclusion the author states that he does not offer these
data as affording a complete explanation of the prevalence of
influenza, but remarks that it is difficult to imagine otherwise
than that such sudden changes from cold to heat, from wetness
to dryness, from midday heat to cold evening fogs, must have
had a very decided and general influence on the health of the
human body. i
IV. HISTORY OF SCIENCE.
A short Account of some MSS. Letters (addressed to Mr. Abra-
ham Sharp, relative to the Publication of Mr. Flamsteed’s
Historia Celestis, ) laid on the table, for the inspection of the
Members of the Association. By Francis Batty, V.P.R.S.,
President of the Royal Astronomical Society.
Tues letters belonged to the late Mr. Abraham Sharp, and
were found some years ago in a box deposited in an old lumber.
room, filled with various books and papers, which had been
considered as of so little use that they were frequently taken
out by the servants to light the fire, and were otherwise de-
stroyed and lost. The present collection of them, which was
preserved from such destruction, consists of above 120 letters
from the celebrated Flamsteed, and of about half that number
from Mr. Crosthwait, his assistant at the Royal Observatory,
all addressed to Mr. Sharp, who at that time lived at Little
Horton, in Yorkshire, on an estate of his own. It is probable
that these are the letters alluded to in the life of Mr. Sharp,
inserted in Dr. Hutton’s Mathematical Dictionary, the parti-
culars of which, however, have never yet been made public.
They are now the property of a relation of the late Mr. Sharp,
residing in London, by whose permission they are exhibited for
inspection.
It is well known that Mr. Sharp divided the mural are that
was erected at Greenwich for Flamsteed’s use, and that he
was for some time the assistant there. He afterwards retired
to his estate at Little Horton, where he lived a very secluded
life, passing most of his time in astronomical calculations.
Flamsteed employed him to compute the places of several of
the stars in his Catalogue, from the original observations ; and
_an extensive and friendly correspondence was kept up between
them till the time of Flamsteed’s death, and was afterwards
continued with Mr. Crosthwait, who superintended the print-
TRANSACTIONS OF THE SECTIONS. 463
ing of Flamsteed’s works. ‘This correspondence embraces a
variety of subjects; but the principal, the most novel, and the
most interesting is the account of the repeated difficulties and
impediments which delayed and almost prevented the printing
of the Historia Celestis.
The date of the first letter, in the present collection, is
February 6th, 1701-2, at which time it appears that Flam-
steed was preparing to publish his work, which was not com-
pleted till twenty-four years afterwards, being six years after
his decease. He commenced the publication at his own cost
and risk; but after he had expended a considerable sum
of money, the subject was mentioned to Prince George of
Denmark, who undertook to defray the expense of bringing
out the work: and here his troubles began; for, in the first
place, the Prince declined the publication of the maps, which
Flamsteed considered the most important part, and such as,
in his opinion, would tend most to the “ glory of the work ;”
and secondly, the committee of the Royal Society, to whom
the superintendence of the business was intrusted, appear, from
the whole tenor of these letters, to have thrown every obstacle
in the way to prevent the progress of the printing. It is not
directly stated who were the members that formed that com-
mittee, but it is evident from the correspondence that Newton
and Halley formed a part of it ; and Flamsteed can never touch
on this subject (and it forms a prominent portion of his letters,)
without expressing his opinion, in no very courteous language,
of their unfriendly and hostile conduct towards him.
It was in 1704 that the Prince offered to undertake to defray
the expenses of the printing ; but so many impediments were
thrown in the way (oftentimes frivolous and vexatious,) that it
was not till the end of the year 1707 that the first volume only,
the least interesting part of the work, was completed. Before
the second volume was commenced,’ the committee required
Flamsteed to deposit in their hands a duplicate copy of the
Observations, as well as of his Catalogue, which he accord-
ingly did, sealed up. New causes for delay, however, were
brought forward, and before the second volume was sent to
the press Prince George died. During the whole of this time
Flamsteed had received only £125 towards the expenses of the
work ; and as he saw no prospect of any further support from
Government, he resolved to wait for better and more favour-
able times.
He then demanded from the committee the return of the ma-
nuscript Observations and Catalogue which he had deposited
in their hands, which request they appear to have refused.
464. THIRD REPORT—1833.
The breach was now complete, and the subsequent letters are
filled with complaints of the conduct of the committee ; and
Flamsteed eventually commenced legal proceedings against Sir
Isaac Newton for the restitution of the MSS. But it is prin-
cipally on Dr. Halley that the force of his indignation falls ;
and if the circumstances referred to in the letters be correct,
(of which there does not seem to be any doubt, although the
motives of the parties may have been misinterpreted,) Flam-
steed had just cause for complaint and redress; for he charges
Halley, in direct terms, with having surreptitiously purloined
the manuscript Observations and Catalogue deposited with the
committee, and with having published them in a garbled and
incorrect manner. It is acknowledged that the seals were
broken; but it is pretended that this was done by an order
from the Secretary of State, for what purpose, however, does
not appear. It is notorious that Halley did publish an edition
of Flamsteed’s Catalogue, and extracts from his Observations,
in the year 1712, which is the work alluded to by Flamsteed ;
and as Flamsteed could never recover back the MSS., there
is no doubt that these were the documents made use of. In
fact, the matter is not disguised by Halley, in the preface.
Flamsteed remonstrated against this conduct; calls Halley ‘a
malicious thief,” and bestows on him other opprobrious epithets.
In the year 1716, Flamsteed obtained an order from the King
to have the remaining (unsold) copies of this work delivered up
to him, for the purpose of being destroyed: 300 copies were
consequently sent to the Observatory, which, he says, he ‘‘ sa-
crificed to truth”; and he appears to have missed no oppor-
tunity of destroying every copy that came into his possession.
Such is Flamsteed’s history of the edition of 1712.
During all this time, no further progress had been made in
printing the Observations. The first volume only was com-
pleted, but this did not contain any of the observations made
with the mural arc at Greenwich; the second, which was to
commence with those observations, was not yet begun. Flam-
steed, however, had printed, for private circulation only, a cor-
rect copy of his Catalogue of Stars, to counteract the effect of
Halley’s spurious edition; but no steps had been taken towards
forwarding the main work, which had now lain dormant upwards
of ten years, and which was much increased by the numerous
observations made during that period. At length, not being
able to regain possession of the MSS., he was obliged to copy
them again from the original entries, which was a great trouble
and expense to him; and towards the end of the year 1717,
he sent the first sheet of the second volume to the press; re-
TRANSACTIONS OF THE SECTIONS. 465
solved to proceed in the work at his own cost. Before
his decease, which happened on Dec. 31st, 1719, he had
completed that volume, having been occupied nearly nineteen
years in the prosecution of the work, struggling with difficul-
ties of various kinds, and thwarted and opposed in various
ways. Itis to his perseverance and public spirit, supported
afterwards by the gratuitous exertions of Mr. Sharp and Mr.
Crosthwait, that we are indebted for the British Catalogue,
and for that vast mass of observations made at the Royal
Observatory, which are still of use in various branches of
astronomical research, and which will render his name illus-
trious as long as the science exists.
The correspondence of Mr. Crosthwait relates principally to
the difficulties, impediments, and delays which still prevented
the work from being brought to a final conclusion ; and it may
be safely stated, that had it not been for the extraordinary
exertions of Mr. Sharp and Mr. Crosthwait, the whole would
never have been completed. ‘The Catalogue was reexamined
and compared with the observations, and afterwards reprinted
with several amendments. The preface cost him much trouble:
it was required to be translated into Latin, but no one could
be found adequate to the task, though repeatedly attempted.
Mr. Pound undertook it, but eventually declined it; and it
was at last accomplished by a Dissenting minister. The third
volume was at length finished, and the whole work published
in 1725, six years after Flamsteed’s death.
There remained now only the maps, the construction and en-
graving of which appear to have cost as much trouble and vex-
ation as the letter-press. Only one of them was finished (Orion)
when Flamsteed died. For the rest we are indebted to Mr.
Sharp, who constructed them anew, according to Flamsteed’s
principles, from the Catalogue. Sir James Thornhill drew the
figures of the constellations, and recommended engravers for
the work; but the charges of the English artists were consi-
dered so enormous, that Mr. Crosthwait went over to Holland
for the express purpose of engaging some of the best Dutch
engravers to complete the work. ‘The vexatious delays which
necessarily occurred by adopting this method, its increased ex-
pense, and the constant attention requisite to prevent mistakes,
dispirited Mrs. Flamsteed, and a temporary stop was conse-
quently put to the work, although Mr. Sharp (now much ad-
vanced in years) and Mr. Crosthwait were willing to continue
their services. Atlength, some English engravers being found
who offered to execute the maps at a more moderate expense,
the labours of these gentlemen were renewed, and continued till
1833. 2u
466 THIRD REPORT—1833.
the time of Mrs. Flamsteed’s death, which took place on July
29th, 1730.
Here the correspondence ceases, probably on account of the
circumstances mentioned in the last letter, whereby it appears
that Mrs. Flamsteed did not leave either Mr. Sharp or Mr.
Crosthwait a single farthing for all their services; neither had
they received any remuneration since Mr. Flamsteed’s death
for their unparalleled exertions in her behalf.
*.* Since the above statement was written, Mr. Baily has
discovered amongst Flamsteed’s manuscript papers, deposited
at the Royal Observatory at Greenwich, all the Answers of Mr.
Sharp to the above letters of Flamsteed; thus constituting a
complete correspondence between the parties for nearly eighteen
years.
CORRIGENDUM IN PROFESSOR POWELL’S PAPER.
In the abstract, given in the Proceedings of the Physical Section, of Professor
Powell’s paper a formula is introduced (p.377) which the author finds, since
the paper was printed, is incorrect; this however does not affect the rest of the
paper: but the whole will shortly appear in detail in another form.
a
RECOMMENDATIONS
OF
THE BRITISH ASSOCIATION
FOR THE
ADVANCEMENT OF SCIENCE.
Tue following Reports on different Branches of Science have
been drawn up, at the request of the Association.
Vol. I.
On the progress of Astronomy during the present century, by
by G. B. Airy, M.A., Plumian Professor of Astronomy and
Natural Philosophy, Cambridge.
On the state of our knowledge respecting Tides, by J. W.
Lubbock, M.A., Vice-President and Treasurer of the Royal
Society.
On the recent progress and present state of Meteorology,
by James D. Forbes, F.R.S., Professor of Natural Philosophy,
Edinburgh. —
On the present state of our knowledge of the Science of
Radiant Heat, by the Rev. Baden Powell, M.A., F.R.S., Sa-
vilian Professor of Geometry, Oxford.
On Thermo-Electricity, by the Rev. James Cumming, M.A.,
F.R.S., Professor of Chemistry, Cambridge.
On the recent progress of Optics, by Sir David Brewster,
LL.D., F.R.S., &c.
On the recent progress and present state of Mineralogy, by
the Rev. Wm. Whewell, M.A., F.R.S.
On the progress, actual state, and ulterior prospects of Geo-
108: by the Rev. Wm. D. Conybeare, M.A.,F.R.S., V.P.G.S.,
Clea, the recent progress and present state of Chemical Sci-
ence, by James F. W. Johnston, A.M., Professor of Chemistry,
Durham.
On the application of Philological and Physical Researches
to the pea of the Human Species, by J. C. Prichard, M.D.,
F.R.S.,
2H2
468 THIRD REPORT— 1833.
Vol. II.
On the advances which have recently been made in certain
branches of Analysis, (Part I.,) by the Rev. G. Peacock, M.A.,
F.R.S., &c.
On the present state of the Analytical Theory of Hydro-
statics and Hydrodynamics, by the Rev. John Challis, M.A.,
F.R.S., &c.
On the state of our knowledge of Hydraulics, considered as a
branch of Engineering, (Part I.,) by George Rennie, F.R.S., &c.
On the state of our knowledge respecting the Magnetism of
the Earth, by S. H. Christie, M.A., F.R.S., Professor of Ma-
thematics, Woolwich.
On the state of our knowledge of the Strength of Materials,
by Peter Barlow, F.R.S.
On the state of our knowledge respecting Mineral Veins, by
John Taylor, F.R.S., Treas. G.S., &c.
On the state of the Physiology of the Nervous System, by
William Charles Henry, M.D., F.R.S.
On the recent progress of Physiological Botany, by John
Lindley, F.R.S., Professor of Botany in the University of Lon-
don.
The following Reports have been undertaken to be drawn
up, at the request of the Association.
On the theories of Capillary Attraction and of the Propagation
of Sound as affected by the development of Heat, by the Rey.
John Challis, M.A., F.R.S., &c.
On the state of our knowledge of Hydraulics, (Part II.,) by
George Rennie, F.R.S.
On the present state of our knowledge respecting the con-
nexion of Electricity and Magnetism, by S. H. Christie, M.A.,
F.R.S., Professor of Mathematics, Woolwich.
On the state of the science of Physical Optics, by the Rev.
H. Lloyd, M.A., Professor of Natural Philosophy, Dublin.
On the state of our knowledge respecting the application of
Mathematical and Dynamical principles to Magnetism, Electri-
city, Heat, &c., by the Rev. Wm. Whewell, M.A., F.R.S.
On the recent additions to our knowledge of the Phenomena
of Sound, by the Rey. R. Willis, F.R.S., &c.
On the state of our knowledge respecting the relative level
of Land and Sea, and the waste and extension of the land on
the east coast of England, by R. Stevenson, Engineer to the
Northern Light-houses, Edinburgh’.
1 Communications of facts relative to this subject are much wanted, and may
be addressed to Mr. Stevenson, Civil Engineer, Edinburgh.
RECOMMENDATIONS. 469
On the state and progress of Zoology, by the Rev. Leonard
Jenyns, M.A., F.L.S., &c.
On the state and progress of Systematic Botany, by G. Bent-
ham.
On the state of our knowledge respecting the influence of
Climate upon Vegetation, by the Rev. J. S. Henslow, M.A.,
Professor of Botany, Cambridge.
On the state of Physiological knowledge, by the Rev. Wil-
liam Clark, M.D., F.G.S., Professor of Anatomy, Cambridge.
On the state of Pathological knowledge, by John Yelloly,
M.D., F.R.S.
RECOMMENDATIONS
OF
THE COMMITTEES,
WITH NOTICES OF DESIDERATA IN SCIENCE BY THE
AUTHORS OF REPORTS.
[The Recommendations adopted at the Cambridge Meeting have an asterisk
prefixed. |
ASTRONOMY.
Tue Committee for Mathematical and Physical Science stated,
that it would tend much to the advancement of astronomy and
the art of navigation, if the observations of the sun, moon, and
planets, made by Bradley, Maskelyne, and Pond, were reduced.
It was resolved by the General Committee, that a represen-
tation to this effect from the British Association be submitted
to Government, in the hope that public provision might be
made for the accomplishment of this great national object; and
that a deputation, consisting of Professor Airy, Mr. Baily, Mr.
Davies Gilbert, and Sir John Herschel, be appointed to confer
with the Lords of the Treasury on the subject.
‘The application was immediately complied with by the Go-
vernment, and an advance of 500/. has been made by the Trea-
sury towards the reduction of the observations from the year
1750 to the present day.
470 THIRD REPORT—1833.
Desiderata noticed in Professor Airy’s Report, p. 187.
1. Directions for placing a thermometer so as to indicate cor-
rectly the Temperature of the Air at the place of observation,
for Refraction-corrections, the external and internal tempera-
tures being supposed as nearly as possible equal.
2, Experimental Data for the Theory of Refraction—
What is the law of the decrease of temperature, or of
density, in ascending ?
How does this vary at different times ?
Can any means be contrived for indicating practically at
different times the modulus of variation ?
Does the refractive power of air depend simply on its
density, without regard to its temperature ?
Is it well established that the effects of moisture are al-
most insensible ?
Can any rule be given for estimating the effect of the
difference of refraction in different azimuths, accord-
ing to the form of the ground?
When the atmospheric dispersion is considerable, what
part of the spectrum is it best that astronomers should
agree to observe ?
3. An investigation of the coefficient of Nutation from the
Greenwich circle-observations. ;
4, The reduction of Bradley’s and Maskelyne’s Observations
of the Sun and Planets, on a uniform plan.
5. Remeasurement! of the elongation of Jupiter’s Satellites,
to correct the estimate of the mass of Jupiter.
6. Separate investigations, from observations, of the diminu-
tion of the aphelion distance and perihelion distance of Encke’s
Comet, for the purpose of testing the truth of Encke’s assumed
law of density of the resisting medium.
7. Calculations of the perturbations of Biela’s Comet for the
interval between 1772 and 1806, and of those of the node and
inclination from 1806 to 1826, for the purpose of ascertaining
the identity of the comet of 1772, and examining whether this
comet gives any indication of a resisting medium.
8. Verification of Burckhardt’s formule in the Mémoires
de U Institut for 1808, and extension of them to terms depend-
ing on the inclination.
9. Theory of the perturbations of Pallas, and of Encke’s
Comet.
1 Professor Airy himself has since made the required measurements, and
given a determination of the mass of Jupiter.
RECOMMENDATIONS. ATI
TIDES.
* That a sum not exceeding 200/. be devoted to the discussion
of observations of the Tides, and the formation of Tide Tables,
under the superintendence of Mr. Baily, Mr. Lubbock, Rev.
G. Peacock, and Rev. W. Whewell.
That the Association should endeavour to procure the gene-
ral establishment of systematic Tide Observations along the
coasts of Great Britain and Ireland, and that the standing Com-
mittee on Tides be requested to select such places' as may
appear to them most important for this purpose; that the di-
rection, and, if possible, the intensity of the wind should be ob-
served, as well as its critical changes after having set for some
time in a particular direction; and that the altitude of the cur-
rents of air should also be, as far as possible, remarked.
METEOROLOGY.
1. That the Committee in India be requested to institute such
observations as may throw light on the horary oscillations of
the barometer near the equator.
_ 2. That the Committee in India be requested to institute a
series of observations of the thermometer during every hour of
the day and night.
3. That a similar hourly register be established at some mili-
tary or naval station in the South of England?.
4. That the decrease of temperature at increasing heights in
the atmosphere should be investigated by continued observa-
tions at stated hours and known heights. The hours of 93
A.M. and 84 p.M., as giving nearly the mean temperature of the
year, are suggested for the purpose. (See Report, p. 218.)
5. That persons travelling on mountains, or ascending in bal-
loons, should observe the state of the thermometer, and of the
‘dew-point hygrometer, below, in, and above the clouds, and
determine how the different kinds of clouds differ in these re-
spects. (See Report on Meteorology, vol. i. p. 245.)
6. That the temperature of springs should be observed at
different heights above the mean level of the sea, and at dif-
ferent depths below the surface of the earth, and compared with
1 Directions for observing the Tides, extracted from Mr. Lubbock’s Report,
and Mr. Whewell’s Memoranda, are inserted in the Appendix.
? Observations in agreement with this recommendation have been commenced
at Plymouth and Devonport, under the directions respectively of Mr. G. Har-
vey and of Mr. Wm. Snow Harris.
472 THIRD REPORT—1833.
the mean temperature of the air and the ground.—Detached
observations on this subject will be useful, but a continued and
regular series of results for each locality will be more valuable’.
(See Report, vol. i. p. 224.)
7. That series of comparative experiments should be made on
the temperature of the dew-point, and the indications of the
wet-bulb hygrometer, and that the theory of this instrument
should be further investigated. (See Report,vol. i. p.243—246.)
8. That particular attention be paid to the improvement of
the instruments of meteorological research.
9. That Mr. Phillips, and Mr. Wm. Gray, jun., be requested
to undertake a series of observations on the comparative quan-
tities of rain falling on the top of the great tower of York Min-
ster, and on the ground near its base ; and that similar obser-
vations be instituted at other places”.
A standing Committee was appointed, consisting of Profes-
sors Airy, Christie, and Forbes, Dr. Dalton, Dr. Robinson, Mr.
Potter, and Mr. Scoresby, to draw up instructions? for ob-
serving Auroras, and to endeavour to establish corresponding
observations in every part of the kingdom.
Desiderata noticed in Prof. Forbes’s Report.
1. Verification of Dr, Dalton’s theory of the constitution of
the atmosphere, by direct experiment. (Report, vol. i. p. 206 ;
Phil. Trans. 1826.) E
2. Experiments in various latitudes upon the temperature of
the earth at moderate depths, by means of thermometers with
long tubes; with a view to determine the position of the ‘ in-
variable stratum,” where external causes cease to produce any
effect. (Report, vol. i. p. 221.)
1 The height of the springs may be determined with sufficient accuracy by a
common portable barometer.
2 The observations at York have been made at three adjacent stations of
known height, with gauges made on the same mould, and measured by one gra-
duated glass vessel: they have been continued from the Ist of February 1832
to the present time. From the results, it has been inferred by Mr. Phillips
that the diminution in the quantity of rain, at the higher stations, has a certain
constant dependence on the height of the station, and on the condition of the
air as to moisture in the different periods of the year. For the further elucida-
tion of this subject, it is desirable that experiments upon the same plan should
be tried in other situations, and especially where the climate is of a different
character from that of York ; in the humid atmosphere of Cornwall, for exam-
ple, and in the drier air of the midland counties. Gauges exactly similar to
those in use at York will be supplied from thence to persons undertaking to try
these experiments, on application to the Secretaries,
3 An abstract of the directions which have been drawn up by the Committee,
is given in the Appendix.
a a
RECOMMENDATIONS. 473
3. Experiments on the solar and terrestrial radiation. (Re-
port, vol. i. p. 222.)
4. Observations on the horary oscillations of the barometer,
at considerable heights above the sea. This more particularly
applies to places near the equator’.
5. Additional observations to determine what is the influence
of the moon on the height of the barometer. (Report, vol. i.
p- 234. See also Arago, Annuaire for 1833.)
6. The application of the hygrometric correction to the ba-
rometric formulz for heights. (Report, vol. i. p. 254.)
_ 7. Observations on the phenomena of wind at two stations,
at considerably different elevations, (p. 249.) The direction of
the wind should be noted in degrees, beginning from the south
and proceeding by the west.
8. Magnetical observations, regularly conducted, especially
with a view to auroral phenomena.
OPTICS.
* That a sum not exceeding £50 be appropriated to the
construction of a telescopic Lens, or Lenses, out of rock-salt,
under the direction of Sir David Brewster.
Desiderata noticed in Sir David Brewster's Report.
The determination of various constants, namely,
1. The refractive indices of the two pencils in all crystallized
bodies, measured in reference to definite points of the spectrum.
2. The angles at which light is polarized by reflection from
crystallized and uncrystallized surfaces.
3. The inclination of the resultant axes of crystals having
double refraction, for different rays of the spectrum.
4, The dimensions of the ellipse which regulates the polariza-
tion of metals and their alloys.
5. The circularly polarizing forces of fluids and solutions.
6. The refractive and dispersive powers of ordinary solid and
fluid bodies, measured according to the method of Fraunhofer.
7. Experimental determination of the effects of the absorp-
tion of light by gases upon the light of the fixed stars. (p. 322.)
1 Those who may possess such observations, continued for one or more weeks,
with observations of the temperatures of the mercury and of the air, and the
probable corresponding temperatures of the air at the level of the sea, are re-
quested to transmit them to Professor Forbes, Edinburgh. _ The local position
of the point of observation should also be noticed.
474. THIRD REPORT—1833.
MAGNETISM.
1. That a series of observations upon the intensity of 'Ter-.
restrial Magnetism be executed in various parts of the king-
dom, similar to those which have been carried on in Scotland
by Mr. Dunlop. (Some experiments, made in consequence of
this recommendation, by Dr. Traill, are given in the published
Reports of the Association, page 557.)
2. That observations should be made in various places with
the Dipping-needle, in order to reduce the horizontal to the
true magnetic intensity.
* A standing Committee, charged with promoting these
objects, has been appointed, consisting of Professors Christie,
Forbes, and Lloyd. The latter gentleman has undertaken to
make observations on the magnetic intensity in Ireland, before
the next Meeting of the Association.
Desideratum noticed in Prof. Christie's Report.
* A regular series of observations conducted in this country
on the diurnal variation of the needle.
ELECTRO-MAGNETISM.
The Committee recommend for further examination the Elec-
tro-magnetic condition of mineral veins. (Consult on this sub-
ject the paper of Mr. Fox, Phil. Trans. 1830.)
RADIANT HEAT.
Desiderata noticed in Professor Powell's Report.
1. Improvement of the means of obtaining accurate indica-
tions of small degrees of radiant heat: the thermo-multiplier
of MM. Nobili and Melloni to be subjected to examination’.
(vol. i. p. 297, &c.)
Determination of the following questions (p. 298.) :
2. Do the ratios of the conducting powers of substances re-
main the same for all thicknesses ?
3. It is alleged that in certain cases simple heat is radiated
freely and directly through transparent media : Is it meant that
1 Professor Forbes gave an account of the performance of this instrument
at the Cambridge Meeting.
RECOMMENDATIONS. 475
the manner of its transmission in such cases is strictly analogous
to that in which light is communicated ; or is it only an ex
tremely rapid communication by conduction? What circum-
stances can be fixed upon to determine our view of the matter?
4. Taking into account the thickness, state of surface, &c.,
of a body exposed to radiant heat, does any portion of time
elapse before it acquires heat from the source; or before it
begins to radiate it again, when acquired ? and how soon will
it commence radiating on the opposite side; or according to what
law does the heat distribute itself over or through the body?
These questions are put in reference chiefly to the action of
the body as a sereen, and to the possibility of accounting for
an apparently direct transmission of heat without the necessity
of supposing any other principle than that of conduction.
5. What are the modifications which radiant heat undergoes
in passing through small apertures? (p. 299.)
6. Sir J. Leslie found that the focus for simple heat, in the
concave reflectors he used, was different from and nearer to
the reflector than that for light: Is this confirmed by more
extensive and exact observations? and what is the precise focal
distance in different cases? (Leslie’s Inquiry, p. 14.)
7. What is the proportion of heat reflected at different in-
cidences ?
8. What radiation takes place in vacuo? (p. 300.)
CHEMISTRY.
1. That British Chemists be invited to make experiments
for removing doubts respecting the proportions of Oxygen,
Azote, &c., in the atmosphere; for determining the proportions
of Azote and Oxygen in Nitrous Gas and Nitrous Oxide ; and
for more accurately investigating the specific gravity of the
compound gases in general.
2. That Dr. Dalton and Dr. Prout be requested to institute
experiments on the specific gravities of Oxygen, Hydrogen,
and Carbonic Acid, and that a sum not exceeding 50/. be ap-
propriated to defray the expense of any apparatus which may
be required.
3. That Dr. Turner! be requested to extend his researches
into the atomic weights of the elementary bodies, and to re-
port on the progress recently made inthis branch of chemical
science.
1 Dr. Turner reported the progress of his researches to the Meeting at
Cambridge.
476 THIRD REPORT—1838.
4. That Mr. Johnston! be requested to undertake the expe-
riments which have been suggested to the Committee, into the
comparative analysis of Iron in the different stages of its ma-
nufacture.
*5, That a series of experiments on the effects of long-con-
tinued heat be instituted at some iron-furnace, or in any other
suitable situation; and that a sum not exceeding 50/. be placed
at the disposal of a Sub-Committee, consisting of Professor
Daubeny, Rev. W. V. Harcourt, Professor Sedgwick, and
Professor Turner, to meet any expense which may be in-
curred *.
*6, That inquiry be made as to the most perfect method of
purifying Mercury, and that the true specific gravity of the
metal be determined.
*7, That an examination be made into the nature and quan-
tity of the gases given off from thermal waters, whether there
be any variation in these respects according to season of the
year, hours of the day, or condition of the atmosphere ; and
whether there be any changes of temperature in the same
waters.
*8. That the gaseous products which are discharged from
the chimneys of smelting and other furnaces and fireplaces be
examined, at various periods of the operations carried on in
them, with a view of ascertaining the compounds which are
formed when the processes are most successfully conducted,
and also of detecting the existence of compounds which may
perhaps be new or valuable.
MINERALOGY.
1. That Professor Miller be requested to undertake an ex-
amination of the form and optical characters of those Crystal-
lized Bodies which have not been previously determined, and
that Chemists be invited to send him specimens of perfect ar-
tificial Crystals.
2. That Dr. Turner, Professor Miller, Mr. Brooke, and the
Rev. Wm. Whewell, be requested to cooperate in prosecuting
and promoting the following inquiries, with a view to examine
the theory of Isomorphism, and the connexion between the
crystalline forms and chemical constitution of Minerals :
1 Mr. Johnston reported the progress of his researches to the Cambridge
Meeting.
2 These experiments have been instituted by Mr. Harcourt, in Yorkshire, at
the Low Moor Iron Works, the property of Messrs, Hird and Co., and at the
Elsecar Furnace, belonging to Earl Fitzwilliam.
RECOMMENDATIONS. ATT
1.) To determine whether the angles of varieties of the same
species (in the usual acceptation of identity of species) are
identically the same, under various circumstances of colour,
appearance, and locality ; and if not, what are the differences.
2.) To determine the chemical constitution of such varieties,
—the specimens, mineralogically and chemically examined,
being in all cases the same.
3.) To determine what quantity of extraneous substances
may be mixed with a crystalline salt, without altering its form.
4.) To determine the angles of the various species or vari-
eties of isomorphous or plesiomorphous groups, and their
respective chemical composition’.
Desiderata noticed in Mr. Whewell’s Report.
1. To determine the optical differences on which depend the
distinctions of the different kinds of lustre, metallic, ada-
mantine, vitreous, resinous, pearly. :
2. To determine whether the oblique rhombic prism consti-
tutes a real system of crystalline forms, or is a hemihedral
form of the right prism.
3. To determine the limits of magnitude and simplicity in
crystallometrical ratios.
4, 'To determine whether chemical groups are strictly iso-
morphous, or only plesiomorphous.
5. To determine whether the angles of plesiomorphous
crystals are separated by definite or by indefinite steps.
6. 'To determine what are the differences of chemical com-
position corresponding to differences of optical structure in re- |
sembling minerals, as apophyllite, tesselite, leucocyclite.
GEOLOGY.
*1, That measurements should be made, and the necessary
data procured to determine the question of the permanence or
change of the relative level of Sea and Land on the coasts of
Great Britain and Ireland; and that for this purpose a sum not
exceeding £100 be placed at the disposal of a Sub-Committee,
consisting of Mr. Greenough, Mr. Lubbock, Mr. G. Rennie,
Professor Sedgwick, Mr. Stevenson, and the Rev. W. Whewell:
—the measurements to be so executed as to furnish the means
of reference in future times, not only as to the relative levels
1 Professor Miller reported the progress of these inquiries to the Cambridge
Meeting.
478 THIRD REPORT—1833,
of the land and sea, but also as to waste or extension of ‘the
land.
*2. That Mr. Rogers (Professor of Chemistry in Philadel-
phia) be requested to furnish an account of the progress which
has been made in investigating the Geology of the United States
America.
3. That Professor Phillips be requested to draw up, with such
cooperation as he may procure, a Systematic Catalogue of all
the organized fossils of Great Britain and Ireland, hitherto de-
scribed, with such new species as he may have an opportunity
of accurately examining’.
4. That Mr. John Taylor be requested to collect detailed
sections of the Carboniferous series of Flintshire, with a view
to a comparison with the same series in other parts of England ;
—with a view also of ascertaining the circumstances under which
the Mountain Limestone is developed, after its suppression in
certain coal-fields in the central parts of England.
5. That the attention of Geologists be invited to those coal
districts in the midland counties of England, where, the Car-
boniferous Limestone and Old Red Sandstone being deficient,
the coal measures rest immmediately on the Grauwacke and
Transition rocks ;—with a view to discover whether any cir-
cumstances connected with the physical structure of that part
of the island can be stated, explanatory of the local absence of
the two great formations above mentioned.
6. That sections and plans should also be collected of the
Coal-fields of Worcestershire, Shropshire, Staffordshire, Che-
shire, Lancashire*, and the south-western part of Yorkshire*.
7. That the Faults or Dykes in the carboniferous rocks in
Flintshire should be examined, with a view to ascertain whether
some remarkable differences in their character may not be
observed, as compared with that of veins and dykes in other
districts.
*8. That collections be made of accurate plans of ‘‘ heaves”
in the Veins of Cornwall and the North of England, with a
view to determine how far the apparently horizontal heaves may
be explained by vertical motion.
*9, That the direction, intersection, inclination, and breadth
1 This catalogue is commenced, several monographs are composed, and a
general basis is arranged. Communications, lists of organic remains, notices
of localities, and specimens of new or undescribed species may be addressed to
Mr. Phillips, Museum, York.
2 Mr. Elias Hall of Castleton has constructed a map and sections of the Lan-
cashire coal-field.
3 Mr. Hartop exhibited at the Cambridge Meeting a correct map and de-
tailed section of the coal strata on the river Dun.
RECOMMENDATIONS. 479
of the non-metalliferous fissures which cross the planes of the
strata, and in some instances divide many contiguous strata,
should be observed, in relation to the same circumstances in
the dykes and mineral veins of the vicinity ; with a view to
ascertain whether there be any and what connexion between
these phenomena’.
*10. That the history of ancient vegetation should be further
examined, by prosecuting the researches into the anatomy of
fossil wood which have been exemplified in Mr. Witham’s re-
cent volume.
11. That the quantity of Mud and Silt contained in the water
of the principal rivers of Great Britain should be ascertained,
distinguishing, as far as may be possible, the comparative quan-
tity of sediment from the water at different depths, in different
parts of the current, and at different distances from the mouth
of the river; distinguishing also any differences in the quality
of the sediment, and estimating it at different periods of the
year; with a view of explaining the hollowing of valleys, and
the formation of strata at the mouths of rivers.
12. That the experiments of the late Mr. Gregory Watt, on
the fusion and slow cooling of large masses of stony substances,
should be repeated and extended by those who, from proximity
to large furnaces, have an opportunity of trying such experi-
ments on a large scale; and that trial should be made of the
effect of long-continued high temperature on rocks containing
petrifactions, in defacing or modifying the traces of organic
structure, and of the effect cf the continued action of steam or
of water at a high temperature, in dissolving or altermg mine-
rals of difficult solution.
*13, That the dimensions of the bones of extinct animals
should be expressed numerically in tables, so as to show the
exact relations of their dimensions to those of animals now
living; and also to show what combinations of dimensions in
the same animal no longer exist.
* 14, That the following Geological queries be proposed :
1.) Are there any instances of contorted rocks interposed
between strata not contorted ?
2.) Is there any instance of secondary rocks being altered in
texture or quality by contact with gneiss or primary slates?
3.) Is the occurrence of cannel coal generally connected with
faults or dislocations of the strata?
‘ Mr. Phillips has undertaken to state the results of his examination on this
subject in certain parts of the North of England, and requests to be favoured
with communications relating thereto.
480 THIRD REPORT—1833.
4.) What is the nature of the pebbles in the new red sand-
stone conglomerate in different districts: do they ever consist
of granite, gneiss, mica-slate, chert, millstone grit, or any other
sandstone which can be distinctly traced to the coal series ?
5.) Is. the Red Sandstone of Kelso contemporaneous with
that of Salisbury Crags; and what relation do they respectively
bear to the adjacent coal-fields ?
6.) What is the exact northern boundary of the coal-field of
the River Liddle?
7.) What are the relations as td age of the two series of whin
rocks, one running north-east along the Liddle in Roxburgh-
shire, the other south-east in the neighbourhood of Melrose
and Jedburgh ?
8.) Can the Limestone of Closeburn in Dumfriesshire be re-
cognised beyond that valley?
9.) Does the Wealden formation exist in the midland counties
of England ? .
10.) What is the character of the districts in which ores of
manganese occur?
11.) What is the history of the Heematite of Dalton in Lan-
cashire, in relation to the beds in which it occurs?
12.) What are the mineralogical characters of the several
beds comprised in Forster’s Section of the Strata in the North
of England; and what are the fossils contained in each ?
Desiderata noticed in Mr. Conybeare’s Report.
1. An accurate examination of the conclusions deducible from
the known density of the earth, as to the solid structure and
composition of the interior.
2. The attention of residents in our remote foreign depen-
dencies is invited to the two great questions of comparative
Geology and Palzontology. 1. Is there or is there not such a
general uniformity of type in the series of rock-formations in
distant countries, that we must conceive them to have resulted
from general causes of almost universal prevalence at the same
geological era? 2. Are the organic remains of the same geo--
logical period specifically similar in very remote districts, and
more especially under climates actually different; or are they
grouped together within narrower boundaries, and under re-
strictions as to geographical habitats analogous to those which
prevail in the actual system of things? (p. 410.)
3. Anexamination of the geological structure of the countries
constituting the great basin of the Indus, where, if in any part
of India, it is supposed a complete series of secondary strata
may be expected. (p. 396.)
RECOMMENDATIONS. 481
Desideratum noticed in Mr. Taylor's Report on Mineral
Veins. .
A correct account of the affinity that the contents of a vein
bear to certain of the rocks in which the fissure may be situated,
ZOOLOGY.
The Committee recommend to the consideration of Zoologists
the following subjects of inquiry :
*], The use of horns in the class Mammalia; the reason of
their presence in the females of some, and their absence in those
of other species ; the connexion between their development and
sexual periods; the reason of their being deciduous in some
tribes, and persistent in others,
*2. 'The use of the lachrymal sinus in certain families of the
Ruminantia.
*3. The conditions which regulate the geographical distri-
bution of Mammalia.
*4.. 'The changes of colour of hair, feathers, and other ex-
ternal parts of animals ; how these changes are effected in parts
usually considered by anatomists as extra-vascular.
*5. The nature and use of the secretions of certain glands
immediately under the skin, above the eyes, and over the nos-
trils, in certain species of the Grallatores and Natatores; the
_ nature and use of the secretion of the uropygial gland.
*6. How long and in what manner can the impregnated ova
of fishes be preserved, for transportation, without preventing
vivification when the spawn is returned to water.
*7, Further observations on the supposed metamorphosis of
Decapod Crustacea, with reference to the views of Thompson
and Rathke. |
*8. Further observations on the situation of the sexual or-
gans in male spiders, and on their supposed connexion with the
alpi.
‘ “9. The use of the antenne in insects. Are they organs of
hearing, of smell, or of a peculiar sénsation ?
*10. The function of the femoral pores in Lizards, and the
degree of importance due to them as offering characters for
classification.
BOTANY.
1. That Botanists in all parts of Great Britain and Ireland
be invited to compose and communicate to the Meeting of the
1833. 21
482 THIRD REPORT—1833.
Association, Catalogues of County or other local Floras, with
indications of those species which have been recently intro-
duced, of those which are rare or very local, and of those which
thrive, or which have become, or are becoming extinct; with
such remarks as may be useful towards determining the con-
nexion which there may be between the habitats of particular
plants, and the nature of the soil and the strata upon which they
grow; with statements of the mean winter and summer tempe-
rature of the air and the water, at the highest as well as the
lowest elevation at which species occur; the hygrometrical
condition of the air, and any other information of an historical,
ceconomical, and philosophical nature.
*2, That Professor Daubeny be requested to institute an ex-
tended inquiry into the exact nature of the secretions by the
roots of the principal cultivated plants and weeds of agriculture;
and that the attention of Botanists and Chemists be invited to
the degree in which such secretions are poisonous to the plants
that yield them, or to others; and to the most ready method of
decomposing these secretions by manure or other means.
* A Committee was formed to conduct a series of experi-
ments on the growth of plants from seeds, and to preserve the
results of their experiments, in order to establish the identity
or confirm the specific distinctions of certain allied plants, and
to communicate the results obtained, from year to year, at the
Meetings of the Association.
Mr. Don, Librarian to the Linnean Society, has undertaken
to be the channel of correspondence on this subject.
Desiderata noticed in Professor Lindley’s Report.
1. An accurate account of the manner in which the woody
part of plants is formed. ‘‘ Perhaps there is no mode of pro-
ceeding to elucidate this point, which would be more likely to
lead to positive results, than a very careful anatomical examina-
tion of the progressive development of the mangel wurzel, be-
ginning with the dormant embryo, and ending with the perfectly
formed plant.”
2. An investigation of the comparative anatomy of flowerless
plants, with a view to discover in them the analogy and origin
of their organic structure.
_ 3. The cause of the various colours of plants.
4, The nature of the fecal excretions of cultivated plants,
and of common weeds; the degree in which those excretions
are poisonous to the plants that yield them or to others; the
most ready means of decomposing such excretions by manures
or other means.
RECOMMENDATIONS. 483
ANATOMY AND PHYSIOLOGY.
*], That the effects of poison on the animal ceconomy should
be investigated and illustrated by graphic representations ; and
that a sum not exceeding 25/. be appropriated for this object.
Dr. Roupell and Dr. Hodgkin were requested to undertake this
investigation.
*2, That an experimental investigation should be made of
the sensibilities of the Nerves of the Brain; and that a sum not
exceeding 25/. should be appropriated to this object. Dr.
Marshall Hall and Mr. 8. D. Broughton were requested to un-
dertake these experiments.
ARTS.
* That Mr. Dent be requested to communicate to the next
Meeting of the Association, a statement of the performance of
his chronometer with a glass balance-spring.
Desideratum noticed by Professor Barlow in his Report on
the Strength of Materials.
A set of experiments on the application of a straining force
on vertical columns (of timber, iron, &c.).
STATISTICS.
*1, That Colonel Sykes be requested to prepare for publi-
cation his valuable statistical returns, collected by himself in
India, relative to the four Collectorates of the Deccan, subject
to the Bombay Government.
*2. That Professor Jones be requested to endeavour to ob-
tain permission to examine the statistical records understood to
exist in great number in the archives of the India House, and
to prepare an account of the nature and extent of them.
*3. The inquiries of this section are restricted to facts re-
lating to communities of men which are capable of being ex
pressed by numbers, and which promise, when sufficiently
multiplied, to indicate general laws.
* A permanent Committee of this section was appointed.
Professor Babbage was requested to act as Chairman, and Mr.
Drinkwater as Secretary.
In a Report since addressed to the Council by this Committee,
it is stated, that the Committee having deemed it expedient to
promote the formation of a Statistical Society in London, a
public meeting was held on the 15th of March, 1834, at which
212
484 THIRD REPORT— 1833.
it was resolved to establish such an institution. The Society
already includes more than three hundred members, and has
issued a statement of its objects and regulations, which is sub-
joined in the Appendix.
The Committee remark, that ‘ though the want of such a
society has been long felt and acknowledged, the successful
establishment of it, after every previous attempt had failed,
has been due altogether to the impulse given by the last Meet-
ing of the Association. The distinguished foreigner (M.
Quetelet) who contributed so materially to the formation of the
Statistical Section, was attracted to England principally with a
view of attending that meeting; and the Committee hail this
as a signal instance of the beneficial results to be expected
from that personal intercourse among the enlightened men of
al] countries, which it is a principal object of the British As-
sociation to encourage and facilitate.”
GENERAL SCIENCE.
* That a sum not exceeding 100/. be appropriated towards
the execution of a plan proposed by Professor Babbage, for
collecting and arranging the Constants of Nature and Art'.
APPENDIX
CONTAINING DIRECTIONS FOR OBSERVATIONS ON THE TIDES,
AURORA BOREALIS, &c.
TIDES.
OxsErvaTions of Tides along the coasts of Great Britain
and Ireland will be valuable, both in the construction of more
accurate tide tables, and as data towards the perfection of the
theory of tides.
Observations of the tides should record particularly,
The time in hours and minutes, and height of high water
daily, or if convenient every tide.
The time and height of low water.
See Appendix, p. 490, for an Abstract of Mr. Babbage’s Plan.
he” ex. tea aie ee ake
f
RECOMMENDATIONS. 485
The direction of the wind, and the height of the barometer
and thermometer.
The direction and velocity of the stream of flow and ebb.
At what hour (with respect to the time of high water and
low water) the slack water after the stream of flood, and after
the stream of ebb, respectively occur.
The height of the water must be given from some fixed mark
or line, which should be described accurately, so that it may
be easily found again at a future time. The observer ought to
state the manner in which the height was measured ; the man-
ner in which the moment of high water was fixed upon; the
time employed, whether apparent or mean solar time, and how
it was obtained.
The height of the water at the end of every minute, for
half an hour before the expected time of high water, and until
there can be no doubt that the time of high water is past.
Machines to dispense with this minute attention are described
in the Philosophical Transactions, 1831, and in the Nautical
Magazine for October 1832".
The uncertainty occasioned by waves may be avoided by
making the observation in a chamber, to which the water has
access by a small opening, or by fixing in the water an upright
tube, (of wood or iron, for instance,) the bottom or sides of the
tube being perforated ; in either case an upright measuring
rod, carefully graduated, and connected to a float, will rise and
fall with the tide, and permit, at any moment, the height of the
water to be read off against the collar through which it works.
This rod may be so constructed as to leave a moveable index
at the highest and lowest points.
A long series of continued observations can alone be of use
towards the determination of the dependence of the time,
height, and other circumstances of high and low water upon
the places and distances of the sun and moon; but a smaller
number of observations will often be sufficient to determine the
establishment of any place, with more or less accuracy, accord-
ing to the number of observations ; and the best mode of do-
ing this is by comparative observations with some place of
which the establishment is accurately known, or where obser-
vations are continually carried on. A few sets of comparative
observations of neighbouring places will give the relative time
of high water at these places with considerable accuracy ; and
thus the motion of the tide-wave and the arrangement of the
1, Tide-guages may be seen in operation at St. Katharine’s Docks, London.
An excellent one has lately been set up near Bristol by the Literary and Phi-
losophical Institution of that city.
486 THIRD REPORT—1833.
cotidal lines (or lines along which it is high water at the same
instant,) will be discovered. It would be very desirable for
those who have the opportunity, to combine so as to effect the
detailed description of the tides through some small extent of
coast, such as that which has been effected by M. Daussy for
the west coast of France.
AURORA BOREALIS.
Notwithstanding the attention which has been paid to the
phenomena of the Aurora Borealis, and the various hypotheses
which have been imagined to explain them, it will be found
that there is a want of information on the points which are
most necessary as bases of induction; and the British Asso-
ciation have therefore been induced to appoint a Committee in
the express view of directing observers to the really important
features of this meteor, and of obtaining, by a system of con-
temporaneous observation, data which experience shows cannot
be derived from insulated exertion.
The following are the most important points which demand
the attention of observers:
1. The elevation of the auroral arches and streamers above
the surface of the earth.
2. The determination of the question whether the auroral
exhibition is accompanied by sound.
3. The existence of recurring periods of frequency and bril-
liancy in the Aurora.
4. The influence of arches, streamers, and other auroral
phznomena upon the magnetic needle.
1.) It is recommended to all who intend to observe Auroras,
to make themselves well acquainted with the names of all the
principal stars to the north of the equator, especially those
which do not set here. This will be most easily done by stu-
dying a celestial globe. Good maps of the stars may also be
consulted with advantage. Either the proper names or the
Greek characters with the name of the constellation will be
sufficient.
Persons who may prefer to determine the angular elevation
and position of the arches and streamers by graduated instru-
ments, must be supposed well accustomed to the use of them ;
they may, however, be reminded, that telescopic sights are
for this purpose useless, and that steady instruments, which
can be handled with ease and expedition, are much more avail-
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Tat, SAS:16! Long, W. 2* 26°
hem.
7, 25—Strong illumination to the N. W., which gradually expanded to a polot
few degrces E. of N., and toa puint nearly W. The places of greatest Hlomina.
tion variable, but chiefly near the magnetic meridian, After some time ascending
spires of yellowish light in several directions. No well defined Juminous masses,
§, 5.—The light assumed the form of an ill-defined arch; the vertex was
nearly in the magnetic meridian, the western end reached the horizon under
‘Arcturus, the curve passed under 6 and y Ura Majoris. Its breadth was con-
inidernble, the lower edge ill-defined, and scemet to blend itself with the common
ight of the region. a
‘Sireake of Nght rose occasionally towards ti
by We, and W. Cloude of extreme blacnest were scattered through the
Jcq of the Aurora, Stars distinctly, but rather dimly sen through the
fhtest part of the Aurora.
onith, expecially from N, by Evy
§ 40.—The black clouds had disappeared,
& §5.—The upper part of the arch better defined than before, passed between
jf Urex Maj. and very scar & Uraw Maj. Its vertex in or near the
sit sie meridian. Lower edge still very ill-defined. For a few minutes
ea inous region was divided hy a concentric band of a dark dirty grey colour
the lower arch was ill-defined and unsteady.
ie
fo iwo arches
o,10-—Arch nearly as before. A great expansion of light where the N. B.
sehof the arch touched the horizon, spreading out to a place a few deprecs
er Gspellas the centre of this bright cloudy mass of light was about 35° E.
he magnetic meridian. A few patches of clouds in this region were faintly
Miated on the edger, as if by the light of the Aurora transmitted through
Remithere was also n'slight expansion of cloudy light where the N. Ws limb
yearth came sown to the mountain tops, (65% W. of the raagnetic north.)
M ps-—Arch nearly as before, its lower edge better defined, breadth nearly
vealto the distance between the pointers of Urea Major. and the upper pointer
ee marly in the centre of the bright space between the upper and lower curves.
Teter still nearly in the magnetic meridian. Below the luminous zone, the
Te own to the horizon, was of a most remarkable dark dirty grey colour, through
se Arcturus was ecen to shine dimly, as if through afog- The great mass of
wir itthe N. E. end of the arch broke up into vertical masses, separated from
haber by a dark colour like that under the arch. ‘The dark grey part under
{fant pierced by cloudy flashes of light. ‘These gradually increase in number
ey iniemity, and traverse the dark space in waves or zig-zags, being on the
ote juniiel to the horizon, During their passage they sent up spires of in-
sey green light resting on light of a faint reddish tinge. Soon after, the arch
ve erved to break up in points like the teeth of a comb, and the whole space
Mich had been occupied by the dark grey colour was broken up into ribs and
tee of lisht, especially in the western region. ‘This appearance was succeeded
{rndulation’ propagated towarda a spot S. E. of the zenith, The undulations
ited to be propagated in interrupted arches of light, being visible only in those
Fite where the lines of undulation crossed certain vertical streamers, All
jee ndolations seemed, however, to haye one common relation; the vertex of
teh arch being nearly in the magnetic meridian. For several seconds there was a
wilalefined arch passing through a Lyre.
9,40.—Great streaks of light parallel to the magnetic meridian ;
the N. W.; white blotches of light in region S, K. of the zenith.
9, 45 —Soeeession of xtreansera ascending from the W. and N. This illumi-
scion seems to be propagated by them to the region between Jupiter and. «
lim. It ecemed ns if certain portions of the heavens in this region reflected the
ct of the nvcending streamers; as the mame definite portions of space were illu
cued during each coruscation of the ascending light.
1. 0.—Hright illumination towards the N. Dark patchy clouds to the N. W.,
ef some dark horizontal etreaks of clouds illuminated ot the edges. At this
vere many streamers appearing to diverge from a point below the horizon,
setly below the end of the Bear's Tail (y Ura Major.) those which were ncurly
Sant N. declining 15° from the perpendicular, Soon afterwards undulations
ial to Le propagated along these diverging lines, and amorphous blotches of
ii, extending in one direction ax far as Jupiter, were #cen in the region S. of
iinith, Some of these were stationary and constantly iHluminated others were
Gknary but were only illuminated at intervals. AU that distance from tho N.
witon, which seemed to be the seat of propagution, the luminous blotehes never
ul the forin of streamers or spires of light.
10. 10.—Siriw and spires of light nearly in the same direction as before. but
be tright. No light propagated to, or reflected from, any cloudy spaces S. of
& renith
10. 15.—Greatest illumination in the Mog. N. Bright streaks of light and
ses propagated to the zenith, Stara shone brightly through the brightest light.
W. 20.—No spires or beams of light, but wndulutions propagated from the
x N. Phenomena repeated wll 10. 40, nearly.
ae ere illumination due Nz Brigit space extends to Gemlnl and to
the W. Fine streamers from the N, The bright space arranges itself into an arch,
fommencing nearly N.. pasing through » Urece Major. ; about 25° high near
the inagactes meridian (measured only by a geological clinometer.) Below the arch
he eame dirty grey colour noticed before. Fora short time here appeared a
the four stars of the Hears
followed by streamers and beams of light ascending
dark clouds
was
sceond arch passing throug!
10. 50.—The arch gone
from Mag. N-
11. 5.—Strong illumination towards the N. W.
towards the zenith, but no streamers.
. 25.—Few undulations ¢ greatest
il toavery Juminous to Mag, Ne; brightest part defined above by an arch
2i* high; the light seemed to extend to the ho ons ‘This was afterwards broken
up, first into ascending spires of light, ani then Into undulations.
12, 10._The light was dispersed in fleecy ill-defined masses, extending from
the N. nearly as far as the W.
Fine undulations propagated
iumination in the N.
12, 40.—A very strong {lumination continued till nearly this time, when the
observations were discontinued, as the phenomena presented nothing of a definite
character.
DENT.—GENERAL REMARKS.
During nearly the whole time of observation, the wateh-face could be read with
great ease, and several of the notes were written W ith no otber light than that of
the Aurora.
It may. T think. be observed generally that the places of grentest iMlumination
scern liable to be broken up into parts, separated frnm each other by spaces of the
Girly grey colour above mentioned, and quite distinet from the inky colour of the
patehes of clouds.
Lattempted, several times, to ascertain the variation of the ncedie, but found
the mounting was not sulllciently delicate to give resulis worth recording.
DENT, near Sedbergh, Yorkshire, "
TABULAR CONSPECTUS OF OBSERVATIONS ON THE AURORA BOREALIS
OF THE 12th OF OCTOBER, 1833, REDUCED TO GREENWICH MEAN TIME.
MANCHESTER. YORK. GUISBOROUGH.
Three sets of Obervatiors by R. Potter, jun. P. Clare, and W. Hadfield. J. Phillips. WW. L. Wharton.
N. Lat. 538 297 Long. W. 2° 13! Nu Lat. 53° 58° Long. W. 1° 4 N. Lat. 54°31" Long. W. 1* 3’
6, 5 —Poiot arches ard streamers noticed. (IR. P.)
6, 41) —Long and large streamer directed towards the zenith. (It, P.)
7. 0}. —Irregular nebulous masses to 60° alt. and more.
7. 24—Portion of arch §. of zenith covered the principal stars in Delphinus
and Aquila, it was 5° broad, passed southwards and vanished.
7. 40}.—Lightin the north which had heen 20m. stationary, at 15° or 20° alt.
and about 100° extent on horizon is now disappearing,
&. 10}.—Bright light in the N.
§. 39.—An arch ill-defined, about 18° high in the middle.
ere Me mrch has risen a Title, fe better defined, and a dark: shade appears
clow ite
8, 534.—The arch has its vertex under % Urea Maj. and its upper edge touches
y Urs Maj., altitude about 19° 30. (R. P.)
8. 54.—Arch about 24° above the horizon at its vertex, 5° broad ; below it is
1 dark parallel space 5° broad; and below this a second parallel arch of light
334° broad. ‘The epace below this arch to the horizon is very dark like a dense
binck cloud. One foot of the exterior arch is nearly west, and the other foot about
35° E. of N. the vertex is in the magnetic north. (P. C.) Mr. Hadfield says
20° olt. and horizontal extent 120°.
_ 9. 9—The two arches remain in the same position. Stars are distinctly seen
in the upper luminous arch, and also in the space within the lower luminous arch.
9, 14).—n Ursa: Maj. in the upper edge of the arch, the height of which by
measure = 21" 10% (It. P.)
9, 21,—Beam or streamer, the first seen this evening, darted suddenly upwards
from the higher arch about 30° E, of N. It was visible 30 seconds. (P. C.)
9, 22.—A beam or streamer in the same position, visible 10 minutes.
9, 27.—A sinall black cloud visible in the dark space within the Jower arch,
about 15¢ I of N. and 10° high.
9, 29.—A beam or streamer, rose from the dark space within the Jower arch
10° E. of N. and continued visible for 2 minutes. Clouds are rising in N. W. #0
5 to cover a portion of the light.
9, 31. —Streamers are shooting up rapidly in the W. and the boundary of the
arch is much less distinct.
9, 33. —Streamers and gleams or broad flashes of light are rising from various
parts of the arch, they soon covered almost the whole of the northera part of the
hemisphere, and passed to the south a little beyond the magnetic zenith. The
archi has disappeared, but a strong light remains in the north.
9. 41-—For the Inst 10 minutes the #treamers have been very active, and broad
flashes of light have suceceded each other with scarcely any intermission, in the
northern part of the hemisphere: the clouds have increased 40 as to obscure most
of the aky.
10. 9, —Cloudla disappearing, streamers active.
10. 39.— Since the last observation the display of treamers and coruscations
has been fine. Arch observed at this time, its lower edge had its vertex in Benet
nasch (16° alt.) and passed a little below A in Bootes, and alittle above > in the
foot of Urs. Maj.
11. 9.—Since the last observations the streamers and coruscations have
diminished in number and brilliancy. Now very few are to be seen, but a bright
light continues in the magnetic Ns
11, 39.—The light in the north increasing.
12, 9—IJt has continued to increase. Another arch is visible in magnetic N-
the highest point of which és about 15° above the horizon, Vertex in Mizar,
12 24 —Streamers begin to arise from various parts of the arch.
12, 39.—Streamers much increased in number and activity + also coruscations
and large masses of light like white clouds, that almost cover the northern part of
the hemisphere,
12. 49.—The light is more brilliant, the arch has disappeared ; streamers very
bright and active, particularly inthe N. K, ‘The sky is. covered with streamers
and gleams of light from nearly the northern horizon to a little beyond the
magnetic zenith, ‘The streamers form a corona at the magnetic zenith, from
which point the Pleiades are about 1° south.
12. 54—Many bunds or fillets of light have been {instantly formed, and then
immediately rose toward the zenith ; their first appearance was in the direction
id form of the luminous arch of 8. 54,5 then they suddenly tose in the centre
towards the zenith and disappeared. ‘The east and west extremities of these bands
acemed to move through a very sinall space and gave the appearance as if the
extreme points were stationary, whilst the highest point moved round a centre
with a velocity that earried it through 60° in about one-third of a second of time 5
the other portions of the bands passed through a less space us they approximated
to the K. and W. cade, For about ten minutes these bands of light succeeded
each other with gnat rapidity. ‘he streamers and coruscations of light continued
very active.
Ty. 9 The comscations, streamers, and bands of light have been diminishiog
in activity and brijlianey for 10 minutes, but during the last half hour the bril-
Hiancy, extent, and geuvity of the aurora far exceeded the appearances in any
previous part of right.
m3. Poth eer ‘and coruscations bave ceased, but thereis & broad light
dn the north.
13. 39,—Th
light diminishes in brilliancy.
hem.
6. 4-—Mean time. The appearance of the northern sky led me to suspect that an aurora had commenced. :
G. 44.—By this time the doubr was entirely removed ; beams had been sceo playing, and bright fluctuating light was at in=
tervals excited at detached points along an arch, rectangled to the magnetic meridian, as if along this line thin vaporous clouds Or
amoke-wreaths were illuminated from behind. One continual beam was tcen N. 20 W. The phenomena were chiefly on the
eastern side of the magnetic meridian.
6. 52—A falling sur was scen, passing nearly horizontally from E. to W., through an arch of 10% east of the Pole star, It
was bright. Another faint falling star seen through a shorter arch above the Great Bear.
7. 14.—A falling star from W- to E., declining 40°, colour, red.
7. 14.—A beam of light N. by W-
7. 39-—Falling star, directly downwards in the line of the magnetic meridian, seemed to fall through 15° from the arch which
was now forming. ove
7. 44.—An arch of light was now distinct (above a dark horizon band), its lower edge one-third of the height of & Ursa: Majoris
7. 52.—The arch had risen higher, its lower edge was now half the hcight of 6 Ursa Muj., and its upper edge two-thirds of
that height. No streamers were visible at this time, nor had many been seen before.
7. 56.—The summit of the arch was now 3* below the stars 8 and y Ursa Maj. It had been rather bright and of a
yellowish hue, not unlike some distant clouds, a resemblance augmented by its great breadth, which was twice as great as that of
the black space beneath. A singular notch was noticed in the upper edge of this arch, bearing N. by E. It now began to fade
and to sink a little.
7. 57-—Suddenly It appeared double, in consequence of the production of a very narrow faint arch above that secn before, and
separated from it by a dark band.
7. 58.—This upper arch rose, so as to include 6 and y Ursa: Maj., in its middle.
8. 2.—It had vanished away, after rising still higher. 5
8. 4—A beam of light, slightly arched, and directed obliquely upwards, from about 4 degrees (by estimation) to the right
(south) of the Pleiades, between q Arietis and Jupiter. This singular beam, brightest in the middle, was so unlike the others, that
T hesitated for some time to record its appearance. It lasted, with hardly a perceptible change of place towards the south, for
half-an-hour, but its brightness was variable.
8. 6.—The arch appeared divided by @ transverse black clouds
hem
$, 20.—Well defined arch, passing between « and PB Ursce
Majoris its summit somewhat above ¢ Ursa Majoris, no radia-
tions.
8, $5.—Arch 2¢ or 3¢ higher; faint radiations.
$, 50.—Nadiations and coruscations, all converging to the
head of Andromeda.
8. 16.—The broad belt of light in the north was divided
by several (ransverse arched bands.
8. 24—It had beeome higher, but was more confused.
& 29,—Falling star from just under Jupiter, its course N.
declining 20°,—rapid.
8 S4—Arch irregular, banded, the upper edge between
and f Urs Moj.
9. 19 —Falling star from Polaris direct through Dubbe.
9, 0,—Brilliant radiations with prismatic colours, con-
verging to 2 Andromedm, accompanied with sheets of light
moving with vast rapidity to the same part of the heavens;
summit of arch moved considerably eastward.
9. 10,—Continuous sheets of light and. radiations from the
whole horizon, between W.N. W. and E. N.E,, all converging
to the same part of Andromeda, but upon reaching that point
apparently checked in their further progress, and (those from.
the N. W, especially) twisted as it were for a short distance
toward the S. £. and then dissipated in space,
9. 29.—At this time the aurora assumed a totally new and
far more imposing character. Beams of greater brilliancy shot
tip in the west, and the dark horizon band was traversed, in
arched lines, from W. to E,, by roundish masses of strong
light, orange-coloured beneath, from which sprung, irregularly,
many short beams of paler colour: then at intervals a wild
Fluctuation of almost. connected light from W- to KE, with beams suddenly arising from a general arched basis of light, below the
more regular arch previously noticed, which became less and Jess distinct, as the undulations grew more frequent, nd the bears
rose higher. ‘The undulations of light became every moment more rapid and extensive, lost their transverse movement and rose
higher into the sky, till they covered with their pale and restless illumination the whole of the northern hemisphere, flashed over
the zenith stars, and even to a cousiderable distance south. As soon us the strangeness of the spectacle permitted me to examine
with calmness, I found that these flashes seemed all to spring from an arched luminous base (probably the perspective union of
their images) with a rapid but limited undulation; the higher above this base the appearances) were exami the more
decided was the evidence of intermitting action, the more disjoincd became the upward waves of light, and at length it was evident,
that all these waves rose towards the zenith with a motion continually accelerated, and an individuality always growing more
complete, It was weldom that any two waves flashed at the same instant across the culminating point; when they did so, the
light was sometimes augmented there. * (Note,) >
9. 40.—At this time, the Hashes frequently extended much
beyond the zenith stars
9, 50.—The arch in the N. N.W, became again distinct,
including « Urew Maj,, its centre being in line with « Ursce
Maj.
9, 45.—Similar appearances ; arch ill defined.
9. 57.—Now, and also several times before, the flashes cx-
tended over Jupiter. A beam was seen passing through « Uru
Maj.
‘The flashes now became lower and less extensive.
10. 10,—Beams of light travelling to the westward.
10, 13,—The zenith has been clear for some minutes.
10, 34.—Arch noticed again, its centre under ¢ Ursm Maj.,
is height in the middle of the light equal to one-half that
of) Ursce Maj.
10, 44—And later, till near twelve o'clock. ‘The arch
north waa subject to much variation,
rose at intervals,
the
Beams and faint flashes
10, 45.—Arch vory distinct, its summit considerably lower
than when Just observed.
11. O.—Sheets of light still fying toward the head of An-
dromeda,
11. 15.—Some clouds (cirro-strati) slowly approaching from
the N. Sheets of Jight and radiations belng distinctly above the
sgion of these clouds,
11. 35.—Splendid sheets of light; ill defined arch.
11. 50-—Arch ili defined, Its summit near 5 Ursce Majoris,
more cirro-strati, evidently floating below the radiations.
12, 4,—There remained only a vague Illumination in the N, W. K =
Towards 13. the phenomena were repeated with greater illumination; the waves again passed the Zenith, and at Ri
(43 in. N. W. by N. of York) were seen to pass over Jupiter. z ers
YORK.—MAGNETIC OBSERVATIONS.
7. We—Till this time, the needle closely watched wns certninly unaffected by the aurora.
§. 9.—The southward end of the needle deviated six and seven minutes K. 5 beams travelling east.
9, 34.—From this time it deviated very rapidly to cast
9, 4—It had reached its maximum deviation to the east.
It was at this time that the flashes began to
cross their culmina-
ting point. Deviation i. 50 minutes
9.43. 3 45 10S remicen a
9. cmprety 13 1h (8 ereresiic conormnencion
9. viation W. 1 10. 10, Beams travelling weat
cn seeenenen) 3 10. 13, ae
10. 0. a0 10. 3h ;
10, FE Soto sees
shail make a few remarks.
the eastward deviation of the south end of the needle, the flashes were much more abundant on the castern side of the magnetic
meridian, 3. It appeared to me protable, that the deviation of the needle was aflected by the movement of the beams, in such a
way that its southward end deviated to the same side as the beams moved. 5
YORK.—GENERAL REMARKS.
For eleven days before the grand aurora of the 12th of October, the barometer had been very high, and the weather remarkably
dry; the sun powerful, the nights chill and dewy; on the 11th of Oct, the barometer began to fall, and continued to fall till mid-
day on the 12th. There was rain on the 11th, ond on the 12th till 2p, m. Irom midday on the 12th, the bara i
{and continued to rise until 9a. m. on the 1th), the air became colder and drier. i ie ae cen at
1 call them weres, nor only because of thet
ion of hight and darkness, by whieh.
pparent origin in distant undulations of uminons mars, bot also. because of a xery sin
feov nMfected In is upward cau througu the shy. The ine along which any one wave pasved
3Conce, orin succession, but only in cer realy rect sich succer
spolsy=fesembling nothiog so cruel as 5 ca ol tansparent white tmove,—were
ely Highcand dark. Tesppeared to
iy was irregularly che torso mate my Tmagin
Tro anc, I2eemed, on a gigantic scale, not unilie the appearance tou cloud amumer, wien IL callea
"The culiminating point of these waits was at timesina continual Bott eat une vari
+ continual Batter, In consequence of the ¥arious arrival 6!
ferent quarters; bot Ht perbape never bappened thet any thing like radiatiog Ii yy s ‘The i\lomli mating? of all this af
Beat Seales peo ar UN erent es RUE ner pad
the magucti¢ needle, chart was obliged Lo aeglect some Boe beams which appeased in various directions between N, W. and N. by Ex Zt
er Lowards the zenith.
" ‘one ware followed anoth
inagjacent™
CAMBRIDGE.
Professor Airy.
N, Lat. 52° 13° Long. EB. 0° 6
bm.
6. 32.—Several faint streamers directed to 9 point S. of «
Cygni, the elevation of their tases being perhaps 15°, and
of their tops 60% ; moving slowly towards the W. ; a faint bank
of light in the N.
6. 53,—No streamers ; generally a faint light in the north.
7. 27.-—Much the same.
7, 52.—In the north a banked yellow cloud, its height half that of
streamer about as high as the Pleiades, directed toward = Cygni.
HERON COURT, 4m. N. W. of Christchurch, Hants,
Hon. Charles Harris.
Ny Lat. 509 43" ‘Long. W. 1* 0°
y Ursa: Majoris. One degree to the right of the Pleiades a
‘This streamer remained stead
7, Sk—The upper boundary of ihe bright loud was extomely sharps it Begamin te ek chaos
above Arcturus, below y Ursa: Maj. at exactly half the elevation of y Ursa Maj
to the Jeft of Arcturus, passed a very little
the N. nt about half the azimuth O€ B Auriges ‘The Slash back belgw Feached to hee Wott ive eet eae of
7. 59.—A black line was discoverable very near the upper bounda .
alittle, thus widening the black line, About Arcturus Healer ee
8. 2.—The upper part after
0 that its elevation was perhaps
} of that of y Ursw Maj.
1g considerably hnd wholly disappeared, and the lawer had
‘boat half the height ; it was very black,
The upper part rose and the lower fell
wunk a little under y Ursa Majoris
a The high ;
* Aritis, parallel to that above mentioned (7. 58.) but hitched, e Pavs Nos mew a bitle further west. A streamer through
8 7A streamer exactly below Polaris, which pluny
downwards into the blacks a _—
8. 12.—More diffuse to the west, the dark part more illu
minated.
8. 44.—No remarkable alteration,
9, 38—The eastern boundary of the arch as before + the
western had advanced nearly to the W. ‘The lower edge of the
bright cloud sharply defined, and its height not quite half the
height of y Urs@ Moj.; the upper edge extended upwards
about two-third of the remainder of the space towards y Ursue
Maj.
9, 42.—A gentle appearance of waving was seen, confined
first entirely within the limits of the bright cloud, and looking
like very long horizontal waves, very narrow in the vertical di-
rection, running vertically upwards. In a few minutes the
waves became considerable, reached as high as » Ursa Majors
and still increasing. ‘Throughout the appearance of the wavings
it was evident that the waves or pulses and the streamers were
wholly tineonnected; the pulses fashed over the streamers
without altering them.
10. 0.—In the N. a very bright patch from which vivid
streamers broke. ‘Towards the W. it was more lumpy. Pulses
continued.
10, 12.—The bright bank had almost entirely lost its smooth
outline, and was broken into irregular toothed lumps. Pulses
continued, The pulses when highest extended up to 6 U. Minoriss
10, 27.—Little light the black below much diminished in
breadth, No pulses (I believe.)
11. 47.—Rather lighter.
13. 0.—Pulses were seen.
\
\
hem.
2/23. —Brights irregular arch, ike a |
ABav ariboyetia tera tf ania ae SRE EC
8. 37—Its greatest intensity in N.N, W,, was a litt
a in Canes Venaticl, which was scen, but faintly, oeO
‘The lower edge of the arch was about 3° below this star, ‘The
base of the arch about this time became irregular, aiid. coruscae
tions were shot up along the whole linc,
9. 57.—Large bodies of light traversing from B. to Wy
across the N,, and shooting up brilliant coruscations in
N.N. E., Neand N. W., some of them reaching an altitude
of nearly 60°; they were accompanicd by faint flashes of
ight, at right angles to the coruscatious or beams, and appa
rently bebind them, resembling narrow Juminous bands of
smoke, perpetually rolling up and disappearing.
10. 7.-—A bright coruscation shot through the stor & in
Ursa Major. ‘The main body of light now faded away, but
the flashes still continued.
10. 22.—Flashes more brilliant, and accorpanied by other
flashes or rapid passages of light from to W. and W. to Es
alorg apparently a line of vapour, as if they were electric dis
charges conducted along it: three or four successive Mashes
seemed to light up the same irregularities in the form of the
conducting medium, as if a band of vapour existed, invisible
except when the clectric current passed through ite
10, 37.—A low arch again formed, its base scarcely 6” above
the horizon, extending to about 7°; between this and 17° the
flashing continued, but never rose above Denetoasch Jo Ursa
ajor.
10, 52—A brond coruscution remained some time immedi-
ately under Mizar und Alioth in Urs Major, extending
further to the horizon, the ashing being vivid across its upper
portion,
‘Whe coruscation moved slowly westward and faded away.
CAMBRIDGE.—GENERAL REMARKS.
In the pulses I noticed clearly what I had noticed very well on a former occasion, (I think in 1827, certainly before 1626) that
it was not like clouds of light passing upwards and continuing luminous in their course till they vanished 5
definite spots only of the sky had the faculty of receiving illumination in the order of vertically upwards
but it was as if certain
From the odd way in
Which these spots were distributed, it sometimes appeared ay if the pulses flashed obliquely upwards.
In the morning there had been a squall from the N. W. with heavy rain:
very clears
she aftermoon dull till near sun-set, when it became
FIFESHIRE.
Mr, Lawrence Buchan observed at about 9 r, »f the auroral arch passing near the zenith. (/R; 1’)
ARMAGH.
Rev. Dr. Robinson.
N,Lat.54°21' Long.W.6°30.
be ~
8. 11.—Above a luminous
mass on the horizon are four
parallel arches, 3° asunder.
The upper edge of the lower
arch pasted below 1 and 9 Ursa
‘Majoris, and as much below ¢
9. 1—Three le
arches, the prineipal one has
its upper edge on Polaris, and
midway between Capella and
A Aurigw; its lower a tittle
above £ and y Urs Minoria,
9. 6.—Archinsameplace,
but interrupted by what seem.
like black streamers, directed
one towanl 6 Aurigw, tho
rites a above Capella,
ielr edges
las semen
9. 11,—Upper ede of
has risen to pr ant Copel,
and seer rch haw risen
neath it, its upper edge o
Zand 2 Urwo Mifrts, fn the
first are now three of the black
streamers, the upper cromed
by stripes of light Ba N. Be
9. 3).—Sheet aurora rolling
in muvee from all points of the
northern horizon, to a part
Aye W. and 1° N, of @ Ans
dromedan,
10. 14—Streamers cone
verging to the samo point.
Tn that region distinet portions
of sky become repeatedly
Wuminous when — streamers
reach then
retaining the same
outline ike invisible clouds
suddenly lighted up by thems
10. 20.—The mass of light
In the Ne W, (below whieh no
dark space wan visible at any
Lime this evening, perhaps on
account of have) nearly exe
Uinet, and a fow fuint streamers
‘lone shew themselves
11. G.—A_ renewal of
streamers low down on the
N. W.5 above Lyra and y
Draconis, below Una there ts
sheet aurora with o tendency
to condense itself in tho
direction of arches. The
motions are much less rapid
than those of the streamers,
and its waves, even when they
reach the zenith, much fainter.
‘Whe light of the aurora waa
sufficient to allow of counting
seconds on a chronometer.
AURORA BOREALIS
TAN TIME.
CAMBRIDGE.
Professor Airy.
N. Lat. 52¢ 13’ Long. E. 0° 6’
8.
8. |
vertex [{
h. 1
|
{
. 8. 25.—The aurora appeared in the form of a large bright cloud, bounded on
shooting ower side by the horizon, and on the upper side by an arch of a small circle
norther} giffering much from a great circle). The extremities of the arch were in
60° alten, E. and W. N. W. or nearly W. The upper boundary was lower than 6
ge Majoris by § x distance from « Urse Majoris to 6 Urs Majoris. Several
ll black clouds were scattered over the aurora-cloud, and above it were several
ly illuminated, whose light appeared to originate simply in the illumination
e aurora.
3. 35.—No change, except that the whole appeared to have moved a little to
* “west.
movem, 58.—The form and brightness of the arch had not sensibly altered; but a
the UPP, black cloud on its face attracted particular attention. The western ex-
it VanIShity of this cloud was below y Urs Majoris, its horizontal length fully three
rose hig.; the distance from f Ursze Majoris to y Urs Majoris, its vertical breadth
S. of thi than one-fourth of its length, the eastern end being somewhat broader than
at theit western, The aurora-cloud suddenly formed itself into streamers, (or
was n€,mers were formed in front of it) some perhaps 30° or 40° high, but lasting in
traces ¢ state only for an instant, and two streamers of sensible breadth shot up either
Were V@ ont of the black cloud or through it, so as to illuminate it, near its western
inclined mity in two nearly vertical lines, corresponding to the course of the
connectamers, whose upper and lower parts were visible above and below the cloud.
* ,markable change in the zonstitution of the cloud followed immediately ; the
10. tern half became curdly, the upper edge of its small pottions being luminous 3
western half began to disappear ; at 9. 15. no trace of the cloud discoverable.
11. 9. 10.—A shooting star from E. to W. very nearly through 3 Urse Majoris.
light of the aurora-cloud gradually diminished ; the part which remained
est was a little E. of N. where some light was still visible at 10, 30.
und the dipping-needle to be unaffected by this aurora at Armagh. It was
the dark segment was formed at about 123 h.; the phenomena ceased
The greatest intensity of the aurora was in the direction of the magnetic
|
18th, at 8. 34. a low arch was seen there passing below the feet of U.
(in the middle) above the horizon; at 8. 50, the lower edge of the lower
arick. é
TABULAR CONSPECTUS OF OBSERVATIONS ON THE AURORA BOREALIS
OF THE 17th OF SEPTEMBER, 1833, REDUCED TO GREENWICH MEAN TIME.
YORK.
J. Phillips.
Lat. 53° 58’ Long. W. 1° 4,
h. m.
8. 0.—Auroral arches and beams in the N. N. W.
8. 9.—Arch 3° or 4° broad, including in its middle and
vertex § Urse Majoris. It gradually and constantly increased
in breadth and rose in position.
8. 14.—Arch includes, nearly in the middle of its breadth,
Dubhe, Arcturus, and Capella. From this time it grew fainter
and rose higher.
8. 34.—Beams or streamers in great number and brilliancy,
shooting upwards in narrow distinct lines athwart the whole
northern sky, in front of the arch, from the horizon to about
60° alt.
8. 44,.—The arch (which after passing Polaris in its upward
movement shewed itself double) was now in two distinct parts 5
the upper rose most rapidly to within 15° of the zenith, when
it vanished. The lower arch became indistinct, and the beams
rose higher and more frequently, directing themselves to a point
S. of the zenith. Many of these beams were at one time joined
at their bases into a singular reversed arch, of which the centre
was near the Pole star. These streamers shewed momentary
traces of colour; in the line of the magnetic meridian, they
were vertical, towards the horizon E. and W. their tops were
inclined probably 2U° to the South. They appeared wholly un-
connected with the arch,
9. 4,.—No arch visible,
10. 49. ) A low faint arch stationary, its upper edge nearly
to reaching to » and y Urse Majoris; its vertex under
11. 19. ) Mizar (alt. about 18° in the middle.)
seen at Brussels by M. Quetelet, who in a letter to Professor Airy gives the following description of it.
MANCHESTER.
P. Clare, W. Hadleigh, and R. Potter.
Lat. 53° 29’
h. m.
Long. W. 2° 13°
8. 9.—Arch at its summit 32° high, very brilliant.
8. 18,—Arch almost exactly includes a and # and y and 3
Ursa Majoris. ( R. P.)
8. 24.—The arch 7° broad, includes Dubhe, Arcturus, and
Capella, so that Capella is on the extreme upper edge; Dubhe
rather above the middle of the breadth, ahd Arcturus rather
below the middle. Centre of the arch a little ER. of § Urse
Majoris, Extent of the arch 130°. (P. C.)
8. 27.The upper edge of the arch coincides with » and g
Ursa Majoris ; the lower edge with 3 Urse Majoris.
8. 40},—Arch 38° or 39° high, and extending about 160°
on the horizon. (R. P.)
8. 44,—-Many streamers in the N. directed towards the
magnetic zenith.
8, 44.—Arch passed over Arcturus, S. of Polaris, 3° or 4°
north of Algol, ending obscurely near the Pleiades (alt. about
60°, vertex in the magnetic meridian.) /(W. H.}
8. 49.—Half the hemisphere illuminated; many bright
Streamers and flashes of light rose from the magnetic N.
8, 54.—Coruscations frequently ending in an arch 30° or 33°
S. of the zenith ; the southern edge of the arch passing 1° N.
of the Pleiades. 1° N, of Scheat, 2° N. of the highest star in
Delphinus, and just touching y Aquila, and » Serpentis. (W7. H.)
From this time the streams and light diminished, and were
subject to slight changes till
11. 0., when the sky became cloudy.
1m. W.N.W.ofGOSPORT.
Hon. C. Harris.
Lat. 50° 48) Long. W. about 1° 9’
Cirro-strati clouds ob-
scured the auroral arch, which ap-
peared soon after sun-set.
h, m.
9. 524. —A beam in the W. be-
tween £ and y Ophiuchi. It seemed
to swerve off gradually to the west-
ward.
10. 44.—It had faded away.
10. 494. ? Arch from N. W. to N.
to N. E.. Its vertex under
il. 44. N ¢ Urs Majoris, and the
edge of its base half-way between
that star and the horizon.
GENERAL REMARKS,
This aurora was seen in many parts of Ireland from 9 to 11, and at later hours of the night of the 17th ; as at Adare, Limerick, Armagh, and Dublin. Professor Lloyd found the dipping-necdle to be unaffected by this aurora at Armagh. It was
CAMBRIDGE.
Professor Airy.
N. Lat. 52¢ 13’ Long. E. 0° 6!
he m.
8. 25.—The aurora appeared in the form of a large bright cloud, bounded on
the lower side by the horizon, and on the upper side by an arch of a small circle
(not differing much from a great circle). The extremities of the arch were in
the N. E. and W. N. W. or nearly W. The upper boundary was lower than £
Urse Majoris by 3 x distance from « Ursa Majoris to & Ursa Majoris. Several
small black clouds were scattered over the aurora-cloud, and above it were several
faintly illuminated, whose light appeared to originate simply in the illumination
of the aurora,
8. 35.—No change, except that the whole appeared to have moved a little to
the west.
8. 58.—The form and brightness of the arch had not sensibly altered; but a
long black cloud on its face attracted particular attention. The western ex-
tremity of this cloud was below y Urs@ Majoris, its horizontal length fully three
times the distance from £ Urse Majoris to y Urs Majoris, its vertical breadth
less than one-fourth of its length, the eastern end being somewhat broader than
the western. The aurora-cloud suddenly formed itselt’ into Streamers, (or
Streamers were formed in front of it) some perhaps 30° or 40° high, but lasting in
this state only tor an instant, and two streamers of sensible breadth shot up either
in front of the black cloud or through it, so as to illuminate it, near its western
extremity in two nearly vertical lines, corresponding to the course of the
streamers, whose upper and lower parts were visible above and below the cloud,
A remarkable change in the constitution of the cloud followed immediately ; the
western half became curdly, the upper edge of its small-portions being luminous ;
the western half began to disappear ; at 9. 15. no trace of the cloud discoverable.
9, 10.—A shooting star from E. to W. very nearly through § Urs Majoris,
The light of the aurora-cloud gradually diminished 3 the part which remained
longest was a little KE, of N. where some light was still visible at 10, 30.
Towards 10 p. m, (Brussels time) an aurora borealis was visible ; the dark segment was formed at about 124 h.; the phenomena ceased
about 3 in the morning. There were no streamers, (jets lumincux,/ and the light of a yellowish white colour, did not rise above the horizon more than 20 to 30 degrees. The greatest intensity of the aurora was in the direction of the magnetic
meridian to the north.
State of the atmosphere—York. Temp. 50.
Barom, 29.682 rising.
On the 12th and 16th of September, auroral beams had been seen at York and Greta Bridge; on the 18th, at 8. 34. a low arch was seen there passing below the feet of U.
Maj., its upper edge very near : and 4 of that constellation. At Durham, about 8. 0., two distinct arches were seen, the upper one 16°, and the lower and brighter one 7° (in the middle) above the horizon; at 8. 50, the lower edge of the lower
arch was well defined, and 4° above the horizon.
Auroral phenomena were also seen on this evening at Lymington, and a low arch was noticed by Lord Adare, near Limerick.
RECOMMENDATIONS. 487
able for observations of these faint and often fluctuating me-
teors than others of a more refined construction.
2.) It is recommended that a magnetic needle be kept in a
proper place, suspended by a silk fibre or slender hair, (a
point-support not being delicate enough,) and so mounted that
deviations can be observed to the accuracy of 1’. It has been
found convenient to fix in a garden a stone pedestal, on which,
at three invariable points, the frame of the magnetic needle
rests under a glass cover. The needle, 9 inches long, and of
such a weight as to perform about 10 vibrations in a minute, is
suspended by one slender hair. There are simple contrivances
to steady the needle when required, and to adjust the length
of the suspending hair. The scale is divided in degrees for
30° on each side of the centre, and in 10’ for 1° on each side.
There is no vernier, but the place of the needle on the scale
is read off with great ease by looking through a fixed magni-
fying glass, from an opening at some height above, so as to.
avoid sensible parallax. Professor Christie has described more
complete apparatus for this purpose, in the Journal of the
Royal Institution, New Series, vol. ii. p. 278. The observer
must leave his watch with the assistant, very carefully remove
all keys, knives, and other things containing iron, from his
dress, and all loose iron tools and utensils, to at least 20 feet
distance from the needle. If these precautions are not scru-
pulously attended to, the results will be fallacious. It is proper
to caution the observer that there is a regular daily variation
of the needle, independent of the Aurora.
Dipping-needles, unless constructed with the utmost care,
cannot be considered very satisfactory instruments; yet, if
' their suspension be sufficiently delicate, they may probably
very well answer for observations during Aurora, of which the
object is to determine not the absolute dip of the needle, but
the change of dip occasioned by the Aurora. The same pre-
cautions of one certain position, removal of iron, &c., are ne-
cessary, as in the use of the horizontal needle.
3.) It is recommended that arrangements be made for ascer-
taining the error of a watch. If near an observatory of any
kind, the watch should be compared with the transit clock
there, immediately after an Aurora: if there is a good meridian
line or good dial, the error of the watch on mean time should
be found as soon as possible. If a watchmaker in the neigh-
bourhood has a good regulator, the watch should be adjusted
by it, and the mode of keeping the regulator should be ascer-
tained: if a mail-coach from London passes near, the guard’s
watch may be consulted. The longitude of the place of ob-
488 THIRD REPORT—1838.
servation should be ascertained from a map or otherwise. 'The
attention of observers is especially called to the point of ascer-
taining the time correctly, as it is one of the most important
points, and the one which probably will require the longest
forethought.
4.) In default of intelligence of an Aurora, the observer
should go out of doors to some station where the horizon is
pretty clear, and look about every evening at 10, Greenwich
mean solar time, as near as may be. He should keep a journal,
noting for this time every evening whether there was an Aurora:
a single word will be sufficient.
5.) As soon as the observer perceives or receives notice of
an Aurora, he should, if accustomed to magnetic observations,
observe the magnetic needle, and should go to some command-
ing situation with his watch in his hand, and a note-book. A
person so prepared will have little difficulty in fixing on the ap-
pearances most worthy of notice. We may, however, point
out the following :
I. If there is an arch, the positions of its two boundaries,
its terminations, &c., should be noted by the way in
which they pass among the stars, (the proportion of
distances between the stars admitting of very accu-
rate estimation by the eye). If, as rarely happens,
the sky is cloudy, the observer may notice the ele-
vation and extent of the arch, by moving till it appears
to touch the top of some terrestrial object, noting his
situation as well as he can, and the next day observing
with a theodolite the angular elevation and azimuth of
the object; or ascertaining the height and horizontal
distance, and thence computing the angular elevation,
and observing the azimuth by a common compass: but
it is recommended not to adopt this method when the
observation of stars is practicable. Notice should be
taken whether one edge is better defined than the
other; whether there is a clear sky or dark cloud
above or below; whether it terminates at the end in
sky or in cloud; whether there is any dark band in
it; whether in its general composition it is uniform or
striated ; whether stars can be seen through it, &c.
II. If any change takes place in the situation or appear-
ance of the arch, the observer should instantly look
at his watch and set down the time, and then proceed
to note the change.
Ill. If there are beams or streamers, the time should be
noted ; then their position among the stars; then their
a
‘RECOMMENDATIONS. 489
height among the stars; their motion (whether vertical
or horizontal); the velocity of motion (by the time of
passing from one star to another); their changes ; their
permanency ; whether they appear to affect the arch,
or to be entirely in front of it.
IV. If there are any black clouds in the luminous region,
notice should be taken whether the streamers seem to
have any relation to them; whether the arch seems
to have any‘relation to them; whether and in what
manner they increase or disappear.
V. If there are waves or flashes of light, the observer
should notice the time of beginning and of finishing ;
the general extent of the flashes (up and down, as
well as right and left); whether the flash is a real
progress of light or successive illumination of different
places ; and anything else that strikes him.
VI. The existence and change of colours will, of course,
be noticed.
VII. From time to time, the needle should be observed.
If there are two persons capable of accurate obser-
vation, it is most desirable that one should steadily
watch the needle, and the other the sky.
6.) When all is over, the observer should immediately put
his rough notes in form, and as soon as possible should com-
pare his watch with the regulator or other authority for his
time.
7.) The next day he should, from a celestial globe, take the
altitudes and azimuths by means of the stars; he should reduce
his observed time to Greenwich mean solar time, and he should
append these reductions to his rough observations. In this
state the observations are fit for publication, and adapted for
immediate use. It is desirable that they should be transmitted
without delay to the Assistant Secretary of the British Asso-
ciation, Museum, York.
FALLING STARS.
M. Quetelet’s mode of observing and recording the charac-
teristic circumstances of these meteors is contained in the fol-
lowing extract of a letter from him:
“‘T take my station out of doors, in a situation which com-
mands a good view of the sky, with a good map of the heavens
spread out before me. When a falling star appears, I mark on
the map the point of its commencement, the line of its course
490 THIRD REPORT—1833.
amongst the nearest stars, and the point where it vanished.
This is done by an arrow-line, which marks the apparent di-
rection and extent of the course of the meteor. ‘The time is
carefully noted ; a number of reference is placed on the line,
and the principal circumstances of the meteor are then regi-
stered in tables of the following form:
Magnitude Duration of Time of
Epoch. No. relative to Stars. the Appearances. Apearannes Remarks.
&
Aug. 29 1 2 Q"5 105 6! 4",
It is important to remark whether the falling star leaves, or
not, any trace of its course, as sometimes happens, in the form
of reddish scintillations. The condition of the atmosphere, as
determined by the usual instruments, should be noted: the
time must be accurately ascertained. More than one observer
should be engaged at each station, because the meteors some-
times succeed one another very quickly, and the duration of
the phenomenon is too short to permit one person to note the
position, time, and circumstances of each, with sufficient pre-
cision }.”
CONSTANTS OF NATURE AND ART.
«* Amongst those works of science which are too large and
too laborious for individual efforts, and are therefore fit objects
to be undertaken by united academies, I wish to point out one
which seems eminently necessary at the present time, and which
would be of the greatest advantage to all classes of the sci-
entific world.
*‘ T would propose that its title should be The Constants of
Nature and of Art. It ought to contain all those facts which
can be expressed by numbers in the various sciences and arts.”
(Babbage, Edinburgh Journal of Science, N.S., No. 12.)
The following extracts from Mr. Babbage’s general plan of
contents will exemplify the objects and arrangement of the
proposed work.
These contents should consist of:
1. All the constant quantities belonging to our system ;—as,
distance of each planet,—period of revolution,—inclination of
orbit, &c.,—proportion of light received from the sun,—force
of gravity on the surface of each, &c.
1 Contemporaneous observations are especially desirable on this subject.
Persons desirous of undertaking the investigation are therefore requested to
apply to a member of the Auroral Committee, or to the Assistant Secretary
at York, for information of the evenings and hours appointed for this purpose.
a
a, ee
RECOMMENDATIONS. 491
2. The atomic weight of bodies.
3. List of the metals, with columns for specific gravity,—
electricity,—tenacity,—specific heat,—conducting power for
heat,—conducting power for electricity,—melting point,—re-
fractive power,—proportion of rays reflected out of 1000,—at
an incidence of 90°.
4, Specific gravities of all bodies.
5. List of mammalia, with columns for height,—length,—
weight,—-weight of skeleton,—weight of each bone,—its great-
est length,—its smallest circumference,—its specific gravity,—
number of young at a birth,—number of pulsations per minute,
—number of inspirations per minute,—period of blindness after
birth,—of sucking,—of maturity,—temperature,—average du-
ration of life,—proportion of males to females produced, &c. &c.
After enumerating twenty such general heads of Constants,
Mr. Babbage observes, that ‘most of them already exist, and
that the difficulty of collecting them consists chiefly in a judi-
cious selection of those which deserve the greatest confidence.
It would be desirable, however,” he adds, “ to insert the heads
of many columns, although not a single number could be placed
in them; for they would thus point out many an unreaped field
within our reach, which requires but the arm of the labourer
to gather its produce into the granary of science.” Mr. Bab-
bage expresses his opinion, that if any scientific body of men
would undertake to form such a collection, and to revise it from
time to time, it would be a work fraught with advantages to
knowledge, by continually leading to the more accurate deter-
mination of established facts, and to the discovery and mea-
surement of new ones. ,
Persons desirous of undertaking or cooperating in the exe-
ecution of any of the foregoing Recommendations, are requested -
to make known their intention to the Secretaries of the British.
Association, Museum, York.
PROSPECTUS
OF THE
OBJECTS AND PLAN
OF THE
STATISTICAL SOCIETY OF LONDON,
Founded on the 15th March, 1834.
Tue SratisticaL Society or Lonpon has been established
for the purposes of procuring, arranging, and publishing “ Facts
calculated to illustrate the Condition and Prospects of Society.”
_* The Sratisticat Soctery will consider it to be the first and
most essential rule of its conduct to exclude carefully all opé-
nions from its transactions and publications,—to confine its
attention rigorously to facts,—and, as far as it may be found
possible, to facts which can be stated numerically and ar-
ranged in tables.
The first operation of the Society will probably be to sub-
divide and organize its general council in such a manner as may
enable that council to deal conveniently with all the subdivisions
of the subject-matter before it. Those subdivisions will ne-
cessarily be numerous.
The whole subject was considered, by the Statistical Section
of the British Association at Cambridge, as admitting a division
into four great classes :
1. Economicat Statistics.
2. PoxiticaL STATISTICs.
3. Mepicat STATISTICS.
4. Morat anbD INTELLECTUAL STaTISTICs.
If these four classes are taken as the basis of a further ana-
lysis, it will be found that the class of
Economical Statistics comprehend, 1st, the statistics of the
natural productions and the agriculture of nations ; 2ndly, of
manufactures ; 3rdly, of commerce and currency; 4thly, of
the distribution of wealth, or all facts relating to rent, wages,
profits, &c.
Political Statistics furnish three subdivisions: 1st, the facts re-
lating to the elements of political institutions, the number of
electors, jurors, &c. ; 2ndly, legal statistics ; 3rdly, the statis-
STATISTICAL SOCIETY. 493
tics of finance and of national expenditure, and of civil and
military establishments.
Medical Statistics, strictly so called, will require at least two
subdivisions; and the great subject of population, although
it might be classed elsewhere, yet touches medical statistics
on so many points, that it would be placed most conveniently,
perhaps, in this division, and would constitute a third sub-
division.
Moral and Intellectual Statistics comprehend, |st, the statistics
of literature ; 2ndly, of education ; 3rdly, of religious instruc-
tion and ecclesiastical institutions; 4thly, of crime. Although
fourteen subdivisions have now been enumerated, it is pro-
bable that more will be required.
It will not of course be necessary to have a distinct Sub-com-
mittee of the Council for each of these subdivisions; but a
convenient division of the Council, and an arrangement of the
individuals composing it, so as best to deal with all the different
portions of the common subject, will be a necessary preliminary
to any systematic course of inquiry.
When these subdivisions are established, it will be for them,
subject to the approbation of the Council, to sketch the outline
of their own operations. A few observations on the more
general efforts and objects of the Society are all that need be
presented here.
It will be desirable that the Society should, as soon as possi-
ble, endeavour to open a communication with the statistical de-
Ae he established by Government at the Board of Trade.
ithout such a communication, constantly kept up, the Society
can never be assured that it is not doing unnecessarily what the
Government is doing at the same time and better. ‘The result
of such a communication would probably be that the Society
would abandon to the care of the Government some part of this
very extensive field of inquiry altogether, and more of it par-
tially, which would still leave a very sufficient, though a aes
overwhelming task to the Society.
The Society, having its own work thus somewhat limited and
defined, may next proceed to consider the best means, Ist, of
collecting fresh statistical information ; and, 2ndly, of arranging,
condensing, and publishing much that already exists. Towards
collecting fresh statistical information, the first step in order,
both of time and importance, would be the arrangement of a
good set of interrogatories, to be drawn up under the superin-
tendence of the Sub-committees, and afterwards examined,
sanctioned, and circulated by the Council. The careful execu-
tion of this task is essential both to afford guidance and aid to
494. THIRD REPORT—1838.
individual inquirers, and to protect the Society against the in-
flux of imperfect or irrelevant statements. Willing agents of
inquiry exist in abundance quite ready to aid in collecting ma-
terials ; but few of these agents take a very wide view of all the
objects of statistical inquiry, and indeed few have very distinct
notions about the precise information the Society may wish to
collect, even as to any one object. To sketch, therefore, di-
stinctly by means of interrogatories, carefully and succinctly
drawn, the whole outline which it is wished to fill up, is the
only way to secure to the Society the full benefits to be expected
from their zeal. _ It is difficult to overrate the importance of the
step which will be made towards the accumulation of statistical
knowledge from all quarters of the globe, by the publication of
such a set of questions; but the operation will be as laborious
as it is important. It properly may, and probably will, form the
chief object of the exertions of the Council during the first year
of the Society’s existence.
Obvious advantages may be drawn from communication with
intelligent Englishmen about to travel abroad, with residents in
the Colonies, and with colonial gentlemen resident in England.
The Society has already the satisfaction of knowing, that it will
have friends and assistants equally zealous and able in our
western colonial possessions. Various societies, foreign and do-
mestic, abound both in our own country and on the Continent,
some of them already devoted to this subject, and others very
willing to take it up. In addition to those already in existence,
the Society may hope to see other local societies springing up
in every part of the British dominions, in direct and constant
connexion with the London Society, circulating its queries in
their immediate neighbourhood, and collecting and authenti-
cating the answers. A body of facts can be thus most conve-
niently collected, which may properly enter into a common pub-
lication, and will afford safe grounds for comparing the present
condition and future progress of different parts of the empire.
The London Society, therefore, will carefully cultivate a con-
nexion with, and. attend to the wishes and suggestions of, such
local societies, and will look forward to their multiplication
and correspondence as among the best supports of its own
continued efficiency.
The collection, by such means and agents, of new statistical
materials will form, it will be remembered, only one part of the
Society’s work. To condense, arrange, and publish those al-
ready existing, but either unpublished, or published only in an
expensive or diffused form, or in foreign languages, would be a
task of equal usefulness. Authentic statistical accounts, even
STATISTICAL SOCIETY. 495
of an old date, may perhaps advantageously receive some atten-
tion. Our Oriental dominions alone present a field of statistical
research as interesting as it is immense. Many materials, col-
lected from that field by the meritorious exertions of the East
India Company, are known to be in existence, and it is to be
hoped that, sooner or later, they will be brought through some
channel before the public.
To point out such existing collections, old and new, their
character, value, and the degree of interest attached to them,
will form an appropriate part of the duties of the Sub-commit-
tees of the Council, and will itself be a considerable step in
statistical knowledge. The extent to which the Society shall
deal with the existing materials so pointed out to it, can only
be considered when the means and resources it is to possess
are better ascertained.
It will of course be one prominent object of the Society to
form a complete Statistical Library as rapidly as its funds may
admit.
The proposed annual subscription to the Society is two
guineas, which may be compounded for by one payment of
twenty guineas.
COUNCIL AND OFFICERS
Elected at the General Meeting, 3rd May, 1834.
President.—Marquis of Lansdowne.
Treasurer.—Henry Hallam, Esq.
Secretaries.— Woronzow Greig, Esq. Charles Hope Mac-
lean, Esq. E. Carleton Tufnell, Esq.
Charles Babbage. Esq. William Burge, Esq. Rev. Geo.
D’Oyley, D.D. John Elliot Drinkwater, Esq. Howard El-
phinstone, Esq. Earl Fitzwilliam. Rt. Hon. H. Goulburn, M.P.
Joseph Henry Green, Esq. Edmund Halswell, Esq. Dr.
Bisset Hawkins, M.D. Rt. Hon. Fr. Jeffrey, M.P. Rev.
Richard Jones. John Lefevre, Esq. Sir Charles Lemon,
Bart., M.P. Rt. Rev. Lord Bishop of London. S. Jones
Loyd, Esq. Rev. T. R. Malthus. G. R. Porter, Esq. Vis-
count Sandon, M.P. G. Poulett Scrope, Esq., M.P. N.W.
Senior, Esq. Dr. John Sims, M.D. Lieutenant-Colonel
Sykes. Thomas Tooke, Esq. T. Vardon, Esq. Rev. W.
Whewell.
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497
OBJECTS OF THE ASSOCIATION.
Tue AssociaTion contemplates no interference with the
ground occupied by other Institutions. Its objects are,—To
give a stronger impulse and a more systematic direction to sci-
entific inquiry,—to promote the intercourse of those who culti-
vate Science in different parts of the British Empire, with one
another, and with foreign philosophers,—to obtain a more gene-
ral attention to the objects of Science, and a removal of any dis-
advantages of a public kind, which impede its progress.
RULES.
MEMBERS.
All Persons who have attended the first Meeting shall be en-
titled to become Members of the Association, upon subscribing
an obligation to conform to its Rules.
The Fellows and Members of Chartered Societies in the Bri-
tish Empire shall be entitled, in like manner, to become Mem-
bers of the Association.
The Office- Bearers, and Members of the Councils or Managing
Committees, of Philosophical Institutions shall be entitled, in
like manner, to become Members of the Association.
All Members of a Philosophical Institution, recommended by
its Council or Managing Committee, shall be entitled, in like
manner, to become Members of the Association.
Persons not belonging to such institutions, shall be eligible,
upon recommendation of the General Committee, to become
Members of the Association.
SUBSCRIPTIONS.
The amount of the Annual Subscription shall be One Pound,
to be paid in advance upon Admission ; and the amount of the
composition in lieu thereof, Five Pounds.
MEETINGS.
The Association shall meet annually, for one week, or longer.
1833. 2K
498 RULES OF THE ASSOCIATION.
The place of each Meeting shall be appointed by the General
Committee at the previous Meeting ; and the Arrangements for
it shall be entrusted to the Officers of the Association.
GENERAL COMMITTEE.
The General Committee shall sit during the time of the Meet-
ing, or longer, to transact the Business of the Association. It
shall consist of all Members present, who have communicated
any scientific Paper to a Philosophical Society, which Paper has
been printed in its Transactions, or with its concurrence.
Members of Philosophical Institutions, being Members of
this Association, who may be sent as Deputies to any Meeting
of the Association, shall be Members of the General Committee
for that Meeting.
COMMITTEES OF SCIENCES.
The General Committee shall appoint, at each Meeting, Com-
mittees, consisting severally of the Members most conversant
with the several branches of Science, to advise together for the
advancement thereof.
The Committees shall report what subjects of investigation
they would particularly recommend to be prosecuted during the
ensuing year, and brought under consideration at the next Meet-
ing. They shall engage their own Members, or others, to un-
dertake such investigations ; and where the object admits of
being assisted by the exertions of scientific bodies, they shall
state the particulars in which it might be desirable for the Ge-
neral Committee to solicit the cooperation of such bodies.
The Committees shall procure Reports on the state and pro-
gress of particular Sciences, to be drawn up from time to time by
competent persons, for the information of the Annual Meetings.
LOCAL COMMITTEES.
Local Committees shall be appointed, where necessary, by the
General Committee, or by the Officers of the Association, to
assist in promoting its objects.
Committees shall have the power of adding to their numbers
those Members of the Association whose assistance they may
desire.
OFFICERS.
A President, two Vice-Presidents, two or more Secretaries,
and a Treasurer, shall be annually appointed by the General
Committee. ©
RULES OF THE ASSOCIATION. 499
COUNCIL.
In the intervals of the Meetings the affairs of the Association
shall be managed by a Council, appointed by the General Com-
mittee.
PAPERS AND COMMUNICATIONS.
The General Committee shall appoint, at each Meeting, a
Sub-Committee, to examine the papers which have been read,
and the register of communications ; to report what ought to be
published, and to recommend the manner of publication. The
Author of any paper or communication shall be at liberty to re-
serve his right of property therein.
ACCOUNTS.
The Accounts of the Association shall be audited, annually,
by Auditors appointed by the Meeting.
TREASURER.
Joun Taytor, Esq., 14, Chatham Place, London.
LOCAL TREASURERS.
Dr. Dauseny, Oxford. Rev. Tuomas Lusy, Dublin.
Prof. Forsrs, Edinburgh. Dr. Pricuarp, Bristol.
JonatHan Gray, Esq., York. Grorce Parsons, Esq., Birming-
Prof. Henstow, Cambridge. ham.
Witt1am Horton, Esq., Newcas- | Rev. Joun J. Tayter, Manchester.
tle-on-Tyne. H. Wootcomsz, Esq., Plymouth.
2x2
at
>
INDEX.
—=
Oxszcts and Rules of the Associa-
tion, 497.
Officers, Council, Committees, &c.
XXXviil. ,
Proceedings of the General Meeting,
ix.
of the Sectional Meetings,
XXxil.
of the Committees, xxxv.
Recommendations of the Commit-
tees, 469.
Absorption of light by coloured me-
dia, on, 373.
Achromatism of the eye, on the, 374.
Actinometer, the principle and con-
struction of the, 379.
Adam (Dr.) on some symmetrical
relations of the bones of the me-
gatherium, 437.
Agardh (Prof.) on the originary
structure of the flower, 433.
Algebra, on the science of, 185;
signs of transition, 232; signs of
discontinuity, 248; convergency
and divergency of series, 267.
Analysis, on certain branches of, 185.
Antimony, glass of, its power to re-
flect light, 377.
Architecture, naval, on, 430.
Atomic weights, experiments on, 399.
Attraction, electrical, some new phe-
nomena of, 386.
Aurora borealis, on an arch of the,
401 ; directions for observations
of the, 486.
Baily (F.), account of some MS.
- Letters relative to Flamsteed’s
Historia Celestis, 462.
Barlow (P.), report on the strength
of materials, 93.
Barometer, new, on the construction
of, 414.
, portable, new method ofcon-
structing, 417.
Barometer, wheel, on the construc-
tion of a new, 414.
with an enlarged scale, 414.
Beams, on the effect of impact on,
421.
Blackwall (J.) on the structure and
functions of spiders, 444.
Botany, on the philosophy of, 27.
Brain, on the physiology of the, 63.
Buckland (Rev. Dr.), address on re-
signing the President’s Chair, ix.
Carlile (H.) on the motions and
sounds of the heart, 454.
Challis (Rev. J.), report on hydro-
statics and hydrodynamics, 131.
Christie (S. H.), report on the mag-
netism of the earth, 105.
Chronometers, application of a glass
balance-spring to, 421.
Circulation in plants, on, 32.
Colours of plants, on the, 55.
Compressibility of water, on, 131,
353,
Cumming (Rev. J.) on some electro-
magnetic instruments, 418 ; on an
instrument for measuring the heat-
ing effect of the sun’s rays, 418.
Decomposition, on electro-chemical,
393.
Dent (E. J.) on the application of a
glass balance-spring to chronome-
ters, 421.
Daubeny (Dr.) on the action of
light upon plants, 436.
Earth, on the magnetism of the,
105.
Eddies in rivers, on the causes of,
169.
Eel, on the reproduction of the, 446.
Electrical attraction, some new phz-
nomena of, 386.
Electricity, on, 390.
Electro-chemical decomposition, on,
393.
502
Electro-magnetic instruments, on,
418.
Endosmose and Exosmose, on the
cause of, 391. oe
Equations, on the theory of, 296;
composition of, 296; general so-
lution of, 305.
Eye, on the achromatism of the, 374.
Faraday (M.) on electro-chemical
decomposition, 393.
Fielding (G. -H.) on the peculiar at-
mospherical phznomena during
the prevalence of influenzain 1833,
461.
Flamsteed’s Historia Celestis, ac-
count of some MS. Letters rela-
tive to, 462.
Flowers, on the structure of, 433.
Fluid motion, review of the theory of,
131.
Fluids, on the motion of in pipes and
vessels, 135, 153; on the resistance
of, 149, 153; on the velocity of
propagation in, 136, 153.
Genera and subgenera, on, 440.
Glass, its colouring matter dimi-
nishes its power of transmitting
heat, 382.
of antimony, on its power to
reflect light, 377.
Gray (W.) experiments on the quan-
tities of rain falling at different
elevations, 401.
Hamilton (W. R.) on the character-
istic function in optics, 360.
Harlan (Dr.) on some new species of
fossil saurians, 440.
Harris (W. S.) on some new phzeno-
mena of electrical attraction, 386;
on the construction of anew wheel-
barometer, 414.
Hawkins (J. I.) on the locomotive
differential pulley, 424.
Heart, on its motions and sounds,
454.
Heat, radiant, experiments on, 381.
Henry (Dr. W. C.), report on the
physiology of the nervous system,
59.
Herschel (Sir J. F. W.) on the ab-
sorption of light by coloured me-
dia, 373; on the principle and
INDEX.
construction of the actinometer,
Hodgkinson (E.) on the effect of im-
pact on beams, 421; on the strength
of cast iron, 423.
Hydraulics as a branch of engineer-
ing, on, 153.
Hydrostatics and Hydrodynamics,
report on, 131.
Influenza of 1833, peculiar atmo-
spherical phenomena during the
prevalence of, 461.
Iron, mean strength and elasticity
of, 103.
, carbonaceous, method of ana-
lysing, 400.
, cast, on the strength of, 423.
Jenyns (Rev. L.) on genera and sub-
genera, 440. :
Johnston (Prof.) on a method of ana-
lysing carbonaceous iron, 400.
Leaves, on the theory of wood being
generated by the action of, 36; on
the arrangement of, 40; on the
structure of, 41.
Life, on the term, 59.
Light, on its absorption by coloured
media, 373 ; on the power of glass
of antimony to reflect, 377 ; on a
phznomenon in the interference
- of, 378.
Lindley (Prof.), report on the philo-
sophy of botany, 27.
Lloyd (Rev. H.) on conical refrac-
tion, 370.
Locomotion, on the function of, 68.
Locomotive differential pulley, in-
vestigation of the principle of the
424,
Macartney (Dr.) on the natural hi-
story of the common toad, 441; on
the structure and functions of the
nervous system, 449.
MacVicar (Rev. J. G.) on electricity,
390.
Magnetism of the earth, on, 105.
Materials, on the strength of, 93,
103, 421, 423,
Medulla oblongata, on the, 72.
Megatherium, on some symmetrical.
relations of the bones of, 437.
INDEX.
Melloni(M.), experiments on radiant
heat, 381.
Miller (Rev. W. H.) on the con-
struction of a new barometer,
414.
Mineral veins, on the state of know-
ledge respecting, 1.
Mines, on the depths of, 427.
Morphology, on the theory of, 50.
Mytilus crenatus, on the naturaliza-
tion in England of, 448.
Naval architecture, on, 430.
Needle, on its variation, 106; on the
change in its direction, J07; on
the diurnal change in the varia-
tion, 108.
, dipping, on a peculiar source
of error in experiments with,
412.
, magnetic, on the dip of,
109 ; on the variation of the dip,
110.
Nerves, on the, 80.
Nervous system, on the physiology
of the, 59; on the structure and
functions of the, 449.
Newman (J.) on a new method of
constructing a portable barometer,
417.
Cirsted (Prof.) on the compressibi-
lity of water, 353.
Optics, on the characteristic function”
in, 360.
Owen (J.) on naval architecture,
430.
Peacock (Rev. G.), report on certain
branches of analysis, 185.
Phillips (J.), experiments on the
quantities of rain falling at differ-
ent elevations, 401.
Physiology of the nervous system,
59; of the brain, 63.
Plants, on the circulation in, 32;
on the structure of the axis, 33;
on the cause of the formation of
wood, 36; on the arrangement of
leaves, 40; on the structure of
leaves, 41; on the anther, &c.,
43; on the origin of the pollen,
44 ; on the fertilization, 45 ; on
the origin of organs, 49; on the
theory of morphology, 50; on the
503
theory of gradual development,
53; on their irritability, 54; on
the action of coloured light on, 54;
on the various colours of, 55; on
excretions, 56; on the structure of
the flower, 433 ; on the action of
light upon, 436.
Pollen, on the origin of, 44.
Potter (R. jun.) on the power of glass
of antimony to reflect light, 377;
on a phenomenon in the interfer-
ence of light, 378; on an arch of
the aurora borealis, 401.
Powell (Rev. B.) on the dispersive
powers of the media of the eye, in
connexion with its achromatism,
374,
Power (Rev. J.), inquiry into the
cause of endosmose and exosmose,
391.
Prideaux (J.) on thermo-electricity,
384.
Rain, experiments on the quantities
of falling at different elevations,
401.
Refraction, conical, on, 370.
Rennie (G.), report on hydraulics as
a branch of engineering, 153.
Respiration, action of the medulla
spinalis and oblongata on, 73.
Saurians, fossil, new species of, 440.
Scoresby (Rev. W.) on a peculiar
source of error in experiments
with the dipping-needle, 412.
Sedgwick (Prof.), his addresses, x.
XXVii.
Solar rays, on an instrument for
measuring their heating power,
379; on the diminution of their
intensity in traversing the atmo-
sphere, 380; on an instrument for
measuring the heating effect of,
418.
Spiders, on the structure and func-
tions of, 444.
Spinal marrow, on the, 74.
Stars, falling, mode of observing, 490.
Statistical Society of London, objects
and plan of, 493.
Steam-engine for pumping water,
421.
Strength of materials, on, 93, 103,
421, 423.
504:
Taylor (J.), report on the state of
knowledge respecting mineral
veins, 1; on the depths of mines,
427.
Telescope, reflecting, 420.
Terrestrial magnetic force, on the
direction of, 106; on the intensity
of, 118.
Thermo-electricity, on, 384.
Thermostat, or heat-governor, on the,
419.
Tides, directions for observations of
the, 485.
Timber, table of the mean strength
and elasticity of, 103.
Toad, on the natural history of, 441.
Trigonometry, on the science of, 288.
Turner (Dr.), experiments on atomic
weights, 399.
Ure (Dr.) on the thermostat, or heat-
governor, 419.
Vegetable anatomy, on, 27; vege-
INDEX.
table fertilization, 45 ; vegetable
physiology, 49.
Veins, mineral, on our knowledge
respecting, 1.
Vibrations, musical, in tubes, on,
140.
Water, on the compressibility of,
131, 353.
a steam-engine for pumping,
421.
Waves, on the problem of, 142.
Wharton (W. L.) on a barometer
with an enlarged scale, 414.
on asteam-engine for pump-
ing water, 421.
Whewell (Rev. W.), his address, xi.
Willcox (C.) on the naturalization in
England of the Mytilus crenatus,
448.
Yarrell (W.) on the reproduction of
the eel, 446.
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