THE LONDON anp EDINBURGH { | PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. CONDUCTED BY SIR DAVID BREWSTER, K.H. LL.D. F.R.S, L. & E. &e. RICHARD TAYLOR, F.S.A. L.S.G.S. Astr. S. &e. AND RICHARD PHILLIDS, F.R.S. L. & E. F.G.S. &e. “Nec aranearum sane textus ideo melior quia ex se fila gignunt, nee noster | + vilior quia ex alienis libamus ut apes.” Just. Lips. Monit. Polit. lib.i. cap. 1. ViOds.E. NEW AND UNITED SERIES OF THE’ PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. JULY—DECEMBER, 1832. ae LONDON: PRINTED BY RICHARD TAYLOR, RED LION COURT, FLEET STREET, Printer to the University of London. SOLD BY LONGMAN, REES, ORME, BROWN, GREEN, AND LONGMAN ;‘ CADELL BALDWIN AND CRADOCK}; SHERWOOD, GILBERT, AND PIPER ; SIMPKIN AND MARSHALL; AND §S. HIGHLEY, LONDON:!—BY ADAM BLACK, EDINBURGH; SMITH AND SON, GLASGOW; HODGES AND M‘ARTHUR, DUBLIN; AND G. G, BENNIS, PARIS, 4 TABLE OF CONTENTS. NUMBER I.—JULY. M. Rudberg on the Refraction of the differently-coloured Rays in Crystals with one and two Axes of Double Refrac- tion (continued) ........- 24s. ee eee es Ragin leis ay-ueiaaleiale Sir D. Brewster’s Observations on the preceding Memoir ..... Mr. J. E. Drinkwater on the Invention of the Telescope. ..... On the Encouragement of Science by the King of Denmark, . Mr. P. Barlow’s Additional Experiments on the Strength and Stiffness of Acacia, ..........2600cecee eer tee et eeeeee Sir D. Brewster on a new Species of Coloured Fringes pro- duced by Refraction between the Lenses of Achromatic or Compound Object-Glasses ........-0-+-+eeeeeeeneeeee Mr. J. Blackwall’s Remarks on the Diving of Aquatic Birds .. Addition to the Analytical Investigation of a Formula for the Relative Importance of the Boroughs. And Reply to Dr. M‘Intyre's Remarks ...... sees seee ce cece etter sees Mr. W. Sturgeon on the Distribution of Magnetic Polarity in Metallic Bodies ...... cenesse eens ces tme tees sees seen ee Rev. J. Challis on the Resistance to the Motion of smal] Sphe- rical Bodies in elastic Mediums ...........--+++---++-- Signor Salvatore Dal Negro’s New Experiments relative to the Action of Magnetism on Electro-dynamic Spirals, and a Description of a new Electro-motive Battery; with notes by M. Faraday, Esq. F.RS....:.....-20 22 eee eee ee esenee Mr. J. D. Forbes’s Account of some Experiments in which an Electric Spark was elicited from a natural Magnet ....... Mr. B. Bevan’s Remarks on Mr. White’s Experiments on the Cohesion of Cements; with a tabular View of their Results Mr. R. Potter's Addendum to the Paper on a Method for giving the Figures of the Conic Sections to Concave Lenses GMO ACCU. nie slas(taiwie come cere <= = 520 neces emma gs ss Mr. R. Potter’s Experiments to determine the Reflection at the second Surface of Flint-Glass at Incidences at which _no Portion of the Rays passes through the Surface. ..... Sir J. F.W. Herschel on the Action of Light in determining the precipitation of Muriate of Platinum by Lime-water... . Proceedings of the Royal Society ........-+-0+-+ee+erees ———— Linnzan Society ......-.6--.-s+000 — at the Friday-Evening Meeti Institution of Great Britain........--- 0+. essere eer cee of the Cambridge Philosophical Society......... — British Association for the Advancement OF SCIENCE 6. oe cere se cevsccesee cues Mrrerrerice Le r a2 (ea Page 72 15 17 iv ’ CONTENTS. Safety-tube for the Combustion of the Mixed Gases Oxygen and Hydrogen, invented by Mr: Hemming ............ Conversion of Hydrocyanic Acid and Cyanurets into Am- monia and Formic Acid—Isomeric Modification of Tartaric PCIG DT MeDPACONMOL ees nc. ni ye nai eine es te aera M. Pelouze on the Formation of Carbonate of Lime under the PmudenCe af SUMAN. sot toc. 2c or neeienee Seen ae © ee Extemporaneous Solution of Chlorine—Separation of Per- oxide of lron from Protoxide of Manganese, by M. Liebig Separation of Peroxide from Protoxide of Iron, by the same —Separation of Peroxide of Iron from the Oxides of Cobalt and Nickel, by the same—Preparation of Metallic Chrome, |) dh CA 1] a I eR el ss Sl rc Occultations of Planets and fixed Stars by the Moon, in CLL 1h ie as - Rea Re Au ctl mie fn. Se ba RNG tah Meteorological Observations made by Mr. Thompson at the Garden of the Horticultural Society at Chiswick, near . London; by Mr. Giddy at Penzance, and Mr.Veall at Boston NUMBER II.—AUGUST. Sir D. Brewster on the Effect of Compression and Dilatation pponthe Metin, », :.c/serde, see Rea iby tp ian sss aaah Rev. C. P. N. Wilton’s Sketch of the Geology of Six Miles of the South-east Line of the Coast of Newcastle in Australia Mr. J. Blackwall’s Observations on the House Spider, in reply to a Statement in the Zoological Journal, quoted in the Phil. Mag. and Annals, vol. x, p. [S40 sac sere ot pyc ae opal Mr. J. Nixon’s Particulars of the Measurement, by various Methods, of the Instrumental Error of the Horizon-Sector described in Phil. Mag. vol. lix. (continued)............-: Dr. E. Turner on some Atomic Weights..........--e+ecss Mr. G. H. Fielding on a new Membrane in the Eye........ Mr. B. Bevan on the Investigation of the Strength of Timber and other Materials, with reference to the recent Experi- ments and Communications of Mr. Peter Barlow, jun...... Rev. W. D. Conybeare’s Inquiry how far the Theory of M. Elie de Beaumont concerning the Parallelism of Lines of Elevation of the same Geological /Era, is agreeable to the Phzenomenaas exhibited in Great Britain (continued ) Prhehte Mr. J.O. Westwood’s Descriptions of several new British Forms amongst the Parasitic Hymenopterous Insects. .......... Prof. M. A. Kupffer’s Notice of some recent Magnetical Dis- COMGINOS 5 esa. love waren laslt RAIS Seeger eae t ae aoe areas eae M. G. Fuss’s Account of the Magnetical and Meteorological Observations made at Pekin, . Note on the Mean Temperature of Nicolaieff. Communicated bee. Mie ISAM TON: 5. t3 125s 4 ce wake traded debe ates deus obo BURR M. Rudberg on the Refraction of differently-coloured Bae in Crystals with one and two Axes of Double Refraction . 89 92 CONTENTS. y Page Sir D. Brewster's Observations on the preceding Memoir.... 146 Dr. W. H. Fitton’s Notes on the History of English Geology . 147 Account of an Experiment in which Chemical Decomposition has been effected by the induced Magneto-electric Current. By P. M.; preceded by a Letter from M. Faraday, Esq.... 161 New Books: — Dr. Goring’s Microscopic Cabinet¥ of select PeMAEEC OWCCIS fo es sss * cac.0 so pps wp « tems es So een ah 20D On the Cause of the Production of Heat by Friction and Per- cussion—Preparation of Chlorate of Potash ............ 164 DiGi POSIT OL MEIN oe ne wim ahr oo) winin's wa 0 > oo ot «Mr isiaseiene 165 Experiments on Bees’ Wax and Vegetable Wax............ 166 New Patents—Occultations of Planets and Fixed Stars by the Nea ie TOPE MU POPE RPE Sef etate wns larote ’otang oe sae 0's myarianehe otee 167 Meteorological Observations ................- Sere pobe 168 NUMBER III—SEPTEMBER. Sir D. Brewster on the Undulations excited in the Retina by the Action of Luminous Points and Lines .............. 169 Mr. R. Potter on an Instrument for Photometry by Compari- son, and on some Applications of it to important Optical Pieepanienasy 3) esses. 2cbier mil? de -bsted. tetashiiok oll 174 _Mr. R. Warrington on the Establishment of some perfect Sy- stem of Chemical Symbols; with Remarks on Professor Whevwell’s Paper on that Subject..............2.+...4. 181 Mr. B. Bevan’s Tabular Abstract of the Results of Captain Lloyd’s Levelling from the Sea near Sheerness te the River Thamesiat dopdom Bridge y.3)..nates\sl od: sc.cdoaerendl dee 187 Mr. J. Blackwall’s Description of a Species of Arachnida, hitherto uncharacterized, belonging to the Family Araneide 190 ' Mr. B. Boddington’s Accurate Statement of Facts relative to a Stroke of Lightning, which happened on the 13th of April lc ey oes 0 rt EES OOD CUB OE DAO D OC OOm ia Orin,” 191 Mr. J. F. Daniell’s Further Experiments with a new Register- Pyrometer for Measuring the Expansion of Solids........ 197 New Books:—Mr. Edmonds’s Life Tables—Mr. E. Hodgkin- son on the Forms of the Catenary in Suspension Bridges, &c.—Theoretical and Experimental Researches to ascertain the Strength and best Form of Iron Beams, by the*same Author— Mr. C. Babbage on the Economy of Machinery and Manufactures—Comparative Account: Population of Great Britain. Ordered by the House of Commons to be printed, 19th October, 183) (continued); Prof. Leybourn’s Mathematical Repository, No. XXUL............. 204-— 220 Proceedings of the Geological Society.................00. 220 2 ao Royal Astronomical Society........... 234 M. Liebig’s Preparation of Caustic Potash—Analysis of Gums 244 Transit of Mercury observed at Geneva.................. 246 On the Evolution of Heat by Friction and Percussion—Occul- tations of Planets and Fixed Stars by the Moon........ 247 Meteorological Observations. ......2-. 0... c cece eects 248 vi CONTENTS. NUMBER IV.—OCTOBER. Page Mr. T. Smith’s Investigation of certain remarkable and unex- plained Phenomena of Vision, in which they are traced to Functional Actions of the Brain (continued)... vin. cicn'e vie» 249 Prof. M. A. Kupffer’s Note on the Mean Temperature of Se- vastopol, as deduced from the Observations of M. Coumani 259 Mr. J. F. Daniell’s Further Experiments with a new Register- es for Measuring the Expansion of Solids........ 261 Dr. W. H. Fitton's Notes on the History of English Geology (continued) Ses pehinl. Ristiia'l aelyiat ne Ra SRG t oe re 268 Mr. A. H. Haworth’s Odservatzones quaedam ad NaRCIssi- NEAS)SPECEANEES 0. 66S ou a 0 oie Sis ol shel Sollleeh wleibehat inn aft aim anelbis 275 Notice of some recent Observations of Encke’s Comet, and of Gambart’s Comet of July 19 ;—extracted from a Letter from Professor Schumacher of Aiton to the Rev. T. J. Hussey.. 287 Mr. W. J. Henwood on Periodical Variations in the Quantities of Water afforded by Springs;—in a Letter to Sir Charles Lemon; Bart.) MePsd2 53 2 ene ISR a eee 287 Mr. T. Andrews’s Chemical Researches on the Blood of Cho- bera:-Patients:)\.1).)). cd......< SREY BSUS CE ee 295 Mr. R. Edmonds’s Notice of the great Meteor seen on June DOUCHE IER. ITT IST ae ae leks in, Siete eels 306 Mr, J. Prideaux’s Notice of the Meteor of June 29th; and In- quiries relative to certain Points in Magneto- Electricity. . 307 Mr. R. W. Fox on certain Irregularities in the Vibrations of the Magnetic Needle produced by partial Warmth; and some Remarks on the Electro-Magnetism of the Earth. oo GLO Mr. R. Brown’s Remarks on the Structure and Affinities of ephal ates Ui.) oe bod Red ADA Me saint yal ore ate 314 Account ofan Experiment in which part of the Interior of the Eye is exhibited by Reflexion in the Eye-glass of a Tele- BE OP Oe i eicicjete ais} ole!scoleto >. sisiajeteted Sletetcteqereyetarca topes teeta 318 E.W.B. on the true Source of the Amniotic Acid of Vauquelin (Allantoic Acid of Lassaigne): and on the Importance of obtaining Comparative Analyses of the Allantoic Fluid, and the Urine of the young Animal after Birth.........-.... 319 Mr. J. D. Sollitt’s Observations of the Transit of niies on May'5, 1832;;made ‘at Thai a toi a. Soars set ae ee $22. An Ephemeris of the Stars proper to be observed with Mars, at the ensuing Opposition of that Planet................ 323 M. Liebig’s Separation of the Oxides of Lead and Bismuth .. $26: Occultation of Saturn, observed at Geneva—New Process for obtaining Morphia—Occultations of Planets and fixed Stars by the’ Moon, 1n October,’1832: 4. 00. 2020 See 397 Meteorological Observations . ............00ceeleeee eee 328 NUMBER V.—NOVEMBER. Prof. L. A. Necker’s Observations on some remarkable Optical Phenomena seen in Switzerland; and on an Optical Pheeno~ CONTENTS. Vil Page menon which occurs on viewing a Figure of a Crystal or Geo- metrical Solid ;—in a Letter to Sir D. Brewster.......... 329 Mr. R. W. Fox on some Facts which appear to be at Variance with the Igneous Hypothesis of Geologists........ be tras 338 Mr. J. Nixon’s Description of a Repeating Circle, by which any Multiple of an Altitude may be measured from one Ob- Peruationsby the Telescope ..5....<:,.p\.cenioe 2 ve heater 340 Mr. T. Smith’s Investigation of certain remarkable and unex- plained Phenomena of Vision, in which they are traced to Functional Actions of the Brain.. .................... 343 Mr. J. Phillips on the Lower or Ganister Coal Series of York- SIT BS5- SESS Dice SORES Pe SME PTE aC Pht ose 8 Bee 349 Official Documents respecting the Health of the Workmen employed in Cleansing the Public Sewers of Westminster, as affected or not by their Employment, and also during the existence of Malignant Cholera in the Metropolis ; together with authenticated Statements relative to the Health of other Workmen exposed to putrid Effuvia. Communicated ina Letter from Sir Anthony Carlisle...............0..0.4. 354 New Books:— Comparative Account: Population of Great Britain.—Dr. Pearson's Introduction to Practical Astronomy (continued.)—Mr, Tod’s Anatomy and Physiology of the Or- Pon Licnitiive if. tress sie tii us aA 361—375 Proceedings of the Royal Society ..................0005 378 ———— Royal Astronomical Society ........... 390 Zoological Society...............0005 392 ——— Cambridge Philosophical Society........ 400 MMR EN eh oa hth \'n pl'n'y ut OA saild0a otosich sha! akapsdafa cals SIMERS 401 Ga paromn ant Bapion, 6224 64 es Pai hee T e 402 Occultations of Planets and Fixed Stars by the Moon, in Eel in AU Ht» duets mins = ay aanie coaeasy Hered m ckente oe 405 An Ephemeris of the Stars proper to be observed with Mars, at the ensuing Opposition of that Planet (continued) ...... 406 Meteorological Observations... ............0. 0000.0. eee ee 408 - NUMBER VI.—DECEMBER. « Prof. F. Rudberg on the Variations which Temperature pro- duces in the Double Refraction of Crystals .............. 409 Sir D. Brewster on the Action of Heat in changing the Num- ber and Nature of the Optical or resultant Axes of Glau- NGI. Bi A Deis ieriteg i Rees sist eh ytala< ar doerpapabids 4.17 Capt. Luetke’s Account of Experiments with an Invariable Pendulum, during a Russian Scientific Voyage........... 420 Mr. G. Fairholme on the Power possessed by Spiders to escape Seman ain SEC ALCO SICMAMOM fee oes a: - veyed sins w'elers «als 424, Prof. M.A.Kupffer's Note on the Mean Temperature and Baro- metric Height of Sitka, on the North-west Coast of America. 427 Prof. M. A. Kupffer’s Note on the Mean Temperature and Mean Barometric Height of Jloulouk, in the Island of Ounalachka 429 Vill CONTENTS. Page’ Sir D. Brewster's Observations on the Isothermal Lines on the North-west Coast of America, as deduced from the Results in the two preceding Articles. .......... ee 431 Rev. B. Powell’s Further Remarks on. Experiments relative to — the Interference of Light ............ 2%» 10 os nctps a4 sieteanes 433 Sir D. Brewster’s Account of a curious Chinese Mirror, which reflects from its polished Face the Figures embossed upon ee oC) a eee es mee os Mee) com bf -. 438 Prof. Botto’s Notice on the Chemical Action of the Magneto- GIECEMIC TE UETENES ys 6) 050) 5 jo -0 ope eal acai tuys “Eee a pig eleieag ee 44] Dr. Fitton’s Notes on the History of English Geology (continued) 442 New Books :—Dr. Pearson’s Introduction to Practical Astro- nomy.— Bevan’s Guide to the Carpenter’s Rule ..... 450—457 Proceedings of the Royal Astronomical Society ............ 457 ey ees + Loological Society as, 2. .'...°. wees sane 460 et 3 LINNZEAN, NOCICLY A oie oat A so eta) nee 465 E.W.B. on certain Points in the Natural History of the Papuans, ar Amiatic Negros... .... » 5: -sels siguld epetbvet d= ana oieaa 466 Questions as to the Continuation of metalliferous Veins from primary into secondary Formations,..............+++.. 469 Mr. J,O. N. Rutter’s Notice of a new Oxy-hydrogen Blow- POPECEABPAPALUS oo. o5.: aie + oho), «ui slnvale ychajn sls ingle iota 470. Mr. R. W. Fox’s Notice of a Marine Deposit in the Cliffs near PAAIONBER s a- 5's seers se 54>. Liholcanhoreie sede Baan eth elena s seals Se 471 Mr. B. Bevan’s Inquiries respecting the Dimensions and Value of the local Measures in common use at Covent Garden TE Ove a iam Bane rane m2 ots 9 Glee ogee ar 472 An Ephemeris of the Stars proper to be observed with Mars, at the present Opposition of that Planet................ 473 Occultations of Planets and fixed Stars by the Moon, in De- COMMER ASSO bis cclnam de jee ain aean ele Sel camel 474 Meteorological Observations ..........60..c.eceseeerees 473 oe re Pt re are BAL ic 476 PLATES. Plate I. Illustrative of Sir Davip Brewstrr’s Paper on Coloured Fringes, and Mr. Sturczon’s Paper on the Distribution of Magnetic Polarity in Metallic Bodies. — Plate II. Illustrative of Dr. Frrron’s Notes on the History of English Geology. ERRATA. Page 156, line 25, for coming read common. — 157, — 27, for Plate I. read Plate IT. —— 165, — 2, for chlorate of potash read chlorate of lime. — 167, — 4, for 31-2910 read 81-2910. THE LONDON anp EDINBURGH PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES. ] JUL Y . 1832. I. On the Refraction of the differently-coloured Rays in Crystals with one and two Axes of Double Refraction. By M. Rupsere*. A®. the remarkable discovery of Fraunhofer of the dark rays in the spectrum gives an unexpected degree of precision to researches on the refraction of coloured light, it becomes interesting to determine by this accurate method the indices of refraction. With the view principally of constructing more perfect achromatic object-glasses, Fraunhofer himself deter- mined the refraction of the differently-coloured rays for several kinds of flint and crown glass, and also for some other sub- stances that have simple refraction+. But for doubly refract- ing crystals similar researches are entirely wanting, which might show in general how the double refraction varies with different colours, and how this variation produces the different inclination of the optic axes which Mr. Herschel has observed for the differently- coloured rays in crystals with two axes. Besides, an inquiry into the double refraction of coloured light would add to the small number of accurate determina- tions of dispersion which we owe to Fraunhofer. In order to measure accurately the deviation of the ray re- fracted by a prism, as well as its own refracting angle, I used a repeating circle constructed by Lenoir, which Swanberg had used in the measurement of the degree of the meridian in Lapland, and which being divided centesimally gave im- * From the Annales de Chimie et de Physique, tom. x\viii. p. 225, + See Phil. Mag. and Annals, N.S. vol. ii. p, 401.—Enit. Third Series. Vol. 1, No. 1. July 1832. B : one 2 M. Rudberg on the Refraction of the differently-coloured mediately by the mean of the verniers of the alidade 50" centesimal, or nearly 16" sexagesimal. The instrument was arranged in the following manner. The limb being placed horizontally, the upper telescope attached to the alidade was taken away and placed upon one of the arms of a lever, the middle of which rested on the centre of the limb, and the other arm of which was loaded by a counter weight equal to the weight of the telescope. The whole was combined in such a manner that in turning the alidade, we turned the telescope, the object-glass of which described, in consequence, an arc of a circle round the centre of the instrument. To this centre was applied a rod of copper, forming a continuation of the axis. This rod carried a plate about four inches in diame- ter, above which there was fixed, by means of six screws, at the distance of some lines, another plate, which could by this means be made horizontal. In a hollow of this was a ring of copper, which carrying a plate of ground glass, and having its circumference toothed, turned by means of a screw, so that the prism which was always placed on the plate of glass hav- ing its edge in the centre, could be brought into such a posi- tion that the refracted ray had its deviation a minimum. The sun’s light was introduced into the dark chamber through a small opening by means of a heliostate at the di- stance of 33 feet from the centre of the repeating circle. The opening in the window-shutter formed by two plates, one of which was moveable by a screw, could be rendered more or less narrow. The limb remained immoveable during the observations. To be sure of this, the other telescope, which was on the lower surface of the limb, had its cross wires directed to an object which was situated on the other side of the Lake Malarn, at a distance of more than 2500 feet. In order to measure the refracting angle of the prism, the refracting edge being in the centre of the circle, the prism was turned in such a manner that there could be seen succes- sively, by means of the telescope, the two images of a mark which was reflected from the two faces whose intersection formed the edge of the prism. The mark was the bar of the window of a house on the opposite bank of the Lake Malarn, at the distance of more than 2500 feet. It is evident that by turning the point of intersection of the crossed wires respec- tively, upon each of the images of the mark reflected from the two faces, the angle which the telescope describes is exactly double that of the prism. With respect to the angle of deviation, the prism was turned in such a manner that the angle of deviation of the refracted Rays in Crystals with one and twoAxes of Double Refraction. 3 ray was at first the least possible, for example, to the left, and then the least to the right, so that the angle described by the telescope was always exactly the doubie of the angle of deviation. The black lines of which I measured the deviation were those marked B, C, D, E, F, G, H by Fraunhofer. I did not put the prism into the position of least deviation for each individual ray, but put it into this position for one. I measured the double deviation for this one and the others, leaving the prism immoveable, which renders the observation more easy and more accurate. The indices of refraction are easily calculated by this me- thod of operating. The angle which the incident ray makes with the anterior face of the prism being =90°—z, the angle of the refracted ray with the same face = 90°—z, the devia- tion = A, the angle of the prism = s, and the index of re- fraction = 2, we have — ; sin z = 7.sin sin (A+¢—2) =”.sin (e«—2). If the prism is at the minimum of deviation for a certain ray, we shall have for itz = $(A+«) and z=4¢e. Hence sn}A-+¢ fa sin ie For another ray whose deviation in the same situation of the prism is = A —2, and whose index of refraction is = n', we shall have sin 4(A+ 2) = 7! sinz sin (} (A + «)—8) = 7! sin (e—2’/). and making 2! = $e + & we obtain sin }(A+<¢—8).cos $$ =7!' sin he. cosé. cos$(A+<¢—6).sinié =n’ cos $e.sin & And consequently, tang ¢ = tang $8. tang t<.cot (A + «—8). Having calculated by this formula the value of the angle %, we obtain bs pan sn }(A + ¢) sin ($e + ) Secrion 1.—Refraction in Crystals with one Optical Axis. 1. Rock Crystal.—Two prisms of the crystal were cut in such a manner that the edge of the prism was parallel to the axis of crystallization, and consequently the two rays followed the law of simple refraction. The prism was put into such a po- pe? 4 M.Rudberg on the Refraction of the differently-coloured . sition that the line H in the extraordinary spectrum was re- duced to its minimum of deviation; and the other lines not only of this spectrum, but of the ordinary spectrum, ‘were all measured in the same position of the prism. ! As the two spectra always cover one another in part in rock crystal, I employed, in order to be able to observe each of them separately, a plate of tourmaline cut parallel to the axis. When put before the aperture of the eye-glass, it al- lowed only the light of the extraordinary spectrum to pass when its axis was parallel to the axis of crystallization; and when its axis was in a position perpendicular to this, it allowed only the ordinary light to pass. The angle of one of the prisms was 52°°940 or 47° 38! 46", and that of the other 50°372 or 45° 20! 5". These values are the means of several observations, which giving imme- diately the double angle do not differ more than 0°-005 in 16". The observations from which the following indices were cal- culated, were made at a temperature of -+ 18° centigrade. Extraordinary Spectrum. Ordinary Spectrum. Fixed — Prism Prism Prism Prism lines. No.1. No. 2. Diff. No. 1. No. 2. Diff. H 1-56769 1:56776 000007 ... 1.55814 1-55821 0-00007 G 1-56361 1-56369 0-00008 ... 1-55421 1-55429 0-00008 F 1-55892 1-55896 0-00004 ... 1:54960 1-54970 0-00010 EB 155629 1-55634 000005 ... 1:54709 1-54714 0-00005 D 1-55325 1-55531 o-00006 ... 1:54414 1-54423 0-00009 C 1-55083 1:55088 0-00005 ... 1:54179 1:54184- 0:00005 B 1-54987 1-54994 0-00007 . 1-54088 1-54093 0-00005 The differences are evidently only errors of observation. _ By taking the mean of the two results, we shall have the following indices, which can scarcely err 0°00005. Lines. Extr. Ray. Ord. Ray. 1°56772 1°55817 1°56365 1°55425 1°55894 1°54965 1°55631 1°54711 1°55328 1°54418 1°55085 1°54180 1°54990 1°54090 Malus had found for the extraordinary ray the index 1°55817, and for the ordinary ray 1°54843*, which being both situated between E and F, correspond as well as could be expected; as in his time the fixed points or lines in the spectrum were not known. WORE OH * Malus found these two numbers to be the two indices, but he consi- dered 1-54843 as the extraordinary index. It was M. Biot who discovered that the larger index was the extraordinary one.—Evir. Rays in Crystals with one and two Axes of Double Refraction. 5 With regard to the question of the dispersion of the two rays in rock crystal, we find by comparing the ordinary and the extraordinary indices for the different colours, that the double refraction is greater for the violet light, and less for the red light; or in general, that the double refraction is as much stronger, as the individual refrangibility of the ray itself is greater; for by calling n! the index of the ordinary ray, and n!' that of the extraordinary ray, we shall have the following ) nl! . values of ar for the different colours: 1:00613 1:00605 Dob Aa j=) o or © r= 2 hela! : : Whence it follows that the ratio ar Bes On increasing from the red to the violet extremity of the spectrum, and conse- quently that the difference of the velocities of the two rays increases for the different colours in the same direction. 2. Calcareous Spar.—F¥rom this crystal I caused to be cut two prisms having their edge parallel to the axis of crystalli- zation. I could use only one of them, the angle of which was 66°577, or 59° 55! 9", In the extraordinary spectrum it was the line H which was reduced to a minimum of deviation, and the prism remained in this position during the measurement of the other lines of the spectrum. In the ordinary spectrum, on the contrary, which had an extent three times greater, the violet light was very feeble, and the line H very wide; and I chose the line F, which was reduced to the least deviation. Since the prism remained in this position, it is evident that in the value of the index n/, we must make 8 negative for the two lines H and G, but positive for the lines E, D, C, and B. The mean indices are given in the following table. The temperature was + 17° centigrade, Ord. Ray. Extr. Ray. 1°68330 8 1°49780 167617 1°4.9453 1'66802 1°49075 1°66360 1°48868 165850 = 1°48635 165452 1°48455 165308 1°48391 dHabEHar 6 Sir D. Brewster’s Observations on M. Rudberg’s Memoir. The indices given by Malus are 1°6543 and 1:4833. Calling, as before, 7’ the index of the ordinary ray, and 7" that of the extraordinary ray, we have the following values of the ratio n! nl 1°12385 1°12154 111891 111750 1:11582 1°11440 1:11400 From which we see incontestably the increase of the double re- fraction with the individual refrangibility of the colour. hope sad [To be continued. ] Il. Observations on the preceding Memoir. By Sir Davin Brewster, K.H. LL.D. F.R.S. V.P.R.S. Ed. i is impossible to estimate too highly the value of the ob- servations contained in the preceding memoir. To the mineralogist, as well as to the optical philosopher, such obser- vations are fixed data of the highest utility. The only general conclusion, however, which M. Rudberg has drawn from his experiments in the first part of his me- moir, is, that the double refraction increases with the refrangi- bility of the coloured ray ; or, to express the same fact in other words, that the dispersion produced by the extraordinary refraction is greater in proportion to the mean refraction than that produced by the ordinary refraction,—or that doubly re- fracting crystals have two different dispersive powers. This discovery was made by myself so long ago as 1812, and an account of it published in my Treatise on New Phi- losophical Instruments, Edinb. 1813, p. 312-315: in the Philo- sophical Transactions, 1813, p. 107; and in the article Optics, in the Edinburgh Encyclopeedia, vol. xv. p. 544, The fol- lowing is the account of it, which I have published in the first of these works. . «‘ The most singular result, however, which is contained in the following table (‘Table of Dispersive Powers) relates to the dispersive powers of doubly refracting substances. ‘The first experiment which I made upon crystals, was to determine the dispersive power of Iceland spar; and from a cause merely accidental, I corrected the colour of the least refraction. ‘The result thus obtained was 0:026, considerably below water, Sir D. Brewster’s Observations on M. Rudberg’s Memoir. 7 which stands at 0°035 of the scale; and upon comparing it with the place assigned to Iceland crystal by Dr. Wollaston, I was surprised to find that he placed its dispersive power very considerably above water, and even above diamond. This unexpected difference between the two measures in- duced me to repeat the experiments, not only with other prisms of the Iceland spar, but also with other standard prisms of flint and crown glass. These new results served only to confirm the accuracy of the first experiment, and to strengthen my suspicion that Dr. Wollaston had committed a mistake. As this reasoning, however, was founded on the assumption which both Dr. Wollaston and I had made,—that the spar had only one dispersive power,—I resolved to mea- sure the dispersive power of the extraordinary refraction. This new value having turned out to be greater than that of water, I immediately saw that Dr. Wollaston had measured the colour of the greatest refraction, while I had measured the colour of the least; and that this remarkable mineral, which had so long perplexed philosophers by its double re- fraction, possessed the no less extraordinary and inexplicable property of two dispersive powers. In subjecting to exami- nation other crystals that afforded double images,—such as carbonate of strontites, carbonate of lead, and chromate of lead,—I found that every separate refraction possessed a se- parate dispersive power. ‘This general law, though not re- pugnant to any optical phenomena, is still of such a nature, that it could not have been inferred @ prior? from any rela- tion which is known to subsist between the refractive and dispersive powers. No person, indeed, has even conjectured that a double dispersive should accompany a double refractive power: and if we were to reason in this case from an analogy founded on experiment,—an analogy, too, which is by no means remote, we should certainly conclude, contrary to the fact, that the greatest refractive power would be accoihpanied with the least power of dispersion. In all the minerals in which a metal is the principal ingredient, those which have the greatest refractive density have also the greatest faculty of producing colour; while in all the precious stones a high re- fractive power is attended with a low power of dispersion. This remarkable property of a double dispersion, therefore, is contrary to the general results indicated by experiments; and though it appears to exclude some of the theories by which a double refraction has been explained, it certainly adds another to those numerous difficulties with which philosophy has yet to struggle, before she can reduce to a satisfactory 8 Sir D. Brewster’s Observations on M. Rudberg’s Memoir. generalization the anomalous and capricious pheenomena which light exhibits in its passage through transparent bodies.” — In comparing the results obtained by M. Rudberg with calcareous spar with those obtained by Malus, we have been struck with a discrepancy so great that we cannot find any explanation of it. Malus found the two indices for quartz to be 1°55817 and 1:54343. Now if we compare these numbers. with those of M. Rudberg, we shall find that they both correspond to a ray towards the extremity of the green space between. the lines E and F. Thus Extraor. Ray. Diff. Ordin. Ray. Diff. Rudberg... F 1°55894 77 1°54965 192 Malus...... 1°55817 jo¢ 1°54843 165 FE * 1°55631 1°54711 Hence Malus’s extraordinary index corresponds to a ray whose distance from F is 77; while his ordinary index cor- responds to a ray whose distance from F is 122. This dis- crepancy is not at all to be wondered at, and shows us how uncertain are all measures of refractive powers unless they are referred to the fixed lines in the spectrum. The case is widely different, however, with calcareous spar, as the following table shows. Ord. Index. _ Diff. Extr. Index. Diff. . Rudberg... C 1°65452 93 B 148391 61 Malus...... 165429 12] 1:48330 Rudberg... B 1°65308 Here the results of Malus and Rudberg are widely divergent. Malus used the middle green ray of the spectrum (7héorie de la Double Refraction, Deux. Parte, § 42), or that which is half way between E and F, and yet his mean ordinary index corresponds with one of the red rays in Rudberg’s observations! Assuming the same ray in both observations, the mean ordinary index will be as follows: Mean Ord. Index. Diff. Rudberg...... 1°66585 Malus.......-. 1°65429 1159 In the case of the extraordinary ray the discrepancy is still more surprising. Here the mean index of Malus corresponds to a ray distant 61 from B, and existing beyond the end of the visible spectrum formed by light of ordinary intensity. Assuming Mr. Drinkwater ox the Invention of the Telescope. 9 the same rey in both observations as the mean one, the mean extraordinary index will be as follows : " Mean Extr. Index. Diff. as Rudberg........see0e0s 1°48971 641 Malus.vin.iesc.Jbeues. 148330 Dr. Wollaston gives the two indices according to his mea- surements, as 1°657 and 1°488, which are nearer those of M. Rudberg; but as Dr. Young has assured us that the measures taken by Dr. Wollaston are appropriate to the extreme red rays, they throw no light upon the cause of the discrepancy under our consideration. ‘The discrepancies, indeed, become more alarming, and will stand thus, by calling B the ex- treme red ray, and calculating its index from Malus’s index for the middle green. Red Ray B. Ordinary. Extraordinary. Wollaston .... 1°65700 1:48800 Rudberg...... 165308 1°48391 Malus ......... 1°64152 1°47750 Hence it appears that Wollaston’s measures are greater than those of Rudberg, and still more remote from those of Malus. As it is impossible to suppose for a moment that either Malus or Rudberg could have committed errors of observa- tion capable of reconciling these results, we are forced to con- clude, that the experiments of each were made with crystals of calcareous spar which had different degrees of refractive power,—a conclusion which deprives us of the hope of ob- taining invariable physical data for different minerals. Such a result, indeed, might have been expected from the variety of specific gravities which different specimens of calcareous spar exhibit; and all that science can hope to accomplish on this subject, is to define the general limits within which these .Yariations are confined. = TIT. Observations respecting the Invention of the Telescope. By J. E. Drinkwater, Esg.* A VERY interesting article\on the invention of telescopes is printed in the second and third. Numbers of the Journal of the Royal Institution, in’ which it.is. clearly proved that John Lippershey, a spectacle-maker of Middleburg, possessed the invention on the 2nd of October, 1608: that Jacob Adri- .* Communicated by the Author:— In the first'series of Phil. Mag. vol. xviii. p- 245, and vol, xix. p. 66, will be found two, letters, with extracts from ‘old English books, from which the writer infers that the telescope was known in England long before the period of its reputed invention.—Epir. Third Series. Vol, 1. No. 1. July 1832. C 10 Mr. Drinkwater’s Observations respecting aansz (commonly called Metius) also possessed the-art of ma- king them on the 17th of the same month, and that he then professed to have been engaged in the experiments which led him to it during two years previously; and it is advanced as probable that Hans, or his son Zachary Jansen, invented a compound microscope about 1590. Dr. Moll, by whom this paper was communicated, has done me the honour to notice my sketch of the Life of Galileo, in which I had arrived nearly at the same results with respect to the claims of Lippershey and Jansen; although some of my statements were necessarily imperfect, from want of access to those official records, now for the first time produced from the Dutch archives. Dr. Moll has, however, thought fit to com- ment on some assertions of mine in terms which call for some reply on my part: this would have been attempted earlier, had I earlier seen the paper in question. Dr. Moll has also pointed out an error committed by me in calling both Peter Borel the author of the treatise De vero Telescopii Inventore, and William Boreel the ambassador, by the Italian name Borelli; and a similar error in translating the Latin name of Van den Hore, whom I have confounded with his contemporary Gartner, both using the same Latin signature Hortensius. For these, and I fear many other er- rors as well as omissions in that essay, I have little apology to offer, and feel nothing but obligation to those who may be at the pains to discover them. But I wish to defend myself (even when writing anonymously) from the charge which Dr. Moll insinuates, of affecting to quote from books which I know only by extracts. I protest against this practice as a dishonest one, by which stories often obtain currency and credit on the sup- position that they have been examined by several authors, who in fact have merely copied one from another. I consider it essential to the truth of history that the real authority should be cited whenever any is given. In the only instance in my own case where I was not writing either with the original au- thority before me, or an extract copied out of it with my own hand, I have given a double reference (p. 58.) to the author whose statement I repeated, and to the manuscript from which he professed to have drawn his account. It may perhaps be true that Borel’s book is scarce; but I found it in the British Museum, which is tolerably rich in scientific works of the six- teenth and seventeenth centuries; indeed the copy which I used there seems more perfect than the one alluded to in a note on Dr. Moll’s article, for it contains a portrait of Jansen as well as of Lippershey. Although my principal object in this communication is to the Invention of the Telescope. 11 vindicate the honesty of my reference, I cannot refrain from attempting also some answer to Dr. Moll’s challenge “to point out the passage in Borel’s book, in which either Boreel or John the optician exhibit the least intention of throwing Galileo’s discoveries into the shade.” The charge I made was against the author; I have no quarrel with the ambassador, unless so far as he might be concerned in getting up the book in question; and I have Dr. Moll’s own authority for stating that it was written “ probably at his request, and certainly with his assistance”. It is not indeed easy to convey the same im- pression by detached extracts, which is produced by the tone of the whole volume; but afew passages may be especially no- ticed. The eighth chapter contains the following remarks : ‘¢ Some contend that it (the telescope) was known to Bacon the Englishman: some to Baptista Porta, who seems to have said something on the subject, but obscurely.—But the opinion of the majority has been in favour of Drebbel, Galileo, and Me- tius; and they themselves do not blush to claim it, although it may be made clear to every one by public documents that they had recourse to an artist of Middleburg, or borrowed it from him in some way.” This charge is repeated with more parti- cularity against Galileo in the next chapter: ‘* Among this crowd of inventors first appears Galileo, who attributed the in- vention to himself, and to this hour has been puffed as the real inventor, and has exalted himself by his own praises, as ap- pears by his petition to the States of the Republic of Holland.” Borel chooses to disprove this supposed claim by quoting the Mercurio of Vittorio Siri, who relates how Galileo redisco- vered the instrument on hearing that such a thing had been done in Holland. A more candid writer wouid have re- ferred to one of Galileo’s own statements, such as that in the Saggiatore, where he mentions “1 Ollandese primo inventore del telescopio”, or he might have given precisely the same account which he has adopted from Siri, out of ,Galileo’s Nuncius Sydereus. He there says, “A rumour reached me about ten months ago, that a perspective had been worked by a Belgian, by help of which objects, though at a great distance from the eye of the observer, appear as distinctly as if near: and of this certainly admirable contrivance some experiments were noised about, which some believed, others denied. The same thing after a few days was confirmed to me in a letter from Paris by James Badovere, a French gentleman, which at length occasioned that I set myself intently to examine the reason of the thing, and to contrive the means of inventing a similar instrument, in which I soon succeeded by help of the theory of refractions,” &c. Borel had this passage before him; for he has incautiously printed it in another part of his C2 12 Mr. Drinkwater’s Observations respecting book, where he is discussing the subsequent progress of the invention; and it is not easy to imagine why it was suppressed in this place, except that: it would necessarily have interfered with his plan of mentioning: Galileo as one who shamelessly endeavoured to rob the first: inventor of the credit due to him. In his petition to the States, nothing whatever is said about the invention of the telescope. | This first instanceof Borel’s ‘un- fairness made me examine the rest of the book with more jea- lousy. In the twelfth chapter we are told’that: Zachary Jansen discovered the telescope in 1590, and “immediately applied himself to the discovery of stars and other novelties”:—* This new Deedalus saw more with one tube and a single eye than did Argus or Lynceus.” —“ In the moon too, he was the first to discover spots ; and afterwards Galileo following his example observed the same more accurately.” "These passages (in which the allusion to the society of Lincez, of which Galileo was a member, must not be overlooked,) seem to me to justify the first part of my. assertion, that Borel “endeavoured to secure for Jansen, and his son»the more solid reputation of having anticipated Galileo in the useful employment of the invention.” No one had heard of these pretended observations till Borel published his book in 1655, thirteen years after Galileo’s death; nor do they rest on any proof but Borel’s own declaration. There is indeed a communication from Jansen’s son John, with respect to his own discoveries, but it does not contain a syllable in support of his father’s. The substance of this com- munication is given in the fourteenth chapter, which Borel en- titles, ** The excellent evidence of the above-named inventors, by which the foregoing statements are supported.” Dr. Moll finds fault with me for calling this statement a letter from John, and in fact it appears that it is only compiled from such a letter. I was misled by Borel himself, who, in referring to it, invites his readers to “learn what John himself has communicated by his own letters, though there are no means of confirming his statement by other evidence.” In this occurs the following passage, amongst accounts of other discoveries which John positively claims as his own. ‘I have often observed) the planet Jupiter, which appears round and indistinctly spherical. Near him I have occasionally found two little stars, situated at or near the upper part; sometimes also three. But generally I have seen four; and as far as I have been able to observe, they circulate continually round Jupiter: but this I leave to astronomers.” This is the passage by which it seems to me that Borel intended to hint away (as {ar as he durst) Galileo’s claiin to the earliest discovery of Jupiter’s satellites; and itis remarkable that this. communication is given entirely without date, in a work which, being written to establish a chronolo- the Invention of the Telescope. 13 gical fact, is everywhere else very particular in that respect. It certainly is not, as Dr. Moll would have us believe, a mere optician’s report of the performance of his telescopes, but is “the excellent evidence”, by means of which the dis- coveries of John and. his father, ** redounding so much to the credit of themselves and their country”, were to be supported. What is the meaning of that remarkable expression, “ there are no means of confirming his statement by other evidence”? What was it that required additional proof? As Dr. Moll most truly observes, ‘Thousands, certainly hundreds, saw the satellites in 1655; and why should not John, like other people?” That which struck me as remarkable was not that John should have seen them whenever he wrote, or was supposed to write, that letter, but that in 1655 Borel should think worth while to insert amongst his ‘excellent evidence” a declaration that he had; accompanying it with the cautious remark, that he had no proof of it beyond John’s own assertion. ‘This observation acquires additional force from the correction, for which I am indebted to Dr. Moll, that John’s whole letter is not given; and therefore it is to be presumed that Borel extracted from it only that which he thought important. Surely the mere fact that Jupiter’s satellites were visible in his glasses did not merit that distinction in 1655: if they were not, his trade would scarcely have found hima livelihood. If he wanted to give a proof how much his glasses were capable of showing, it would have been more decisive of their excellence to declare whether or not he had ever seen Saturn’s satellite, then recently discovered by Huyghens, of which discovery Borel gives an account in this same book. Even in mentioning the satellites, he would have said simply, ‘1 have seen Jupiter’s satellites”, and would not have given all the particulars of seeing sometimes four, some- times two, or three, &c., unless he was speaking, or wished to be understood as speaking, of something of which he had never before heard. Mr. Dollend or Mr. Tully (if I may be allowed to borrow Dr. Moll’s own illustration), should they be asked at the present day for an account of their best glasses, would scarcely think of stating that there is something like a ring round Saturn; and that, so far as they can judge, it appears to revolve about the planet: nor, if they should communicate such information to Dr. Moll, would it occur to him to quote it as “¢excellent evidence” of the discoveries of these gentle- men. It was not more to the purpose in 1655 to print John’s remark, that, so far as he could tell, there were four satellites which appeared to circulate round Jupiter: since the fact that they did so had been indisputably established more than forty years, their periods had been calculated, and their future ap- pearances predicted ;—unless indeed there was a concealed in- tention of suggesting the idea at some future period, that John 14 Mr. Drinkwater’s Observations respecting had observed these stars independently of Galileo, and if in- dependently, perhaps anteriorly. If it be thought that I have put a meaning on this passage which it was not intended to bear, some excuse may still be found in the fact, that whether or not Borel intended to lay the foundation of a future claim, this end, which as I contend he had in view, has actually been attained. In the Encyclopedia Britannica, under the article ‘Optics,’ the following remark occurs, after the substance of Borel’s account has been stated: ‘ This, it is probable, was the first observation of Jupiter's satel- lites, though the person who made it was not aware of the im- portance of his discovery.” In Dr. Young’s Lectures on Natu- ral Philosophy, the same idea has resulted from the perusal of this passage. Dr. Young says: ‘ The first person, who is cer- tainly known to have made a telescope, is Jansen, aDutchman; —and one of his family discovered a satellite of Jupiter with them. Galileo had heard of the instrument, but had not been informed of the particulars of its construction: he reinvented it in 1609, and the following year rediscovered also the satellite which Jan- sen had seen a little before.’ It cannot therefore be doubted that owing to the manner in which Borel has introduced this account, John, the son of Zachary Jansen, has had the credit of the discovery given to him: it cannot be denied that Borel has claimed for Jansen himself the credit of first using the te- lescope for celestial observations without producing any proof of his assertion, and that he has spoken of Galileo in unbeco- ming terms, and has represented him, contrary to truth, and in the face of his own declaration, as denying the source whence he derived his first knowledge of the instrument. Finding the error which I have just mentioned in works of such reputation, and thinking myself also that Borel’s account was artfully prepared with a view to produce that very misconception, I thought worth while to observe that John was only six years old in 1609, when the satellites were discovered by Galileo, and that therefore his claim must be put out of consideration. As to the question of Borel’s intentions, on which my opinion remains unaltered, I am not so anxious to bring others to agree with me, as to show that I did not venture a random contradiction of a previous statement, without examination of the point on which I pretended to give an opinion. I have one remark only to make on another question con= nected with this subject : Dr. Moll is unwilling to believe that in 1637 the Dutch were inferior to the Italian telescopes, as I asserted on the authority of Hortensius, who wrote to Gali- leo that none could be procured in Holland sufficiently good to show Jupiter’s disc well defined, and of Gassendi, who wrote to him that he could not procure a good one in Venice, Paris, or Amsterdam. Dr. Moll does not notice Gassendi’s the Invention of the Telescope. 15 remark, but says that “‘ Hortensius wanted more than could be accomplished in his time; and even now telescopes of a certain size, which show Jupiter’s disc well defined, are not of every day’s occurrence.” ‘The term ‘well defined’ will of course bear different meanings in different stages of the art: and it is pro- bable that Dr. Moll would be dissatisfied with the performance of a glass, with which Huyghens would have been enraptured. Such expressions are necessarily comparative, and we can only attach a ‘well defined’ meaning to them by comparing contem- porary statements. The letter of Hortensius to which I alluded contains the following passage (Opere di Gal. tom. ii. p. 466. Ed. Pad.): “ De telescopio agere czepimus, comperimusque nulla in Batavia hodie que tantam preecisionem polliceri que- ant, quanta ad eas observationes requiritur. Solent enim etiam optimi discum Jovis hirsutum offerre et male terminatum, unde Joviales in ejus vicinia non recte conspiciuntur.— Omnes arti- fices rudes experimur, et Dioptricae quam maximé ignaros.” Galileo answered in the folllowing terms (p. 474): * Quanto al secondo punto che é del trovarsi Telescopij di maggior effi- cacia di quelli che si fabbricano costi; mi pare d’ aver scritto altra volta la facolta di quello che ho adoprato io esser tale, che mostra primieramente il disco di Giove non irsuto ma ter- minatissimo, non meno che T occhio libero scorga il lembo della Luna, e cosi terminati mostra ancora i Satelliti di quello.” And in a subsequent letter to Deodati he says again (p. 472): ‘Mi vengono ancor domandati dell’ istesso Sig. Ortensio i vetri per un Telescopio, i quali sieno di perfezione tale che mostrino ben terminato il disco di Giove, e chiaramente apparenti i quattro suoi Satelliti, effetto che, come egli scrive non se ha da quelli, che si fabbricano in Olanda: se me succedera pronta~ mente il farne provisione, gli inviero a V. S. molt. Ill. insieme colle presente.” C. Huyghens had made the same complaint of the inferiority of the Dutch glasses (p. 490): ‘ Del resto i Telescopi che si fanno in queste parti non assicurandoci i quat- tro Satelliti di Giove, de’ quali si tratta se non con cérte scin- tillazioni le quale potrebbero impedire I osservazione subite,” &c. There is not even the pretext left that Galileo might entertain a better opinion of his glasses than others would have done; for although Gassendi was dissatisfied with the best glass he could get in Amsterdam, yet on receiving Galileo’s present, he wrote (Venturi, vol. ii. p.21): ‘‘ Hazmio illo telescopio quo me beare dignatus es, effigiari lunam procuro suis linea- mentis et coloribus.” These extracts show that Dr. Moll has been rather too hasty in advancing that ‘the assertion of the inferiority of the Dutch telescopes is wholly unsupported by proof.” There are a few other trifling oversights in his valu- able communication, which I forbear to notice, fearing lest my 16On the Encouragement given toScience by the King of Denmark. motive in doing so should be misunderstood: nor can I con- clude without expressing the great pleasure I have derived from the perusal of his paper, which has finally settled the question of the original discovery, and thrown much light on the early history of this wonderful instrument. - Athenzeum, April 24, 1832. J. E. Drinkwater. IV. On the Encouragement given to Science by the King of Denmark. N various articles published in England relative to the de- cline of science, and the encouragement which is given to it by the Sovereigns of foreign countries, no notice has been taken of the King of Denmark, who has displayed an_ardour and a liberality in the cause of science, in which he has not been surpassed, if he has been equalled, by any other prince.* It is not our design at present to give any account of the scientific establishments which he so liberally supports in his own dominions, of his munificence to the men of science that adorn his reign, or of the honours which he has so judiciously conferred upon them. We propose to limit this notice to the instances of his liberality in rewarding and honouring the distinguished philosophers of other nations,—a species of patronage of the noblest and most disinterested description, and one of which there have been very few examples in the hi- story of Europe. We trust that the example of Frederick VL. will be imitated by other Sovereigns; and that those who pro- mote the common interests of their species by useful inventions and discoveries, will receive some acknowledgement of their services from every nation to which they have been beneficial. The King of Denmark presented the late General Mudge, the Superintendant of the Ordnance Survey; General Muf- fling, the Director of the Topographical Survey of Prussia; Admiral Krusenstern, the celebrated Russian circumnaviga- tor; Baron Alexander Humboldt; Baron Lindenau, &e. with gold chronometers, executed by the celebrated Danish artists Jurgensen and Keffels. These noble and appropriate gifts bore the simple inscription of “ Frederick the Sixth to Bern- hard v. Lindenau;” &c. The King also presented to General Fallon, the Director of the Austrian Survey, a superb pendu- lum clock by Jurgensen; and he sent to our own distin- guished countryman, Mr. Troughton, his gold medal, with the inscription ‘ Merito.” In order to evince his high regard for foreign merit, the King of Denmark conferred the order of Dannebroga on Reichen- * An account of the prize-medal for the discovery of a new telescopic comet, offered by the King of Denmark, will be found in Phil, Mag. and Annals, yol. xi. p. 156. Mr. P. Barlow’s Additional Experiments on Acacia. 17 bach, Fraunhofer, Gauss, Arago, QOlbers, Bessel, Encke, Struve, &c. The same order was intended for General Mudge, but it was signified to the Danish ambassador in London, that no English officer is permitted to accept of a foreign order, unless he has been employed in the military sérvice of the state which offers it, and unless the order is given as a .remu- neration for his military services. This declaration prevented the King of Denmark from offering the same order, as he in- tended to do, to some of the most distinguished English phi- losophers. We are not acquainted with the military regula- tions here referred to; but we can assure our eminent cor- respondent from whom we have received these facts, that there is no power in England that can prevent a British sub- ject from accepting of any honour that may be conferred upon him by a foreign prince. V. Additional Experiments on the Strength and Stiffness of Acacia. By Mr. Peter Bartow, Jun. As. Inst. Civ. Eng. To the Editors of the Philosophical Magazine and Journal. Gentlemen, I N my paper on the strength of different woods, printed in the Phil. Mag. & Annals for March last, I stated my regret that the results on the acacia specimens were not more satisfactory ; and Mr. Bevan, in his remarks on those experiments, (Phil. Mag. and Annals for April,) having expressed the same feel- ing, I endeavoured to find the actual specimen alluded to in my former paper, in which the rope broke, leaving the piece uninjured, in order to repeat the experiment in a more com- plete manner; but I could only find a small fragment of the tree from which the former was cut. It was nearer the out- side, although of the same specific gravity, viz. °710. ‘The largest piece I could cut from the fragment was 27 inches long and 14 inch square; it was supported at 25 inches, ‘The deflection was taken very accurately, and found to amount to ‘075‘of an inch as each of the first four cwt. were applied: here the elasticity appeared to be injured, as the deflection increased to *125, and continued to do so until the piece broke with 896 pounds. ) According to this result the value of S in my table wiil be atk ~ 4ad? number for this wood, exceeds the average run of oak. Its elasticity will be (taking w = 448 and @ = *3 of an inch) Third Series. Vol. 1. No. 1. July 1832. = 1659, which although less than the tabulated 1S Lxperiments on the Strength and Stiffness of Acacia. 3 ‘ E= Aiea = 4609000, still exceeding the oak. If we adopt the modulus of elasticity according to Mr. Bevan, viz. by ex- pressing the deflecting weight by the length H of a column of wood of the same section and specific gravity as the spe- ~ 3 eimen experimented upon, we have m = pin = 3738426, which is less than Mr. Bevan’s number deduced from his ex- periments on acacia. This, however, was evidently an inferior specimen compared with those employed in the former expe- riments, being so near the outside as to take in some part of the sap-wood. Mr. Bevan expresses a wish that I had given the modulus of elasticity instead of the value of E, and observes, “ had this been done it would have appeared that the stiffness of Memel Fir, compared with its weight, is greater than for the other woods.” I do not, however, with every respect for the well known talents of Mr. Bevan, see what advantage is gained by considering the weight of the timber, except in the parti- cular case where the question is the deflection of a beam from its own weight; a case which very rarely occurs in the con- struction of buildings. To give an example of what is stated above, the value of , or the elasticity of Tonquin Bean, is one and a half time greater than that of Memel Deal; that is to say, it required one and a half time the weight to produce the same deflec- tion, and is accordingly expressed in my table by a number bearing the same proportion; but the modulus is less when we use Mr. Bevan’s formula. It will however be observed, that the two formule are esta- blished on the same principles; viz. that the deflection varies in the ratio of the cube of the length divided by the breadth into the cube of the depth; so that in all cases Mr. Bevan’s number may be obtained from mine, by multiplying by 576, and dividing by the specific gravity. It is necessary here to mention, that an error in the for- mula in my former paper may possibly have misled Mr, 3 Bevan. Inthe head of the sixth column, instead of E= ot, Pw it ought to have been E = ada: the numbers, however, are perfectly correct. Some other queries of Mr. Bevan, I am sorry I cannot re- ply to. The price per cubic foot of the different woods I have Sir D. Brewster on a new Species of Coloured Fringes. 19 no means of obtaining, nor can I state the ultimate deflections; they were not considered of importance, and consequently not registered. With respect to the time, each experiment occu- pied fifteen or twenty minutes. VI. On a new Species of Coloured Fringes, produced by Re- _ flection between the Lenses of Achromatic or Compound Ob- Ject-Glasses. By Sir Davin Brewsyer, K.H. LL.D. ERS. VPRS. Ed.* [With a Plate.] j\ a paper which I communicated to this Society in 1815, and which was published in the seventh volume of their Transactions, I described a new species of coloured fringes, produced between two plates of parallel glass. From a con- sideration of the theory of this class of phznomena, it was ob- vious that analogous, though much more complicated, systems of rings should be produced between plates with curved sur- faces, but it was not till 1822 that I succeeded in detecting them; and so completely are these rings concealed by the superposition of similarly situated images, that, in consequence of having forgotten my method of observation, I have expe- rienced the greatest difficulty in rediscovering them. My earliest experiments were performed with a double achromatic object-glass, made by Berge, having a diameter of 2% inches, and 30 inches in focal length. The inner surfaces of the crown and flint glass lenses were ground to different radii, as shown in the section of it at AB, CD, Plate I. F ig. 53 and the outer surface of the flint-glass lens was concave, so that there was left between the lenses a meniscus of air A2 B 3 A. In order to observe the system of rings as nearly as possible at a perpendicular incidence, I placed the smallest flame I could procure at S, about four or five inches distant from the object-glass AD, and interposing a small screen G between the flame and the eye at E, I held the eye as close to 'S as possible, and varied the distance of the object-glass till the inverted greenish-coloured flame + reflected interiorly from the concave surface A 1 B seemed to cover the whole area of the object-glass. When this is accomplished, the rings may, by a slight change in the position of the object-glass, or by screen- ing the image formed by one reflection from A 1 B, be di- stinctly seen over the expanded but enfeebled image formed by a second reflection from the same surface. * From the Transactions of the Royal Society of Edinburgh, vol, xii. - + This flame has a greenish colour, in consequence of the rays which form it having passed through twice the thickness of the crown glass lens A B. D2 “ 20 Sir D. Brewster on a new, Species of Coloured Fringes, When the flame is very small, and the eye sees it projected against the centre of the object-glass, the rings are grouped into. a concentric system, as shown in Fig. 1, approaching closer and closer to each other as they advance from the centre. to the circumference of the lens. Two of these rings, mmmm, nnnn, haying an intermediate position in the system, are di- stinguished trom the rest by their darkness, and by the white- ness of the light between them; and they enjoy the remarkable property of becoming the bounding lines of fowr systems of fringes, into which the general system is subdivided by oblique reflection. In order to observe this interesting change, incline the object-glass so that the point A is further from the eye than B, and so that the eye receives the rays that are reflected ob- liquely from every point of the surface A 1B. At a very slight deviation from a perpendicular incidence, the rings will become smaller and closer on the side A, and broader and wider on the side B, having intermediate breadths and di- stances at intermediate points of the circumference between A. and B. By increasing the incidence, the inner ring aa, Fig. 1, contracts into a sort of irregular crescent aa, Fig. 2. The second and third rings, bd, cc, Fig. 2, do the same as shown at bd, cc, Fig. 2, and at a greater incidence, the dark ring 1”, Fig. 1, assumes a similar form nxn, Fig. 2, and forms the boundary of the remote central system ncbaaben. In like manner, the lower part of the ring 7”, Fig. 1, has inclosed a smaller but similar system of rings, which are shown at 1! 2/n!n!, and may be called the near central system. While these changes are going on, the rings without , Fig. 1, are under- going analogous, though opposite, inflections. The outermost ddd, Fig. 1, divides itself into two unequal portions, which run out into the circumference at the points dd d’ d’, Fig. 2. Then the next ring, viz. the dark one, m mm m, forming the boundary of the remote external system mmm, A, and of the near central system m! m' m' B. The four groups of rings thus developed, assume, at greater incidences, the character shown in Fig. 3, but they are not seen all at once; and in tracing their form, it is necessary to cause the image on which they are produced, to be reflected successively from different parts of the lens. The rings are so closely packed together at a distance from the centres 2, x, to which they are all related, that it is extremely difficult to perceive them. By increasing the incidence still further, the rings close in upon the centres 2, , and become exceedingly close and numerous. The points z,z approach to the circum- ference of the lens, and the rings become more |uminous from seen in Achromatic Object-Glasses. 21 the increase in the reflected light, at increased obliquities of incidence. In some object-glasses the rings are exceedingly numerous and close, whether seen as in Fig. 1, or as in ‘Fig. 3; and when this is the case, the black rings m,n, and the centres 2,2, are near the circumference. In other object-glasses, particu- larly in a large one of Tulley’s, in the Calton Hill Observa- tory, the rings are very few in number, and the dark fringes m,n, and the centres x,z, are advanced considerably from the circumference towards the centre of the lens. In this case the rings are more easily seen, and they undergo very beautiful modifications in passing from a perpendicular to an oblique incidence. There can be little doubt that this variation in the size and number of the rings depends on the thickness of the meniscus of air between the lenses; but in order to put this to the test of experiment I separated the two lenses AB, CD, Fig. 5, and I found the rings to increase in number, and diminish in breadth, in proportion to the distance of the two lenses. Hence it follows, that, in all those object-glasses where the inner sur- faces are coincident, or are cemented by mastic or other var- nishes, no rings will be produced,—and that the number of the rings furnish us with a measure of the difference of cur- vature of the inner surfaces of the combined lenses. In some of the oblique systems of rings which I have ob- served, the outer fringe ” of one of the central systems ap- proached so near the outer fringe m of one of the external systems, that the space between them was straw-yellow, in place of white; and in one case, the four bounding fringes united, and formed a black cross, as shown in Fig. 4. In a large double object-glass, made by Gilbert, 3°8 inches in diameter, and in a similar one by Dollond, 2°75 inches in diameter, the rings could only be seen by looking through the convex side A 1 B, Fig. 5. In the first of these lenses there were only two fringes in the near central system’of rings, so that the inner surfaces must have been nearly coincident. If we separate the lenses a little at A, Fig. 1. and Fig. 5, the system of rings approaches the edge B, and become more numerous and more close to each other. ‘The other systems close, and become concentric to them, and the whole become an elliptical system. When the lenses are separated a little at B, Fig. 1. and Vig. 5, the system enlarges, and the rings grow more nume- rous, the other systems becoming concentric with them, and forming a close system. In a triple object-glass, which gave a system of rings similar 22 Sir D. Brewster ona new Species of Coloured Fringes. to that in Fig. 3, I observed them to. be crossed with another system of minute fringes parallel to one another, and to the line joining the centres z and 2 The object-glass which ex- hibited this curious effect is not now within my reach, so that I am unable to give any further account of this new system. In order to determine the surfaces of the double object- glass, AD, Fig. 5, which are essential to the production of the rings, I covered the convex surface A 1 B with oil of nearly the same refractive power as glass, and the rings wholly dis- appeared. Having removed the oil, I filled with the same fluid the space or hollow meniscus between the lenses, when the rings again disappeared. ‘The lenses being again cleaned, I removed CD, and could no longer observe any fringes. Hence, it follows, that the action of the two surfaces of the convex lens, and the inner surface of the concave one, are necessary to the production of the fringes. From these facts it will appear that the coloured rings arise from the interference of two pencils of light, one of which has suffered three reflections within the convex lens AB, and has passed four times through its thickness, with another pencil which has suffered ¢wo reflections within the convex lens, and one reflection from the inner surface of the concave lens, and has passed four times through the thickness of the convex lens, and twice through the thickness of the meniscus of air. When the light is incident perpendicularly on the centre of the lens, the interval of retardation, or the difference between the lengths of the paths of the two rays, is equai to twice the greatest thickness of the meniscus of air. Hence, if this thick- ness is very small, the tints corresponding to it will be dis- tinctly observed; but if the thickness is considerable, as it often is, the tints will belong to such high orders, that they will only be seen when a small flame of homogeneous light is used. As the incident ray advances from the centre towards the circumference, the meniscus of air diminishes in thickness, and also the interval of retardation, so that the orders of the rings descend, as in Fig. 1. But there is a particular point between the rings m and , where the interval of retardation is nothing, or where the lengths of the paths of the two inter- fering pencils are equal, so that we have a white ring at that place. Beyond this, the interval of retardation becomes per- ceptible, and another system of rings commences, rising to their highest order at the very circumference of the object- glass. When the eye and the flame are in the axis of the object- glass, the isochromatic lines are circles; but at oblique inci- Mr. Blackwall’s Remarks onthe Diving of Aquatic Birds. 23 dences they have the singular forms shown in Figs. 2. and 3, the line where there is no interval of retardation being the boundary of the four different systems of fringes shown in these figures. As the paths of the interfering pencils are performed in three media, crown-glass, flint-glass, and air, and as their lengths vary very quickly and irregularly, as the angle of incidence varies, and as the point of incidence changes its position, the analytical expression of the interval of retardation will be very complex. VIL.) Remarks on the Diving of Aquatic Birds. By Joun Buackwat1, Esq. F.L.S. §c.* D*: DRUMMOND of Belfast, in his interesting ‘* Letters to a Young Naturalist,” p. 201-202, has the following passage on the diving of water-fowl. ‘* Does a cormorant, or a duck, or a grebe, move more rapidly under the surface of water than on it? In several parts of Montagu’s Ornitholo- gical Dictionary, and the still more valuable Supplement to it, you will find illustrations on this point, showing that the same power will cause a much more rapid motion in diving than in swimming; and the cause is this:—When a bird moves in water, or upon it, there is a movement upwards as well as forward; but in swimming, the momentum upwards is lost, and the bird derives benefit only from the forward im- pulse. But in diving, the pressure of the water above pre- vents the ascending movement, and consequently the impetus is not lost, as if the bird were on the surface, and therefore the propelling power is greater; and the bird moves faster, because, in diving, the whole moving power is effective; whereas in swimming, a part of it is lost, and the progress is proportionally lessened.” Many years since, when perusing for the first time the ob- servations on the diving of aquatic birds contained in the In- troduction to the Ornithological Dictionary, p. xxxix.—xl., the insufficiency of Montagu’s attempt to solve this problem was perceived, and I was induced to make a few comments on the subject in my zoological note-book: it is probable, however, that they never would have filled a more conspicuous situa- tion than that which they have so long occupied in its pages, had not my attention been again directed to them by Dr. Drummond’s recent introduction of Montagu’s hypothesis in a work professedly written for the instruction of young persons * Communicated by the Author. 24 Mr. Blackwall’s Remarks on the Diving of Aquatic Birds. who are commencing the study of natural history. Scrupulous accuracy must always be regarded as an object of primary importance in a publication of this description, and I feel con- fident that Dr. Drummond has too much candour and good sense to be offended with the correction of an error into which he has been inadvertently led by the hasty adoption of a doc- trine which is directly opposed to the established principles of dynamics. It is asserted by the advocates of this doctrine, that the action of the legs in diving not only gives to birds a progressive motion, but also a tendency to rise, which tendency being overcome by the pressure of the water above them, the entire moving force is directed in the line of the body, accelerating thereby the velocity with which they pursue their subaqueous course. Now it is a law of hydrostatics, that the pressure of fluids in a state of equilibrium is equal in all directions at the same depth ; whatever obstacle, therefore, the circumstance of pres- sure may present to the ascent of a bird when diving, it must also present, ceteris paribus, to its progressive motion. More- over, it is manifest from the exceeding facility with which the particles of water move among one another, that if any ten- dency upward did result from the action of the limbs of water- fowl in diving, it could not be wholly counteracted by the pressure of the mass of fluid above them; indeed, the specific gravity of such birds being less than that of water, it would not be possible for them to continue beneath its surface, even for a much shorter period than they are known to do, without the employment of physical force to effect their purpose ; hence the fallacy of the argument, that the propelling power is increased on such occasions by the pressure of the super- incumbent water, is rendered sufticiently obvious. It remains to consider what means are actually made use of by birds in diving to overcome the resistance of the medium in which they move, and the tendency upward arising from their small specific gravity; and as Mr. White has illustrated this subject in his usual felicitous manner, in treating upon the Northern Diver, (Colymbus glacialis,) Linn., in the second volume of the octavo edition of his Works in Natural History, p- 184-186, I cannot do better than avail myself of his obser- vations. “Every part and proportion of this bird” (the Northern Diver) “is so incomparably adapted to its mode of life, that in no instance do we see the wisdom of God in the creation to more advantage. The head is sharp, and smaller than the part of the neck adjoining, in order that it may pierce the Mr. Blackwall’s Remarks.on the Diving of Aquatic Birds. 25 water; the wings are placed forward and out of the centre of gravity for a purpose which shall be noticed hereafter; the thighs quite at the podex, in order to facilitate diving ; and the legs are flat, and as sharp backwards almost as the edge of a knife, that in striking they may easily cut the water ; while the feet are palmated, and bread for swimming, yet so folded up when advanced forward to take a fresh stroke, as to be full as narrow as the shank. The two exterior toes of the feet are longest; the nails flat and broad, resembling the human, which give strength and increase the power of swim- ming. The foot, when expanded, is not at right angles to the leg or body of the bird; but the exterior part inclining towards the head forms an acute angle with the body; the in- tention being not to give motion in the line of the legs them- selves, but by the combined impulse of both in an interme-. diate line, the line of the body. ** Most people know, that have observed at all, that the swim- ming of birds is nothing more than a walking in the water, where one foot succeeds the other as on the land; yet no one, as far as I am aware, has remarked that diving fowls, while under water, impel and row themselves forward by a motion of their wings, as well as by the impulse of their feet; but such is really the case, as any person may easily be convinced, who will observe ducks when hunted by dogs in a clear pond. Nor do I know that any one has given a reason why the wings of diving fowls are placed so forward: doubtless, not for the purpose of promoting their speed in flying, since that position: certainly impedes it; but probably for the increase of their’ motion under water, by the use of four oars, instead of two; yet were the wings and feet nearer together, as in land-birds, they would, when in action, rather hinder than assist one an- other.” Mr. White’s description of the manner in which the Northern Diver impels itself through the water by the agency of the legs, which have an extent of motion enabling it to“alter its course in any direction whatever with astonishing facility, is applicable to diving-birds in general; but it does not appear that the wings are so uniformly employed to promote their progress when submerged, as the statement of the natural historian of Selborne would seem to imply. I may remark, in conclusion, that the action of the legs in diving, so far from giving birds an impulse upward and for- ward, as Montagu. has affirmed, evidently tends rather to propel them downward and forward, except when they pur- pose to ascend, and then a change of action, adapted to the accomplishment of the object to be attained, is instantly re- Third Series. Vol. 1, No. 1. July 1832. E 26 Addition to the Analytical Investigation sorted to The simultaneous action of the legs also, directing the impelling power in the line of the body, will explain why the velocity with which aquatic birds move in so dense a fluid as water is greater than that with which they move on its sur- face, where the legs are usually employed alternately, and the moving force cannot be so advantageously applied; and that the velocity is frequently accelerated still further by the in- strumentality of the wings, has been already noticed. Thus, in controverting the erroneous opinions of Montagu relative to the diving of water-fowl, I have endeavoured to substitute for them a satisfactory theory of this remarkable phznomenon. Crumpsall Hall, April 18th, 1832. VIII. Addition to the Analytical Investigation of a Formula for _ the Relative Importance of the Boroughs ; (contained in the March Number of the Phil. Mag. and Annals). And Reply to Dr. M‘Intyre’s Remarks. By the Author of that Investi- gation*. Y referring to the above-mentioned investigation, it will be found that putting H. for the whole houses in all the boroughs; T the whole sum paid in assessed taxes ; B the numerical value of their united relative importance ; Also, putting /, ¢, b for the same of any one of the boroughs; —the relative importance of a borough may be expressed by —_ B { ! H aR eevee eeee (1) b i + 2 . eee in which B may be any number whatever, and m! and 7m! are numbers which serve to adapt the formulae to some hypothesis concerning the relation which House-importance bears to Tax-importance. Such as have taken an interest in the question will recollect that two rules for estimating the importance of a borough were proposed: one was that of LieutenantDrummond, which was adopted by the Governmentin framing the Reform Bill; and another, that proposed by Mr. Pollock in the House of Commons, in opposition to Mr. Drummond’s: this was, in fact, the same in its operation as one proposed by Dr. M‘In- tyre, in December of last year, to Lord Melbourne. The propounders of these rules all asserted that they were founded on just mathematical principles: it might therefore be a ques- * Communicated by the Author. of a Formula for the relative Importance of the Boroughs. 27 tion, whether there could be more than one formula deduci- ble from the data? which were the houses and taxes of the boroughs. The writer of this article had satisfied himself as well as others, by the dictates of common sense, that Lieutenant Drum- mond’s rule was correct. He, however, judged that it might be proper to discuss the subject upon mathematical principles that should be beyond dispute, and he chose the very simple axiom, “ That if a town contain as many houses as are in any number of boroughs, and pay as much in taxes as they all pay, its importance will be equal to the united importance of all these boroughs.” From this he formed a functional equa- tion, and employing the Differential Calculus (not the Calculus of Variations, as Dr. M‘Intyre supposes)*, he determined the form of the function, and proved beyond dispute that it could have but one form, which is that of formula (1) of this article. Lieutenant Drummond has not explained the views by which he was led to his practical rules, given in the parliamentary paper (see page 219 of the Phil. Mag. and Annals for March). It is easy to see, however, that by making m! = n' in the gene- ral formula (1), so that it becomes al h ban BS + ap ; we have immediately Mr. Drummond’s rule. It is true the constant factor m! here put down, was left out in the former communication, because it did not in the least affect the posi- tion of the boroughs in the scale of comparative importance, and the number B was supposed to be 1000000, to avoid fractions in the results: but it was not expected that any one would lay hold of so trivial a matter, in order to attempt to show that Lieutenant Drummond’s rule really involved the absurdity that two is equal to one. It appears, however, that the candour of his opponents was overrated: the objection of Dr. M‘Intyre is a fair specimen of it. ‘The Doctgr stands exposed to some sharp remarks: but at present this purely scientific speculation shall not be contaminated with any thing personal. We shall now proceed to show, by carrying the analysis a step further, that the Doctor’s objection does not apply to the general formula h £ = fp atN (aa b=B{m u +7 T \. Since this must hold true whatever be the magnitude of a * Dr. M‘Intyre’s paper will be found in Phil. Mag. and Annals, vol. xi. p. 360,—Eprvr. E2 28 Reply to Dr. M‘Intyre’s Remarks on borough, let us suppose A = H and ¢ = T; then we ought to have 6 = B, and therefore B=B {ni 5 + naa Hence it appears that m!+n' = 1: This condition will be satisfied if we make eon ae n m! = | — Sm Waites m+n m+n Our general formula now becomes B aie t b= hn 4m Bey +n a eocececsoces (2) Where, as before, m and 7 are conventional numbers, which are to satisfy the hypothesis of some supposed relation between the house- and tax-importance: if these are to have equal weight, then m = n, and the formula becomes 5? ator vob nital TARE (3) Dr. M‘Intyre may now try his criterion of absurdity on either of the formule (2) (3); namely, the supposition that ‘B= 644, H = h+A' and T = ¢+¢; and he will find that they both stand the test. But in his remarks, he has also re- quired that our formula should at the same time satisfy the two conditions aia AB h ‘et TERY Lee? Lovieet Mee y H aps a ~ m+n h Pagt Let us suppose, if possible, that they satisfy these condi- tions; and, taking the product of the two equations, and leaving out common factors, &c. we obtain 2 9 2 h At H t x! (m+n)? = m+ n°+mn (Sebe= aa and hence again, [slags Pay Bie th "peta. BTR ‘and 24 = (+) + (ar)*s the Analytical Investigation of a Formula, &c. 29 h t and = _ a)? =O; h t and at last 5 5 Sikes Wea) Now, if 2 and ¢ be the houses and taxes of the medium borough, the condition will be exactly satisfied ; and it is cer- tain that 4! and z’ being the houses and taxes of any one of the boroughs, we have nearly i e z = pa Je eeenecesececcscccceeceeses coccceecseee(P) Therefore, compounding the ratios «, 8, we have in all the boroughs h' a A =|, nearly. Thus it appears that our general formula satisfies all the conditions which our most strenuous opponent has required, as far as the thing is possible. It has been admitted that a more powerful instrument of analysis was employed in the investigation than was absolutely necessary, (see p. 223 of the Number for March), Neither the learned Doctor, nor the men of Trinity, have however com- plained of this. But the very same conclusions may be ob- tained by the ordinary algebraic analysis, from the simple common-sense principle, that “the importance of a borough may be truly expressed by giving a certain numeral import- ance to each house, and a certain numeral importance to each pound, paid in taxes;” just as we would estimate the share of political influence due to the possessor of an estate from his annual income, found by adding into one sum his rents derived from land of different qualities,—say arable and pasture. Pro- ceeding on this principle: Let x denote the numeral importance of a house, y that of one pound paid in taxes. . Then, B, H, T, 2, 4, ¢ denoting the same as before, we have at = 4). b=wht+yt=aax(h + = ti B=2H+yT=2(H+4 7); In the second equation, x H and y T express the whole rela- tive importance of the two elements, houses and taxes. We may make any hypothesis we please concerning the power of each separately to raise the importance of the borough. Let us suppose that their powers are to each other as a given num- 30 On a Formula for the Relative Importance of the Boroughs. ber m toa given number 7; that is, let cH:yT::m:n3; we have now a third equation; 5 tam i = | ae Sie Which being substituted in the other two, they become vi h t ; b= m {map tna}, «H pa (m + n): and from these, by division, &c. we get ae B h nt - Seats as tap} The same formula as was found by a very different process. The controversy concerning the just rule for estimating borough importance may be explained briefly as follows: All parties agree in deducing it from the two fractions h t H’ < Lieutenant Drummond has placed the boroughs in the scale of relative importance by the formula 1 h t b — 2 H + T t > or at least by a rule equivalent to this formula. Mr. Pollock proposed the formula h t b = ci . TT" Dr. M‘Intyre strongly insists that the true formula should be ee sabi =a: The two last will place the boroughs exactly in the same order. The first, however, is the only rule founded on true principles: the others have been formed from confused or mistaken no- tions about the doctrine of ratios. The question comes at last simply to this :—shall we take an arithmetical or a geometrical mean between the two frac- z h ¢ ; tions =, and ras the measure of the importance of a H borough? In a practical point of view it hardly signifies which rule be followed; yet it would have been discreditable ad Fe ek: oe oe Mi, Festal, pet Be NM rect Li kts ats ee! Lae Bs bet grata eM. Oia se iMy Wag. & Journ, ef Jaence 3B Serves VAALPELL. i, “Aargoons 4 lagnelic Goren mer. Mr. W. Sturgeon on the Distribution of Magnetic Polarity. 31 to the Government to have thrown aside the rule of Lieutenant Drummond, founded on true principles, and taken in its stead Dr. M‘Intyre’s, which satisfies no mathematical principle _whatever. 3 IX. On the Distribution of Magnetic Polarity in Metallic Bodies. By W.Strurceon, Lecturer on Experimental Phi~ losophy at the Honourable East India Company's Military Academy, Addiscombe. [With a Plate.] | my last communication (Phil. Mag. and Annals, N.S. vol. xi. pp. 270, $24,) I described the instrument (fig. 9. Plate III. vol. xi.) by means of which the experiments were first made, which indicated an extraordinary and novel distribution of magnetic polarity on the surfaces of copper and other non- ferruginous metallic discs. I also pointed out, though briefly, the method by which I detected the curiously winding force which actuates the needle on those surfaces when rotated be- tween the poles of a horse-shoe magnet. In that communi- cation, however, I described the distribution of that force no further than as it is developed by one condition of motion given to the disc; i. e. whilst it rotates in the direction of the large exterior arrow, fig. 11. Plate III. In continuation, therefore, I now proceed to show in what manner that force (still supposing it to be the electric) becomes distributed over the surface of the copper disc, when the rotation is carried on in the reverse order; the magnet still remaining in the same position as in fig. 11. Plate III. It may be necessary, how- ever, in the first place, to make some further observations as to the manner by which I have been enabled to trace the curious windings which this force appears to take whilst in operation on the magnetic needle, or the mode by which I obtained the data necessary to the formation of the conclusions at which I have arrived concerning it. * In Experiments 16. and 17. it is shown that when the needle is placed over the centre of the disc, and its axis in the same vertical plane as that joining the poles of the exciting magnet, it is a matter of no consequence in which of the directions the poles of the needle be placed ; the deflections will depend upon the direction in which the disc is caused to rotate. Tor, although the needle will in some cases follow the direction of the rotating disc, and in others travel the contrary way, ac- cording to the character of the pole which is directed towards the pole of the exciting magnet, still it will have a dependence upon the direction of motion given to the plate; so that if the 32 Mr. W. Sturgeon on the Distribution of position of the needle be such that its deflections will corre- spond with the motion of the plate when rotating to the right, its deflection will again correspond with the motion of the disc when the latter is caused to rotate to the left; consequently the deflections in the first case will be contrary to the deflec- tions in the latter case. The same law will be observed when the position of the needle is such that the deflections are op- posed to the direction of motion given to the disc; for if the needle travel towards the left whilst the disc revolves towards the right, it will travel towards the right when the revolution of the plate is towards the left; manifesting in all cases that when the exciting magnet is stationary, the direction of the force which impels the needle entirely depends upon the direction of motion given to the disc. ip This law being understood, we have next to contemplate the direction in which any selected pole of the needle travels whilst the disc is in motion; and a little reflexion will make it readily appear that in whichever of the two positions (Ex- periments 16. and 17.) the needle may be placed whilst the plate is at rest, it will exhibit a constant tendency to assume some determined new position when the motion given to the plate is in one certain direction ; and as constant a tendency to take up some other determined new position when the rota- tion of the plate is reversed. To simplify this point still more, we will first suppose the needle to be placedas in fig. 14. Plate I., s” being respectively the south and north poles. The needle in this position will travel in the same direction as the disc revolves (Experiment 16.) ; and when the revolution of the disc is in the direction indi- cated by the large exterior arrow, the south pole of the needle will be deflected towards the right of the exciting magnet. Again: Let the needle be placed as in fig. 15. s » as before’ being the south and north poles respectively. In this case the’ needle will travel in the opposite direction to that of the re- volving disc (Experiment 17.); but in this, as in the former case (as will be observed by comparing the two figures), when the disc revolves in one and the same direction, as indicated by the large exterior arrows, the south pole of the needle has a constant tendency towards the right hand, as is shown by the small arrows pointing out the direction of its course. Hence the new position for the south pole of the needle, determined by the forces excited in the disc by its revolving in this parti- cular direction, is evidently on the right side of the exciting magnet, or to the right of an observer with the apparatus placed before him, as in fig. 14 and 15. This point being ascertained, the needle is now to be * Magnetic Polarity in Metallic Bodies. aa arranged, first a few degrees from the one, and then a few degrees from the other of its former positions, still keeping the south pole towards the right. The disc is to be put in motion (in that direction only indicated by the large exterior arrows, fig. 14. and 15.), whilst the needle is in each of the positions Jast given to it; and if the south pole now travels in the same direction as it did from both its former positions, it is plain that the excited forces still urge it towards some point, the situation of which is between those in which it was last placed. The needle is therefore again to be drawn still nearer to its destination indicated by the last triais, and the disc again put in motion in the same direction as before; the deflections are again to be observed, and the line, to which they indicate a tendency, to be still nearer approached by the position of the needle, for the next trials. In this manner the line to which the excited forces of the disc urge the needle is to be gradually approached, and its true position at length correctly ascertained. The deflections will gradually diminish, becoming smaller and smaller in proportion to the advances of the needle towards this neutral line : and when it is placed directly in the position of this line, the deflections will cease to be exhibited by the direction of rotation selected for this illustration; for the needle will now have a position of stability, or a position which the forces excited in the disc alone tend to preserve it in. If it be drawn only two or three degrees out of this line on either side, the slightest motion of the disc will urge it towards that line again; and if the needle be made completely indifferent to the influence of any other forces than those excited in the disc, a deviation even of one degree on either side of the neutral line may be detected by a tendency which will be in- dicated to resume the position of that line again whenever the plate is rotated in the proper direction*. - The process of experimenting is exceedingly tedidus, but it is the only method by which the true position, to which the forces excited in the disc tend to urge the needle, can possibly be ascertained. And if those forces be electric, and endued with the same magnetic polarity as that exhibited by the forces of a galvanic conducting wire, then the directions of the electric * I have been particular during this description in adhering to the effects of those forces which become excited by the dise revolving in one direction only; because it so happens that the two neutral lines indicated by the needle whilst placed over the centre of the disc are not coincident, but intersect each other at some considerable angle. [lence, although a position may be given to the needle from which it will not deviate whilst the plate re- volves iv one direction, a considerable deflection may be given by reversing the rotatory motion. Third Series. Vol. 1. No. 1, July 1832. F 54 Mr. W. Sturgeon on the Distribution of tides on the surface of the disc will be at right angles to the several positions which the needle is thus found to assume whilst the disc is in rotatory motion; and it was from nume- rous experiments and observations of this kind, whilst the needle was placed over various parts of the surface, that the necessary data were discovered, and the recurving forces care- fully traced out. The process by which the distribution of polarity on the surface of the disc has been determined being now understood, no further explanation will be necessary to illustrate the sin- gular recurving directions of the excited forces which are sup- posed to actuate the needle on the upper surface of the disc, under the two conditions of rotation, than merely to refer to fig. 16.* and 17. The exterior arrows indicate the directions of motion given to the disc; and the two systems of small recurving arrows in each figure show the distribution and direction of the forces which impel the needle and urge it to a position at right angles to the aggregate of any portion of those forces over which it may be placed during the revolving mo- tion of the disc. It will be observed, by comparing fig. 16. and 17, that the direction in which the aggregate of the forces recurves is nearly if not completely reverse by simply changing the re- volving motion of the disc. The arrows which indicate the direction of those forces are seen to issue from the front of the exciting magnetic pole in fig. 16, but are re-entering at that point in fig. 17. In the former figure also, the arrows are seen re-entering on both sides of the magnet, near to the edge of the disc; but in the latter figure the arrows issue forth from both sides of the magnet, along the same edge; so that the force in the edge of the disc is as decidedly reversed as it is in any part of the area by simply reversing the revolving mo- tion. ‘The curious change in the direction of the force in the edge of the disc is beautifully illustrated by the following ex- periment. Experiment 20. Let the axis of the dise be placed horizon- tally east and west, and consequently the plane of it will be coincident with the plane of the meridian. Let the horse-shoe magnet be so arranged as to embrace the south edge of the disc between its poles, its plane horizontal, and coincident with that in which the axis of rotation is situated. Let also * Since my former communication went to press I have had an oppor- tunity of repeating my experiments on the surface of the disc; from the results of which I have been induced to offer fig. 16. as a more faithful representation of the distribution of the force in the central parts than that which is shown by fig. 11. (Plate III.) yol. xi, Magnetic Polarity in Metallic Bodies. * 35 the north pole be opposite the east surface, and the south pole opposite the west surface of the disc, as in fig, 18, S N repre= senting the upper edge of the disc. 5 Let a magnetic needle be also arranged north and south, close beneath the lower edge of the plate. Rotate the plate in the direction which will carry its upper edge from south to north, (from S to N, fig. 18.). In this case the disc will enter be- tween the poles of the exciting magnet, under precisely the same circumstances as in fig, 11. and 16; the left edge in either of those figures corresponding with the lower edge in fig. 18. The principal force which now operates on the needle will be that in the lower edge of the disc; and the direction of that force will be from north to south, or in the same direc- tion as that in which the lower edge is in mction, (See fig. 11. er 16.) The south pole of the needle is deflected towards the east in precisely the same manner as it would be urged by the polarizing force of an electric current running from north to south through a conducting wire placed above the needle. The needle S N, fig. 18, shows the position into which it is carried whilst the disc is revolving over it. Experiment 21. Let the needle be now placed above the upper edge of the disc, and its axis in the same vertical plane, the rotation being continued in the same direction as before. In this case the force which operates on the needle is trans- mitted from north to south, the upper edge of the disc corre- sponding to the right edge in fig. 11. or 16. The direction of the force is therefore the same in this experiment as in the last; but the needle is now placed above the edge, and the south pole is deflected towards the west. If the disc be rotated in the contrary direction to that in which it proceeded in the two last described experiments, the distribution of the force will be represented by fig. 17, in which case its direction in the edge, both above and below the magnet (fig. 18.), will be from south to north. The south pole of the needle, when beneath the lower edge, will be de~ flected towards the west; but when placed above the upper, edge of the disc, the same pole will be deflected towards the east; showing in a very beautiful and striking manner that the forces in the edge of the disc become completely reversed by simply reversing the revolving motion, and that the distribution of polarity is highly imitative of that which is displayed by the edges of a flag or cake of zinc, when par- tially heated at one end only *; the discovery of which, as I have before stated, gave me the first hint which led to the * See my Paper in the Phil. Mag. and Annals, vol. x. p. 120. F2 36 Mr. W. Sturgeon on the Distribution of success at which I arrived in the investigation I'am now de- scribing*. . . If two or three discs of the same diameter be placed close. together on the same axis, so as to form a compound dise or plate, the forces which operate on the needle are much more powerful than when one disc only is employed. Much, how- ever, depends upon the thickness of the metal, thick dises having a great advantage over those which are very thin; notwithstanding which, a decided uniformity in the distribution of polarity is displayed even in the thinnest copper or zinc foil. | I made a compound disc by soldering the edges of two single ones to a rim or hollow cylinder of copper, about halfan inch deep, so that when completed it formed a cylindrical box, half an inch high, and about ten inches in diameter, having a perforation through its centre for the introduction of the spindle on which it was intended to rotate. When this cylinder was mounted in the place of the single disc in experiment 20. and 21, the deflection of a four-inch needle (neutralized in the usual way) would amount to about 40° with a moderate velocity of rotation. When the velocity was considerable, and the mo- tion equable, the needle would be perfectly steady at that, or at a greater angle of deflection. Straight needles, particularly when they are very long, are by no means well adapted for obtaining the greatest effect from the forces in the edge of the disc whilst rotating in a vertical plane, because of the great distance at whieh the poles are necessarily placed from those operating forces. It is much better to employ needles which are bent into cirenlar ares, having nearly the same curvature as the edge of the disc. Two needles of this form may be advantageously employed at the same time; the one above, and the other below, and both concentric with the edge, as in fig. 25. The needles are at- tached to a straw, or thin slip of light wood, with their poles placed in opposite directions. When thus arranged, their directive force will, in a great measure, be neutralized, both as regards the magnetism of the earth, and that of the exci- * At the time I was making these experiments, I found that the frame of an electrical machine with a multiplying wheel and band was very con- venient for giving the disc a considerable velocity in a vertical plane. A spindle, supported in the pivot-holes of the frame, and furnished with a pulley at one end, carried the revolving disc; and a pile of books formed the stage for the support of the horse-shoe magnet. Some time last summer, however, I constructed an apparatus for the purpose of rotating discs, cylin- ders, &c., on a horizontal axis, which, as it very much resembles a plate machine, it is not necessary to describe in this place,—any further than merely to mention, that it is furnished with neat stages for the support of the exciting magnet and the compass-needles. ; Magnetic Polarity in Metallic Bodies. 37 ting horse-shoe; and as the actuating forces in the edge of the disc operate in the same direction, both needles will be im- pelled in one and the same way ; so that whatever may be their position when deflected, they will constantly appear in the same vertical plane. ‘The arrows in fig 25. show the direc- tion of the aggregate forces in the edge of the disc, when it is rotated in the direction as shown in fig. 16. The singular and complicated distribution of the force dis- covered in these rotating discs of copper, led me to undertake some other experiments, by means of which I considered it possible that I might arrive at some simple law, which would disclose the novel and apparently mysterious arrangement ; for, whether the phzenomena emanate from magnetic or from electro-magnetic action, there appeared to me to be no law yet discovered in either of these branches of research, that would produce a distribution of polarity like that which IL have portrayed in fig. 16. and 17; notwithstanding which, the uniformity of the distribution, which became manifest at every repetition of the experiments, left no doubt as to the im- mutability of some law, to the operation of which the regu- larity of the distribution was entirely owing. In this investigation it was necessary to take into consi~ deration the various directions which different parts of the re- yolving disc assume with regard to the exciting magnet; for, as the poles are not placed in the centre of motion, it is plain that whilst some parts are advancing towards them, other parts are receding from their vicinity ;—some parts again are crossing the magnet to the right, whilst’ others are crossing it towards the left; and all these motions in the disc are going on at the same time; so that upon the whole the apparent complexity of the problem put any inquiry concerning it rather in the position of a ‘ forlorn hope”, than of anything like cer- tainty of success. Considering, however, that as the vicinal regions of the disc must necessarily receive the exciting impressions in a much higher degree than those more remotely situated from the magnetic poles, it might be expected that if any satisfactory conclusions were to be arrived at, those parts of the disc the most powerfully excited were more likely than any other to afford the necessary data. My inquiries were therefore more particularly directed to the investigation of that half of the dise which is nearest the magnet, the: curvilinear direction of which, with regard to the exciting pole, is easily resolved into four rectilinear motions. Let m 0, fig. 26*, be the constant radius situated between * In consequence of an oversight, fig. 26. will not be found in the plate; it will be given m our next Number.—Kprr, 38: Mr. W. Sturgeon on the Distribution of the magnetic poles; then the diameter 2’ drawn at right angles to the former line will be the line of demarcation which separates the disc into the two required halves. . Now when the disc revolves in the direction of the exterior arrow, the quadrantal portion m o 7 will advance towards the pole m; whilst the quadrantal portion m o 7’ will recede from it. ; Let co be any radius of the disc approaching the magnet m; then, in order that any point c in that line may arrive at m, it must necessarily partake of the direction ¢ 6, which would bring it towards the szde of the magnet; and also of the direc- tion 6 m, which would carry it to within the magnetic poles: and as the lines c 6 and 6 m are respectively the exact measures of the spaces through which the point ¢ would have to travel in those directions, whilst approaching the magnet, and are both performed in the same time,—they are also the faithful repre- sentatives of the respective mean velocities with which the point ¢ is carried in each direction whilst advancing from ¢ to m. Now asc 6 and bm are respectively the sine and versed sine of the angle c o m, the mean velocity from ¢ to m in each direction will always be proportional to those lines, from what- ever point of the quadrant the point c has to travel. If c tra- vels through an arc of 90°, or from x to m, the mean velocity in each direction will be equal, because x 0 = om; but if the arc be less than 90°, the mean velocities will be unequal. If the arc 2 c be 45°, the mean velocity from 2 to ¢ will, be in favour of the direction 0 m; but between c and m the predo- minating velocity will be in the direction of c b. Now as the excitation is more powerful in the neighbour- hood of the maguetic poles than in any other part of the disc, the vicinal area c o m of the quadrant 2 0 m will constantly be receiving stronger impressions than the remote area 2 0 c. And as the predominating mean velocity in the area c 0 m is in the direction ¢ b, the ascendant influence will consequently be due to that direction of motion. With regard to the quadrantal area m o n', nothing more appeared necessary to be understood than to resolve its curvi- linear motion into rectilinear directions in the manner already considered in the other part of the disc, supposing it to be receding from the magnet, instead of advancing towards it. Under these considerations the experiments necessary for the inquiry, which at first view had appeared to present con- siderable difficulty, became very much simplified, being re- duced to four rectilinear motions of the plate ;—attending to the velocity in each direction, and taking into calculation the observed phaenomena under each individual circumstance. The experiments were made with a rectangular plate. of Magnetic Polarity in Metallic Bodies. 39 copper, about 18 inches long and 12 inches broad. ‘This plate was placed between the poles of a -horse-shoe magnet, and moved in a horizontal plane. The upper surface of the plate was exposed to the action of the south pole, and consequently the lower surface to the action of the xorth pole of the magnet. Nothing more will be necessary to describe the distribution of the force which operates on the needle, whilst the plate is in motion in the four selected directions, than merely to refer to figures 21, 22, 23, and 24, The exterior arrows in each figure indicate the direction in which the plate is moved; and the curved systems of arrows show the distribution of the force. + ald In fig. 21. the distribution is similar to that shown in fig. Jl. or 16; and the motion of that part of the metal under the strongest excitation in both cases is in the same direction, i.e from left to right. The same comparison may be made be- tween fig. 22. and 17, where both move from right to left between the poles of the exciting magnet. , In fig. 23. the plate is introduced directly into’ the interior between the two limbs of the magnet; and in fig. 24. it is withdrawn in the same right line. The distribution of the forces by these two motions are simple curves, having only one direction in each. ‘In each case, however, the curves have every appearance of being continuous, running into themselves between the poles of the magnet, and forming complete vor- tices round a central nucleus or narrow space joining the ex- citing poles. . Now as the distributions in fig. 23. and 24. are simple vortices, they may be applied to explain the compound distri- butions in the other figures. Let it be supposed that each system of arrows in fig. 23. and 24. represents a complete vor- tex of the force, and let an observer be supposed to be placed in its centre; then as the plate advances towards the polés as in fig. 23, the direction of the force in every point of the vor- tex will be towards the left hand; but when the plate recedes from the magnetic poles, as in fig. 24, the direction of the force will be towards the right hand. These are simple elementary vortices. Apply now each of these elementary vortices to fig. 21. and 22. In each figure the plate is both advancing and retiring from the pole at the same time. In fig. 21. the plate is ad- vancing on the left side of the magnet, and the vortex flows towards the left hand of an observer placed in the centre of its motion. On the right side of the magnet the plate is retiring from the poles, and the vortex is flowing towards the right hand, or in the same direction as in the elementary vortex in 40 Rev, J. Challis on the Resistance to the Motion fig. 24. In this way the elementary vortices in fig. 23. and 24. will explain the compound distributions of force in each individual case, as represented in the figures. In fig. 16. and 17, where the disc revolves on a centre, the excitation arising from the motion being in the direction 0 m on one side of the magnet, fig. 26, is counteracted by the op- posite excitation on the other side of the line o m; for as on one side of the magnet the motion would be advancing, and on the other side retiring, as in fig. 23. and 24. respectively, the forces arising therefrom would nearly, perhaps completely, destroy each other. It is possible, however, nay it is even pro- bable, that all the systems of forces arising from the four recti- linear motions are in play when the disc is revolving on its axis; but the insignificancy of the two last contemplated forces, with regard to those which are due to the motions indicated by fig. 21. and 22, must necessarily render them exceedingly ineffi- cient. If the force be electric, it is likely that the remote parts of the disc serve merely as conductors to that excited in the parts vicinal to the magnet. The small curved arrows in fig. 19. and 20. indicate the dis- tribution of the force in annular discs of copper or zinc, when rotated on an axis in the manner described for complete discs. The large exterior arrows indicate the direction of motion in each figure. The distribution in these annular discs is pre- cisely the same, so far as the metal permits, as that in complete discs. Fig. 27. is intended to show the position of the neutral line on the rectangular plate, when moved in the direction of the arrow between the magnetic poles. ‘The arrow is a right line crossing the magnetic pole, and two inches in front of it, ‘The small needles are placed an inch from each other, and their positions, with regard to the arrow, show the inclination at each station, or the position in which the excited forces in the plate alone would place them. X. On the Resistance to the Motion of small Spherical Bodies in elastic Mediums. By the Rev. J. Cuatuis, Fellow of the Cambridge Philosophical Society*. APHE following observations have reference to the com- munication I made to the Philosophical Magazine and Annals for last March, and the mathematical reasoning therein contained, which being of a novel kind, requires to be con- * Communicated by the Author. ¢ of small Spherical Bodies in elastic Mediums. 4 firmed in every possible way. I shall here attempt to show that the results of that reasoning will serve to explain a pha- nomenon, which, as far as I know, has not ha eee ex- planation. These results were such as follow. If a dicted be made in an elastic medium, in which the pressure is equal to the product of a constant (a°) by the density (¢), by means of a small sphere, the surface of which vibrates while its centre is fixed, and if-v = the velocity at the time ¢, at any point either at the disturbing surface or indefinitely near it, a from the centre = es then, ¥F’ (r—at) 2073 (r=¢@ t) _ @ Nap. log g = The former of these equations shows that v is made up of F' (r—at) pie ie F (r—at) =, distinguished from ar two parts, each other by the denominators 7 and r?. ‘These denomina- tors show that the velocity varies in passing at a given instant from the disturbing surface to a point indefinitely near, in a manner independent of the arbitrary function, and therefore of the disturbance also. We may perceive a natural reason for this, by considering that as the surface expands, the number of particles in contact with it is continually increasing, and to supply the increase the contiguous par ticles must have a motion towards the centre, independent of the motion they receive from the surface; and similarly when it contracts, a motion from the centre. Because a Nap. log g is also equal to / oh it was inferred that this part of the velocity is propagated with the uniform velocity a. The other ‘part, not being accompanied by change of density, is transmitted in- stantaneously, as if the fluid were incompressible. ' . w We considered the case in which F(r—a?¢) = msin nr ae)s which applies to vibratory motion. Let us suppose for greater generality that F (r—a?t) = mxsin = $¢(at—r), and let.r be so small that terms involving higher powers than the first may, be neglected. Then, a) Third Series. Vol. 1. No.1. July 1832. G 42 Rev. J. Challis on the Reszstance to the Motion F(r—at) = m sin 530 (a t) — d(arg an S sin 7g (a t) =r ea cos “P09 F'(r—at) = — aS cos Tae F' (r—at) 8 F(r—at) om sin 72 (24) and v or r Ts r A Now, if the motion of the disturbing surface, instead of being vibratory, be continually increasing or decreasing, A must be indefinitely great compared to 7 (at) during the whole time of the motion: so that sin ee) = “ae and ammg(at) _ es = x) (at), supposing that ny a 7p. At ! (r— I the same time Sgr ib) 23:95 Eee 2 a T os—- ¢ (at) “ur r very small compared to v. Hence in this case of disturbance, the part of the velocity accompanied by change of density is very small compared to the whole velocity, and therefore the change of density itself is very small. Let, for example, ¢ (az) be constant; then v varies inversely as 7°, and — > r 9’ (at) = 0, as we should expect. Again, let v, which we may consider to be the arbitrary velocity given to the disturbing surface, be any function of the time, as f(¢), and let r= 7’ whenv = 0. Thenr =r + f(f(¢) dt, and we(at) = vr? = f(t) (7 + f f(t) dt). Hence it will be found that ¢! (at); which on account of the factor r ¢! (af) is — 7? a a 2 If v be uniform, /' (¢) = 0, and — “ g (ath=— ne : which is a quantity of an order that has been already neg- u oT Zivtih y lected. If v= git, — ie (at) = Tage TF 7 in of small Spherical Bodies in elastic Mediums. 43 which if g represent the force of gravity, both the terms are negligible. Conceive now a small spherical body to descend vertically in the air by the force of gravity. If it be supposed perfectly smooth, it can impress motion on the fluid only in directions perpendicular to its surface. Thus the motion impressed at each instant by the anterior half of the sphere is directed from acentre. If v be the velocity of the sphere, v cos 4 is the velocity impressed in directions making an angle @ with the line of its motion. This case of disturbance is therefore si- milar to the last, in that the motion is from a centre; but differs in these respects,—the motion is not the same in all directions from the centre, and the centre is not fixed. But I have elsewhere given reasons for concluding (Cambridge Phil. Trans. vol. iil. part 3.) that the equations we have been using, and the results derived from them, apply at each instant to every elementary portion of fluid disturbed in any way, provided the condition of the tendency of the motion at each instant, to or from fixed or moveable centres, be fulfilled. If this be admitted, we may at once conclude that the descend- ing sphere is subject to very little change of pressure on its anterior half; for if g = the density of the fluid in contact with any point of it, we find that, rf’ (t) 2v? MuQi@ Re inva a Nap. log eg = 6 in which f'(¢) = = cos §, a quantity not very different from g cos §, since the resistance of the air is small. The same may be said of the posterior half; for it might be shown that the only difference between the disturbances produced by this half and the other, is that the motion is directed towards acentre. Similar reasoning is applicable to any kind of in- creasing or decreasing motion. From all that precedes we draw this conclusion :-— . When a small spherical body moves in a medium like air with a velocity small compared to the velocity of propagation in the medium, and in any manner except in rapid vibrations, the pressure on its surface is at every point very little different from the pressure of the medium at rest. ‘The phenomenon I propose to explain by this result is the spherical form of the drops of rain. ‘That they are spherical is shown by the rainbow. Capillary attraction will account for their assuming in the first instance a spherical form; and from the preceding reasoning it follows that being very small, they do not suffer in passing through the air any inequality G2 44 Rev. J. Challis on the Resistance to the Motion, &c. of pressure which will sensibly alter their shape. An in- equality of pressure very much less than the weight of a drop would suffice to do this. Hence also we may account for the success of the common method of making spherical shot, by letting them fall ina melted state from a great height, so as to become solid in their descent. It appears from our reasoning that the resistance to a small spherical body descending in the air, is occasioned very little by the condensation of the air it encounters, but principally by its putting in motion and partly carrying with it a portion of the Muid. Whatever be the law of resistance in regard to the velocity (which it seems difficult to ascertain), we may con- ceive of the nature of the resistance by supposing a variable mass mf (v) to be always attached to the descending body M, and to be unaffected by gravity; so that if F = the effective ra i gf M = : = 2 MEO . accelerative force, g F (M+ mf (v)); F M+mF(o) The foregoing inquiry will also assist us in ascertaining the nature of the resistance of the air to the motion of a pendu- lum-ball, suspended by a long slender thread. As before, the resistance is not sensibly due to any change of density of the air. The motion being slow and the vibrations of small ex- tent, we may suppose, without chance of sensible error, that the velocity of a particle of the air in the same position rela- tively to the centre of the ball and the direction of its motion, has always the same ratio to the velocity of the ball. Hence if M be the mass of the ball, » that of an equal volume of air, m acertain constant, and v the velocity of the ball, we have this equation of ws viva : Mv?4+mv = 22 (M—z) (hk-2), h—x being the vertical descent of the centre of the ball. : 4 vdv Py Ae Hence the vertical accelerative force, or — Wa? which is a : M— ) i the only one that acts, is g. Maw? and the time of vibra- Ane PD? M+m tion is to the time in a vacuum, as ee Fe tol. These results have been obtained by M. Bessel. (Iesearches on the Length of the Seconds Pendulum: Berlin, 1828.) The last application I propose to make of the preceding analysis, bears upon the nature of light. The undulatory hypothesis of light requires us to give a reason why the planets Mr. Faraday on Sig. Negro’s Magneto-electric Experiments. 45 meet with no sensible resistance from the ethereal medium. Supposing the zther to be constituted like air, and the matter of the earth and planets to consist of very minute spherical atoms, (suppositions, which I have already advanced to ex- plain some phzenomena of light*,) it wiil follow that no part of the resistance, caused by the condensation of the medium, varies as the simple power of the velocity: also the term 4 — eats must be quite insensible. With respect to that part of the motion of the zther which is unaccompanied by change of density, we may say that the velocity of any particle in the same position relatively to the centre of the planet, and to the direction of its motion, has always the same ratio to the velocity. of the planet. The consequence of this would be, that the law of the force tending to the sun would not be changed, but its quantity would be diminished. This effect would be accounted for by taking the mass of the planet of less magnitude than it really is, and therefore probably can- not be easily detected by observations. Hence if any resist- ance be sensible by any change of the orbits or the periodic times, it will depend on the sguare of the velocity. Also it must be much less sensible in dense bodies like the planets, in which the particles that precede diminish the resistance on those that follow, than in such a rare substance as Encke’s comet. This singular body has in fact, in the opinion of competent judges, determined the existence of a medium, or something equivalent, resisting according to the square of the velocity. Papworth St. Everard, April 17, 1832. XI. New Experiments relative to the Action of Magnetism on Electro-dynamic Spirals, anda Description of a new Electro- motive Battery. By Signor Satvarore Dat Necro; with Notes by Micuarr Farapay, Esg., F.R.S., M-R.I. Corr. Memb. Roy. Acad. Scien. of Paris, &c.+ Addressed to Dr. Ambrogio Fusinieri, Director of the Annali g delle Scienze, Sc. Sc. } Sir, N repeating the experiments relative to the action of ter- restrial magnetism on electro-dynamic spirals, an action which was first observed} by the two illustrious Italian philo- * See Phil. Mag. and Annals for March last, p. 161. + Communicated by Mr. Faraday. { (This is an error. A long section is devoted to terrestrial magneto- electrie induction in my original researches (140 to 192) of the date of 46 Sig. Dal Negro’s Magneto-electric Experiments, sophers Nobili and Antinori, it occurred to me to examine the effect of an ordinary magnet on similar spirals at the mo- ment when one of the poles traversed the axis of the spiral (Exp. Res. 39. 41. 114.), and I obtained such results as indi- cated the path which it would be proper for me to follow, in order to profit by this new property of magnetism. Ultimately I succeeded in constructing a new electrometer, by means of which the efficacy of the instantaneous currents discovered by the celebrated Faraday may be augmented without limit, and obtained in succession with such celerity as to render (as it were) continual the action of these currents*. He [Dr. Fusi- nieri] has already witnessed the principal part of these my ex- periments, and more than once has been so good as to assist me faithfully in registering the results, and has solicited a description that might be made public. I did not hesitate to make a brief exposition that might be transmitted and in- serted in the forthcoming number of his Journal. He returned from us as quickly as possible, and did not forget to take with him the magnet I had promised. His most affectionate friend, Padua, April 20, 1832. SatvatorEe Dat Necro. New Experiments, 3c. &c. 1. Place a cylindrical tube of paper surrounded by a spiral of silk-covered copper wire upright upon a little table, and connect the extremities of the spiral with a very sensible gal- vanometer, constructed according to the method of Signor Nobili: introduce the north pole of an ordinary horse-shoe magnet into the axis of the cylinder, and an electric current will be obtained, which will act strongly on the galvanometer. (Exp. Res. 39. 147.) On withdrawing the pole of the magnet, a current, in the contrary direction, will be obtained (Zzp. Res. 39.). On repeating the experiment with the south pole, currents will be manifested in the contrary direction (Zzp. Res. 114. &c.) to those caused by the north pole, and less powerful, as has been observed. 2. Introduce into the same spiral the north pole of a more powerful magnet than the first, and the conflict will pro- duce a much greater effect; I say, “ conflict,” because the December 21, 1831. As my brief letter to M. Hachette is continually taken instead of my memoirs as representing my views of magneto-electricity, I venture to add a few notes and references to this paper, in the same man- ner as I have done to the paper by Signori Nobili and Antinori, at page 401, of the last volume of the Phil. Mag. and Annals.—-M. F.] {* Lhave described at length a different but perfect way of obtaining a continuous current by magneto-electric induction. (Laxp. Res. 90, 154. 155. 156, &c.)—M. F.] with Notes by Mr. Faraday. 47 phenomena in question obey the laws of the collisions of solids. ‘The magnetism of rotation discovered by the cele- brated Arago has already shown what influence motion has in these phenomena. Then slowly moving the magnet, it may be introduced and removed from the spiral without causing any sensible current. To obtain the maximum effect, it is necessary that the magnetic pole should make its en- trance or exit with great velocity. (Exp. Res. 136. 153. 258.) 3. Introduce at the same time the poles of the magnet into two equal spirals, having the same direction, and two contrary currents will be obtained, which would destroy each other if the poles of the magnet were of equal strength. But as the north pole is in our latitudes more active than the south, the effect obtained will equal the difference of the two currents, and be in the direction of the greater force; exactly as hap- pens in the collision of solids. It results from this my expe- riment, that henceforth we may ascertain at once with facility which is the most powerful of two magnets, ‘and how much more active the north pole is than the opposite south pole of the same magnet *. 4. In order to take advantage at the same moment of both the poles of the same magnet, construct two spirals turning in opposite directions, and place them as usual in connection with the galvanometer. Then on introducing the poles of the magnets, an effect will be obtained, equal to the sum of those which could be produced by the poles separately. To mea- sure the effect produced by these two spirals with a more powerful magnet than the first, I was obliged to use a gal- vanometer of only one-twentieth the sensibility of the first. 5. L immediately perceived that this pair of spirals was a valuable element capable of furnishing a mode of augmenting without limit the efficacy of the instantaneous currents. I therefore instantly constructed a second pair of spirals equal (* The statement that the north pole is in our latitudes more powerful than the south is a mistake. The cause of the effects obtained by Signor Negro will be found at p. 147 of my Exp. Research., and is dependent on the inductive force of the earth, as a magnet, upon other magnets, as well as upon soft iron. When a straight magnet is held in the dip, or even vertically with its marked pole downwards, both poles are strengthened ; when held with its unmarked pole downwards, both poles are weakened. And though when a horse-shoe magnet is held with both poles downwards, as in Signor Negro’s experiment, the marked pole is stronger than the un- marked one, it is only because the two limbs are affected as the single magnets just referred to, and the bend of the magnet being the upper part becomes virtually a feeble south pole. If the horse-shoe magnet be held with its poles upwards, then the contrary effect happens, and the unmarked (usually called the south) pole becomes the stronger ; or if both poles are in equal relation to the magnetic dip, then both are equally strong —M.F.] 48 Sig. Dal Negro’s Magneto-electric Experiments. to the first, and putting both in connection with the galva- nometer, I caused two magnets to enter them contempora- neously, and obtained an effect due to the sum of both pair of spirals. On using still more powerful magnets, even the second galvanometer became useless. The galvanometer which I substituted consists of a rhomboidal needle, about five Paris inches in length, and suspended as in the ordinary compass. The wire which connects the extremities of the spirals passes beneath the needle distant about 34 lines, and is parallel to it when the latter is at rest: on obtaining this fortunate re- sult I conceived the idea of constructing a battery of several magnets put in conflict with an equal number of pairs of spirals. Construction of a new Electro-motive Battery. 6. I had at command only four magnets, so that for the present I am limited in my construction to four pairs of spirals, as in the manner following: On a little table is placed one after the other four pairs of spirals, with the axes horizontal, and so that the perimeters of the cylinders shall have the same horizontal line as a common tangent, it being parallel to one of the sides of the table. On a second table con- tiguous to the first, but not in contact, was placed a little carriage consisting of a rectangular table supported on four wheels, by means of which it could easily receive a motion to and fro. The four magnets were placed upon this carriage, so that the poles of each could move horizontally towards the pairs of spirals, and enter within them. The magnets were firmly fixed on the carriage so as not to alter in position, and the latter was so arranged as to move to and fro only in one direction. On moving the carriage, the limbs of the magnets passed at once into all the spirals, and they could be made to enter or move out with the utmost facility, and with any required velocity. That the battery thus disposed may give an electric current equal in force to the sum ofall the currents excited in the pairs of spirals, it is necessary that all the spirals turning to the right should communicate with each other, that they may form a single metallic wire. The same must be done with all those turning to the left. Then these wires are to be connected in the usual well-known manner with a galvanometer, which we may suppose placed on a third little table, so far distant from the magnets that it may not be influenced by their pre- sence. Although these electric currents are only obtained of instantaneous duration naturally, nevertheless with my battery they may be excited successively with such celerity as to pro- Mr. Forbes on an Electric Spark from a Natural Magnet. 49 duce an action, which is as it were continuous*. From the little I have done, and from what I have said, it follows that being able by this method to sum up the simultaneous action of an indefinite number of electric currents, this my battery may become fulminating. I hope I have said enough to enable my readers to com- prehend the mode of constructing this electro-motive battery. Hereafter, and by the help of a figure, I will describe the most useful and convenient distribution of the elementary pairs, and the mode of obtaining the maximum effect when employ- ing the smallest possible number of elements, or of pairs of spirals. — Errata relative to Signori Nobili and Antinori’s paper. At page 402 of the last Number of Phil. Mag. and Annals, line 23,—for electromo read electrotomo; and in the correspond- ing note, for electronic read electrotonic. XII. Account of some Experiments in which an Electric Spark was clicited from a natural Magnet. By James D. Forsrs, Esq. E.BRS. L. §& E. F.G.S.+ (THE recent discovery of Mr. Faraday has conclusively de- monstrated, that in every case where a magnetic current is created (to use the word current in its ordinary acceptation, as indicative of a peculiar condition, and without reference to any theory whatever), a momentary electric current is induced at right angles to it. ‘The experiment may be shown in two ways: either by mechanically causing a magnetic bar to tra- verse the axis of a helix of copper-wire of considerable length, —or by causing a piece of soft iron, placed in the axis of such a helix, to connect the poles of a horse-shoe magnet, and thus temporarily acquire polarity. The second methed is that which in my late experiments I have entirely employed ; and the subject of them has been a very fine natural magnet, capable of supporting 170 lbs. presented to the University by Dr. Hope. I willingly avail myself of this opportunity to express my obligations to that antag ani for the numerous and important facilities which ave been afforded to my researches, in his laboratory, where the magnet still is. My preliminary experiments demonstrated, by the action [* See the note at page 46.—M. F.} + Read before the Royal Society of Edinburgh, April 16, 1832, and abridged from the forthcoming volume of their Transactions: See Phil. Mag. and Annals N. S. vol. xi. p. 359. Third Series. Vol. 1. No. 1. July 1832. EH 50. Mr. Forbes on eliciting an Electric Spark upon the multiplier and upon the frog, that a very powerful and instantaneous current of electricity was conveyed through the helix at the moment of making the contact of the connect- ing iron with the magnet. In an early stage of my experiments I had, as far back as the 30th of March, obtained a spark from the magnet, which, however, being unable to repeat, from circumstances of which I afterwards became aware, I did not choose to publish at the time. I accordingly proceeded closely to investigate the cir- cumstances under which sparks were to be obtained from feeble galvanic currents of Jow intensity. I used the common cylindrical electro-magnetic battery, in which, by varying the charge of acid, I could obtain any required power. ‘Thus I adjusted it till I obtained from a momentary current nearly the same action on the multiplier as 1 had developed by the magnet. Removing it into a dark place, I found that sparks were obtained at the instant of making and breaking the cir- cuit connecting the cups of the battery. Satisfied that I had a sufficient current of electricity, I proceeded to apply to the magnet the conditions which I had found most effectual for eliciting the spark. ‘These were, Ist, That the spark is more easily obtained at the instant of interrupting than that of com- pleting the galvanic circuit: 2nd, That of the combinations which I tried, a fine pointed iron-wire suddenly withdrawn from contact with a surface of pure mercury, forming part of the circuit, was the most regular in exciting the spark, and that a good deal depended upon the suddenness of the inter- ruption; and, 3rd, That the spark was easiest obtained from the mercury, not at the horizontal upper surface, but where capillary action attracted it to the sides of the containing vessel; and that this was independent of the material of the vessel, being the same with wood, glass, and metal. I shall now briefly notice the arrangement of the apparatus with which, on the 13th of April, I succeeded in obtaining the spark at pleasure. The large natural magnet is represented at A. A cylin- drical connecter of soft iron ab, passing through the axis of the helix c, was made to connect the poles of the magnet; ac- curacy of contact was found to be of considerable importance to the success of the experiment, and one side of the cylinder was carefully formed toa curve of about two inches radius for this purpose. I found great advantage from a mechanical guide, not represented in the figure, to enable an assistant to bring up the connecter rapidly and accurately to the magnet in the dark. The helix ¢ consisted of about 150 feet of copper-wire, nearly one-twentieth of an inch in diameter, 74 Jrom a Natural Magnet. 51 inches long, and containing four layers in thickness, which were carefully separated by insulating partitions of cloth and sealing-wax.. The one termination de of the wire, passed into the bottom of a glass tube /, half filled with mercury, in which the wire terminated, and the purity of the mercurial surface is of great consequence to the experiment. The other extremity / of the helical wire communicated by means of the cup of mercury 2, with the iron-wire g, the fine point of which may be brought by the hand into contact with the surface of the mercury in /, and separated from it at the instant when the contact of the connecter ab with the poles of the magnet is effected. ‘The spark is produced in the tube 4. The success of the experiment clearly depends on the syn- chronism of the production of the momentary current by con- necting the magnetic poles, and the interruption of the gal- vanic circuit at the surface of the mercury. This might be pretty nearly ensured by a variety of simple mechanical con- trivances which suggest themselves,—but as these would re- quire very considerable nicety in their execution, I have been satisfied with the precision which may be insured by a good ear and an accurate assistant,—as I have thus, with a little practice, been able to produce, for many times in succession, at least two sparks from every three successive contacts. These sparks have generally a fine green colour; that I obtained on the 30th of March was in every respect similar to those I afterwards procured. ‘The intensity of light varies considerably, as it depends on the degree of accuracy with which the circuit is broken at the moment of contact. Some- times it is highly vivid, and has been seen some yards off in a dark place. As soon as I had the circumstances under my command, I hastened to show the experiment to my brother, who was resent, and to Dr. Gregory, acting secretary of this Society. | tials had the satisfaction of showing it to Dr. Hope, to Sir John Leslie, and ee other gentlemen. H2 52 Mr. Forbes on an Electric Spark from a Natural Magneé. I beg to repeat, that the success of Signor Nobili’s experi- ment is only known to me through the medium of the public prints; I am quite ignorant of the channel by which the re- port reached this country; and, at ali events, not the slightest clew has been given as to his mode of arriving at the result. Postscript.—Since the preceding paper was read, and placed in the hands of the printer, I have seen the account of the experiments of Signori Nobili and Antinori, contained in the Number of the Annales de Chimie et de Physique, dated Decem- ber 1831*; and I have likewise, by the kindness of Mr. Fara- day, received a copy of his paper about to be published in the Philosophical Transactions. From these documents, it is esta- blished, 1st, That Mr. Faraday obtained a spark from a tem- porary or electro-magnet, as far back as November 1831. This I stated to have been the case in the preceding paper, upon Mr. Faraday’s authority, who informed me of it about two months ago; and this was the “cas particulier,” men- tioned in the French version of Mr. Faraday’s letter to M. Hatchette, read to the Academy of Sciences, which gave rise to the experiments of Signori Nobili and Antinori, and who also allude to it in their paper, without knowing the real cir- cumstances of the experiment}. It appears, 2ndly, That the first document giving an account of the excitation of a spark by these philosophers, from a permanent or natural magnett, is dated from the Museum at Florence, 31st of January 1832, was published in the Antologia, bearing the date of November 1831, and afterwards translated into the Annales de Chimie, bearing the date of December. “ It is evident,” says Mr. Faraday, speaking of the former, ‘ the work could not have been then printed ; and though Signor Nobili in his paper has inserted my letter as the text of his experiments, yet the cir- cumstance of the back date has caused many here, who heard of Nobili’s experiments by report only, to imagine his results were anterior to, instead of being dependent upon mine§.” The notice of Signor Nobili’s experiment, to which I have alluded in my paper as having reached me whilst my investi- gations were in progress, was that contained in the Literary Gazette for March 24, stating simply the report of the fact, though without naming any authority. I learn from Mr. Fara- * A translation of the original paper of Signori Nobili and Antinori, with notes by Mr. Faraday, will be found in the Phil. Mag. and Annals, N. S., vol. xi. p. 401.—En1r. + Annales de Chimie, Dec. 1831, pp. 403, 417. t See Mr. Faraday’s note, Phil. Mag, and Annals, N. S., vol. xi. p. 405. —Enrr. § Phil. Trans, for 1832, p. 162, note. Mr. Bevan on the Cohesion of Cements. 53. day, that it appeared there by a circuitous channel of informa- tion, actually derived from Signor Nobili’s communication to himself. The first information I had of Nobili’s method of making the experiment, which was in its simplest form almost the same with my own, and explained in terms nearly identical, was not till the Annales de Chimie for December reached my hands, which was on the 30th of April, when the foregoing paper was in the press. Finally, as far as is yet known, no one except Signori No- bili and Antinori and myself have yet obtained the spark from the natural or permanent magnet. Greenhill, Edinburgh, May 7th, 1832. XIII. Remarks on Mr. White’s Experiments on the Cohesion of Cements ; with a tabular View of their Results, reduced to a common Scale. By B. Bevan, Esq. To the Editors of the Philosophical Magazine and Journai. Gentlemen, A Vata papers on Cements, communicated by Mr. White, and published in the Phil. Mag. and Annals, N. S., vol. xi. © pp. 264 and 333, are of considerable importance, on account of the numerous facts they contain. They enable the architect and builder to know where, and in what manner to apply the different kinds of cement, and the degree of stress which may be safely laid upon them. A careful perusal of the numerous results will point out several common errors, in respect to the cohesive properties of Roman cement and pozzolano, under different modifications, and under various degrees of exposure to moisture. And as you probably may be of opinion that an abstract of the results given in these papers, reduced to one common scale in a tabular form, may be acceptable to some of your readers, and save much time to individuals, I take the liberty of sending one. Cohesive Strength per square Inch. lbs. ~ mean. Cement in bars, age 6 days, 1 dry....c.ccceceeee 474 2 variable ......... 360 $356 $ web ssi.cestebhey, 30} —— age 47 days, 1 dry........ses0066 516 DIVE Tieecteces ees 564 +450 3 Wbescccrccsvccees so! 54 Results of Mr. White’s Experiments on Cements. Cohesive Strength per square Inch. Ibs. Cement i in bars, age 94 days, 1 dry ....eceeeeeees 210 Z VAM. cecacavesces as vn 618 380 3 WEE sscccceereceeee 312% a age 187 days, 1 dry .. Bsc eset oa 534 2 Vateccsenase Phase se 708 so 3 WEE cccccccccaceese $36 Mean of the dry ......... 433 variable ... 562 Wet weccseeee 288 : DVS WALT. vascerw ns esuvessssneseng ue With 51 per cent. of water.........66. 330 WV Wp RI. wos vennpnees qaceenets es Saceses a 3 parts cement, 2 parts kaeid sosaeesEr 456 1 part cement, 1 part brickdust ... 312 Bricks.—3 parts cement, 2 parts sand, 6 months 375 3 2° ‘ 362 All cement ...,....2..0s.e005. 9 months 360 Paving bricks, best sort .......0seeeseees - 253 Sete coc SEP AU MYL 194 Common building bricks, London* ... 4g Common bricks, Soho......secceeseseeseee 412 Brick cylinders laid in cement,....+++++++ +++ sae gite 27 in cement and sind. ihe naubheee - 68 ———————___> tw ccceee eos = 48 ————_E__ eronee saepeeaia tae Brick piers laid in cement, 2 parts; rough lime, 1 pare 1 month 42 sand, LAMAN: veasvns ead ete enn a arts —— ee a pt if 6 weeks. {' —— pure CEMENt vesceeces Pee eee vet 21 a pozzolano, 1; stone-lime, 1... gi —_—— Atkinson’s cement, 1; sand,1 954 —— PUR a sige sasha artesian 4.94 cement, 4; lime, 1. .cccscsecess 17 The apparent deficiency of strength in these experiments probably arose from the position of “the resultant and strain in being on one side instead of in the middle of the piers ? * Stourbridge fire-bricks have a strength of 790 pounds per square inch. The bricks I used at Greenwich Well were made at Fenny Stratford, and would support 715 pounds per square inch, equal to the strength of York- shire stone. Mr. Potter on giving Conic-sectional Figures to Lenses, §c. 55 Force required to crush per square Inch. 5 Se P. 337. A 14-inch brick pier, laid in cement A 470 Pozzolano, 3 parts; ground lime, 1... 296 Atkinson’s cement, 1; sand, 1......... 410 Pozzolanos24gs Hine; 1. 080s ese sais sual GSS Ditto, 3; Dorking lime, 1............. 600 Stone-lime, 1; sand, 3........ Wenecaaeee Soe Portland-stone pier ....... Seaeigit ees - 2300 A small error may be corrected, Phil. Mag. and Annals, vol. xi. page 339, line 20,—for 173} tons, read 149 tons. Yours truly, B. Bevan. P.S.—From the disproportion between the cohesive strength of pure cement, and cement used in brickwork, it is desirable that further experiments should be made on this subject. XIV. Addendum to the Paper on a Method for giving the Fi- gures of the Conic Sections to Concave Lenses and Specula, published in No. XII. of the Edinburgh Journal of Science. By R. Porter, Esq. Jun.* HAVING lately had occasion to look into the Transactions of the Cambridge Philosophical Society, I fell upon a pa- per read before the Society on the 11th December, 1822, by the Rev. W. Cecil, M.A. of Magdalen College, “On an apparatus for grinding telescopic mirrors and object lenses ;” where the author, though his principal object appears to be that of de- scribing a machine for superseding manual labour in the ge- neral workmanship, shows from mathematical principles the quantity which should be worn away at the various points, to bring a concave lens or speculum to the figure of a conic sec- tion. ‘hus far it appears that I am completely anticipated ; but as we differ in our directions for reducing the theory to practice, I submit my claim to the effectual invention to the judgement of the scientific world. Mr. Cecil does not refer to any examination of specula, &c. worked according to his directions. I did not publish my discovery until I had fully proved it, practically, in such large proportions of specula as left no doubt of my procedure being correct. I have prescribed the rotatory effect in the lathe, alone, to be used, even in the finishing process. Mr. Cecil prescribes a small lateral motion as well as a circular one, saying, “to grind * Communicated by the Author. 56 Mr. Potter on the Reflection at the second Surface only by a rotatory motion about the axis would entirely de- stroy the surface, by producing rings.” 1 maintain that with such a lateral motion no true figure of either an ellipse, a pa- rabola, or an hyperbola, can be obtained; and J have found in my experience no ill result to arise from using, as I prescribe, the rotatory motion entirely, whilst producing the change of figure, even with the inferior dexterity which always accom- panies an amateur hand. XV. Experiments to determine the Reflection at the second Surface of Flint Glass at Incidences at which no Portion of the Rays passes through the Surface. By R. Porrer, Esq. Jun.* esis subject is one worthy of attention on several accounts. A prism producing total reflection has been proposed as a substitute for the small plane metallic mirror of the Newto- nian telescope; and it is generally mentioned in all our optical treatises, that considerable advantage would arise from the substitution, without mention being made of the obvious at- tendant disadvantages, which would lead to the idea that these latter are trifling compared with the former. This would tend to lead many to make an experiment, bringing some trouble and expense, but in which they could experience no satisfac- tory result. In telescopes of large size, where the prism in consequence must be large, and the quantity of glass through which the light passes proportionally so, there would, in addition to the aberration and confusion introduced by the prism, be a disad- vantage in point of light also, when the prism became above a certain dimension, depending on the glass which was used. This arises from the property, which all transparent bodies possess, of absorbing a considerable portion of the light which passes through them; and it is greater, even in the most trans- parent of flint glass, than most persons have any conception of. It will be seen, from the experiments about to be related, that with prisms of only the size which I have employed, the light reflected and transmitted does not greatly surpass that reflected by a mirror of speculum metal which has been pro- perly polished. The experiments furnish also a confirmation of the fact, to which I have drawn attention in a former paper, of the great quantity of light lost in achromatic object-glasses of large size, from the unavoidable thickness of the material through which the light traverses. I hope this consideration will induce astronomers to inves- * Communicated by the Author. ‘ of Flint-Glass at Incidences of total Reflection. 57 tigate the point for themselves; and I feel certain they will be convinced of the superiority of the reflecting telescope for all purposes, excepting perhaps the application to divided instru- ments; and increased patronage will undoubtedly bring the working opticians to attain a perfection in execution, which there is now so little encouragement to seek for, from the fa- shionable prepossession in favour of achromatic telescopes/ As a question in physical optics, this subject merits an atten- tion much beyond any which I have been able to give to it, from the difficulty of obtaining a pure glass in sufficient bulk. But though these experiments were only made with prisms of common flint glass, and, as a matter of course, contained many of those waves and strize to which it is subject, yet they give us results which may be taken as proving the truth of the ge- neral opinion,—that no light is lost in what are called total reflections in transparent bodies ; and we should consequently conclude that it is the same for all incidences at which this effect takes place. If there is any variation in the intensity of the reflections, it is evidently very small, and much more perfect prisms and longer attention would be necessary to determine it. It is on account of the imperfection in the glass that I have not so multiplied the experiments as would otherwise have been de- sirable, knowing that no decisive argument could be drawn from them where the differences to be detected, if any, were evidently so very small; and the experiments in photometry with lamps present nothing very enticing and pleasant in them- selves, and require, besides, considerable practice and patience to get uniformly very exact results. d The only correct method of proceeding in this inquiry is to have the prisms formed so that the light may be incident and emergent perpendicularly to the surfaces, and falling at the required angle on the surface producing total reflection; and also, which is of equal importance, that the thickness of glass through which the rays pass may be the same in all. The prisms I have used were similar in shape to fig. 1. 2. and 3, where the distances a b, bc, are equal in all; and by a rectan- gular piece similar to fig. 4, where the length a c is equal to the sum of the two lengths a 4, bc in the prisms, we learn the quantity of light transmitted under all similar circumstances, excepting the total reflection, which enables us to complete our deductions, by allowing for the loss attending a direct transmission. The length a c, or the sum of the lengths a d, b c, was 1°98 inch, and the other dimensions of the sections of the prisms were proportionally as represented in the figures, the depths of each being equal to the depth a e of the rectangular pieces. Third Series. Vol. 1. No. 1. July 1832. I 58 Sir J. F. W. Herschel on the Action of Light in determining Thé prism fig. 1. was cracked in the commencement of the experiments, by being placed too near the flame of the lamp ; but fortunately the light in this prism being incident at 45° on the second surface, it was allowable to use another part of the glass beyond the extent of the crack. The rectangular piece averaged from rays incident. rays transmitted. 3 measurements» LOO! ote. . 8 7896 40 ——_____ a LOO Movie ot ht tiie pe OTe 5 nee tt WOODS we heel Cae ee he The prism fig. 1, where the light was incident on the second surface at an angle of 45°, averaged from rays incident. rays reflected and transmitted. 3,measurements;. 100... .. «6. « 6°97 ——— . 100... ....... 75°23 The prism fig. 2, where the light was incident on the second surface at an angle of 60°, averaged from rays Incident. rays reflected and transmitted. 6 measurements . 100......... 74°97 6 — BLOONS eaten s, cael OSG The prism fig. 3, in which the light was incident on the se- cond surface at an angle of 75°, averaged from rays incident. _ rays reflected and transmitted, Gumeasnrements .j LOO 6. p sie erred © yi dd 5..—...- 100... 2 2. » 76°90 Another set of measurements for the second prism gave 72:92; and thinking that there arose rather more of extraneous light in using the rectangular piece than in using the prisms, I made another set of measurements with it, taking additional precau- tions, and obtained 74°02; but itis probable that in these two last-mentioned cases some unnoticed cause of error had arisen, making the results come out too small. Fig. 1. Fig. 2. Fig. 3. Fig, 4. x be eee b b XVI. On the Action of Light in determining the Precipitation of Muriate of Platinum by Lime-water ; being an Extract Jrom a Letter of Sir Joan F, W. Herscuer, K.H. F.R.S. &c. to Dr. Daubeny*. W HEN a solution of platinum in nitro-muriatic acid, in which, the excess of acid has been neutralized by the * Read before the British Association at Oxford, June 22, 1832; and communicated by request of the Author. the Precipitation of Muriate of Platinum by Lime-water. 59 addition of lime, and which has been well cleared by filtration, is mixed with lime-water, in the dark, no precipitation.to any considerable extent takes place,—for a long while indeed, none whatever ; though after very long standing, a) slight flocky sediment is formed, after which the action is arrested entirely. But if the mixture, either freshly made, or when cleared by subsidence of this sediment, is exposed to sunshine, it instantly becomes milky, and a copious formation of a white precipitate (or a pale yellow one if the platinic solution be in excess, ) takes place, which subsides quickly, and is easily collected. The same takes place more slowly in cloudy daylight. This remarkable action is confined to the violet end of the spectrum. I have exposed tubes of the mixed liquids im- mersed in the sulphuric tincture of red rose-leaves, to strong sunshine for whole days, and (after the first slight deposit al- ready mentioned, which ceases in the first hour,) ‘the remainder is altogether shanwable to red light; but the moment it is taken out of the red liquor and held in free sunshine, the usual pre- cipitation takes place as copiously as if it had been all the time kept in total darknéss. Even yellow liquids suffice to defend it. The precipitate itself is a remarkable one, being a com- bination of the oxide of platinum with lime, in which the oxide seems to perform the part of an’ acid (a property of this oxide which I believe has been before remarked ; though at this distance from my books I cannot say by whom). Muriatic acid dissolves it readily without effecting any decom- position, even when added in too small quantity to take up the whole. Nitric acid also dissolves it; (when newly formed and moist, entirely; when dried, with some residue of oxide). The nitric solution is precipitated by nitrate of silver, and the precipitate, which is ofa high orange colour, and which is a true platinate of silver, is easily distinguished from muriate of silver, not only by its colour, but by its insolubility in the liquid hyposulphites. The above facts were observed by me nearly two years ago, and have been shown by me to a great many individuals at various times in the interval ; among ; whom I may mention the Bishop of Cloyne and Dr. "Somerville, in June last (it I recollect right) ; Sir D. Brewster, Mr, Babbage, Mr. Talbot, and others, in London, last summer, and more recently to yourself; and have been distinctly described to many of my scientific friends in conversation, among whom I will only particularize Mr. Ritchie. I mention these circumstances merely as ascertaining my early and independent observation of a fact which, at the time of its discovery, I considered to be sui generis, and which I sepnpE regard asof slight import- 60 Royal Society. ance either in a photological or a chemical point of view*. My only reason for not at once making it public, was a desire to satisfy myself as to the real distinction (if any) between the white and yellow precipitate formed, when the proportion of lime-water to the platiniferous solution is in excess, and in de- fect, as also to ascertain the nature of that sedimentary deposit which is formed independently of the action of light. With a view to this inquiry, I have now in preparation (as you have seen in my laboratory,) a considerable quantity of the several precipitates in question. Hamburg, June 12, 1832. J. F, W. Herscuen. XVII. Proceedings of Learned Societies. ROYAL SOCIETY. March 15.— PAPER was read, entitled ‘‘ Further Notice of the new Volcano in the Mediterranean.” By John Davy, M.D. F.R.S. Assistant Inspector of Army Hospitals. The author states that since the 25th of October, the date of his last communication to the Society, the crater of the volcano has un- dergone several changes of form, and has now entirely disappeared. He infers from the phenomena observed, that the crater was one of eruption, composed entirely of loose materials, thrown up by volcanic action, and not one of elevation, that is, formed of rock which once composed the bed of the sea. In July the heat at Malta was very close and oppressive, the thermometer rising more than once to 105° of Fahrenheit, and the western sky had a dark lurid red hue: but these atmospheric states are regarded by the author as independent of the volcano, for the temperature of the air in its immediate vicinity was very little affected by it. beri, A Paper was also read, entitled “‘ A method of deducing the Lon- gitude from the Moon’s Right Ascension.” By Thos. Kerigan, R.N. Communicated by Admiral Sir Edward Codrington, F.R.S. The author has recourse to the moon’s right ascension as an ele- ment for determining the true meridian of the place of observation: his method being an extension of that given by himin the first volume of his “‘ Mathematical and General Navigation Tables.” He gives exam- ples of the application of this method, and considers that with the aid of a chronometer showing the approximate mean time at Greenwich, the longitude of any given place may be determined, either at sea or on land, within very narrow limits of error, and with much greater practical convenience than by the ordinary method of lunar distances. March 22.—The reading of a Paper, entitled “ An Account ‘of some experiments and observations on the Torpedo,” by John Davy, M.D. F.R.S. Assistant Inspector of Army Hospitals, was com- menced. * It may be proper to mention that these remarks are made by Sir John Herschel, with reference to the article headed ‘‘ Chemical Action of Light,” &c. given, from the Journal de Pharmacie, in the last Number of the Phil. Mag. and Annals, p. 466.—Eprr. Royal Society. 6L March 29.—A Report, drawn up by the Rev. William Whewell, M.A. F.R.S., and John William Lubbeck, Esq. M.A. V.P. and Treas. R.S., on Professor Airy’s Paper, read before the Royal Society on November 24, 1831, and entitled, “ On an Inequality of Long Period in the Motions of the Earth and Venus,” was read. The conclusion of this Report is as follows : “We regard this paper as the first specific improvement in the solar tables made by an Englishman since the time of Halley, as valuable from the care which the author has employed in the nume- rical calculations, as well as for the sagacity he has displayed in the detection of an inequality so small, and of so large period ; and we recommend its insertion in the Philosophical Transactions.” A notice of Prof. Airy’s Paper will be found in the Phil. Mag. and Annals, vol. xi. p. 117. April 5._The following Report, drawn up by Samuel Hunter Christie, Esq., M.A. F.R.S., and John Bostock, M.D. V.P.R.S., on Mr. Faraday’s Paper, read before the Royal Society on December 15, 1831, and entitled “ Experimental Researches in Electricity,” was read*, Report. In the first section of this paper, the author considers the induc- tion of electricity in motion, ; Shortly after the discovery by Oersted of the influence of elec- tricity in motion on a magnetic needle, it was almost simultaneously discovered by Arago, Davy, and Seebeck, that iron became magnetic by induction from the connecting wire of a voltaic battery, or the passage of an electric current ; but though the effects at first ob- served were afterwards greatly increased by peculiar arrangements, induction was in all cases restricted to iron. Arago’s beautiful ex- periments on magnetic needles vibrating within metallic rings, and on the mutual action of all metals and magnets, when either is in motion, are undoubtedly instances of a peculiar magnetic induction in other metals than iron; but the very doubtful experiment of Am- pére can scarcely be adduced as one. The singular results obtained by MM. Marianini, De la Rive, and Von Beek, referred to by our author, are probably due to electric induction. But none of these can be considered as having originated the discoveries dtscribed in the present paper, excepting so far as all new views originate in the contemplation of results previously obtained. j In this section of his paper the author shows that a peculiar state is induced in a copper wire which is in the immediate neighbourhood of another, through which an electric current passes, that is, which forms the connecting wire in a voltaic circuit. This state of the wire was manifested by its action on a magnetised needle, and by the induction of magnetism in steel wire submitted to its action. Two copper wires, each more than 200 feet in length, were wound in the same direction round a large block of wood, the coils of the * See Phil. Mag, and Annals, N.S. vol. xi. pp. 300, 401, 462, 465 ; and the present Number, pp. 45, 49, & 76. 62 Royal Society. one being interposed between those of the other, and metallic con- tact everywhere prevented. The ends of one wire were connected with a galvanometer, and with the ends of the other, contact could be made or broken with a battery of one hundred and twenty pairs of plates. On the contact with the battery being made, the needle of the galvanometer was invariably impelled in one direction, and on the interruption of the contact, it was always impelled in the con- trary. After the first impulse on the completion of the voltaic circuit, the needle resumed its natural position, no permanent deflec- tion whatever occurring during the time that this circuit remained complete. On substituting a helix of copper wire formed round a glass tube for the galvanometer; introducing a steel needle; making contact, as before, between the battery and the inducing wire; and then withdrawing the needle, previously to breaking the battery contact, it was found to be magnetised. If the contact was first made ; a needle introduced in the tube; the contact broken; the needle on being withdrawn was found to be magnetised to the same degree nearly as the first, but the poles at the corresponding ends were of the contrary kind. If the circuit between the wire under induction and the galvano- meter was not complete when the contact with the battery was made, then no effect on the needle was observable either on completing or again breaking the first circuit. But the battery communication being first made, and then the wire under induction connected with the helix containing the needle, on interrupting the battery circuit, the needle was magnuetised. These last facts, in a theoretical point of view, are most important: they prove that on completion of the voltaic circuit, the state of the wire under induction undergoes a double change, the one momentary, the other permanent so long as the voltaic circuit remains complete, and only exhibiting a momen- tary action on the interruption of that circuit. From the experiments detailed in this section, the author con- cludes, that currents of voltaic electricity produce, by mduction, currents (but which are only momentary) parallel to or tending to parallelism with the inducing currents ; that the induced current, by the first action of the inducing current, is in the contrary direction to, and by its cessation in the same direction as, that of the inducing current. ) The author next introduced iron into his arrangement, by which means a double induction took place, the iron itself becoming mag- netic by induction, in the first instance, and electricity being induced in the copper wire from the magnetised iron, in the second. The effects were here of precisely the same character as before, but greatly increased. By this arrangement unequivocal evidence of electricity in the wire under induction was obtained ; for not only was the needle in the galvanometer violently affected, but a minute spark could be perceived on using charcoal at the ends of that wire. On dispensing altogether with the voltaic arrangement, and sub- stituting for the electro-magnet a cylinder of soft iron, rendered Royal Society. 63 magnetic by contact with two bar magnets, or a common cylindrical magnet of steel, similar results were still obtained. ‘The arrange- ment and the effects were simply these: several helices of copper wire were formed, in the same direction, round a hollow cylinder of pasteboard, metallic contact being prevented between the contiguous coils: of these, either the aliernate ends were united, to form one long helix, or all the corresponding ends to form a compound helix; and within the pasteboard cylinder, a cylinder of soft iron was intro- duced: on the ends of this cylinder being brought into contact with the poles of two bar magnets, united at the other ends so as to re- semble a horse-shoe magnet, the needle of the galvanometer was impelled in one direction, and on the contact being broken, in the contrary. Similar effects were produced by simply introducing a cylindrical steel magnet into the hollow cylinder over which the copper wire was wound. ‘The effects were strikingly increased, but were still of precisely the same character, when Knight’s large com- pound magnet, belonging to the Royal Society, was substituted for the bar magnets. Here, the mere approximation to the magnet, of the compound helix, whether containing the cylinder of soft iron or not, was sufficient to impel the needle in one direction, and its recess from the magnet, to give a contrary impulse. But even here, the effects were purely impulsive, the needle invariably returning to its undisturbed direction, when the contact was continued. As inthe voltaic arrangement, a small voltaic apparatus, sufficient to deflect the needle of the galvanometer 30° or 40°, being intro- duced between the galvanometer and the helix under induction, pro- duced no effect on the impulses given to the needle, on making and breaking contact of the iron cylinder with the magnet: nor did the power of this arrangement appear to be affected after making the contact or after breaking it. Although all attempts to obtain chemical effects or a spark in this ease failed, yet we agree with the author that these experiments prove the production of electricity by ordinary magnetism, and think the reasons which he adduces for its want of energy satisfactory *. This discovery has therefore supplied the link in the chain of con- nexion between electricity and magnetism, which has been wanting since Oersted’s discovery. That the electricity developed acts in a peculiar manner, so far from diminishing the interest attached to the discovery, adds greatly to its value. After the detail of these perfectly original and highly interesting experiments, the author considers the peculiar electric state of the wire when subjected either to volta-electric or magneto-electric in- duction. This state he terms the electro-tonic state. Unlike the induction from electricity of tension or the ordinary * Since this report was written, a brilliant electric spark has been obtained by Mr. Faraday and Mr. Christie with this magnet, by the very means which, at this time, failed, in consequence of two contacts not taking place at the same instant, on which circumstance the success of the experiment appears entirely to depend. 64 Royal Society. induction | froni a magnet, phi Stat’ of the wite As not andlogous to nues, there is no evidence of any change ere taken ‘hee in it, and its change of state is only rendered manifest'at the instant of in- terrupting the circuit or the contact, and at that of again renéwing them ; impulsive forces being brought into action at ‘either Instant, but in contrary directions in the two cases. The author observes, that this peculiar condition shows no MhbWh electrical effects whilst it continues, nor has he yet been able’ to dis- cover any peculiar powers possessed by matter whilst retained in this state ; that no re-action is shown by attractive or repulsive powers ; ; that no retarding or accelerating power is exerted upon electric cur- rents passing through metal in “ithe electro-tonic state, that i Is, the conducting power is not altered by it; that all metals take on this peculiar state; that the electro-tonic state is altogether the effect of the induction excited, and ceases with the fad ueage power ; ‘that this state appears to be instantly assumed, the force brought into action at the instant of its assumption being merely impulsive. , The author considers that the current of "electricity which induces the electro-tonic state in a neighbouring wire, probably induces that state also in its own wire, and that this may be the case with fluids and all other conductors; and concludes that if it be so, it must in- fluence voltaic decomposition and the transference of the elements to the poles. Should facts be found to accord with these views, we consider the author fully justified in his anticipations of the impor- tance of his discovery as applicable to the decomposition of matter, and we certainly feel that the discovery could not have been ‘made by any one more likely to decide this question, or more able to avail himself of a new principle of decomposition when discovered. In the series of actions proceeding from the voltaic battery which this discoyery exhibits to us, a very curious succession is observable. Volta-electricity passes along the connecting wire of the battery, electro-magnetism at right angles to it. By this means the cylinder of soft iron, within the helix i into which the connecting wire is formed, becomes a magnet. If the poles of the magnet be joined by an ‘iron bar, ordinary magnetism passes along this bar, hut magneto-electri- city is induced at right angles to it in a helix wound round it. And again, magneto- ‘electricity i is propelled along the wire, and magnetism is HSE 4 in a steel bar at right angles. This bar may again indies magneto-electricity in a wire ‘at richt angles to it, by which another bar. may become magnetic ; and so on, showing a repetition of" ‘simai- lar powers successively br ought into action, but their _ efficiency at each step greatly diminished. ‘The effects hitherto described were dué to a momentary action : in order to obtain continuous action the author applied the pr inciple of circular motion. For this purpose a thick’ copper d dise was madé to revolve near the magnet, so that a portion near ‘its edge passed between the ends of two bars of iron which concentrated and ap- Royal Society. 65 proximated the poles. The edge and a portion round the centre of the disc were well amalgamated : an amalgamated conductor was ap- plied to the edge of the disc near the poles, and with this, one end of the wire of the galvanometer was connected, the other end being connected with the centre of the disc. While the disc revolved, the needle of the galvanometer was permanently deflected at least 45° in one direction ; and when the motion of the disc was reversed, the permanent deflection was in the opposite direction. When the disc revolved horizontally in the direction of the sun’s daily motion, the unmarked pole being beneath the disc and the marked pole above, it appeared, by the indications of the galvano- meter, that positive electricity was collected at the edge of the disc nearest to the poles: if the marked pole was below and the un- marked pole above, then negative electricity was collected at that part of the disc: and if in either case the direction of the motion was reversed, the nature of the electricity collected at the same place was also reversed. The experiment being made ina still more simple form, by pass- ing a plate of copper longitudinally between the poles of the mag- net, it appeared that positive electricity was collected on one edge of the plate, and negative on the opposite; and if the plate was passed in the contrary direction, then the electricities on the edges were reversed, When a wire was passed laterally between the poles, similar results were obtained. The law according to which the electricity excited depends upon the pole of the magnet near which a wire moves, and the direction of its motion, although not so expressed by the author, appears to be this : Let the wire revolve parallel to itself about a bar magnet, so that its centre coincides with any curve ;-—for example, (in order to mark more readily the points where the direction of the current of electricity changes, ) with an ellipse, the major axis of which coincides with the axis of the magnet, and the minor axis passes through its cen- tre; let the wire be inclined at any angle to the plane of the ellipse, which in the first instance we will suppose to be horizontal, and that the marked end of the magnet is pointing north; and let the wire move parallel to itself in the direction of the sun’s daily motion ; then while the wire revolves from the western extremity of the axis minor round the marked pole to the eastern extremity, the electric current will be from the end of the wire below to the end above the orbit : while it is revolving from the eastern extremity round the unmarked pole to the western extremity of the axis minor, the current of elec- tricity will be from the upper to the lower end of the wire; and whatever position the plane in which the wire revolves may take by revolving about the axis of the magnet, or whatever may be the po- sition of this axis, still the current of electricity will be from the end of the wire in the same position, relatively to the plane of revolution, as before. If the direction of the motion be reversed, the direction of the current will likewise be reversed. It would follow from this, that if two wires ‘parallel to each other, Third Series, Vol. 1. No. 1. July 1852. kK 66 Royal Society. on opposite sides of a bar magnet, and perpendicular to its axis, be moved along the sides of the magnet in the same direction, the cur- rents of electricity in them will be in opposite directions ; and hence we may draw this important conelusion,—that there must be some in- ternal arrangement in a magnet, whether of currents or of particles, which renders the same absolute motion, ‘a motion in contrary direc- tions relatively to such arrangement on the opposite sides of the magnet. From all these experiments the author concludes, that when a piece of metal (and the same may be true of all conducting matter,) is passed either before a single pole, or between the opposite poles ‘of a magnet, electric currents are produced across the metal, trans- verse to the direction of motion; and which therefore in M. Arago’s experiments approximate towards the direction of radii. Assuming the existence of these currents, he satisfactorily accounts for the phenomena observed in these experiments and in those by Mr. Babbage and Sir John Herschel. Thus, the dise revolving in the direction of the sun’s daily motion beneath the marked pole of a Magnet, currents of positive electricity set from the central part to- wards the circumference near the pole, and the action of these cur+ rents is to move the pole also in the direction of the sun’s motion; ‘so that the magnet, if at liberty to:revolve, will move in the same direction as the disc. Electric currents similar'to those produced by passing copper be- tween the magnetic poles, were produced by iron, zine, tin, lead, mercury, and all the metals tried. The earbon deposited in the coal- gas retorts also produced ‘the current, but ordinary charcoal did not; nor could any sensible effects be produced with brine, sulphu+ ric acid, or saline solutions. Although the author succeeded in ob- taining a continuous current of electricity by means of the revolving disc, yet he was not able, by this means, to produce any ‘sensation upon the tongue, to heat fine platina wire, to produce a spark with charcoal, to convulse the limbs of a frog, or to produce any chemical effects. That he should have failed in obtaiming these most striking effects of electricity, we attribute to the feebleness of the electricity excited, and feel assured that by adopting means greatly to increase the intensity, all these effects will result from the electricity derived from ordinary magnetism. wets The facts contained in this paper of Mr. Faraday's, and the:con», clusions which he draws from them are’so important, that we ifeehwe should not have done justice to the communication, had we not given an abstract of the whole, at the same time that we stated our ‘opi+ nion of its value. Had the author’s discovery consisted alone of the simple fact, that steel may be magnetised by a distant magnet, in a manner similar to that employed with the voltaic battery, we should have considered it of the highest importance in the inquiry concerning the connexion between magnetism and electricity ; but when we see permanent effects which, hitherto, have only been derived from electricity, now derived from the common magnet, by calling in’ the aid of motion, showing clearly that electricity can thus be excited ; Royal Society. 67 and find that the laws which govern the pheenomena are established, we cannot but entertain hopes that a door has been opened through which may at length be discovered the precise distinction between two agents which in many respects so greatly resemble each other in their effects and in their laws of acting. Such being our opinion of the results obtained by Mr. Faraday, we can have no hesitation in recommending most strongly the publication of his paper in the Transactions of the Royal Society. (Signed) S. H. Cunisriz. 4 J. Bostock. _ Dr. Davy’s Paper on the Torpedo, was then read in continuation, April 12.—The reading of Dr. Davy’s Paper, entitled, “ An Ac- count of some experiments and observations on the Torpedo,” was resumed and concluded. The late Sir Humphry Davy gave an account, in a paper pub- lished in the Philosophical Transactions for 1829*, of some experi- ments which he made on the Torpedo, with the view of ascertaining how far its electricity is analogous to that of the voltaic, or other galvanic batteries; but the results he obtained were altogether of a negative kind. He was prevented by the declining state of his health from prosecuting this inquiry, which he was still ardently bent upon completing, and which he requested his brother would carry on after his death. The author, accordingly, when at Malta, being ina fa- vourable situation for obtaining living torpedos, made the series of experiments which are related in the present paper. They entirely confirm those of Mr. Walsh made in 1772, and which established the resemblance of the agency exerted by this fish to common elec-= tricity ; and they also prove that, like voltaic electricity, it has the power of giving magnetic polarity to steel, of deflecting the magnetic needle, and also of effecting certain chemical changes in fluids sub- jected to its action. Needles perfectly free from magnetism were introduced within a spiral coil of copper wire, containing about 180 convolutions ; the whole coil being an inch and a half long and one tenth of an inch in diameter, weighing only four grains and a half, and being contained in a glass tube just large enough to receive it. On the electric discharges from a vigorous torpedo being made to pass through the wire during a few minutes, the needles were ren- dered strongly magnetic. The same influence transmitted through the wires of the multiplier produced very decided deflexion of the needle; the under surface of the electrical organ of the torpedo, corresponding in its effect to the zinc plate of the simple voltaic circle, and the upper surface corresponding to the copper plate. No: effect of ignition could be perceived when the discharge from the. torpedo was made to pass through a silver wire one thousandth of an inch in diameter: nor could unequivocal evidence be obtained of the production of sparks on interrupting the circuit; the slight lu- minous appearances which occurred being probably of the same kind * Sir H. Davy’s Paper on the Torpedo will be found in Phil. Mag. and Annals, vol. yi. p. 81. K. 2 68 Royal Society. as those often’ exhibited by 'séa water when agitated.” “A small gold chain, however, coinposed ‘of ‘sixty double Jinks, was’ found ‘to be capable of transmitting the shock ; a fact which seems to show that air Is not iinperteable to ‘the’ electricity of the torpedo. -When fine silver wires, interrupted by a solution of common salt,’ were placed in the circuit, minute bubbles of air collected round the point communicating with the under ‘side of the torpedo, but! none at the other point.” When gold wires, instead’ of the silver ones, were used, gas was evolved from each of the extr emities ;/ but in greatest quantity, and in smaller bubbles, from the lower, ehiny from the upper wire. With a strong solution of nitrate of silver! the point of the lower gold wire became black, and only two or three bubbles arose from it; the point of the upper ‘gold wire remaining bright, and being sunrroulided with many bubbles. Similar, but less distinct, results were obtained by employing a strong solution of superacetate of lead. The remainder of the paper is occupied with a detailed account of the anatomical structure of the electrical organs of the torpedo, and of ‘the- muscles that surround them.. The texture of the co- lumnar portions of those organs appears to be homogeneous, with the exception of a few fibres, probably branches of nerves, which pass into them. » A large quantity of water, separable by evapora- tion, enters into their composition: and they undergo spontaneous changes more slowly than the muscles.. They are incapable of con- traction by any of the ordinary stimuli, and even that of an electric shock from a voltaic battery, applied either to the organs themselves or to the nerves which supply them. . Hence the conclusion jis drawn that these organs are not muscular, but that their columns are formed by tendinous and nervous fibres, distended by a thin) ge- latinous fluid. The anatomical account is concluded by a description of the origin, course, and distribution of the nerves belonging to the elec- trical organs. The author found that the gastric nerves are derived from these ; and hazards the conjecture that superfluous electricity may, when not required for the defence of the animal, be directed to the stomach, so as to promote digestion: in corroboration of which he cites the instance of a torpedo which, when living, had been frequently excited to give shocks, and in whom a small fish found:in its stomach after death, appeared to be totally undigested. The secretion of mucus was also either suppressed or considerably diminished: From the circumstance that the branchie are supplied with twigs of the electrical nerves, the author conceives there may be some connexion between the electrical and the respiratory func- tions ; and that the evolyed electricity may be employed in decom- posing water, and in thus supplying the system with air, in situations where} the animal has not access to that of the atmosphere. The author.considers the mucous system of the torpedo as performing important offices in its ceconomy, in consequence of its connexions with the electrical nerves. Contrary to the statement of Mr. Hunter, he finds that the electrical organs are very scantily supplied with blood-vessels. He concludes by some remarks on the peculiar Royal Society. 69 characters of the electricity of the Torpedo, the, purposes it appears to serve, and the -varieties exhibited) by, different individuals, ac- cording to the age, the'sex, and other circumstances, ». The Meetings of the Society were then adjourned.over Easter to the third of May. ' May 8.—The following Report, drawn up by the Rev. William Whewell, M.A. F/R.S., the Rev. George Peacock, M.A. F.R.S,, and the Rev. Henry Coddington, M.A, F.R.S., on Mr. Lubbock’s Paper, read before the Royal Society Feb. 9, 1832, and entitled, ‘ Re- searches in Physical Astronomy,’—was read. i Report. The method of the variation of parameters as applied to the in- vestigation of the perturbations of the solar system has been suc- cessively developed in modern times. This method gives the vari- ations of the elements of the elliptical orbit in terms of the differentials of a certain function F of these elements, and of the disturbing forces. Euler, Lagrange (1783), Lagrange and Laplace (1808) obtained the formule for da, de,da,dp, dq where p = tan ¢ sin 6,qg= tan ¢ sin 9. Poisson first gave the expression for de. Pontécoulant, p. 330, has introduced di and dy instead of dp and dq; but those develop- ments gave expressions neglecting the square of the disturbing force. Mr. Lubbock has published (in a Paper in the Phil. Trans. April 1830, ) expressions which include the effect of any power of the disturbing force. This method has been principally applied to the secular .in- equalities; but itis susceptible of being applied with no less strictness to periodical inequalities, all of which may be represented. by certain changes in the elements of the elliptical orbit. “But the same problems may also be approximately solved di- rectly; for we obtain a differential equation involving the radius vector and the time. In this equation there occurs the same func- tion & of which we have already spoken; and this function is ex- panded. according to terms involving cosines of the mean. motions of the disturbing and disturbed planet, and cosines of the difference of certain multiples of these motions... This expression has been treated of by various authors, and among others Mr. Lubbock has himself (in memoirs read May 19 and June 9, 1831,) given the ex- pansion of & in a form suited to his present object. The coefficients of the terms in this expansion are arranged, as usual, according to the order of the excentricities, their powers and products, and to the power of the sin? of half the inclination. These eoefficients involve also certain quantities b,,; where n and «have a variety of values; and these quantities depend on the ratio of the mean distances of the disturbing and disturbed bodies from the sun. _ Solving the differential equation which involves 7, by the equating of coefficients, Mr. Lubbock finds a value for the reciprocal of'r in such terms as have been mentioned. By certain algebraical trans- formations of the fractional coefficients in which é occurs, (and by certain equations of condition between bs > 6 bs), and between similar quantities,) the expression for the reciprocal of r is transformed and reduced, the arcs remaining as they were. 3,i? 70 Linnean Society. But by the properties of the ellipse, the reciprocal of r is equal to a series of terms inyolying the excentricities, and involving also co- sines\of the mean anomaly and its multiples :-and. hence the variation of this reciprocal is equal to a similar series, involving sines and co- sines of such arcs, and involving also the variations of the elliptic elements. By substituting the variations of the elliptic elements given by the formule above mentioned, when we put for & its expansion, we have a certain series of sines and cosines with their coefficients multiplied into certain other sines of the same kind. It is found that the sines and cosines thus multiplied produce, by trigonometrical transformations, arcs identical with those which were found in the value of the reciprocal of x obtained by the former method ; and the coefficients are also found to be identical with those resulting from the former transformations and reductions. We have not thought it necessary to verify the somewhat complex reductions by which Mr. Lubbock has shown the identity of the results obtained by these two methods. The mode of proceeding is per- fectly satisfactory, and the truth of the conclusion might have been foreseen. The reductions, however, by which identity was to be exhibited were by no means obvious: and we conceive it not un- likely that the development of them may sometimes be of use in enabling us to judge which of the two methods of solution may be applied with most convenience in particular cases. ‘We are of opinion that this Paper is well worthy of being printed in our Transactions. (Signed) W. WHeEwELL. Gro. Pracock. |” H. Copprneron. LINNZAN SOCIETY. June 5.—A paper was read, entitled, ‘‘ Additional Observations on the Sexual Organs and Mode of Impregnation in Orchidee and Asclepiadee,” by Robert Brown, Esq. V.P.L.S. These additional observations to a paper communicated to the Society in November, and of which an abstract is given in the Phil. Mag. and Annals for December last, relate entirely to Orchidee. The author begins by remarking, that as the tubes forming the mucous cords were never observed in the cavity of the ovarium until after the application of the pollen to the stigma, and as these tubes very nearly resemble those immediately derived from the pollen, he had in the paper referred to considered them as having the same origin. r But as he has since ascertained in several cases, especially in Bonatea speciosa, that the application of a small portion of a pol- len-mass to the stigma is sufficient for the production of mucous cords of the usual size, and as the number of tubes thus produced is much greater than that of the grains of pollen actually applied, he is now led to believe, that these tubes do not immediately pro- ceed from the pollen, though its application to the stigma is neces- sary for their production. In what manner they are generated, however, he does not attempt to explain, He finds in Bonatea Linnean Society. _ 71 speciosa, as well as in the other Orchidee examined with this view, that°the earliest appéarance’ of ‘these tubes is in the tissue of the stigma'in the immediate neighbourhood of the pollen tubes, ‘rom which they are with’ difficulty distinguishable, and only by their generally more flattened and less granular appearance, and by those interruptions in. their supposed cavity which he had formerly ob- served, and termed coagula;—that from this part of the tissue they gradually descend, at the same time increasing apparently both in number and length, until they arrive in the cavity of the ovarium, where the cords which they form also by degrees elongate and sub- divide in the manner described in the original paper. In addition to the account there given, he observes that although in several cases he has not been able to trace any tubes going off from the six principal cords, yet that in others, and particularly in Orehis Morio, he has seen them scattered over the whole ‘surface of the placentz ; and in the same species, in several, though not in many instances, he has been able to trace asingle tube to the aperture of the testa of an ovulum. Since this paper was read, the author has found in Habenaria viridis, in like manner, and in many cases, tubes inserted into the apertures of ovula. To account for the greater part of the flowers of an Orchideous spike being fecundated, which not unfrequently happens, he ob- serves that from the greater degree of viscidity existing in the re- tinaculum than in the stigma, and from the viscidity of the sur- face of this organ being sufficient to overcome the mutual cohe- sion of the lobules:of pollen in most Ophrydee, a single insect may readily impregnate many flowers with one and the same mass of pollen ; a fact which he has confirmed by experiment in Bonatea. He observes, however, that even in Ophrydee exceptions occur to these relative degrees of viscidity, especially in Ophrys, the insect forms of whose flowers are so striking; and as he finds, that in this genus the assistance of insects in impregnation is less ne- cessary, he concludes that these forms are intended rather to repel than attract, and he adds that the flowers of Orchidee having those remarkable forms, resemble the insects of the country in which the plants are found. And lastly, he remarks, that in a few cases, from the relative po- sition of the parts of the flower, the pollen-masses are brought into contact with the secreting surface of the lateral stigmata, and the assistance of insects is therefore wholly superseded, as in Neottia elata, which, accordingly, seldom fails uniformly to ripen its cap- gules, The East India Company have presented to the Linnzan So- ciety their magnificent Herbarium, containing the plants collected between long. 73° to 114° E. and lat. 32°.N. to the equator, by Kénig, Roxburgh, Riittler, Russell, Klein, Hamilton, Heyne, Wight, Finlayson, and Wallich. It includes about 1300 genera, more than 8000 species, and amounts, in duplicates, to at least 70,000 specimens,—the labours of half'a century. 72 Royal Institution of Great Britain. For many years a large portion of these vegetable riches were stored on the. shelves.of the India House, without any one suffi- ciently conversant in, Indian Botany to arrange and render them subservient to the cause of science,,_ On the arrival in this country of Dr.Wallich, the distinguished superintendant. of the Company’s Garden at Calcutta, in the year 1828,—who brought with him an immense accession to the Herbarium from various parts of India, especially Nipal and the Burmese Empire,—the Court of Directors instructed. him to make a Catalogue of the aggregate collection, and to distribute duplicate specimens to the more eminent Societies and naturalists throughout Europe and America, __ This immense labour has occupied Dr. Wallich for the last four years; and it is the chief selection from these various Herbaria, destined for the museum of the India House, which the Court of Directors have, with princely munificence, presented to the Linnean Society. The liberality of the East India Company has been duly appre- ciated throughout the wide circle of science. It has been acknow- ledged by letters and addresses from the different Societies and individuals honoured by their patronage ; and this last act of their bounty will endear them still more to the promoters of Botany, by placing the treasures they possessed along with those of Linnaeus and Smith. ; The Linnzan Society purchased, two years ago, at an expense of 3000/., the collections of Linnzus and of the late excellent Sir J. E. Smith ; and since that the Herbarium of the Society has been further enriched by the treasures of the East, it forms collectively one of the most interesting and important in Europe. : The East India Company have set an example of a wise and liberal policy, which will be followed throughout the world, not only by Societies, but by those enterprising individuals who have, to their own honour, made large collections of the objects of natural history; and it is a source of national congratulation that at this moment the naturalists of Europe feel indebted to this country for the most extensive contribution that was ever made to their botani- cal collections. We owe this general feeling of respect towards us to the enlightened conduct of the Court of Directors, who have done more to diffuse a knowledge of Botany than was ever done by any Government or association of persons on the globe. A deputation from the Council of the Linnzan Society, headed by the President, Lord Stanley, waited on the Chairman of, the Court of Directors, on the 26th instant, with an address expressive of the high sense the Society-entertains of the honour conferred upon it by the liberality of the East India Company. , a ———— FRIDAY-EVENING PROCEEDINGS AT THE, ROYAL INSTITUTION : OF GREAT BRITAIN. slga April 13.—Dr. Marshall Hall onthe Laws which govern the mu- tual relation of Respiration and Irritability. The object of this lecture was briefly to present the results of an Royal Institution of Great Britain. 73 experimental investigation into the ratio which obtains between the quantity of the réspiration and the degree of theirritability in the different series and forms of being in the animal kingdom. ~ The quantity of the respiration is expressed by the quantity of oxygen removed in a given space of time. The degree of the irritability is denoted by the Hepied laid dura- tion of the contraction of the heart and of other muscular ‘parts, on the application of'a given degree of stimulus. These two propefties are “always found to be in an inverse ratio to each other.“ In animals of a high respiration, as the birds and the mammalia, the degree of irritability i is low; in animals of a low re- spiration, as the tortoises, the serpents, the batrachia, the degree of irritability is extreme. _ It is absolutely necessary to distinguish activity from irritability. The former seems to depend upon ‘the action of a highly arterial blood upon the nervous system, and is great in birds and the mam- malia; the latter is inherent in the muscular fibre itself, and seems to result from its peculiar organization and condition at the time. The law of inverse respiration and irritability applies not only to the different individuals of the animal series, but to the different forms. of the same animal. The egg, the tadpole, the larva, have respectively a lower respiration and a higher irritability than the same beings in their subsequent higher states of existence. _..The same law still obtains in animals which undergo a change of condition from the operation of some natural causes, as in the dipr- nation. and hibernation of the bat; in torpor from cold in animals which.do, ordo not, hibernate; in the case of the privation of food, &c. But the most extraordinary exemplification of this law is in the double heart of birds and of the mammalia itself. The left side of this organ, which receives a highly arterialized or respired blood, possesses a low degree of irritability ; the right side, which receives blood of an unrespired. character, possesses a high irritability: the latter continues to beat after the former has ceased its contractions, Various deductions were drawn. from’ these observations... It was shown, that'with the high respiration and low irritability coincide, ‘d. great necessity for air and food; 2. a high ensidal temperature ; 3. great activity ;)4. little tenacity of life; and, 5. a greater power of bearing augmented than diminished stimulus in ‘general :+-And. that witha high irritability and a low respiration co-exist, 1. the power of sustaining the privation of air, of food, &c.; 2. alow animal tempe- tature ; 3. little activity ; 4. great tenacity of life; and, 5. little power of bearing the action of augmented stimulus. The former class are more injured by exposure to cold, the latter by heat. The lecture was concluded by a hasty reference to the interesting facts detailed by Legallois and by Mr. Edwards, which, although given in an isolated form’ by those authors, admit of being readily explained and arranged by a reference to the law,—that the quantity of the ‘respiration is inversely as the degree of the irritability, and to the corollaries which flow from it. Third Series. Vol.1, Nov), July 1832. L - 74 Royal Institution of Great Britain. May 4.—Mr. Cottam on the application of cast-iron to bearing purposes, especially in the-form of beams, girders, brackets, &c. &c. — love! The cross levels of the sector were successively adjusted: to their marks, when both extremities of the horizontal wire, as measured by, the square telescope, had been found, from the Instrumental Error of his Horizon-Sector. 105 indications of Fortin’s level, to be of equal height. It was discovered that the process of adjustment had, however, dis- turbed the parallelism of the vertical wire to the plane of the arcs; the latter being now a little out of perpendicular, yet by a quantity too minute to affect the result of the measure- ments, unless the figure of the cylindrical rings proved enor- mously bad. The horizontal wire of the sector being scrupulously ad- justed, the vertical ene served to regulate the pearl slips of the proof-telescopes; effected by making their edges parallel toit. With this precaution, cross levels for the proof-tele- scopes, otherwise indispensable, were quite superfluous. To insure the constancy of the adjustment of the zero-line of each index to that of its corresponding arc, Mr. Lealand had recently fitted to each index a powerful clamping appa- ratus. And it may here be remarked, that the clamping of the indices, the fixing of the levels, &c., were completed many days before the measurements were undertaken, and had passed in the interim through a range of temperature and moisture of great extent. The trial of the reversing points of the great levels of the sector took place, as soon as possible after every set of mea- surements, with the instrument standing on the plank, to which it was generally glued, in lieu of placing it, in a dif- ferent temperature, on the stone pillar. To guard against the slight unsteadiness of the plank, the square telescope was stationed near the sector, the bubble of its highly sensible level being kept stationary between two certain marks of its scale some moments before the reading of the sector levels commenced. . The trials, which were very numerous, were not so accordant with each other as might have been antici- pated from the extreme care devoted to them. ‘Some of the discordancies were wholly inexplicable ; one level continuing constant during the repetitions, and the other oscillating 2’ or upwards about what proved to be the mean. Process of Measurement.—The sector* (of which the line of collimation will represent the ray of light from the distant object of our theory,) being placed at the northern end, and Dollond’s telescope at the southern end of the plank, the mid- dle line of the pearl slip of the latter was got to be in a line with, or of the height of the horizontal wire of the sector, the vertical wire of the latter apparently bisecting the slip. The level of the sector, then uppermost, and that of Dollond’s tele- scope’ being both noted, the other telescope was removed, and * Any other telescope would have equally answered the purpose. Third Series, Vol. 1. No. 2. Aug. 1832. F ‘ 106 Mr. J. Nixon on the Measurement of the the square one oceupied its place. Keeping the sector-level exactly at its mark, a certain division of the pearl slip of the square telescope was made coincident with the horizontal wire of the sector. Fortin’s level was then read off. Substituting for the sector Dollond’s telescope, with its level stationary at the previous mark, the division of the narrow slip of the square telescope was got in a line with the middle division of the broader slip of Dollond’s telescope, (both slips being longitudinally bisected by the same (imaginary) vertical line,) and the position of Fortin’s level subsequently noted. It is now evident that when (the centre of) the bubble of Fortin’s level stood at a point of its scale between, and equi- distant from, its last and previous positions, the line of colli- mation of the square telescope must have been truly horizon- tal. ‘This level point, as it may be termed, came out, Feb. 9th (1832), at 124°5 of Fortin’s scale. 10th 124 °7 ditto. 11th 124 °5 ditto. As one degree of the scale answers to 0'"6, the deviation from the mean was limited to a range of 0-1. Hence the method, from its great simplicity and accuracy, might be successfully applied to astronomical instruments. Lastly, the square telescope, being still in its place with its bubble at the level point, the sector was placed to the north of it (in lieu of Dollond’s telescope), and its horizontal wire made coincident with the division of the slip before as well as after the cylinder of the sector had been inverted within its Ys; the reading of the great level uppermost succeeding each coincidence. With the difference between the reversing point and re- gistered position of each level we compute the observed de- pression of the (level) line of collimation of the square tele- scope, which will be equal to the error of the sector. During the experiments a thermometer, constantly on the plank, ranged between 55° and 57° Fahr. ; but a more certain criterion of the uniform temperature of the levels was afforded in the lengths of their bubbles, which occupied constantly the same number of degrees of their scales. 1832. Feb. 9th. Temp. 57° F. Error = 18!*] 10th. 57 20 11 Me 19!" Repetition of the Fourth Method, with the Object-Glass fixed within the Eye-end of the Cylinder. — The results of the measurements were, 11th. 57 ae 19°71 Being unable to explain why the average of the measure Instrumental Error of his Horizon-Sector. 107 ments by the last and preceding methods should exceed by 7'' those derived from the eleventh method, the eye-piece of the sector was taken out of its cylinder and replaced by the object- glass (described page 339), which was attached to the cylinder by two screws passing through a slit in the latter. By this ob- ject-glass the level line of collimation of the square telescope, measured twice, (precisely on the same plan as previously by the proper object-glass of the sector,) appeared under an elevation, not of about 20" as might have been anticipated, but of only 5-7. Although the reversing points of the great levels (which were obtained with both object-glasses remain- ing within the cylinder,) had not varied materially from their preceding value, yet to avoid all risk of error, a set of mea- surements were immediately undertaken, without the slightest alteration in the state of the sector, by its own object-glass, which gave 21"-9 for the error. As the average of the re- 21:9-+5°7 a sults by the two object-glasses 4 = a=) hy! ‘8, ) agrees within the fraction of a second with that by the eleventh me- thod, it is highly probable that the measurements by the ad- ditional object-glass were vitiated either by the tube con- taining it projecting so much beyond the cylinder as to pro- duce flexure, or because the tube did not fit perfectly tight within it. In fact, when the cylinder was raised carefully out of, but immediately replaced within its Ys, by taking hold of the two tubes containing the object-glasses, the inclination of the line of collimation of the additional object-glass varied se- veral seconds. It should also be remarked that the error by the tenth method, which differs slightly in principle from the eleventh, but does not require an additional object-glass to the sector, indicated the error to be 21"*3. On the other hand, it must in candour be admitted that a deflection of the pro- jecting tube occasioned by its own weight would lower the line of collimation of the (adjusted) sector, and tend to augment its constant error. Professor Bessel states that the pivots of the axis of his meridian circle are cylinders, of unequal diameter, and that their axes are not situated in the same straight line. The formulze for the requisite corrections (all the principles of which, I must confess, I do not fully comprehend,) are given in the Phil. Mag. vol. Ixiii. pages 434 and 435. It has been mentioned, (Phil. Mag. and Annals, N.S. vol. x. page 344), that on reversing the cylinder of the sector when fitted up with an extra object-glass placed within the eye-end, P2 108 Mr. J. Nixon-on the Measurement of his Horizon-Sector. the line ofcollimation of the latter deviated 11" in azimuth from an exactly opposite direction. As the cylindrical rings are of unequal diameter, they cannot both come in contact with the same Y at equal heights within it; it would there- fore require an almost impracticable symmetry in the sides of the Ys to insure to the axis of the cylinder a precisely oppo- site direction when reversed within them. With a view to determine whether the deviation proceeded from the irregu- lar figure of the Ys or from the excentricity of the rings, the sector, containing its own and the additional object-glass, was fixed between two proof-telescopes; but the experiments were abandoned on discovering that the line of collimation of the proof object-glass was irremediably so much out of parallel with the axis of the cylinder, that neither the level of Fortin, nor the longer one of Lealand, could measure the angle. The only consistent theory that can be suggested in expla- nation is that which assigns a flexure, not to the projecting tube, but solely to the cylinder of the sector. ‘The conse- quences would be an increased elevation of the lines of colli- mation of both object-glasses, occasioning an augmentation of the constant error with an object-glass (in its usual situation) at the thicker end of the cylinder, and a diminution of the error when the object-glass made use of is placed at the smaller extremity. Were the cross wires fixed equidistant from the ends of the cylinder, half the sum of the instrumental errors by the two object-glasses'(as the increment in one and the decrement in the other produced by flexure would be: equal and opposite quantities,) should be equivalent to the error arising solely from the unequal diameter of the cylindrical rings. This half-sum or mean error has been found: by the eleventh method to amount to 14”; and the purely cylindrical error comes out by the first method at 17". Admitting the total error for the proper object-glass to be 20", its value for the additional one should be (14—Z0—14 =) 8"; which ex~ ceeds the actual measurement by only 2". The cross wires are fixed nearest the smaller end of the cylinder, which would make the flexure most, and the total error least, for the addi- tional object-glass. But were we to confide in the results by the first methods, the flexure for the proper object-glass would be (20—17 =) 3", and for the other (17—6 =) 11". . [To be continued.] {109 \J XXIII. On some Atomic Weights. By EpwArp TURNER, M.D. F.R.S. Lond. & Ed., Sec. G.S., Professor of Chemistry in the University of London.* » lean adoption by British chemists of the opinion, that atomic weights are multiples by whole numbers of the atomic weight of hydrogen, and the experimental contradiction given to that opinion by so distinguished an analyst as Berzelius, induced me about three years ago to undertake an inquiry into the subject. As nearly the sole evidence in proof of the multiple theory is embodied in the First Principles of Che- mistry, published by Dr.'Thomson, I turned to that work with the view of putting some of the statements, contained in it, to the test of careful experiment. I commenced with investiga- ting the composition of the chloride of barium, because Dr. Thomson had employed it as a means of obtaining a con- siderable number of his results. My inquiry, published in the Philosophical Transactions for 1829+, proved the existence of a material error; and Dr. Thomson has since acknowledged it by changing the equivalent of barium from 70 to 68 t., It is obvious that this error vitiates many of his other equivalents; and that as so great a mistake has been committed in.a fun- damental question, an inquiry into the accuracy of minor points is superfluous. I apprehend, therefore, that the atomic weights ‘at present employed by British chemists are unsupported by satisfactory experiments, and that those who adopt the multiple theory cannot adduce exact analyses in defence of the practice. With this feeling I have occupied my leisure for some time past in examining the equivalents of several important substances, endeavouring to ascertain the value of the numbers adopted in this country compared with those of Berzelius. I. shall confine myself entirely to results, partly because some. of the points are not yet settled to my satisfaction, and partly because I hope early in the ensuing winter to lay the details in a more perfect form before the Royal Society. Lead.—The equivalent of lead is frequently employed as the basis of calculation in chemistry. ‘The number adopted .in this country, on the authority of Dr, Thomson, is 104. Berzelius has lately repeated his earlier experiments on the * Read before the Chemical Section of the British Association at Oxford, June 27, 1832; and communicated by the Author. + Dr. Turner’s paper “ On the Composition of Chloride of Barium,’’ will be found in Phil. Mag. and Annals, N.S. vol. viii. p. 180.—Eprr. t Dr. Thomson’s correction will be found in Phil. Mag. and Annals, NS. vol. x. p. 392.—Enpir. 110 Dr. E. Turner on some Atomic Weights. subject, by reducing oxide of lead to the state of metal by means of hydrogen gas. ‘Taking his two most widely differ- ing results, the equivalent of lead, oxygen being 8, will be 103°42 in the one case, and 103°64 in the other. His mode of analysis, though apparently easy and simple, is by no means free from practical difficulty. My experiments were made by converting the oxide into sulphate of lead, a method, I be- lieve, susceptible, with the requisite precautions, of greater ac- curacy than that employed by Berzelius. After many trials I feel certain that the equivalent of lead is not higher than 103°6. It is probably somewhat lower; so that 103°5, nearly the mean of Berzelius’s experiments, is very near the truth. This point I hope to clear up by renewed experiments, which are rendered necessary by the extreme difficulty of getting oxide of lead in a state of adequate purity. In the mean time 103°5 is the nearest approximation which experiment justifies : it is useless to go beyond the first decimal, because we are ig- norant whether 103°5 is greater or less than the real number, The following experiment will test the value of this esti- mate :—If the equivalent of lead be 103°5, then 100 parts of metallic lead should yield 146°38 parts of sulphate of lead. The mean of several closely corresponding experiments b Berzelius is 146°419 ; and the mean of my own is 146°401. If 104 were the equivalent of lead, 100 parts ought to yield 146°16 of the sulphate,—a number differing widely from the result of experiment, and much beyond the errors of manipulation, Chlorine.— The most satisfactory experiments I have met with respecting the equivalent of chlorine are those of Berze- lius. He obtained from 100 of chlorate of potash 39°15 of oxygen, and 60°85 of chloride of potassium; and found that 100 of chloride of potassium correspond to 192°4 of chloride of silver. According to my own experiments, 100 parts of silver give 132°8 of chloride of silver,—an estimate extremely close to that of Berzelius. From these data it follows that the equivalent of chlorine is 35°45, To compare with this number the equivalent of chlorine determined in a totally different manner, | prepared some very. pure chloride of lead, and separated its chlorine by means of nitrate of silver. From the best experiments I could make, 100 of chloride of lead correspond to 103°24 of chloride of silver. Now, even taking as the equivalent of lead the thea- retic number 104, the preceding analysis gives 35°578 as the equivalent of chlorine; and when we take the more correct equivalent of lead 103°5, that of chlorine is 35:45, identical with the number deduced from the experiments of Berzelius. The equivalent of chlorine commonly used by British che- mists, namely 36, is therefore erroneous. Dr. E. Turner on some Atomic Weights. 111 | I may add that the preceding analysis agrees closely with that of Berzelius; but I prefer my own result, because my chloride of lead appears to have been purer than the speci- men employed by him, dissolving in water without the slightest residue. It affords an instructive test of the value of the atomic weights current among us. For, supposing 104, 36, and 110 to be the respective equivalents of lead, chlorine, and silver, it follows that 100 of chloride of lead should yield 104°28 parts of chloride of silver, instead of 103:24 as given by experiment. In fact, as will immediately appear, the equi- valent of silver is still more erroneous than those of lead and chlorine. Silver.—My first attempts to determine the equivalent of silver were by means of the oxide; but different analyses dis agreed so widely, that I was obliged to resort to another me- thod. Knowing very nearly the equivalent of chlorine, that of silver may be inferred from the composition of the chloride. According to Dr. Thomson, 100 parts of silver correspond to 132-73, according to Berzelius to between 132°75 and 132-79, and by my experiments to 132°8. The coincidence is very close, and therefore the principal difference in the equivalent 6f silver will depend on that of chlorine. If 36 be assumed as the equivalent of chlorine, that of silver is 110; and it is 108-08 if 35°45 be chosen as the equivalent of chlorine. An extremely slight difference in the number for chlorine, such as lies entirely within the ordinary limits of error, would raise the equivalent of silver to 108°1 or rather higher, or depress itto108. While the matter is uncertain it will be most con- venient to employ the whole number. In order, by an independent analysis, to ascertain which of the numbers above mentioned is the more accurate, I prepared some very pure nitrate of silver, kept it for some time in fusion, and converted it into chloride of silver. After repeated ex- periments, I find that 100 of the chloride of silver corresponds to a quantity of fused nitrate, varying from 118°544 to 118°50. But the theoretic quantity deduced by adopting 110 and 36 to represent silver and chlorine is 117°81, which differs widely from the result of actual experiment; whereas, supposing the equivalent of silver and chlorine to be represented by 108 and 35°45, 100 of chloride of silver should correspond to ‘218°51 of the fused nitrate. This, then, is additional evidence in favour of the atomic weight of chlorine as above stated. Nitrogen.—I have endeavoured to ascertain the equivalent of nitrogen by the analysis of the nitrates of silver and lead. 1. From the analysis just stated, [consider 100of thechloride of silver, containing 75°3012 silver, to be equivalent to 118°5 of 112 Dr. E. Turner on some Atomic Weights. nitrate of silver. -.Calculating from these elements, and with 108 as the equivalent of silver, we shall find 14°06 as the equivalent of nitrogen. — It will be 14-046 if the equivalent of silver be 108°1, g. As a mean of three closely corresponding analyses, made by converting the nitrate into sulphate of lead, I find that 100 parts of sulphate of lead correspond to 109°307 of nitrate of lead. Calculating the equivalent of nitrogen, on the pre- sumption that 103°5 and 40 are the respective equivalents of Jead and sulphuric acid, we shall find it to be 14°101. Berzelius calculates his equivalent of nitrogen from an analysis of nitrate of lead, and estimates it at 14°18. The difference between us principally depends on a different esti- mate of the composition of the oxide of lead; and until this point shall be settled with more precision than at present, no certain inference can be deduced from the analysis of the nitrate. I have more confidence in the estimate from nitrate of silver, and feel little doubt that 14 is a very close approxi- mation. Some analyses of nitrate of baryta, but which are not fully in a state for publication, induce me to believe that the real equivalent of nitrogen is nearer 14 than 141. Barium.—From the analysis of chloride of barium, published in my Essay on that compound, no inference could at first be drawn in consequence of the uncertainty respecting the equi- valent of chlorine. Now, however, that we have reason to take 35°45 as the equivalent of chlorine, it follows from my analysis that the equivalent of barium is 68°76; and according to the analysis of chloride of barium by Berzelius, it is 68-588. I believe the equivalent. of barium is intermediate between 68°6 and 68°8, and in the absence of more exact knowledge 68-7 may be taken as a very good approximation. The general conclusions which I deduce from the preceding account are the following: 1. The atomic weights commonly used by British chemists lave been adopted without due inquiry, and several of the most important ones are erroneous. 2. The hypothesis, that all equivalents are multiples by a whole number of the equivalent of hydrogen, is inconsistent with the present state of chemical knowledge, being at vari- ance with experiment. 3, The subjoined equivalents are very nearly correct :— TCAs op ncanesccndye cts panneps este 1 03:5 x GHPGMMEO Hi oon oc FH I MA S545 Nitrogen .ssssescscssseeseseeessee 14 f.b8. of XXIV. On a new Membrane in the Eye. ByGrorer Hunstey Fieipinc, Member of the Royal College of Surgeons in Lon- don, Member of the British Association for the Advancement of Science, Curator of Comparative Anatomy to the Hull Literary and Philosophical Society, &c. &c.* ACCORDING to the accounts we find in standard ana- _~~ tomical works, we are taught to believe that the Pig- mentum nigrum of the eye is placed immediately behind, and in contact with the retinat. We are further taught that the colour of this pigment varies greatly in different animals, and that it is of a very light colour, or even wanting, in the night- prowling animals {, Now, the membrane I have discovered is immediately be- hind, and in. contact, with the retina: it presents a fine co- loured appearance, which varies in different animals; and is of a very light colour in the night-prowling animals. _ It is eyi- dent, therefore, that what I term a membrane, is usually esteemed to be a pigment. To prove that it is a membrane will be the object of the present paper. Ist. What are the nature and properties of the pigment of the eye? It is a mucous substance combined with carbona- ceous matter on which its colour depends§; it stains white paper; it is removeable by washing ||; no known chemical agent has any power either to alter or remove its colour 4. _ Take a section of a beast’s eye from which the whole of the humours and the retina have been carefully removed : you will find a brilliant spot of coloured surface which was evidently immediately behind the retina. The colour will generally be found to be blueish-green, with frequently a tinge of yellow, the circumference round this spot (which spot varies in size, from occupying three-fourths to less than one-fourth of the hollow of the globe,) is of a deep blue. Now take a piece of white paper and apply it to the blue or green part, you will obtain no stain; wash, it with water, you will not remove the colour, nor stain the water :—here then are two easy proofs that its colour is of a different nature from that of the true pigment of the eye. _ But it may be said, that what I am describing is the Tape- tum; and if so, unless we are to regard tapetum and pigmen- tum as synonymous terms (which Cuvier, Richerand, John * Communicated by the Author :—This paper is an abstract of part of one read before the late Meeting of the British Association for the Ad- vancement of Science, at Oxford. + Bell, Fyfe, Monro, Shaw, &c, &e. t Bell, Fyfe, &c. § Young. || Bell. q Bighiat. Third Series. Vol.1. No.2. Auy 2 Q 114 Mr. G.H, Fielding on a new Membrane of the Eye. Hunter, Fyfe, and others seem to do), we shall have two dif- ' ferent things occupying the same place, which is impossible. Other anatomists* regard T'apetum and Membrana Ruys- chiana as synonymes; and, as Sir Charles Bell justly observes, considerable confusion prevails respecting the precise mean- ing of the term Tapetum. He, however, defines it to be a pile or fleece laid upon the Membrana Ruyschiana, and states the pigment to be spread upon the tapetum next to the retina, and consequently between it and the retina. It is useless, however, disputing about terms; for all anatomists seem agreed that the pigment is placed immediately behind, and in contact with the retina; and as the part of which I am treating is immedi- ately behind, and in contact with the retina, I apprehend that the following proposition will be the only one I shall have to prove, viz. that the substance placed immediately behind, and in contact with the retina, and known by the name of Pig- mentum nigrum, is a membrane, and not a pigment. Ist, We have already seen that it does not stain paper, and is not removeable by washing.—2ndly, ‘Take a section of an .eye in which the colours are vivid, place it on the table in a bright light, and fixing your eye on any part, steadily, walk round the table, you will find the colour varies according to the different positions you view it in.—3dly, It presents a bright polished surface, like that of a well-finished mahogany table.— 4thly, Carefully detach a small portion of this substance, and put it between two thin pieces of glass ; it will present a hard and well-defined outline, and on putting the glasses in closer approximation and suddenly relaxing them, you may perceive the substance expand and contract. Again, view this portion by reflected light, you will perceive its usual colour, but with transmitted light you will have a totally different one. In this point it follows Sir Isaac Newton’s laws as regards the colours of thin plates.—5thly, I detached very carefully a small por- tion of this substance, and placing it between two pieces of fine thin glass subjected it to examination through a fine achro- matic Amician microscope by Chevalier; the colour of the portion thus examined, was pale blue by reflected, and red- dish-yellow by transmitted light. When placed in the field of the microscope the same change of appearance was observed to take place on viewing it as an opake and as a transparent object. With a power of 800 to the diameter, not only were blood-vessels apparent, but even the globules in those vessels ! and by increasing the magnifying power to its utmost extent, the globules appeared of the size of a very small pin’s, head. I once thought I could trace nervous filaments, but do not * Shaw and others, a i A —. Mr. G. H. Fielding on a néw Membrane of the Eye. 115 feel quite confident on this head.—6thly, It is possible by che- mical agents (which, according to Bichat, have not the slightest effect on the pigmentum of the eye) to destroy and restore these colours at pleasure. Take a section of a beast’s eye in which the colours are vivid, and dip it into any dilute acid (nitric, muriatic, or sulphuric), you will perceive the colours immediately begin to fade; now dip the portion in cold water, and on taking it out you will find the colours have disappear- ed; dip it again into the acid, and the colours will reappear as if by the touch of a magic wand; immerse it again in the water, and they will disappear; and so on as often as you please. ‘The same effect is produced by a solution of ammo- nia. With a pigment this could not occur; and my impres- sion is, that these beautiful colours depend upon the thickness and disposition of the thin laminz of which by dissection I can prove this membrane to be composed. ‘The cause of the disappearance and reproduction of the colours by chemical agency. I conceive to be merely the effects of heat and cold upon these thin plates, causing alternate expansion and con- traction *.—7thly, The true pigment of the eye will be found in the same eyes which possess this brilliant substance ; but it will be found behind this part, and most plentiful on the pos- terior surface of the choroid in connection with the sclerotic membrane. ‘Thus, in the ox, this substance presents a fine blue tint intermixed with green and yellow, and behind it we have the true pigment, of a rich brown; in the sheep it is very similar ; in the deer the bright part is pale blueish-white, the Dignent a very light brown; in the cat and fox it is a fine olden yellow, and the true pigment a rich black.—Ssthly, ‘This membrane (as I must term it) is spread over the whole internal surface of the choroides, next to the Tunica Jacobi or external coat of the retina. It varies in thickness, and conse- quently in the number of its lamine. It is thickest where the lightest and most brilliant colours are seen, and thinnest in the circumference where it appears of an intense blue colour, and where, no doubt, the colour of the Membrana Ruyschiana underneath affects it. It is very remarkable that neither the extent of the bright surface presenting these varying colours, nor the tint of the colours themselves, are uniform in animals of the same species.—9thly, Minute injection of the choroid does not affect this membrane,—10thly, I have performed all these experiments on the eyes of the sheep and the ox. As ~* Are not these changes of colour more probably referrible to the alte- rations of texture necessarily induced upon so delicate an organized struc- ture by the application of chemical agents ?—Eprv. oO ~ 116 © Mr. Bevan on the Strength of Timber, &c. regards the human éye, I have had very little opportunity’ for investigation ; and though I have proved its existence, I can- not say that it ever presented any distinctly coloured appear- ance. This, however, will be accounted for'when I come, in another paper, to treat of the effects produced by this mem- brane, on Vision, and to show the necessity that such a mem-~ brane should exist. The name I propose to apply as most descriptive of its appearance, is Membrana versicolor. XXV. On the Investigation of the Strength of Timber and other Materials, with reference to the recent Experiments and Communications of Mr. Peter Barlow, Jun. By B. Bevan, Esq. To the Editors of the Philosophical Magazine and Journal. Gentlemen, LLOW me to express my thanks to Mr. Barlow for his additional experiments, and for his candid reply to my observations on his first paper. Experiments of this kind, carefully conducted, are of considerable importance at. this time, and will for many years remain so, and tend to add a lasting value to your Magazine. There are many persons who study the properties of tim- ber and other materials, who have not the opportunity. of trying experiments on a proper scale; and those who have the means of doing so, frequently want the disposition, even if they possessed the abilities. Communications of this nature are fre- quently of more advantage to the practical mechanic than the more abstruse and refined theoretical speculations, which al- ways confer great credit and value on your Magazine, Both have their value; but if we estimate their importance by the number of persons likely to be benefited, those which come within the reach of the practical man will be most valued. To encourage investigations of this nature, was the object I had in view when I made my first remarks on Mr. Barlow's communication, and not to excite any unpleasant feeling in the author. My suggestion that it would be for the benefit of science to observe as far as could be a uniformity in the specifi- cation of the properties of timber and other materials, was not intended to imply any censure upon him for adopting an.arbi- trary number,—which can readily be reduced to the: modulus of elasticity by any mathematician,—but, to. recommend. the use of that more generally adopted specification. rot As Mr. Barlow -affirms he ‘*does not see what advantage ee with Reference to the Experiments of Mr. P. Barlow, Jun. 117 is gained by considering the weight of the timber, except in the particular case where the question is the deflection, of a beam from its own weight,” I must therefore be allowed to show that this) remark has been rather inadvertently made; and I doubt not, that. Mr. Barlow will, upon further. consi- deration, see that in almost all buildings and machinery, the weight of the materials used in their construction is a most essential matter of consideration. ‘There may be some few constructions which would be improved by an increase of weight; but generally the value of materials will be estimated in the direct ratio of the strength, and inversely as the weight, when the durability and other qualities remain the same: thus if a new species of wood, equal in durability to oak and teak, could be found of equal strength, but of Aa/f the specific gra- vity, would it not be preferred for almost all purposes both in naval and civil architecture, and for machines of almost every description? The same may be said of metals,—the less the weight, and the greater the strength, the more valuable they will be. If I could construct a crane for moving heavy loads with good Memel timber, at half the expense and of two-thirds the weight of one made of Locust-tree,—should I be excused in adopting the Locust-tree on account of saving two or three cubic feet of wood ? I am ready to admit that there are cases in which space is of importance, as well as strength, but in such cases iron and steel are preferred to wood. It is not my intention to repre- sent that lightness and strength are the only qualities to be attended to, well knowing that other qualities for particular purposes are of importance: but the present discussion does not involve those considerations, but simply the strength, re- lative to the weight; so that when all other things are alike, the value will be in proportion to the height of the modulus of elasticity. To render the subject a little more plain, we may calculate the quantity of timber required to form a beam of 20 feet length of bearing, to support a given load, to which a deflec- tion of half an inch may be allowed. This beam, if madé of Tonquin Bean, will require about 16% cubic feet; and if made of Memel timber of the same breadth, will require about 192 cubic feet to possess the same strength; but the Memel beam will only weigh $rds of the Tonquin beam, or $70 pounds less, and has therefore the advantage in point of weight.’ In point of cost, it will depend upon the price per foot of each species, Should the Tonqtin beam be $s. 64d., while the Memel cost 3s. per foot, the-cost would be alike: except, therefore, this 118 Rev. W. D. Conybeare’ on M.de Beaumont’s Theory heavy timber can be procured nearly at the price of Memel, there will be no advantage derived from using it, so far as strength is a matter of consideration. But for its hardness, it may be preferable for blocks and for cabinet work. Mr. Barlow supposes I have been misled by the small error in his formula, at the head of the sixth column. Being well aware of the principle upon which that column was formed, I made use of the correct formula; and although it may appear strange, it is quite true that I did not discover the error until pointed out by Mr. Barlow in his last paper. . The above remarks are not intended to depreciate the value of Tonquin Bean and the other species of wood in the market, but simply to prove that a species of wood ( Memel Deal) which is now supplied in large quantities, will answer all the pur- poses of the builder. I sincerely hope that whenever oppor- tunity occurs, either to Mr. Barlow or others, they will con- tinue to favour the public with similar valuable information through the medium of your Magazine. I remain, Gentlemen, yours very truly, Leighton, July 11, 1832. B. Bevan. XXVI. Inquiry how far the Theory of M. Elie de Beaumont concerning the Parallelism of Lines of Elevation of the same Geological Aira, is agreeable to the Phenomena as exhibited in Great Britain. By the Rev. W. D. ConyBeary, M.A, F.R.S. V.P.G.S. Instit. Reg. Soc. Paris.* ae following remarks were drawn up by the author, in consequence of an inquiry proposed to him by the British ‘Association for the Promotion of Science, at its first meeting atYork, in1831, “how far the theory of M. Elie de Beaumont, concerning the parallelism of the lines of elevation produced by geological convulsions of the same zra, appeared to be con- firmed by the phenomena of our own island.” ‘This question was referred to Professor Sedgwick and Mr. Conybeare; but circumstances having prevented their communication, the lat- ter alone is responsible for the views contained in the present memoir; although, in the hope that some opportunity of inter- course would have occurred, he may occasionally have used the plural number. He has now only to add his earnest hope that nothing in the following communication will be so mis- construed, as to seem to imply any other feelings than those of the highest respect for the very distinguished talents of M. de Beaumont; for with them, on the contrary, from the period * Communicated by the Author. of the Parallelism of Contemporaneous Lines of Elevation. 119 of the short geological excursion he had the pleasure to make in his company during his visit to England, he has ever been most deeply impressed ; and on the present subject he re- gards the views M. de Beaumont has announced, as exhibiting the first attempt to take a generalized and combined survey of some of the most important phznomena which fall within the province of our science, and as one of the most masterly con- tributions which that science has recently received. But there will always. be some danger, when new generalizations first burst on the mind, of their being carried too far; and this dan- ger will be in proportion to the ardour and vigour of the in- tellect from which they emanate. A fair and candid conside- ration of conflicting phenomena appears to be the only way of guarding against this danger: the character which Aristotle has given of Plato, “he doubted and investigated,” must be that of the sincere lover of philosophical truth in every age. The sectional researches proposed by the British Associa- tion being simply intended to invite discussion, the publica- tion of any materials collected for the purpose remains, of course, with the contributors. The accompanying paper is therefore offered to the Editors of the Philosophical Magazine and Journal of Science, should it suit their pages. Sully, July 4, 1832. The question referred to our consideration by the former Meeting of this Society may be thus briefly stated. If we examine the phenomena which appear to have resulted from the action of the causes which have elevated at various geolo- gical periods the strata of the earth’s crust, especially with reference to the line of direction in which those causes have acted, how far does it appear that these phaznomena,—as pre- sented by our own island,—confirm or militate against the hypothesis announced by M, Elie de Beaumont,—as resulting from his observations on the principal continental chains,—that the:elevating forces which have acted during the same geolo- gical periods have acted in parallel lines of direction; and, e contra, that those whose activity must be referred to differ- ent epochs have not acted in parallel lines.* In attempting an answer to this question, it may be observed, that as the conclusions of geological science ordinarily must be deduced from the generalization of very multifarious local details widely scattered, and such as can be collected only by the united and long continued exertions of many independent observers; so it were worse than presumptuous for individuals entering for the first time on a branch of the subject, hitherto * An Extract from M. de Beaumont’s exposition of his hypothesis will be found in Phil. Mag. and Annals, N.S, vol. x. p, 241.—Epr. 120 Rev. W.\D. Conybeare’s ox, M.de Beaumont's Theory almost unexplored, to pretend to offer more than a partial and imperfect contribution to its investigation, requiring much ex- tension, and probably many corrections, before it can be con- sidered as having accomplished anything beyond a general tracing out of the line of inquiry to be pursued. The first point in this inquiry is obviously to determine the geological epochs to which the several elevations we observe should be referred. Now. we have direct evidence which can enable us to do this, in very few cases; those, namely, in which, as in the Isle of Wight, we observe the immediate con- tact of the strata affected by the elevating force, with, those which have been unaffected by it; and where moreover these strata also are terms immediately following one another in the regular geological series:—it is evident that this second condition is no less essential to determine the exact geological gra of the disturbance than the first; otherwise, where dis-+ turbed and undisturbed strata of remote age are in contact, the disturbing force may have acted during any portion of the long interval which must have elapsed between the deposition of the earlier and later formations: e.g. in the Boulogne di- strict at Hardinghen we see the elevated strata of carboni- ferous strata and ‘coal at the foot of the horizontal strata of chalk; and near Namur, in contact even with the tertiary for- mations. -Now it is evident, that so far as the indications af- forded by these localities are concerned, the disturbing forces may have acted at any time between the formation of the car- boniferous rocks and the tertiary deposits; and it is. only by extending our observations across the transition chains of the Ardennes,—which appear to have been affected by the same disturbances, and which abut on the South against undisturbed horizontal strata of new red. sandstone, muschelkalk and keu- per,—that we can assign the epoch at the close of the carboni- ferous period, and anterior to the formation of the new, red sandstone, as the probable geological date of the agency of the disturbing force. uch ' Inmany cases, however, we are not thus able to trace the disturbed district on any of its boundaries in contact with un- disturbed beds immediately consecutive in age to. some of the disturbed strata; but are reduced to reason from. the looser analogy afforded by similar disturbances of the same rocks, but in unconnected geological localities; and it need not be urged that we should be careful not to assign too much im- portance to conclusions thus obtained. C Again; even as to the convulsions affecting the very same geographical district, it is too much to assume, without distinct evidence, that they have all been produced by one single shock, rather than by a series which may pep A! at of the Parallelism of Contemporaneous Lines of Elevation. 121 intervals through a long period of ages: thus in’ the example cited, of the transition rocks of the Ardennes and the coal- fields of the Meuse, it is evident that all the rocks anterior to the new red have been violently convulsed, and those subse- quent have been little, if at all thus affected. But who shall say that all this disturbance was produced at one blow? This point, indeed, admits of determination by carefully examining whether a general conformity does or does not pervade the whole of the disturbed series;—for if there be anything like general interruptions in that conformity, every such interrup+ tion would clearly indicate a distinct zera of convulsion. Now, @ priori, it should certainly appear that the idea of a series of successive convulsions seems most conformable to the only analogy presented by actual causes, the operations of volcanic forces ; and the careful and minute examinations which would be necessary to ascertain every interruption of conformity in the strata of the disturbed districts have hitherto scarcely in any single instance been accurately made. Having thus candidly avowed the difficulties and obscurities which hitherto overcloud this important branch of geolo- gical inquiry, we may proceed to state the few data on the subject which are as yet to be considered as tolerably ascer- tained, so far as the geology of this Island is concerned; and in doing this we shall find it most convenient to begin with the convulsions of the most recent order which have been here observed ; those, namely, which have occurred during the period of the tertiary formations. The tertiary formations, and the chalk on which they rest, have participated in the general elevation of all the secondary strata of the Island, of which the general line of bearing is from N.E. to S.W., but there is no appearance whatever of this elevation having been the result of any violent sudden or single convulsion; on the contrary, everything indicates that it was a gradual, gentle, and protracted upheaving (to borrow a German term), con- tinued without interruption during the whole period of the formation of all these strata; or perhaps some persons may be inclined to refer it rather to an equally progressive depression of the basins of the surrounding ocean: as all the phenomena ‘simply indicate a relative change of level, they will admit an ‘equally ready explanation on either hypothesis. We may ob- ‘Serve a very general tendency to parallelism between this line, (although the result of a cause certainly continuing to act in the same direction in the tertiary epoch,) and the earlier and more violent convulsions which we shall hereafter find to have affected the older carboniferous strata before the deposition Third Series. Vol. 1. No. 2. Aug. 1882. R 122 Rev. W.D. Conybexre'on'M.de Beaumont’s Theory of the new'red sandstone; for the general line (N.E. S.W.) above indicated, may ‘be more correctly described as a curve running nearly N. and S. in the northern part of its course, and trending towards an E. and W. direction towards the South; and in like manner we find the carboniferous lines of elevation generally ranging N. and S.\ in our northern counties, and E. and W. in the southern. But independently of this general elevation, we find in the southern counties three parallel lines of elevation ranging E. and W., and indi- cative of more abrupt and violent action, which appears to have occurred during the tertiary epoch, and which may very probably be regarded as strictly contemporaneous. ‘The first and most important of these lines of disturbance, is that which having traversed the Isle of Wight, strikes and ranges through the peninsula of Purbeck, and then produces the anticlinal line and parallel faults of the Weymouth district; thus ex- tending over more than sixty miles. It must have produced an angular movement of the strata of many thousand feet, as it has thrown the chalk, plastic clay, and London clay into a vertical position. The section in Alum Bay distinetly exhibit- ing the contact of the disturbed and undisturbed strata, shows this derangement to have been effected by a single and most violent convulsion, of which the zra is most distinctly marked and. precisely limited, being subsequent to the formation of London clay, and anterior to the alternations of fluviatile and marine deposits which characterize the basins of the Isle of Wight and Paris. Il. The anticlinal line of the Weald of Kent and Sussex, ranging from the North of Hastings tothe North of Petersfield. —This is the cause of the elevation of the north and south chalky downs, and its disturbing effects may be most strongly traced in the narrow chalky ridge of the Hogsback (in the former), where the strata are considerably inclined : it may very probably be referred to the same era as the foregoing line of disturbance, to which it is very nearly parallel. We may consi- der this anticlinal line as prolonged through the chalk by Win- chester, and a little north of Salisbury, and thus reaching the Vale of Wardour, which is what Professor Buckland terms a Valley of Elevation: here the Portland limestone is thrown up, and the strata often considerably inclined. On the whole, however, the line now described is rather an anticlinal line of very gentle curvature, than one indicating violent disturbance. It is impossible to dismiss this line without observing how ex- actly. parallel, it is to the much older lines of elevation of the transition strata of the Quantock Hills and the Forest of of the Parallelism of Contemporaneous, Lines of Elevation. 123 Exmoor, which, when the eye glances,over, the map, appear to be its prolongation, and yet are really anterior to the age of the new red. sandstone*. III. A third parallel anticlinal line traverses the Vale of Pewsey, another valley of eievation on the greensand, sepa- rating the chalky ranges of Salisbury Plain and Marlborough Downs.— The protrusion of the greensand, in the prolongation of this line at, Ham and Kingsclere, (see Buckiand’s paper +, Geol. Trans. 2nd series, yol. ii.) within the western angle of the London basin, may be referred to the same line of ele- vation, which will give it an extent of about 30 miles, Iam not aware that its effect on the contiguous tertiary strata has been noticed, and can therefore only conjecture that it will probably, on examination, prove exactly contemporaneous with that of she Isle of Wight. The above elevations, that of the Isle of Wight certainly, and those of the Weald and Vale of Pewsey, by the most pro- bable analogy appear to have taken place subsequently to the formation of the inferior tertiary strata, and before the more recent beds. Elie de Beaumont assigns only the systems of Corsica and Sardinia to this epoch, and characterizes them as having a north and south direction; whereas our examples uniformly range E. and W. Supplement to 1.— Although in the northern portion of our Island the absence of cretaceous and tertiary formations de- prive us of this direct test of the sera of the disturbances which have there affected the strata, yet the association of many of these disturbances with apparently the newest varieties of the trap formation, and their intimate analogies, in general direc- tion and in most of their geological circumstances, with those which we trace on the, opposite side of a narrow channel, in the basaltic area of Ireland, must at once induce us to refer them to.a similar age; and in Ireland this is shown, by the presence of the chalk through which the basaltic eruptions haye burst and overflowed, to be posterior to that of the cre- taceous formation. On the Scotch coast, in Skye and Mull, we only see the basalt in contact with the oolites and lias, - which, as at Portrush, &c. in Ireland, are dislocated, altered, and overflowed by it. But to consider the case.more generally, we shall find the general bearing of all the strata in Scotland, as in England, N,.E. and $.W., and the same line is. pro-. tracted into Ireland; this is the general bearing of the southern * See Geol. Trans. vol. ii. 2nd series, for Dr. Fitton’s Hastings Section, and those of the Western Weald, where the anticlinal line ranges through Hastings, and comes north of Petersfield. + An abstract of this paper will be found in Phil, Mag. vol. Ixv. p.214,—Eb. R 2 “ 124 Rev. W.D. Conybeare on M. de Beaumont’s, Theory | transition chain, of Scotland, calied the Iuead Hills, which» is continued on the Ivish coast by the transition ranges of Down ; of the primitive chain of the Grampians, continued in Lreland by the lines of the Derry mountains, &c. ; and of the principal undulations of the Grampians, as evidenced, by the direction of the great depression which affords a line for the Caledonian canal. Much of this process of elevation appears to have been like the general elevation of the English strata, gradual and gentle; at the same time that it ranges exactly parallel to:many lines of disturbance which have been evidently violent, and) pro- duced by sudden convulsions limited to definite single, pe+ riods., This general elevation clearly continued to act through the tertiary period, because in the Irish portion we see the terminal escarpments of the chalk and of the incumbent ridges of basalt conforming to these general lines. The dis- turbances effected in the oolitic strata of Scotland, near their contact with the granitic chains of Sutherland, are obviously of indefinite age. We shall notice them, therefore, more at length when speaking of the disturbances generally affecting the oolites, and only mention them here to state that we have no clear evidence which negatives the supposition that they may have taken place even as late as the tertiary period. Supplement to II. Disturbances during the period between the age of the tertiary formations, and that of the new red sand+ stone. — Elie de Beaumont has distinguished four different epochs of disturbance during this period: 1. that of the Rhe- nish system affecting the rothetodte and all the substrata; 2. that of La Vendée and Morvan, to extending the muschélkalk ; 3. that of the Erzegebirge, the Cote d’Or and Mount Pilate, including the oolites; and 4. that of the Pyrenees and Appen- nines, which has also disturbed the cretaceous formations. Our own island, however, affords us few well marked -ex~ amples of disturbance during this period, and these scarcely ever afford us sufficient evidence to pronounce on their exact zera; so that we must.as yet treat of this part of our subject with a much more vague generality. otal In Yorkshire, indeed, in examining the stratification beneath the cretaceous Wolds, we discover that the. oolitic series is unconformably arranged, exhibiting a| convex: curvature and anticlinal line beneath, the absolutely horizontal line:of junc tion of the superimposed chalk ; but here the curvature is very gentle, and no signs of violent disturbance are exhibited : this anticlinal line appears to range nearly E. and W. As the chalk and its greensands also at the S.W. extremity in Dorsetshire, | overlie the edges of the inferior rocks as far as the red marle, we of the Parallelism of Contemporaneous Lines of Elevation. 128 have here again a want of exact conformity ; but the difference is ‘scarcely any where sufficient to be sensible to the eye, and can only be recognised: by its ‘results on the grand Scale?! yet these instances are sufficient to show that the elevating forces have acted somewhat differently in the oolitie and cretaceous systems. In Dorsetshire, indeed, the oolites are affected by considerable disturbances in the vicinity of Weymouth, ‘but these appear ‘to have been connected with the convulsions which overthrew ‘the Isle of Wight in the tertiary period. In Yorkshire, we observe ‘on the coast a considerable dislo- eation of the alum shale near Cloughton: this point is the more worthy of especial notice, because it is situated in the prolongation of the line of the great Cleaveland basaltic dyke, which extends from the central ridge of carboniferous lime- stone, and ranging nearly in an easterly direction, intersects the coal-measures, new red sandstone, and even the oolites; so that this point indicates a connexion of the disturbances which have here affected the oolitic system with the convul- sions and basaltic dykes of the coal-field. The Northumber- Jand coast near the mouth of the Tyne presents a still more decided: evidence to the same effect (so far at least as the magnesian limestone is concerned); for this latter rock is here thrown down by the great 90-fathom dyke, by far the most important of the faults which affect the Newcastle coal-field, inasmuch as it occasionally deranges the level of the strata oneither side of it no Jess than 140 fathoms. It ranges east and west for about ten miles, when it crosses the Tyne; but in the upper part of the valley of the SouthTyne, in the prolonga- tion of this line there is an immense fault, called the Stubbick dyke, operating in the same direction, which may therefore be very probably considered as its continuation, and which occasions a long narrow subsided strip of the upper coal-mea- sures to extend transversely across nearly the whole breadth of the mountain limestone chain; so that we must regard this dislocation as one of the most considerable with which we are acquainted. It affects the magnesian limestone not only at Cul- lercoats, but seven miles further on its course at Killingworth; and the same distance from any other locality to which ‘the magnesian formation now extends. ‘The depression occasioned by the fault becoming here much more considerable (440 fa- thoms), a small portion of the lower magnesian sandstone or rothetodte here: becomes included, as’ the upper member of the subsided mass of strata:—the inference is clear; that this sandstone formation must at the period when» this’ subsi- dence took place have extended continuously to this point; and that therefore its removal over a tract at least six miles 126 Rev. W. D. Conybeare on. M. de Beaumont’s Theory. in length, must have subsequently been effected by denuding causes of the most violent agency, excepting where a single fragment of it was sheltered from their action by the depres- sion occasioned by this great fault. On the coast south of Cul- lercoats this same sandstone is traversed by a basaltic dyke: it is true that our evidence as to the date of the convulsions ex- tends only in Northumberland to the magnesian lime, and in Yorkshire to the alum shale; yet the general analogy of the two cases may incline us to consider them as contempora- neous: but the question will still remain, how much younger they may be than the age of the most recent of those rocks which is associated with the inferior oolite. Their direction is nearly, but not exactly parallel, both ranging nearly E. and W.; but the eastern extremity of the main Newcastle dyke in- clines a little to the north, and that of the Cleaveland dyke to the south. The general direction of the faults affecting the in- termediate (Durham) coal-field is nearly similar; and: the cir- cumstances I have mentioned render it very desirable.to trace the prolongation of their lines towards the overlying range of magnesian limestone, and to examine how far this rock ap- pears affected by them. In the paper on the magnesian lime~ stone, in the Geol. Trans. 2nd series, vol. ili. some trifling faults affecting this rock in Yorkshire are noticed; but their general direction seems to be at right angles to those now no- ticed, and parallel to the general. elevation of the strata, 190)! -'The traces of the oolitic formations in Scotland haye been much disturbed: those in the islands. of Mull and Skye by the eruption of the trap rocks, (as we have already noticed, p. 123,) most probably during the tertiary period. The lines of diree- tion are here very variable: along the coast of Sutherland, near the Brora coal-field (which, as in the eastern Moorlands of York, is associated with the inferior oolite), the lias and» oolites come in contact with the granitic mountains, and are much disturbed, the lines of direction being variable, but ge- nerally inclining to parallelism with the primitive chains which | range ‘N.E, and S.W. Although these disturbances are, in juxtaposition to the elevated primitive chains, it would be too hasty an inference to refer them to the protrusion of the gra-. nite; the granite may already have assumed its actual posi-. tion relative to these superstrata, and both the primitive and. , secondary formations may have appeared together at some’ later epoch. As we have here no younger formations than the» oolites to afford us the means\of comparison, we must be un- able to pronounce definitively how recently these convulsions: may have taken place. [To be continued. ] Puthaye. >] XXVII. Descriptions of several new British Forms amongst the Parasitic Hymenopterous Insects. By J. O. Westwoop, FB S,| SC. . Familia Cuatcipip®, Westw. 1. Brachymeria, Westw. in Steph. Cat. 393. Chalcis. Spin. Chalcide typicali (Ch. Sispes) differt corpore obtusiori, antennis bre- vioribus crassioribus, abdomine subsessili, subconico, vix compresso coxisque posticis brevioribus.—Chalcis minuta, Fab. 2. Pachylarthrus, Westw., Pteromalus, p. Dallm. Sw.Tr.1820. Caput latum, palpis maxillaribus articulo ultime maximo inflato ; antenne 13-articulate, articulis 3 et 4 annuliformibus, 11-13 clavam parvam for- mantibus ; abdomen ¢ breve subtriangulare.— Pach. insignis, Westw. Aureo- viridis, antennis palpisque fulvis, pedibus flavis. 3. Trigonoderus, Westw. in Steph. Cat. Mand. p. 396. Cheiropacho Westw. affine. Thorax subovatus, collare triangulare, antenne 2 13-articulate, articulo 2do minuto, 3tio longitudine 1mi dimidio, articulis 4—8 paullo brevioribus cequalibus, ultimis 5 clavam (articulo 8vo paulld majorem) formantibus.—TJ?r. princeps. Westw, Obscuré zneus, thorace posticé aureo nitenti, abdomine aureo-viridi, cyaneo nitenti; antennis nigris basi ferrugineis; alis hyalinis nubilé elongata centrali fuscescente, pedibus ferrugineis, femoribus basi pulvillisque nigris. Exp. alar. 6 lin. 4. Ormyrus, Westw. Antenne breviores crassee ut in Cheiropacho formate. Thorax convexus; abdomen. 9 cylindrico-convexum apice conicum, thoracis latitudine et illo paullo longius, segmentis 2—5 hirsutis punctatis et in singuli disco, serie transverso impressionum denticulatarum ornatis. Oviductus breviter exsertus.—Orm. punctiger, Westw. Aureo-viridis, abdomine cupreo parum nitente. Antennz nigra, apice fuscz ; scutellum nitidissimum ; pedes nigro- virides, tibiis anticis geniculisque posticis obscuré ferrugineis; tarsi pallidi; ale. vix fulvescentes. 5. Theocolax, Westw. Apterus. Caput subhorizontale subquadratum planum, antice minimé tridentatum. Antennz mediocres, 11-articulate ; articulo 2do majori arti- culis 3—8 sensim crassioribus, ultimis tribus clayam, articulo priori (8vo) majorem formantibus. Collare magnum triangulare. Abdomen oviductu breviter exserto.— Th. formiciformis, Westw. Fulyo-fuscescens, abdomine obseuriori. ‘6. Macroglenes, Westw. Caput latum, oculis partem ejus majorem occupantibus, antenna breves, apicibus crassis, 10-articulatz articulo 2do mediocri, 3—5 minutis, 6to magititudine 2di, 7mo precedenti majori; ultimis tribus clavam magnam formantibus, abdomen compressum.—Macr. oculatus, Westw. Atro-cerulea oculis rubris aut piceis tarsisque pallidis. 7. Cerchysius, Westw. Encyrtus, p. Dallm. Curt. Tibiz intermedi# alarumque nervi Encyrti. Antenne cylindrice, apice paullo crassiores, 10-articulate, articulis 2—7 subzequalibus; ultimis * Communicated by the Author. 128 Mr. Westwood’s Descriptions of several new British tribus clavam compressam formantibus apice obtuso ;. abdomen .oviductu valido exserto, abdominis fere longitudine.—Encyrtus urocerus, Dallm. Sw. Trans. 1820. p. 368.—Sp. 2. Cerch. stigmaticalis, Westw. Czruleo- viridis abdomine cyaneo, antennarum flagello oviductuque omnino nigris 5 alis fascia paullé ante medium pallidé fuscescente, stigmate obscuriori ra- mulo stigmaticali fusco. 8. Cirrospilus, Westw. ' Eulopho affinis, et plis minisve fulvo variegatus. Caput antice, inter oculos, emarginatum ; antenne @ breves crass 7-articulate, articulo 2do 3tii dimidio longitudine, hoc 4to longicri, ultimis tribus clavam, articulo 4to vix crassiorem, fermantibus. Abdomen (petiolo brevi distincto) de- pressum ovatum, posticé conicum.—Cirr. elegantissimus, Westw. Caput, thorax, pedesque pallidé flavescentes, oculis capitisque vertice nigris; linedque irregulari per medium thoracis currenti, antic? posticéque dilatata, nigra. Abdomen fulvum, macula centrali irregulari-quadrata alteraque postica subtrigona, nigris. Antenne fusca. 9. Euplectrus, Westw. ane Eulopho affinis. Caput parvum; antenne graeiles 9-articulate articulo 2do breviori, articulis 3—6 ovatis, ultimis 3 clavam (vix articulo 6to majorem) formantibus. Thorax ovato-circularis anticé subacuminatus, Abdomen (petiolo brevi distincto) thorace majus, circulare, spatuliforme, depressum. Coxe postice permagne tibizeque postice calcari longo instructae.—Eupl. maculiventris, Westw. Capite thoraceque nigris abdomine fulvo, lateribus anticis fasciisque transversis apicalibus fuscis. Antenne, os et pedes, fulvi.. 10. Dicladocerus, Westw. Eulopho typicali (Eul. ramicornis) differt antennis ¢ tantim biramosis, se. 9-articulatis articulo 2do parvo, 3tio 4toque longioribus, horum singulo ramum elongatum e basi emittente; 5to 6toque crassioribus simplicibus, ultimis 3 clavam brevem formantibus.— Dicl. Westwoodii, Steph. Cat. 397. No. 5501. Caput thoraxque purpurei viridique nitentes, abdomine cy- aneo-nigro, basi lateribus zneis, antennis cyaneo-nigris, pedibus zeneo-nigris geniculis articulisque tarsorum basalibus pallidis. Familia Procrorrupip#&. 11. Platymischus, Westw. 7 Apterus, depressus, angustus. Caput subquadratum anticé subacumi- natum. Antenne 14-articulate, articulo 1mo maximo, subtriangulari; 2do parvo; 3tio illo majori, interne producto; articulis 10 sequentibus subzequalibus, filiformibus ; 14mo paullo longiori. Thorax oblongo-quadra- tus. Femora incrassata. Tarsi antici articulo Imo dilatato; abdomen feré thoracis magnitudine, segmento 1mo maximo.—P7. dilatatus. Steph. Cat. Mand. p. 399. Niger, nitidus, thorace posticé villoso, antennarum articulis tribus basalibus pedibusque rufescentibus. 12. Megaspilus, Westw. in Steph. Cat. Mand. 400. Cera- phoron, Latr. Curt. et Jurine? E Ceraphrone typicali (Cer. sulcatus, Jur.) differt, alis superis nervo costali incrassato, stigmate maximo suborbiculari vel semicirculari, cellula apicali unica incompleta, ramo arcuato formata; antennisque fractis et in utroque sexu 10-articulatis, apice in @ vix vel minimé incrassato.—Cer. Dux, Curt: Brit. Ent. pl. 249. f. 1.3.4.5, 8, ¢. la. ?. of M. Kupffer’s Notice of some recent Magnetical Discoveries. 129 “13. Paramesius, Westw. Cineto Zenuino afinis. Caput subquadratum tuberculo antico; antennz $ corpore toto longiores, graciles, filiformes, 13-articulatz, articulis longi- tudiné subzqualibus (2do 3tioque minutis exceptis) articulo 4to ad basin minimé exciso ; abdomen elongato-clavatum, petiolo tertiam partem longi- tudine zquante, alarum nervi ut in Cineto gracilipede (Curt. Brit. Ent. 380. fig. 9.) at areola marginalis paulld longior et basi truncata est.—Par. rufipes, Westw. Niger, nitidus, antennis fuscis, pedibus rufis. 14. Aneurhynchus, Westw. Galeso affinis. Caput transversum tuberculo brevi antico, trophis brevibus, antenne ¢ vix corporis longitudine, filiformes, 14-articulate, articulo 1mo simplici, 2do minuto, 3tio tenui, et paulld longiori, 4to crassiori, et ad basin externé rainime exciso. Alz stigmate nullo distincto, sed nervo sub- costali basali, cujus apex alarum marginem anticum non attinet sed obliqué in alarum disco. breviter protenditur, indé ad alarum apicem reflectitur areolam marginalem elongatam efformante, nervi reliqui ut in Cineto graci- lipede.—An. galesiformis, Westw. Niger nitidus, antennarum, articulo 2do pedibusque rufo-piceis, femoribus basi obscurioribus, alis pallidé fuscescen- tibus. 15. Spilomicrus, Westw. Sibsenus Diapriam cum Galeso connectens. Caput transverso-quadratum. Antenne 9 capite thoraceque paullé longiores, 13-articulate, ad apicem sensim incrassate; ale stigmate parvo ante medium alarum, quadrato, apice interné deflexo, ramulum parvum, versus basin alarum reflexum, emittente; areola basali subtriangulari; nervi reliqui ferd ut in Paramesio, at indistinctissimi. Metathorax utrinque posticé spinosus. Femora cla- vata, pedunculus abdominis mediocris, striatus.—Spil. stigmaticalis, Westw., Niger nitidus, pedibus obscuré piceis, alis pallide flavescenti-fuscis, stigmate nigro. . 16. Epyris, Westw. Bethyllo affine. Caput mediocre subconvextim; antennz elongate filiformes 13-articulate#, articulo singulo cylindrico nec ad basin tenuiori. Thorax elongato-ovatus. Metathorax supra longitudinaliter 3-carinatum. Ale areola unica apicali longioriincompleta areolisque duabus basalibus longi- tudine zqualibus.—Epyr. niger, Westw. Niger, abdomine nitido, tibiis tarsisque plus minusve piceis. MMVIII. | Notice of some recent Magnetical Discoveries. By _M. A. Kurrrer, of the Imperial Academy of St. Petérs- _ burg; ina Letter to Six Davin Brewster, KH. LLAD. Sc. 'Y means of a number of experiments continued during the greater part of the winter of 1881, I have found thatthe intensity of the magnetic forces, in bars of steel, is diminished as much by the action of cold as by that of heat: I speak here of that part of the magnetic intensity which is lost when we €xpose a magnetized bar to a temperature higher than any which it has experienced since it was magnetized, and which is no longer found’ after cooling. I have henée adopted a more satisfactory method to procure maguietized cylinders o' Third Series. Vol. 1. No. 2. Aug. 1832. Ss 130 M. Fuss’s Account of the Magnetical and a constant force, for measuring the intensity of the earth’s magnetism. I not only plunge them several times in boiling water, but I cool them as often down to —20° or —25° of Reaumur, which is not difficult in our climate. This method has succeeded so perfectly, that I can recommend it to scien- tific travellers. I have also established the existence of a daily variation in the inclination of the needle and in the magnetic intensity, by direct methods; that is to say, by observing every day the march and duration of the oscillations of a dipping-needle, very long, and suspended on a knife-edge. I have found that the inclination is several minutes greater at 11 o'clock in the morn- ing than at 11 o'clock in the evening. The intensity, on the contrary, is greater in the evening than in the morning. XXIX. Account of the Magnetical and Meteorological Obser- vations made at Pekin, by M. Grorce Fuss. Communi- cated in a Letter from M. A. Kuprrer, of the Imperial Academy of St. Petersburg, to Sir Davip Brewster, K.H. LL.D. &c. M FUSS, the perpetual Secretary of the Academy of St. e Petersburg, has just communicated to me a letter which has been addressed to him from Pekin by his brother, who is at present with the Mission which the Russian Government sends out every ten years. At my request the Academy of St. Petersburg furnished M. Fuss (who set out from this place in the spring of 1830,) with all the instru- ments necessary for making magnetical observations. He has with him two declination needles, one of which was executed by M. Gambey of Paris, and which will serve also for ob- serving the hourly variations of declination ; and these needles will remain at Pekin after M. Fuss’s return to Russia, about the end of the present year. M. Fuss has also a dipping-needle, which is also from the workshop of M. Gambey ;—several magnetic cylinders for observing the intensity, and a chrono- meter, besides the instruments for astronomical observations. The magnetical observations will be continued at Pekin, after M. Fuss’s departure, by M. Kowanko, officer of mines, who will continue there during ten consecutive years. I send you an extract from this letter, and beg that you will communicate it to the Royal Society of Edinburgh*, and insert it in your Journal. * The sittings of the Royal Society of Edinburgh were concluded before the arrival of this letter. Meteorological. Observations made at Pekin. 131 Letter from M. George Fuss ¢o his Brother at St. Petersburg. « Pekin, April 22, 1831. <¢ In spite of the numerous obstacles which presented them- -selves during my journey from Kiankso to Pekin,—both from the difficulties of the road, and from a distrust of our Chinese escort,—I have been able to deterinine at seventeen points, the inclination and the magnetic intensities ; and at eight points the declination and the latitude. The longitudes have not been determined by the precise methods which were particularly re- commended in my instructions (the transits of the moon and the occultation of stars); for the erection of the transit instru- ment and the great telescope would have excited too much the attention of the Chinese, and awakened their distrust. I hope, however, that in returning I shall be less embarrassed, and that I may then be able to occupy myself more success- fully with the exact determination of the geographical position of some important points. At Dyan-dsia-keou, (Khalgan,) however, I have observed for the longitude the occultation of a small star in Capricorn, of the seventh magnitude, by the moon. « Soon after our arrival at Pekin, there was constructed, at my request, in the garden of the Mission, a column of masonry for astronomical observations. A tent, ofa particular construc- tion and very commodious, sheltered the observer from the ‘wind and the weather. The only inconvenience of this loca- lity is, that the horizon is covered almost all round by adja- cent houses. ‘The cross of the Church of the Mission, which is distant from my little observatory only about ten toises, serves as a mark for the declination needle. *‘ Though this distance is not very great, I have however obtained a very satisfactory agreement among my observa- tions, after having cut smali cavities for receiving the screws of the needle in the plate of marble which covers the column, and upon which the instrument is placed. The declination needle of M. Gambey gave me, on the 10th of January, 1831, at Pekin at 3" p.m., a declination of 1°42! 57" W. The dip- ping-needle of Gambey gave, on the 30th of December, 1830, a dip of 54° 52!-1, which is a mean between the results ob- tained by two different needles. The method of arbitrary azimuths* gave me, on the 6th of April, 54° 50!"7. It is proper to remark here, that the Chinese do not employ iron in the construction of their houses. I have also observed the horary variations of declination during the winter solstice, and during * An account of this method will be found in my Memoir on the Dip at St. Petersburg, inserted in Poggendorf’s Annals, Observation 1.— Note by M. Kupffer. . S2 182 M.A. Kupfter’s Note on the Mean Temperature of Nicolaief]’ the spring equinox, on the same days and at the same hours at which M. Kupffer observed at St. Petersburg. Ihave also determined the intensity of the terrestrial magnetic forces at Pekin, and at other points of my journey. ‘“* Relative to the geographical position of Pekin, I have ob- served, Ist, eleven transits of the moon by the transit instru- ment; 2ndly, a central eclipse of « Tauri by the moon, with the great telescope of Dollond; 3rdly, during twelve days from the winter solstice to the present time, the height of the sun at noon for the determination of the latitude, which I have found to be nearly 39° 54! 9"; and, 4thly, ten times, the transits of different stars across the plane of the prime vertical, to de- duce the latitude according to the method of Bessel. “¢ [ have observed also since my arrival, four times a day, the state of the barometer and thermometer. The greatest baro- metric height of 345°7 French lines took place on the 8th of March at midnight; and I am informed that on the same day, in the northern provinces, there was felt an earthquake. The smallest barometric height took place on the 20th of April, at six in the evening: it was 330°9 lines, and it was followed by a tempest. The greatest heat which has yet taken place was on the 20th of April, at 4" p.m. : it was 25° cent. The greatest cold was 13° cent.: it took place on the 5th of February, at 6"a.m. Inthe same month, however, on the 17th, the tempera- ture rose even to 10°5 cent. The cold was constant durin the second half of the month of January: in the other half, as in the month of December and the beginning of the month of February, the temperature oscillated round the point of the congelation of water; since the 13th of March it has been constantly warm. A barometer and thermometer will remain at Pekin, which will be observed during the ten years that the Mission will remain in China*.” XXX. Note on the Mcan Temperature of Nicolaieff, as de- duced from the Observations of M. Coumani. By Professor M. A. Kuprrer, ofthe Imperial Academy of St. Petersburg.t COUMANTL, at Nicolaieff, has communicated at differ- Le enttimes tothe Academy of Sciences at St. Petersburg, meteorological observations, carried on by himself, and through his means, with a perseverance, well worthy of imitation, at Nicolaieff and Sevastopol. ‘These observations are reduced with much order, and to, the register of each month is an- nexed a very elegant graphical view of the results. * All the dates in this letter are reckoned by the New Style. + Communicated by the Author, © M.A. Kupffer’s Note on the Mean Temperature of Nicolaieff. 138 - Nicolaieff is situated on the Black Sea, in north lat. 46°58’ 4, and in longitude 32° 0’ east of Greenwich; and its height above the Black Sea is about 20 toises. The following are the mean results of these observations ; and it must be observed that they are reckoned according to the Julian Calendar, which is still employed throughout all Russia. The observations were made twice a day at 105 a.m. and 10" p.m,, and the maxima and minima were also observed. Tas_e I. Mean State of the Octogesimal or Reaumur’s Ther- mometer at Nicolaieff, in the Years 1827—1830. 1827. 1828. 1829. 1830. Mean of|Mean of|Mean of| Mean of| Mean of|Mean of Meanof}Meano 102 a.m.) Maxim, |105 a.m.) Maxim. |10" a.m.) Maxim. |10° a.m.|Maxim, and and and and and and and and 104 p.o.|Minim, |10® v.a.|/Minim., |105 p.m,|Minim. |105 v..1.|Minim. o | o 3 p10 fon | ie | oe ° January i 03)+ 05|— 78|)— 77|— 76|— 60} — 7:8} — 7:5 February} — 0:5 08) — Ll} — 1:4] — 1:2} — 0-5) — 2:7] — 2:5 March + 53 56) + 52/4 53/4 49/4 48/4 28] +4 3:0 April 99! 106] 15-4) 11:0} 109] 11-0 99| 96 ay 166 16-9 145 14:5 13° 13°2 156 15:7 June 19°3 197 19°3 19:1 16-2 16°9 16°8| 16:8 July 199| 205] 187| 189] 182} 184] 183] 184 August 15°7 17:0 16°3 16°8 16°2 16-6 17°3 17°3 Septemb 11-4 11°6 10°9 10:9 13°6 13'7 10:9 10:9 October 63 6°4 3°4 34/+ 39)+ 41 4:8 51 Novemb + ¥1}+ 10/4 04/4 05} — 41] — 4:2 oo 33 Decemb. | — 26) — 26) — 64) — 45} — 41) —°38 | + 1:6) + 1-7 Means + 85 /|+ 90/4 7:-4|+ 7:2 + 66|+ 7:0|+ 7:6|+ 7:6 dts Reaumur. Fahr. Mean Temp. of 1827—1830, at 105 a.m. and 10" p.m, ...... +7952 48°-92 Mean Temp. at the hours of Max. and Min..............0.00- +7.:70 49 +32 Taste Il. Mean Temperature of Wells at Nicolaieff, in 1827, 1829, and 1830. January ... February... sen eee In 1828 the o Mean of 1827 Mean of 1829 November December One n een were enaneee ene e ee ee eeeeeeeeeees bservations on the temperature of this well were interrupted ; but they were resumed in 1829, and obser- vations were also made on another well. 134 M.A. Kupffer’s Note onthe Mean Temperature of Nicolaieg- A spring at Nicolaieff gave in 1830 the following results : January... +9°6 April... +94 DULY (evaves +9°4| October... +955 February Q°5 || May .....6 9°5||. August....|. 9:4 || November}....9:6 March ...| +9°3 | Jitie’%..... +9-4|| September] +9°5|| December} +9-6 Mean...... 9°°5 Reaumur...... 53°38 TasielII. Extreme Variations of the Octogesimal Thermometer at Nicolaieff, in each of the Months of the Years 1827—1830. — Max. | Min. °° ° + 4:2 159 20'9 24:0 27°2 27°3 28°1 21°6 141 November... E ; 8:0 December... 2 A A + 80 January nde ne +4 ay NE) GF COS A ee on oun eR oO bse November... December... 5 TABLE IV. Winds which blow at Nicolaieff during the greatest Heat and greatest Cold of each Month. Winds during |Winds during Max. Temp. | Min. Temp. 1828. | 1830. | 1828. | 1830. Winds during |Winds during Max. Temp. | Min. Temp. 1828. | 1830. | 1828. {y#830- January) Sw | NE |NNE|NNW/July ...| SE | SSE |WSW ‘Feb.....| SSE | SW | NNW). NW | August |\WNW| NNE| NNE | NNW. March | SW | SSE| W |NNW/Sept....| SSE | SW | NW | SW April.... SSE | SE | NW | N October WNW| SW N W NE | Wsw| Nw | Calm |/Nov. ...) SSE | SW sw |ssw.|. NE | NW |lDec. ..|_SW_]| SSE Sir D. Brewster on his Formule for Mean Temperatures 135 Taste V. Greatest Variation of the Octogesimal’ Thermo- meter at Nicolateff; on the different Days of each Month. Greatest Variation in a Day. Greatest Variation in a Day. 1827. | 1828. | 1829. |1830. 1827. | 1828. | 1829. | 1830. c ° ec ize), ° ° ° ° Jan.....,) 80 | 13:1 | 10:2 | 9°9 |\July ...| 11-8 | 15:5 | 11:4 | 13:5 Feb. ...| 14:3 | 8-8 | 10°7 | 9:5 ||August} 9:7 | 13:1 | 12:3 | 13-5 March | 10-1 | 10-9 | 12:3 | 11-2 ||Sept. ...) 10°8 | 13-7 | 12:4 | 12-0 April...|. 14-9 | 12:9 | 119 | 142 |!Oct. ...|.13°5 |. 9:1 9:8 | 11-7 May ...| 10°0 | 11°5 | 13:1 | 15-0 ||Nov. ...) 7:0 | 9:2 | 7-9 | 52 Juness..| 14°0 111-2 |:13°0° | 11-5 || Dec. ...| 7:7 8-7 7:9 73 Tasik VI. The Means of the Maxima and Minima of each Day, for every Month of the Year. ° ° ° ° o Oo Lae — 49— 7:0) 2-1/— 4:9/—10:1| 5:2 37 + 09/4 1:4) 23)+ 1:9,— 2:9) 48/4 0-5|— 5:4) 5-9 43 81) 24) 5°7| 80+ 1:5) 65) 5:6/+ 0-5) 5:1 54 15°7| 6:3} 94) 15-4) -6°5| 8-9} 13:9) 5-2} -8-7 90 190} 10:1) 8°9| 17:3) 9:0) 8-3) 20:5) 10:8] 9:7 9:0 23°6| 14:6) 9°0| 21-1) 12°7| 8-4} 21-1] 12:5] 8-6 8-7 23°4, 14:0) 9:4) 22:8) 14:0) 8:8) 23:0) 13:3) 9:7 93 21-5) 12:1) 9-4] 21-3) 11-9) 9-4) 21-7) 12:7) 9:0 9°3 15"l} =6°8) 8:3) 18:2 91) 91) 15-4) 6-7] 8-7 87 5°2/+ 1°7| 3:5/+ 68\+ 1:3) 5°5| 8:4) 1-7) 6-7 52 + 2-4/— 1:4) 38|/— 2:0— 6:4) 4-4) 4°5)/4+ 2:0] 2°5 36 — 23)\— 67| 44|— 14— 62 48\+ 3-6\— 0-2| 3:8 43 [Observations on the preceding Results. In a paper on the Mean Temperature of the Earth, pub- lished in the 9th volume of the Edinburgh Transactions, and also in the Edinburgh Journal of Science, No. VIII. p. 300, I have shown that the temperature of the globe is distributed in reference to two axes different from the axis ef rotation; and I have constructed formula, founded on this principle, for ‘computing the mean temperature at any point of the earth’s surface. In order to compare this theory with observations, especially round the Asiatic Pole of maximum cold, it became desirable to have accurate observations on the mean tempera- ture of various points in the interior of the Russian empire. Professor Hansteen, previous to setting out on his journey to Siberia, kindly undertook to procure for me such observa- tions; and for the same purpose Professor Kupffer, of St. Petersburg, has had the kindness to send me several valuable 136 M. Rudberg on the Refraction of the differently-coloured sets of reduced observations, which are of the highest value im reference to this important branch of meteorology. These ob- servations will be published in successive Numbers of this Journal ; and while they will enable me to compare my own theoretical view with observations, they will be received by the scientific meteorologist as data of inestimable value in fixing the principles of this new science. It appears from the first of the preceding tables, that the mean’ temperature of Nicolaieff for four successive years, from 1827—1830, at 108 a.m. and 10° p.m. is 7°52 Reaumur, or 48°°92 Fahr. When we correct this result by + 0°122, the quantity by which the mean of 10 and 105 differs from that of | the 24 hours, we obtain, Fahr. Corrected mean temp. of Nicolaieff ......s0ceeseseee. 49°04 Add for elevation of 20 toises...... oP was eee epetieets “36 Mean temp. of level of sea ........scesecesevereeee 4.9940 Mean temp. calculated by formula T = 86°3 sin. D — 3°5 D, the dist. from the Asiatic Pole being — 3! js 07 by San sip Sie abe o-siellbicte altalps clot de boiled Chis uebe obistetal, da} SoaReD Difference between the observation and the formula +1993 The mean temperature of the year 1827 at Nico- Fateff wast Bally. ..0cve oe wines oth antnate oncds'ens sb cevety 52°4 So that the formula gives a result within the varying limits of observations. for different years, and differing very little. from the mean result. D. B.}) XXXI. On the Refraction of differently-coloured Rays in wea with one and two Axes of Double Refraction. By . RupBere. [Continued from page 6.] Section Il. Refraction in Crystals with two Optical Azes. He crystals of this kind, which I have been able to pro- cure, were arragonite, colourless topaz, and the topaz of Schneckenstein. I have not, however, been able to make usé of the last of these, of which I have large and fine specimens, because throughout their interior there are cleavage planes, which being always parallel to the external planes reflect the’ sun’s rays in so confused a manner, that the spectrum is not distinct. I have consequently been able to make experi- ments only with arragonite, and white or colourless topaz. Before givino*an accotmt of these experiments, I shall briefly: explain the’ theory of double refraction in crystals with two . & Rays, inCrystals with one and two Azes of Double Refraction. 137 axes, because it is only by this elegant theory of Fresnel that we can find the directions in which the prisms must be cut. Fresnel founded his theory on two hypotheses, viz. 1. That in doubly refracting crystals the elasticity of the vibrating medium is different in different directions; and 2. That the vibrations of the light polarized are at the same time perpendicular to the direction of its propagation and to the plane of polarization, He supposes that in every crystallized substance there are three directions perpendicular to each other, called axes. of elasticity, according to which the elasticity may in general be different. Ifthe elasticity is the same in all these three direc- , tions, the crystal belongs to the regular system, and has no double refraction. If it is equal in two directions, the crystal, refracts doubly, and has one optical axis; and if the elasticity is unequal in ail the three directions, the crystal has ¢wo optical axes. From this difference of elasticity there results for light a different velocity, which ought necessarily, in general, to become unequal for the two rays into which the light becomes divided itself, and whose planes of polarization are perpen- dicular to each other. There are in crystals with two optical axes only two directions; that of the axes themselves, in which the two rays are propagated with the same velocity. Con- sequently, in order to appreciate the velocity of the two rays in any direction, we must determine their planes of polariza- tion, which is done by the following considerations. The plane in which the two optical axes are situated contains also two of the axes of crystallization, one of which bisects the acute, and the other the obtuse angle of the optical axes. If we con- ceive, then, two planes passing through the direction in which we wish to have the velocity of the two rays, and respectively through each of the optical axes, the plane which bisects the angle formed by these two planes will be the plane of polari- zation of one of the rays, that of the other being perpendicular to this plane, and passing through the given direction. It follows from this, that if the light comes in a direction perpendicular to one of the axes of crystallization, one of the rays ought to have its plane of polarization perpendicular to this axis. The velocity with which these vibrations are pro- pagated, depending only on the elasticity in the direction of this axis, it is evident that it remains the same whatever be the direction of the ray in the plane perpendicular to the axis. The other ray, on the contrary, whose plane of polarization passes through the axes, and consequently changes: with its direction, will have different velocities in different directions, because its vibrations being always made in the plane of the other two axes of crystallization, may become successively pa- Third Series. Vol. 1. No. 2. August 1832. ¥ 138 M. Rudberg on the Refraction of the differently-coloured rallel to both of these axes, and consequently undergo every change of velocity of propagation which the difference of elas- ticity in these two directions admits. If therefore we cut a prism in such a manner that its edge is parallel to one of the axes of crystallization, that of the two rays. whose piane of polarization is perpendicular to the axis ought to have a constant velocity, and follow in its refraction the law of Descartes (Snellius). The velocity of the other ray depends on its direction in reference to the other two axes of crystallization. Having thus cut three prisms, each of which had its edge respectively parallel to one of the axes of crystallization, and determining in each prism the index of re- fraction of the ray whose velocity remains invariable, we shall have the three elements on which the double refraction of the crystal depends. The exposition of the results of the mathematical. theory of Fresnel will illustrate still better what we have said. Calling, in the spirit of the system of emanation, v', v' the velocities of the two rays, ¢’, <’ the angles which the two optical axes form with the common direction of the rays, we shall have the velocity of one of these by the equation v? = A + B.sin? 4 (ce — e"), and that of the other by the equation J?= A+ B.sin} (2 + el), in which A and B are constants. It has already been remarked, that two of the axes of cry- stallization are situated in the same plane as the optical axes, and that the third is perpendicular to this plane. I shall in the sequel call the axis of crystallization which bisects the acute angle of the optical axes the aais A, that which bisects the obtuse angle the azis B, and that which is perpendicular to the plane of the optical axes the axis C. From the pre- ceding observations we conclude, 1. If the edge of the prism is parallel to the axis A, and if the two rays are consequently refracted in a plane perpen- dicular to this axis, we shall always have, if the angles ¢/ and «" are reckoned from the axis A, <’ + «” = 180°, and therefore v? = A + B. cos? 2’, and v//® = A + B. This last velocity is constant, and is that of the ray whose plane of polarization is perpendicular to the axis A. The velocity of the other ray depends on the value of the angle ¢', which may vary from 90° to 90° — } a, calling @ the acute angle of the optical axes. The value of the square of this velocity will.thus vary . between A and A + Bsin* da. Rays, in Crystalswith one and two Axes of DoubleRefraction. 139 2. If the edge of the prism is parallel to the axis B, we have always « = <”, and consequently v? = A and'v? = A + B sin? el!” The velocity v is in this prism constant, and belongs to the ray which is polarized in a plane perpendicular to the axis B. The velocity of the other ray depends on the value of ¢! between the limits 4 « and 90°. Hence the square of the velocity may vary between A + Band A + Bsin? a. 3. If the edge of the prism is parallel to the axis C, we shall always have e’ = <" + a; hence v2? = A+B. sin*? 1a, and v2?—= A+B. sin? (2! + 42). In this prism the velocity v’ is constant, and belongs to the ray whose plane of polarization is perpendicular to the axis C. As the angle ¢’ may have different values from 90° — 4. to — 4a, the square of the velocity of the other ray will vary between A and A + B. If in the three prisms, cut as now described, we observe the deviation of the ray, whose velocity remains constant indepen- dently of the direction, and if we calculate the index of retrac- tion, we shall have the values of three quantities A, B and z. Calling 7’ the index in the prism whose edge is parallel to A, n” that in the prism whose edge is parallel to B, and 7!" that in the prism whose edge is parallel to C, we shall have, the velocity of light in air being taken as unity, n?—>A+ Bn”? = Ayn’? =A+B.sin® da, and consequently / os rt ie hai nll? m= qlll2 Az=n?, B=n” — nn’, and sin?4 a= n’? a n!//2 hi I come now to an account of my experiments. Arragonite.—Out of a crystal of this mineral from Bohemia, I cut three prisms: 1. The prism A having the edges of its refracting angles parallel to the axis A of the pyramidal crystal. A, No. 1, and A, No. 2, are two different refracting angles. 2. The prisms B had their edges parallel to the axis B; the two are marked B, No. 1. and B, No. 2. 3. The prisms C had their edges parallel to the axis C; two of them thus cut are named C, No. 1. and C, No. 2. The light which moves with a constant velocity may be known by its passing through a plate of tourmaline, having its axis parallel to the edge of the prism. The prism A, No. 1.—Refracting angle 66° 43’ 17’. Temp. + 19° cent, In the spectrum, where the deviations were the Te 140 M. Rudberg on the Refraction of the differently-coloured _- greatest, the ray F was brought to a minimum of deviation, and in the other spectrum the ray H. The prism A, No. 2.—Refracting angle 51° 48’ 31’. Temp. + 18° cent. The rays F in the two spectra were brought to a minimum of deviation. The following are the indices of refraction for the spectrum, whose plane of polarization is perpendicular to A. Fixed Prism A, Prism A, lines. No. 1. No. 2. Diff. H 1°54226 . . 1954225 = 000001 G 1°53880 . . 1°53885 . . — 0:00005 F 1°53480 . . 1°53478 . 4. + 0:00002 E SS RD SCOR: ft ky ROO be — 0:00001] D stl FRSOIID ooh io Od 1 + 0:00004 C 1°52818 . . 152822 . . — 0:00004 mB -. 1°52747 i°52751L . . — 0:00004 These differences are evidently errors of observation, and the invariability of the velocity of the ray polarized perpen- dicularly to the axis A is consequently well established. With respect to the other ray, its velocity cannot be constant accord- ing to theory; and this is proved by observation, as is shown by the two following measures in the spectrum whose plane of polarization passes through A. Prism A, Prism A, Now: No.2. Diff. Tl ie te L099: esse a ODGO'. « os AO le HOG Bae 1G 9509.~ 2 A LOOT2S ve ie LOrOUaae Prism B, No. 1.—Refracting angle 36° 13’ 30’, Temp. + 18°. In the spectrum with the greatest deviations, the ray F was reduced to a minimum of deviation, and in the other the ray H. The same was the case in Prism B, No. 2.—Refracting angle 40° 12’ 3’. Temp. -+ 18°. The following were the indices of refraction. Prism B, Prism B, No. 1. No. 2. Diff. How 1°71019 . . #1°71004 . . 000015 Ge: 1 ZOB2S wits bs 20381. 2's 100014 Des 169520 . . 1°69510 . . 0-00010 aod 1°69091 2S. “1690782 i O00018 i) 2% 168595 . . 1°68583 . . 0:00012 Gr FSAI -6B206) Ye VD G8200; 157 i 000006 iBe™ 168066 . 1‘680587 0:00009 The differences here, though greater than in prism A, owing to the difficulty of cutting a face exactly perpendicular to the plane of the optical axes, are yet sufficient to prove the invari- ability of the velocity of the ray polarized perpendicularly Rays, in Crystals with one and two Axes of Double Refraction. 141 to B. That the velocity of the rays in the other spectrum varies, is proved by the two following observations. Prism Bj’ = s«éPrism BB, Nom hss No. 2. Diff. BE ys AGA P4D oye PSSST PHONO MOOR Ge? 1 B38 498" 2 13529. 2» 000086! Prism C, No.1.—Refracting angle 29° 43! 21". Temp. +17°. The ray H was in both spectra brought to a minimum devia- tion. Prism C, No.2.—Retracting angle 41° 34’ 32’. Temp. + 16°. In the spectrum of greatest deviation the ray F, and in the least the ray H, was brought to a minimum deviation. The following were the refractive indices in the spectrum, whose plane of polarization was perpendicular to the axis C. Prism C, No. 1. Prism C, No. 2. og A (ODL Zee te isle aT OD 169830 . . . . 1°69843 1:-69049 . . . . 169058 I GoOSa teh eie = LOGO So W-GSUS fats bs te vaett Le Gol oo WOR ET Gukeoie y eine eG ae opueapil OMOSZ anes Vou ite ietey Leos The indices vary in the other spectrum, as the following observations show. Prism C, No, 1. Prism C, No. 2. Fi oe DARAS at «0 Eh AGG TSS BOO Geodon th lu agree) . All these observations incontestably confirm the fundamental theorem of Fresnel, that the velocity of one ray is invariable as long as its plane of polarization remains the same. The following means of the two systems of indices for the three spectra, whose planes of polarization are perpendicular to the three axes of crystallization, exhibit the elements of re- fraction of arragonite. Axis A. Axis B. * Axis C. Be eye 0h 549296) chine EOVIONL |g spp 70509 Gn iin, 158882 5 6 ,5.)0970818) 4615 49954169836 Fine 153479 coe 169515 + 169053 Ut sp folk pl" DSZO4O Yes cor, L698 ips ny 68634 Do AF Psi, ABSOLB ous, (lL 68E89 ypicnras d COROT oa 9 1952820 un Ki 2°68208 Adn..67779 BAS 5 62749" 2 oe) L6806E 2.6 1167681 Calling x, x” and n”” the indices for the spectra polarized perpendicularly to the axes A, B and C, and calculating the mn" m" . n ratios —— and —-, we shall find n n WOOHAAT 142 M. Rudberg on the Refraction of the differently-coloured », Ratio wie Ratio ee nr n pi lOSES ie poco. se O02 Ea: eh Lr LOOSR eich sel tre), ls OO8S4: on AGED eo. ort as 1002 73 WHOS 22s sek exe JL OOLOY) LO G4 es tare «lOO Log ei OUGOr en te reuee as LOZ ae eed OO Aa roe.) vee, fel UC ae Hence every colour in arragonite has a double refraction as much greater as it is more refrangible. This result agrees with that for rock crystal and Iceland spar; and we may there- fore conclude in general, that Each colour has its individual double refraction as much greater as its own refrangibility is greater*. By means of the preceding values of the indices n’, »” and n'', we may calculate the angle of inclination « of the optical axes 11/2 112 nie _ n so @ es chico kp han, by the formula sin? l@ = IE ye * BS in the following table. H . 20° 25’ 6! G SA UQOVER TS IEG F 20 Oo 50 E V9 53+) MO D 19° 37 8 C 2 TOM Bsr ta B - 19 44 40 Hence we see that in arragonite the inclination of the optical axes diminishes continually from the violet to the red light. Dr. Brewster gives for the true inclination of the optical axes 18° 18’, calculated from the observed apparent inclination. But as he has not given the value of this apparent inclination, nor the index which he made use of to calculate the true in- clination, it is impossible to compare his result with that of my experiments. Having several times measured the apparent inclination of the axes by means of a plate with parallel faces cut perpen- dicularly to the axis A, I found it a little more than 32°. To make a comparison with this value, we must calculate the apparent inclinations from the true inclinations as given in the above table. This is easily done; since we can now determine the velocity of light in the direction even of an optical axis. If we insert in the formule, given at the beginning of this sec- tion (p. 138), «/ =o, and e = a, we obtain v? =v? = nl? _ (nl? — rn) sin? a in which v= v” = 7’. * See our last Number, p. 6. + See the next Article. Rays, inCrystals with one and twoAzes of DoubleRefraction. 143 The ray which in emerging from the plate deviates accord- ing to the law of Descartes (Snellius), takes a direction with- out, making with the normal of the plate an angle } 7, which is calculated by the formula sin $7 = 7” sin} a. The following are the values of z for the different colours. - Apparent Inclination of the Optical Axes. lla) 4 ol Be EE, ste LOO. MOU eas A he Loo ese The mean inclination is about 34°, which differs about 2° from the observed inclination. Notwithstanding the difficulty of taking this angle with precision, the difference of 2° is still too great. I cannot tell the cause, unless the two rays, which, within the plate, pass.along the same optical axes, separate at their egress. The preceding experiments having demonstrated that the ratio of the indices of refraction varies in the three spectra with the colours, the true ratio between the elasticities of the vibrating medium along the three axes of crystallization cannot be determined. If we take the elasticity of the vibrating me- dium in air to be unity, the elasticity along the axis A will be co@ kwh cr ieo hep han, oo 69 er =) 7z3 since the velo- n 1 1 => along B = Fl? and along C = oar : ] 1 ae : cities being ay? yl? and 57 in the system of undulations are as the square roots of the elasticity. But when the ratios 2 yee : aye and ~ 7s change with the colours, they do not express exactly the ratios of the elasticity along the three axes of cry- stallization. However, in taking the elasticity along the axis A as unity, and calculating the above ratios for one of the middle rays of the spectrum, such as F, we shall have the fol- lowing elasticities for Arragonite. A B C 1 0°81975 0'82424 And for calcareous spar, ' Along Axis. Perpendicular to Axis. 1 0°79874. Colourless Topaz.—The prisms of this mineral were cut in the same manner as those of arragonite. As the two spectra always cover one another, I used a plate of tourmaline to 144 M. Rudberg on the Refraction of the differently-coloured separate them in the manner -already: described’ for tock crystal. pesos DIGY 1 | Sirsth OA .. Prism.A, Nov 1.— Refracting angle: 30° 15! 29". ‘Temp. +19°.. Inthe spectrum of greatest deviation, the ray F was reduced to the minimum deviation, and in the other the ray H. Prism A, No. 2.—Refracting angle 42°40! 16": The following were the indices observed in the spectrum perpendicular to A. Prism A, No. 1. Prism A; No. 2: Diff. 163506. . 1°63490 . . +0°00016 163123 . . 1°63140 . . —000017 1°62652 . 162408 . 1:62109 «» |» 5 6RB8O ~ « dORYS1 And in the spectrum polarized parallel to A. Prism A, No. 1. Prism A, No. 2. Diff. H . . 162551 . . 162758 -. . 000207 G . 0.162156... 1°62374 0. (000010 Prism B.—Refracting angle 49° 3' 8". Temp. +19°. In both spectra the ray H was brought to the minimum deviation. Prism C.—Refracting angle 38° 38’ 54". Temp. 16°. In both spectra the ray H was brought to a minimum devia-. tion. The foilowing are the indices for the spectrum polarized perpendicularly to the axes A, B and C. i A. B. CW aw, 1635065 2h P6269"... IZ 7as 1563123" - °. 162154... 6250 1°62652 ff ON*6T701 2. 1619T4 1°62408 . . 161452 . . 1°61668 PGQV09!) 8? AGLIGL OS sO 8s 7a 161880 ... 1°60935 . . 1°6114+4 161791 . . 160840 . . 1°61049 DOO mAa woOoRaar "“ , And the ratios 7 a will be as follows: ! I Ratio Ratio 77 ghue (1°OOS6E6 *5) 365) 1'00595 St SHOE TS «6 EO0D9T7 . 100456 . . 1°00588 1:00458 . . 1:00592 1°00455-. . 1:00588 100459. . 1:00587 1:00461 . . *1:00591 WOOn ar Rays, in Crystals with one and two Axes of Double Refraction. 145 These ratios differ so little from each other, that one would be led to regard the differences as only errors of observation. They, however, appear to increase a little from the violet to the red, and consequently do not contradict the result ob- tained for Iceland spar, rock crystal and Arragonite. The inclinations of the optical axes calculated by the formula 12 UE Hie n'!? — 9 sin? a = —;—;,s are as follows: nl? — lll? Inclination of the Optical Axes. Fiee(. 54°5200" G 55 34 24 Bie se SH OF 194 E . . 56 40 30 .. ... 56, 3808p Cc JON cone B,.. .ob Sco Abstracting the irregularities in these values towards the red extremity of the spectrum, it appears that the inclination of the optical axes goes on diminishing with the refrangibility of the rays, whilst the contrary takes place in Arragonite. With regard to the value of the inclination, Dr. Brewster has found it = 65°, and M. Biot = 64° 14!. This difference of more than 8°, appears to indicate errors in the determina- tion of the indices, unless the inclination in different speci- mens of colourless topaz is different, as Dr. Brewster found it to be for different kinds of Brazil topaz. It is to be observed, that all the prisms with which I made the preceding observa- tions, came from the same topaz. Having after this only thin plates, I could not, on account of the great extent of the ellip- tical rings, measure the inclination of the axes with precision. Taking for topaz as for Arragonite the elasticity along the axis A as unity, the following will be the elasticities along the other axes. A. B. C. 1 1:01186 1:00922 In his memoir on Double Refraction (Mém. de l Institut, tom. vii.) Fresnel has given from his experiments on diffrac- tion made with colourless topaz, the ratio between the least and greatest velocity. He found it 0'9938. My experiments tt 1 make the mean result ag? a 0°99412, which ex- ceeds the former by 00003. Assuming the ratio 0°9938, and I the inclination of the optical axes = 65°, the ratio ie may be fou®g by the equation, Ne Ne ie n n n — Third Scries. Vol. 1. Noe. Aug. 1852. 1 3 146 Sir D. Brewster’s Observations on M. Rudberg’s Memoir. We.thus obtain 6:99560. .My experiments give ae = 0'99542, which is 0:00018 in defect, ‘These differences, however, evi- dently arise, on the one hand, from the difficulty of determining these ratios by experiments on refraction with prisms. different= ly cut, with a precision comparable to that which we obtain, by means of experiments on diffraction; and.on the other hand from the probable inaccuracy in the value. of the inclination. of the optical axes found by the observation of the coloured. rings, XXXII. Observations on the preceding Memoir. By Sin Davin Brewster, K.H. LL.D. F.RS. VP RS. Ed. . PY CIV hs TAN DING the great accuracy and value of the preceding observations, and the importance of the deductions which the author has drawn from them, yet we are constrained to state, that almost all the general principles at which M. Rudberg has arrived have been previously esta- blished. by English philosophers, though not by observations made by means of the fixed lines in the spectrum. The variation of the inclination of the optic axes with the different colours of the spectrum, and the increase of that angle with the refrangibility of the colour in some crystals, such as Arragonite, and its decrease with the refrangibility in other crystals, such as topaz, is the discovery of Sir John I. W. Herschel, and one of the most important that has been made on the subject of double refraction ; and yet the name of Sir John Herschel is not once mentioned. Sir John indeed did’ not examine Arragonite and topaz, but he found the very same phznomena in sulphate of barytes and Rochelle salts ; andas 1 had myself discovered that all those crystals in which the in- clination of the optic axes increases with the refrangibility, have the red ends of their systems of rings znwards, or towards the axis A; while those in which this inclination decreases with the refrangibility have the red ends of their rings outwards, or, to- wards the axis B, and had determined that drragonite had the red ends of its rings inwards, and ¢opaz the red ends outwards *; the variation of the inclination of the optic axes in these two mi- nerals, and its inverse character, were both known’ before M. Rudberg’s experiments. ‘To M. Rudberg, however, there’ remains the merit of having given the values of these’ angles,’ and that too in reference to fixed points of the spectrum,.. . It is impossible to overlook the great difference between, theory and ohseryation in the inclination of the. optic axes of Arragonite and topaz as given by M. Rudberg. His observa~! Art. Optics, in the Edinburgh Encyclopedia, vol. xv. p- pastas _ Dr.F PROGRESS ov GEOLOGY 1n- ENGLAND — tions mak eee ong a to my ob the rea : a Upon re- é z ards I j ypon mes 3 z tion of th Z apparent spectrum. tions; $0 that whic The di greater i optic axe structure Taking clination 64 22/51 used, can will no ¢ specimen In exp valuable he will ex refraction other phi and that ‘a proper labours. XXXIL Me SMT, 1887 Section ef, ENGLAND WALES; m Snowdon to Londoy To the Gen N ar Feb nhasy Wit Vang vale” ¢ hay vaLe® $ OP. Lanny Sa vail x : “tla Ludlav TEIN . 7 » wonersrrat Esoreneh : fe i - ——" et Teka burs ts ' Riiloaers EST aes = = a heltenham Sen : | ees g E 25 24 25 Gatley am : ; a Menta 20 Won rome a " vi n Blue Mar oelir Olen, trom the Triyonometrical Survey — The tontous Historterd um the nec Pom the necrtiity of representing the distances anik altitudes by sith — - ~~ Dr. Fitton’s Notes on the History of English Geology. 147 tions make the apparent inclination in Arragonite a little more than 32°, whereas the theory makes it fully 34°. According to’ my observations, the apparent inclination was $1° 15’, and the real inclination 18° 18’, computed with an index of 1-693. Upon re-examining this crystallized plate some years after- wards, I found that its surface was inclined to the axis A; and upon measuring the inclination, I found that the true inclina- tion of the optic axes was 17° 33’, which corresponds to an apparent inclination of about 29° 56’ for the mean ray of the spectrum. Different crystals, however, have different inclina- tions; so that we are not entitled to compare this result with that which is deduced from theory. The discrepancy between theory and observation is still greater in topaz, amounting to 8° in the inclination of the optic axes, if the specimen used by M. Rudberg had the same structure as that which was used by M. Biot and myself. Taking the index of topaz at 1-636, I found the apparent in- clination of the axes to be 121° 16', and the real inclination 64° 22, which, from the excellence of the specimen which T used, cannot, I think, err above half a degree. M. Rudberg will no doubt measure the inclination of the axes in every specimen by which he has obtained the theoretical inclination. In expressing a hope that M. Rudberg may continue his valuable observations, with other crystallized bodies, we trust he will excuse us for adding, that though the subject of double refraction is under the deepest obligation to M. Fresnel, yet other philosophers have wrought in the same field before him; and that his transcendent merits would not be diminished by a proper recognition and acknowledgement of their antecedent labours. XXXUI. Notes on the History of English Geology. By ‘or , _, Wiir1am Henry Firton, M.D, F.R.S. Sc. ‘To the Editors of the Philosophical Magazine and Journal. Fi : Gentlemen, AN article which I published in the Edinburgh Review for += February 1818, On the Geological Map, and other works: of Mr. William Smith*, having been frequently referred’ to, the historical part of it was printed, with some additions, ‘in + The following is a list of Mr. Smith’s works, prefixed to the articlé in the Review,—vol. xxix. p. 310, &c. ““ 1. A Delineation (Map) of the Strata of England and Wales, with Part of Scotland; exhibiting the Collieries ‘and Mines, the Marshes’ and Fenlands originally overflowed bythe Sea, andthe Varieties of Soil accord. : i J 9 ~ 448 © Dry Fitton’s Notes on the History of English Geology. 1821, for insertion in a Journal more immediately devoted to science than that in which it originally appeared ; | but its publication was at that time prevented by accidental circum- stances. As the Review has been more recently mentioned by the late President of the Geological Society, in announcing the award of the first Wollaston Medal to Mr. Smith*, I now beg leave to place at your disposal one of the printed copies above mentioned. I remain, Gentlemen, &c. &c. London, July 1832. Wm. H. Frrron. A Map may not, at first sight, appear to come within the scope of a literary publication; but the performance now be- ° fore us, with the other works connected with it, has more than ordinary claims upon the attention of the public. It con- tains a great deal of information, of practical importance as well as speculative interest. It is the first work of the kind that has ever appeared in England; and it is the production, after the labour of more than twenty years, of a most inge- nious man, who has been singularly deficient in the art of in- troducing himself to public notice. Mr. Smith is by profession a civil engineer, and, we are in- formed, is particularly skilled in that department of his business which relates to draining, and the structure of canals. It ap- pears, that in the course of the inquiries to which his occupa- tions naturally led him, he had occasion, many years ago, to observe the regularity and steadiness of the order exhibited by the strata in the vicinity of Bath; and about the year 1798, he drew up a tabular view of the stratification of that district, which in fact contained the rudiments of all his subsequent dis- coveries, and was in itself a proof of great sagacity and appli- cation. In the course of different journeys afterwards made, he not only recognised, among the strata in the North of England, several of his old acquaintances at Bath, but was surprised to ing to the Variations of the Substrata, illustrated by the most Descriptive Names.—15 sheets, coloured. Carey, London. August, 1815. : «2. A Memoir of the Map and Delineation, &c. pp. 51. 1815. «‘ 3. Geological Section from London to Snowdon, 1817.” 4. A Series of County Maps, on a much larger scale than that of the General ‘ Delineation, &c., coloured to correspond with it. 1817. “° 5. Strata identified by Organized Fossils, containing Prints on’ co- loured paper of the most characteristic Specimens in each Stratum. 4to. Published in Numbers. 1816. “6, Stratigraphical System of Organized Fossils, with reference to the Specimens. of the original Geological Collection in the British Museum, 4to, 1817.” * See Phil. Mag. and Annals, Nu. vol. ix. p. 275.—Kore. Dr. Fitton’s Notes on the History of English Geology. 149 find them in the same company with which, they are associated in that neighbourhood : and, after full investigation, he became at last convinced, that the series of beds was uniform through- out the whole of the south-eastern portion of the island; and that the edge of every stratum, with very few exceptions, might be traced, uninterruptedly, from one shore to the other, ina direction from S.W. to N.E. These important observations, which were made, we have no doubt, without any acquaintance with previous publications on the subject, led very naturally to the project of a map, in which they might be embodied and combined, and gave birth to the valuable works at present under our consideration. It has been unfortunate for the celebrity of Mr. Smith, that he did not communicate to the public, in a more early stage of his inquiries, some general account of the principles which he had developed, with an outline at least of the detail. If, for example, he had given to the Royal Society a list and brief description of the English strata, his claims would have been recorded in the most dignified and authentic form, and. his further progress would, no doubt, have been assisted by, all those who felt an interest in the subject. His wish, however, seems to have been to abstain from publication till his project _was completed; and the accomplishment of this purpose was from time to time delayed, in part, by his necessary attention to the pursuits of his profession; by the great expense attend- ing an undertaking of such magnitude; and by his anxiety to give his work that perfection which every discoverer is natu- rally ambitious of conferring on his publications. In the mean ‘time, as his inquiries advanced, he did not hesitate to make known the facts and inferences which occurred to him, and to exhibit freely his maps, sections and specimens *, with the warmth and liberality, and we may add, with the want of pru- dence, which are frequently characteristic of men of talents. “Not only the elements, but a great part of the detail, of the ‘present performances, were thus, in fact, made public; and .the knowledge so diffused has had a most important, though unobserved, effect upon the labours of all succeeding inquirers ; who were, perhaps unconsciously, but not less really, indebted to the author for very essential assistance in their progress, long before the productions now before us had actually issued from the press. In an early stage of his inquiry, Mr. Smith communicated his observations to the Rev. Joseph Townsend, the author of [* Some of the documents here referred to, of very early date, have re- cently been presented to the Geological Society :—1832.}—See Phil. Mag. and Annals, N.§., vol. ix. p, 281.—opir. 150 Dy? Fittbri’s Wores onthe Fistor oy English Geology). a well-known book of travéls’'in® Spain; ‘and subsequently to Mp. Fareys'‘who was*at' that | time we ‘believe his’ pupil’; two gentlemen who must, in fact; be Considered ’as the chief editors of his! opinions! The'title of the book ‘in °which Mr. Pown- sénd has oiven an account of Mr. Smith’s discoveries, * The Character of Moses established for Veracity'as an Historian*,” was certainly not calculated to attract the attention of geolo- gists, and has apparently very little connexion with the stra- tification of England; but the ingenious author conceived the crédibility of the Mosaic account of the creation, to derive im= portant support from the existing appearances of the globe; and, for the purpose of illustrating those appearances, he has. entered into a full description of the British strata. He pro- fesses however, very candidly, to have obtained his kncw- ledge of the subject almost entirely from Mr. Smith; of whom, after ‘stating that, with a view to the completion of his own work, he had lost no opportunity of conversing with foreign. mineralogists of eminence, he thus expresses his opinion :— ~ **'The discoveries of this skilful engineer have been of vast ‘importance! to geology, and will be of infinite value to this ‘nation. To a strong understanding, a retentive memory, in- ¢defatigable ardour, and more than common sagacity, this ex=' ‘ traordinary man unites a perfect contempt for money, when “compared with science. Had he kept his discoveries to him-" ‘self, he might have accumulated wealth; but, with unparal- © Jeled disinterestedness of mind, he scorned concealment, and ‘ made known his discoveries to every one who wished for in-. ‘formation. It is now (1813) eleven years since he conducted ‘the author in his examination of the strata which are laid” ‘ bare in the immediate vicinity of Bath; and subsequent ex- cursions in the stratified and calcareous portion of our island «have confirmed the information thus obtained +.’ ar Mr. Farey, the other person above mentioned, who is him- self a geologist of no inconsiderable merit, has not confined. himself to the diffusion of Mr. Smith’s opinioris; but has very” strenuously asserted the claims of his preceptor, not merely to having’ actually traced and demonstrated the order of ‘the ' strata in England, and devised for their discrimination a num+~ ber of subordinate distinctions, to which we believe his: title” cannot be disputed ; but to his having been the first to‘ascer~~ tain’ “that the fossil productions of the strata are not aeci~~ ‘dentally distributed therein, but that each particular, species ‘ has its.proper.and invariable place.in some particular stratum; ¢ and:to: having»proved that some one or two, or more, of these» * Two vols. 4to. 1813-1815, Bath and London (Longman)... op + Townsend, vol. i. Introduction, pp. 4, 5. ee ae Dr. Fitton’s Nofeson the History of English Geology, 151 ‘species of fossil:shells may serveias new, and, more. distinctive ‘ marks of the identity. of most.of the strata-of England *..Now; UPAR these’ points we..shall, observe—1st, That.we do, believe Mr, Smith; to haye, been led by his own obseryations,,to: the discovery of the doctrines,and facts which are claimed for him by. Mr, Farey,,.. But, 2ndly,. It is, equally, certain, that.a. very near approach had been, made. by preceding writers, to the. doctrines maintained by, Mr. Smith upon the subject of strati- fication ; and, more especially, as to the possibility of deducing, distinctive characters of the strata from their organized \con- tents :—though it. is only candid to allow, that. the passages, which bear upon these points might possibly have slept much longer in the volumes which contain them, if the attention ex- cited by Mr. Smith’s publications had not led to their detec- tion ;,and that the light in which they now appear to us is very’ different from what it would have been without such assistance. 3rdly, ‘That Mr. Smith deserves, undoubtedly, the credit, of having first conceived, and actually executed, with. extraor- dinary devotion, the project of tracing the strata entirely across this island; and of having thus established upon, positive, evi- dence, principles till then (at the utmost) considered rather as. probable than as true. It is therefore very far from ourjin- tention, in the subjoined sketch of the progress of opinion and » discovery respecting the newer and more regularly stratified » portion of the globe, to detract from the great merit of Mr. Smith’s investigations; or to impeach, if we may be allowed the expression, his consciousness of discovery: our sole object being to found the history of this subject, upon what we think must be regarded as the only safe and tangible standard in the chronology of science,—the relative order of publication +. The French Encyclopédie Méthudique contains, under. the article Physical Geography, published in 1796, by the late M. Desmarestt, a full account of some of the principal publi- cations upon that subject, to the middle of the last century ; from whence may. be obtained some valuable facts, diluted very. prenifully with. speculation. about, the primeval. state of the globe... But, on the whole, these volumes have not. much increased our respect for the geologists of the last two cen-. turies;and_we can select from the list of philosophers. whom they enumerate, the names of a few only who have given any- thing. substantial to the science of geology, . It isjonly: fair to. * Phil. Mag. vol. li. p. 173, &c. rs ? [In this and some other paragraphs, in which additions have been made to:the original: paper, the style of the Review has been preserved; to‘avoid the necessity of changing the form of the whole.] t Encycl, Méthod., Geogr. Physique, tom. i. 152 Dr. Fitton’s Notes on the History of English Geology. add, that we are far from supposing Mr. Smith to have beeérr acquainted with these writings. ar * The zeal with which the collection of organized fossils was’ pursued during the latter part of the seventeenth century was very remarkable; and perhaps there is not any thing more extraordinary in the history of geological opinions, than the doctrine maintained at that period by Ray, Lister, and other eminent naturalists, respecting the substances now tmiversally’ considered as the remains of animated beings. ‘'The gfeat: ‘ question now so much controverted in the world,’ Di Plot - tells us, in 1667, ‘is, Whether the stones we find in the ‘fort ‘ of shell-fish, (and in his plates they are, with the caution usual” ‘ at that period upon this subject, denominated ‘formed stones,’) ‘ be lapides sui generis, naturally produced by some extraordinary’ ‘ plastic virtue, latent in the earth, in quarries where they are ‘found; or whether they rather owe their form and figure to’ ‘the shells of the fishes they represent:*’—and this learned writer gives no fewer than seven reasons for adhering to the former of these opinions, in opposition to the sentiments of Hooke and other persons, who entertained more rational views. It will seem almost incredible to those who are acquainted with the works of Cuvier, and other inquirers of our days, that such a notion could at any time have found supporters: and itis the more strange that Lister should have maintained these’ views, as he was an excellent conchologist, and is to this day, we believe, considered as one of the best authorities in that de- partment of natural history: vet Woodward says of him, that” notwithstanding the strongest evidence, * he bravely continued ¢ to the last firm and unshaken in his opinions +.’ ra This curious absurdity affords a good illustration of the dan-. ger of hypothesis in natural history; since it. was connected with, if it did not originate in the assumption, that a general’ deluge was the only cause that could have occasioned the de- * Natural History of Oxfordshire, p. 111. + Catalogue, part ii. p. 6.—[The following specimen of Lister’s reason- ing upon this subject, will show, that notwithstanding his aecordance with the great error of his day, he had some very just notions respecting fossil ' species. ‘ We will easily believe, he says, ‘(what I have read in Steno’s ‘ Prodromus) that all along the shores of the Mediterranean Sea, there ‘ may all manner of sea shells be found promiscuously imbedded in rocks ‘ or earth, and at good distance too from the sea. But for our English in- ‘land quarries, J am apt to think, there is no such matter as petrifying of ! ‘ shells in the business: but that these cockle-like stones are everywhere as ‘ they are at present, Lapides sui generis, and never were any part of an ‘animal. It is most certain that our English quarry shells (to continue that” ‘ abusive name) have no parts of a different texture from the rock in-qués- ‘ tion whence they were taken ; that is, that there is no such thing’as shell’: ‘in these resemblances of shells, and that they never were any part of an \ Dr. Fitton’s. Notes on the. History of EnglishGeology. 153 position of the bodies in question: For, as such an event must evidently have been too transitory to have produced appear- ances observable at great depths from the surface, and within the substance of strata in which no marks of disturbance were to be detected, there was no resource but in denying that the fossils of the solid beds had ever been endowed with life. The obstinacy with which the doctrine was adhered to, is no less surprising. Palissy indeed is praised by Fontenelle in 1720, for having overthrown it more than a century before *; yet in the year 1708, a book was published by Scheuchzer, under the title of Piscium Querele et Vindicie, where the fishes, entombed in stony substances, are represented as deploring, in very pathetic language, the indignity under which they suf- fer, in being degraded from the animal kingdom to the rank of mere inorganic matter. This remonstrance, however, does not seem to have been effectual; for Woodward, in 1723, still thought it necessary to reason against the doctrine we have mentioned: and afterwards, so late as 1752, M. Bertrand, a Swiss clergyman, made a last effort in its favour, contending that fossils are nothing more than links in the progressive series by which unorganized matter is connected with the ani- mated world; or perhaps the unfinished materials (¢ in fieri,’ . as Dr. Plot had long before expressed it,) out of which the Creator might have formed, and in part did form, the existing races of similar beings. : In the Philosophical Transactions for 1684, there is pub- lished, ‘An ingenious proposal for a new sort of maps of * countries ; together with tables of sands and clays, such as aré * chiefly found in the north parts of England, by the learned * Marrin Laster, M.D.’+.—* We shall then,’ the author be- ‘animal. My reason is, that quarries of different stone yield us quite ‘ different sorts of species of shells, not only from one another,—but I dare * boldly say, from any thing in nature besides, that either the land, or salt or ‘fresh water doth yield us. ”Tis true that I have picked out of one quarry * of Wansford very near resemblances of Murices, &c.; and yet J am not con- ‘ vinced that I did ever meet with any of these specics of shells anywhere else * but in their respective quarries: whence I conclude them to be Teordes sui * generis, and that they were not cast in any animal mould, whose species or “race is yet to be found in being at the present day !’—Phil. Trans.—Low- thorp’s Abridgement, vol. ii. p, 425.] * Eneycl. Méthod. tom. i. p. 406.— Bernard Palissy was born between 1514 ana 1520. He delivered his opinions at Paris.in 1575, in public lee. tures of which he has given an entertaining account in a treatise “ Des Pierres.’ His works were republished in 1777, by Faujas St. Fond ; and Fontenelle is there quoted (among a crowd of authors who commend him) from L’ Histoire de ? Académie, 1720, p. 5. + Phil. Trans. vol. xiv. p. 739, &c. In the title, this paper is stated to have been ‘ Drawn up about 10 years since, and delivered to the Royal “Society, March 12, 1683. —As Dr. Lister lived till 1712, this precision as to dates seems to imply that his priority had been questioned. Third Series, Vol. 1. No.2. Aug. 1832. X - oO 154 Dr. Fitton’s Notes on the History of English Geology. gins, ‘be the better able to judge of the make of the earth, ‘and of many phenomena belonging thereto, when we shall ‘ have well and duly examined it, as far as human art can pos- ‘ sibly. reach, beginning from the outside downwards. As tor ‘ the inward and central parts thereof, I think we shall never ‘ be able to refute Gilbert’s opinion thereof, who will, not with- ‘ out reason, have it altogether iron, And. for this, purpose, ‘it were advisable that a soile or mineral map, as. I may call it, ‘ were devised. The same map of England may, for want ofa ‘ better, at present serve the turn. It might be distinguished ‘into countries, with the rivers and some of the noted towns ‘ putin. The sole might either be coloured, or otherwise. distin- ‘ guished by variety of lines or etchings; but the great care, must ‘ be, very exactly to note upon the map, where such and.such ‘ soiles are bounded. As for example, in Yorkshire, 1. The ‘ Woolds; chaulk, flint and pyrites, &c. 2. Blackmoor ; moores, ‘ sandstone, &c. 3. Holderness; boggy, turf, clay, sand, &c. ‘4. Western mountains ; moores, sandstone, coal,- ironstone, ‘ lead-ore, sand, clay, &c. Nottinghamshire ; mostly gravel peb- « bles, clay, sand-stone, Hall-playster or gypsum, &c._. Now “if it were noted how far this extended, and the limits of each ‘ soil appeared upon a map, something more might be compre- ‘ hended from the whole, and from every part, than I can pos- ‘ sibly foresee, which would make such a labour well worth the ‘ pains. For I am of opinion, such upper soiles, if natural, ‘ infallibly produce such under minerals, and, for the most part, ‘in such order. But I leave this to the industry of future ‘ times.’ re So far, therefore, as the project of a geological map, the credit of originality is clearly due to Dr. Lister; and this may be allowed to atone for his adherence to the absurd hypothesis already mentioned, as to the origin of fossil remains. ' The arrangement of the “soiles” in Yorkshire, in the pas- sage above quoted, accords with the more recent geological divisions of that county:—The Woolds apparently correspond- ing to the chalk formation; Blackmoor to the oolites, sands, and lias of the Eastern moorlands; Holderness to the deposits above the chalk; the Western mountains to the coal-formation with the subjacent limestones; and the gypsum, &c. of No#- tinghamshire, perhaps to our red-marl and red-sandstone. There is nothing, however, relating to stratification in Lister’s paper, nor to the order, or superposition, of the “soiles:” and the only point deserving of notice, in his ‘scheme of sands ‘and clays,’ which is in general confused and erroneous, is, that in mentioning the sands of Boulogne and Calais, he observes that ‘although that is not England, yet the sea has but.ac- *‘cidentally divided us. For from Dunstable, ex. gr. in Eng- Dr. Fitton’s Notes on the History of English Geology. 155 ¢ Jand, even as far as to the walls of Paris by Calais is, as it © were, a continued woolds of chalk and flint. The geological labours of Woopwarp deserve very honour- able mention; for he appears to have had some correct no- tions as to the general structure of the globe, and the proper method of pursuing the investigation of it; though his views -were warped by the taste for antediluvian history which then prevailed, and his opinion that mineral substances were dis- posed in the earth according to the order of specific: gra- vity, is singularly at variance with many of his own observa- ‘tions. ‘1 made strict inquiry (he tells us,) wherever I came, and ‘aid out for intelligence of all places where the entrails of the “earth were laid open, either by nature (if I may so say,) or ‘by art and human industry. And wheresoever I had notice ‘ of any considerable natural spelunca or grotto, any sinking ‘ of wells, or digging for earth, gravel, chalk, coal, stone, mar- “ble, ores of metals, or the like, I forthwith had recourse ‘thereunto; where, taking a just account of every observable “circumstance of the earth, stone, metal, or other matter, “from the surface quite down to the bottom of the pit, I en- ‘tered it carefully into a journal which I carried along with ‘me for that purpose.—The result was, that in time I was “abundantly assured that the circumstances of these things in “remoter countries, were much the same with those of ours here ; ‘that the stone and other terrestrial matter in France, Flanders, © Holland, Spain, Italy, Germany, Denmark, Norway, and ‘ Sweden, was distinguished into strata or layers, as it is in * England ; that those strata were divided by parallel fissures; “that there were inclosed in the stone, and all the other denser “kinds of terrestrial matter, great numbers of shells, and other ‘ productions of the sea, in the same manner as in that of this *tsland*, ~The zeal with which Woodward devoted himself to natural history was very remarkable; and his Catalogte of English Fossils+ is alone sufficient to entitle him to the gratitude of succeeding inquirers. ‘The collection, to which the catalogue Yelates, is still preserved at Cambridge, and is to this day of great value as an object of reference :—and the professorship which bears his name in that University, in the hands of the able naturalists who have successively held the office, has * Nat. Hist. of the Earth, 1723, pp. 4, 9. _ ¥ ‘An Attempt towards a Natural History of the Fossils of England, &c. ‘or a Catalogue of English Fossils’ in the collection of J, Woodward, M.D, 2tomes. Lond. 1728 and 1729. ck : Xi2 ’ re | if 156 Dr. Fitton’s Notes. on the History of English Geology. contributed, and still continues powerfully, to diffuse a taste for geological inquiry. d sees rag ort A letter from the Rey. Mr. Hottoway to Dr. Woodward, published in the Philosophical Transactions for, 1723, gives ia good description of the Fullers’-earth-pits| near, Woburn in Bedfordshire ;—pointing out one of the most striking features in the:physical geography of England ; and:connecting) it so distinctly with the order of the,strata, as toexcite some: sur- prise that the application of the principle was not! soonerex- tended to other portions of the island.—‘ For the-geographi- ‘ cal situation of these pits, they are digged that ridge ‘of © sand-hills by Woburn ; which near Oxford is\called Shotover; ‘on which lies Newmarket-heath by Cambridge, and) which § extends itself from east to west, everywhere, at about the di- ‘ stance of eight or ten miles from the Chiltern-hills,—which in « Cambridgeshire are called the Gog-Magogs, in Bucks and -€ Oxon, the Chiltern-hills, from the chalky matter of which ‘ they chiefly consist : which two ridges you always pass in going _* from London into the North, North-east, or North=west:coun- _* ties. After which you come into that vaste vale, which makes ‘the great.part of the midland. counties, and:in which are-the * rivers Cam, Ouse, Nen, Avon, Isis, and others;—which) I ‘ take notice of, because zt confirms what you say of the:regular © disposition of the earth into like. strata, or layers of matter -* coming through vast tracts; and from whence I make a:ques- ‘tion, whether. Fullers’-earth may not probably be found; in ‘ other parts of the same ridge of sand-hills among other like ‘ matter ?’* vly 9 STUKELEY, the celebrated antiquary, has pointed:out the im- portant fact in the disposition of the strata in England, that the steepest sides, or escarpments, are turned towards: the west, or north-west: but he. hastily generalizes this observa- tion, and ascribes the fact gratuitously to the rotation of the globe+. The Itinerary of this. writer contains many notices respecting the rocks and fossils of the districts he has de- ‘scribed ; to which his index refers, under the title of * Memoirs ‘ towards a British Map of Soils,’ with allusion, apparently, to ‘the project of Dr. Lister, already mentioned: and his notions about fossils appear to have been more correct than those of his predecessors. ; Ne 3 * [Phil. Trans. vol. xxxii. p. 419.— Newmarket is here erroneously placed on the ridge of Woburn sands (now called the lower greensand): it is on the chalk, and the sands in its neighbourhood are above that stratum. The “ question,” at the,close of the passage, has been justified by the discovery _of Fullers'-earth.in the lower partof the Woburn sands, almost throughout their course in England.] i a ‘uth piaerarian Curioswumy&e. By Wm. Stukeley, M.D. &c. Londow, folio, 24, p. 3. drat ot Dr. Fitton’s Notes on the History of English Geology. 157 » The opinion of Stukeley as to the effect of the rotation of the earth on the position of the strata, was not long: after adopted by Mr. Srracuey, the author of two valuable papers on part of the Somersetshire coal-district *, which, consider- ing the date of their production, deserve particular attention. The first of these papers gives an account and section (Plate IL. fig. 2:) of some coal-mines about ten miles S. W. of Bath ;— detailing the order and composition of the beds,—and noti- cing their highly inclined position, their interruption by ridges -(faults);—the occurrence above the coal-measures, of free- stone (oolite), lias, and red-marl, in.some places to the depth of 12 or 14 fathoms: but, it is added, while the coal beds of the country all dip about 22 inches in a fathom, ‘the (superior) * beds of stone and marl, different from coal, lie all horizontal. In the second of the papers above referred to, Mr. Strachey states, that as he had ‘ never heard any coal was found to the « west or south of Mendip-hills ; so Cotswold to the N.E., and ¢ the chalk hills of Marlbury Downs and Salisbury Plain, seem £to set bounds to the coal country;’ and in a section which ac- scompanies this paper, he places the chalk horizontally above the lias, red marl, &c. and, like those strata, unconformably \to the coal beds. At the close of these descriptions the author extends his views, and baving ‘ drawn,’ as he tells us, ‘ the different § strata (which have come to my observation) on a supposed ‘plane, as they there lie; I protract the same in a globular “projection, (see Plate I. fig. 2, A and B.) supposing the mass ‘ of the terraqueous globe to consist of the foregoing or per- ‘haps of ten thousand other different minerals, all originally, § whilst in a soft or fluid state, tending towards the centre; it ‘must mechanically, and almost necessarily, follow, by the § continual revolution of the crude mass from west to east, like ‘the winding up of a jack, or rolling up the leaves of a paper ‘ book, that every one of these strata (though they each reach ‘the centre,) must in some place or other, appear to the day, ‘in which case there needs no specific gravitation to cause the “lightest to be uppermost, &c. for every one in its turn, in ‘f£some place of the globe or other, will appear near the surface ; '¢ and were it practicable to sink a pit to the centre of the earth, ‘all the strata that are would be found in that pit, and aceord- ‘ing to the poet, ponderibus librata suis.’ ,, * Phil. Trans. 1719, vol. xxx. p. 968 ; 1725, xxxi. p. 395: published also in a separate tract, entitled ‘ Observations on the different Strata of Warths * and Minerals, more particularly such asare found in the Coal-mines of Great * Britain,’ by John Strachey, Esq. London, 1729, 4to, p.16. Fig. 2 ef the anvexed Plate is copied from this tract, and differs a little from that in the Phil. Trans. 158 Dr. Fitton’s Notes on the History of English Geology. We have copied the Plate connected with the former of these papers: of Mr. Strachey (fig. 1.), because it represents very correctly one of the most striking geological features of the South-west of England, the unconformable position of the superincumbent beds, from the red marl upwards, to that'of the coal strata*. And it will be perceived that the order of the strata given in the first “ globular projection,” (fig. 2. A) as derived from actual. observation, coincides with that which modern inquiry has brought to light :— Strata mentioned by Sthachéy: Modern Names. sr@Ohalky ts .i0. sta ar chalRs © Freestone .\.....eeeeee0e. OOlites. ¢ Limestone... i Whar y iss. Se eeenanye . © Yellow. earth ¢ Red earth... be eee © Coal cliffs ig: red marl. coal formation. Cw “Coal. avn. AOL, ‘ Lead, copper, &c.’....... metalliferous rocks. The second diagram (Pl. II. fig. 2. B.) is also inserted here, as it affords a striking proof of the very low state of geological speculation at the period of Mr. Strachey’s inquiries; since an author, whose ‘productions were thought worthy of publica- tion by the Royal Society, and who appears to have’ been’an excellent observer, could venture to connect with ca So ver ot crude an hypothesis. The eloquence of Burron had great effect in attracting at- tention, not only to the splendid speculations which may be connected with geology, but to the importance of organized re- mains, and to the light which may be thrown by them upon the structure and history of the globe. But the most remark- able views entertained about ‘this period appear to have been those of Roverxe; though it is, perhaps, impossible, at present, to judge of the precise value of his labours; for, like Werner, he delivered his doctrines’ principally in lectures. He an- ticipated, or was coincident with Lehman, in the distinction (previously intimated, we believe, by Steno and Targioni,) of the primary from the newer rocks, under the denominations of Pancienne and la nouvelle terre; and found. reason, also.to make a division between the older and more recent of the se condary depositions, distinguishing the former by the title of Travaille intermédiaire; a discrimination and a name coming a [This however now appears to be rather the exception than the gene- ral rule of structure. In the North of England, and in the Isle of Arran, the superior beds are conformable to those of the coal formation. See Proceedings of the Geol. Society, p. 41, and Geol. Trans., 2nd Series, vol. ili. p. 33.] Dr. Fitton’s Notes on the History of English Geology. 159 very near to the Transition class of Werner,—whom he’ like- wise anticipated in noticing the comparative ratity and: pe- culiar character of the fossils contained. in. these intermediate rocks*.. The account given by Desmarest, who was Rouelle’s pupil, of his observations-on. the newer portion of the globe, and on the nature of the operations by which fossil bodies were distributed, is especially deserving of notice: — ‘ En examinant la nouvelle terre, et en observant les différens ‘ corps marins qui se trouvent si fréquemment et si abondam- “ment dans les couches horizontales, Rouelle reconnut que ces ‘ corps n’étoient pas jettés au hazard ni dans l’état de confu- * sion que l’on avoit imaginé communement avant lui. J vit * que ces coquilles n’ étoient pas les mémes dans toutes les contrées: * que certains individus se rencoutroient constamment ensemble, * tandés que d'autres ne se trouvoient jamais dans les mémes lits, * dans les mémes couches ; et ce qui aprés cette méme considéra- * tion, est trés-important, il vit gue ces collections de coquilles ‘ fossiles, a la surface de certaines parties de nos continens, * étoient dans le méme état @ arrangement et de distribution que *.dans le. bassin de la mer ; ou certains animaux testacés affectent “de vrvre ensemble attachés aux mémes parages, et d’y former ces ‘ espéces de sociétés ou, familles, de méme que certaines plantes qui ‘eroissent toujours ensemble a la surface de la terre-—En effet, “une inondation passagere telle que le déluge, auroit da met- ‘ tre le désordre.et la confusion par-tout, si Pon edt chargé ses ‘ eaux de transporter les corps marins dans V’intérieur. de nos ‘continens. Puisqu’au lieu de cette confusion, on reconnoit un ‘ ordre constant dans Varrangement des coquilles, dont certains ‘individus font bande a part, et ne se confondent point avec § dautres qui ont aussi leur familles séparées, il faut recon- ‘ noitre dans ces arrangemens non-seulement le travail de Ja ‘mer, mais encore que ce travail n’a point été dérangé, par ‘les événemens qui ont mis 4 see nos continens de la nou- ‘ velle terre +.’ Rouelle distinguished, under the general name of Amas, the various assemblages of fossil shells in the earth, and gave de- lo, He placed the coal formation in the intermediate series. See Encyel. Méthod., Géogr. Phys. tom. i. pp. 412, 413, 477, 815: and compare with Jameson’s Geognosy, pp. 80, 81, 146.—Rouelle was born in 1703, and died in 1770. No dates are given in Desmarest’s notice of him ; nor does his Eloge (Hist. de 0 Académie, 1770,) contain any account of his geological epinions. Bernard de Jussieu, the botanist, was his friend, and the com- panion of many of his geological excursions. Some curious particulars aut his lectures are to be found in the Baron de Grimm’s Jorrespon- nce, —t Encycl. Méthod., Géogr. Phys. tom. i. pp. 416, 417. 160 Dr. Fitton’s Notes on the History of English Geology. nomivations, to some of those which had fallen under his. own observation in. France, derived from the predominant species. In order to judge of the approach which he thus made to more modern opinions, greater detail would be necessary than we are possessed of. If the amas meant beds, the: coincidence would be complete;.and even what we haye quoted indicates a very near approach to the principles, of which the French na- turalists have since made such admirable use in their examina- tion of the country round Paris; and which have furnished Mr Smith with the title of one of his publications, Strata Identified by Organized Fossils*. 3 jorhis a ” Tn a treatise which Lenman published in 1756+, he claims for himself the credit of being the first to observe and: describe correctly the structure of stratified countries: but he does not seem to have been acquainted with the papers of Mr. Strachey above referred to. He supposes that coal+beds are the lowest of the stratified substances; that various '* pierres feuillettes’ occupy the middle portion, and the beds that af ford the saline springs (fontaines salantes), the uppermost of the strata; which arrangement, he asserts, is universal. He lias detailed the order, composition, and thickness of the strata, which surround the nucleus of the Hartz mountains, and oceur in detached portions in the north-east of Germany; pointing out the identity of certain beds, which are’ separated from — each other by intervals of several miles, but without asserting that the corresponding strata are absolutely continuous. | His treatise is interspersed also with very good remarks upon the nomenclature and general relations of strata, and on the import- ant purposes in practical mining, which may be promoted by the study of them; and his observations, we have reason to be- lieve, are regarded in Germany as having thrown considera- ble light:on the geology of that country. . ad rts ia (To be continued. ] * [ Desmarest’s exposition of Rouelle’s doctrines, in asubsequent volume of the work last referred to, (ii. p. 346, &c., article Amas, &c.) which however was not published until 1803, contains some passages’ expressing yet more nearly, the most recent views of geologists, as to the diffusion of organized ‘remains, and their relations to the strata in which they occur. But, there is, still no distinct enunciation of the principle,—that strata may be traced, in detached and remote situations, by means of their fossils, which Mr. Smith had been acting upon for more than thirteen years, at the time of ‘¢his last publication. ‘The words “ font bande a part,” in the latter“part of the passage above quoted, are ambiguous; but they seem rather to relate to horizontal extent, than to vertical superposition, ] ; ; al + Versuch einen geschichte von Floets Geburgen, ‘Berlin, 1756. Trans- lated by Holback, with other productions of Lehman, under.the title of Traités de Physique, &c. Paris, 1759,. volviii. Pe Toe Son XXXIV: Account of an Experiment in which Chemical Decom- position has been effected by the induced Magneto-electric: _ Current. By P. M.; preceded by a Letter from MicHaEr Fanapay, Esq. D.C.L, ERS. dc. . ’ To the Editors of the Philosophical Magazine and Journal. Gentlemen, ON returning to town yesterday, I found the inclosed letter : it is anonymous, and I havé no means of referring to its author. But as it describes an experiment, in whicli chemical decomposition is for the first time obtained by the induced magneto-electric current, I send it to you for publication, if you think it worthy. I cannot, from the description, decide whether the effect is really chemical; it may or it may not be so. A careful di- stinction must at present be drawn between real chemical decomposition and the mere effects of a succession of electric sparks, I hope the author will describe the results in a more precise manner, and corroborate them by other chemical ac- tions. I presume the writer can have no objection to the publica tion of his letter; and for my own part, I would rather avoid being in exclusive possession of anonymous philosophical in- formation, lest any mistakes should hereafter atise as to dates, But if you publish the letter, favour me by thanking the author fpr ibis i I am, Gentlemen, yours, &c. » Royal Institution, July 27th, 1832. M. Farapay.- y ite Yo Michael Faraday, Esq. . Sir, pbhe From having read in the Proceedings of the [Royal] Institu- tion your interesting pavers on magnetism*, I was tempted to . try an experiment, which succeeded beyond my expectations, and which, if tried on a larger scale, I am in hopes would _ prove very intéresting, 4 a I thought that, in place of making use of one powerful Magnet, there would be considerably more effect (like in the Voltaic pile) by having’ a number of smaller magnets, con- _nected with one wire or hélix ; and also, instead of ; getting the spark at- making or breaking contact, it would be still better » to make the instantaneous reversal of the poles the cause. [ have contrived to do this in a very simple way; and with a * See Phil. Mag. and Annals, N.S. vol. xi. p. 300, 465.— Epi, Third Scries. Vol. 1. No. 2. August 1832. 4 162 Experiment in Chemical Decomposition. small battery of magnets I have actually decomposed water. You. will therefore excuse me for making this communication to you in this manner. kK ~A wheel and axle is. connected.to..a: frame; and. turned by the handle ; a number. of. magnets ' (there must not. be an odd number) is inserted round this wheel, and firmly secured in their berths, the wheel having spaces cut out to receive them, as shown in fig. 2.; two of the magnets are shown in their place at fig.1, b 0; in the same figure are the lifters, which are secured firmly to a board fast to the frame, as will be shown immediately. In placing the magnets in the wheel, which you perceive are the horse- shoe ones, every second magnet is placed differently. If the magnet at No. 1 has the north pole next the edge of the wheel, and the south next the axis, No. 2 has the south 2 at the circumference, and the north at the Bink ik axis, and so alternately ; the ends of the 3 magnets project a little beyond the sur- face.of the wheel. There are as many lifters as magnets, placed firm ina board, exactly to correspond with the wheel, but made firm to the frame, and in such a manner as to per=' mit the wheel to turn readily, so that the magnets will pass close to them. When any one magnet is in contact with a lifter, all the others are the same. In passing the wire round these lifters, care must be taken to make the turns of the helix be reversed in every second lifter, so that the currents of electri- city will be all in one direction, although the poles of the mag- nets are reversed; by connecting the two ends of the wire to guarded points, and inserting them in a small tube containing. water, on turning the wheel the decomposition will take place rapidly. I put a small projector on the wheel at every magnet, \ » which, on touching a spring, separated the two wires every ° time; and at the moment the pole was reversed, the spark be-~ came visible. Wishing you success in this very interesting _ field for discovery, I am, Sir, Your very humble Servant, Ra Mi | {163 J XXXIV. Notices respecting New Books. ; The Microscopic Cabinet of select Animated Objects, with a Description. of the Jewel and Doublet Microscope, Test Objects, &c.: to which are subjoined Memoirs on the Verification of Microscopic Phenomena, and au exact Method of appreciating the Quality of Microscopes and Engiscopes. By C. R. Gorine, M.D. Illustrated by Thirteen Coloured Plates from Original Drawings and numerous Engravings on Wood. -By Anprew Prircuarp, N preceding Numbers of the Edinburgh Journal of Science, we have had occasion to speak very highly of the improvements in the microscope, which have been made by Dr. Goring and Mr. Pritchard, and of their joint work entitled Microscopic Illustrations, &e. The work, of which we now propose to give a brief notice, though a separate and independent publication, may yet be regarded as a » continuation of their former labours. The first thirteen chapters, which occupy about a third of the volume, contain popular and ge- neral descriptions of the aquatic larvee of insects, crustacea and ani- malcula; and these descriptions are illustrated by ten beautiful and highly finished coloured engravings. The 14th and 15th chapters treat of jewelled microscopes and microscopic doublets. The 16th chapter, which is one of the most important and interesting of the whole (and of which we may give a separate account in a future Number), treats of the history of test objects, and of the method of viewing them. The objects here described are divided into two classes: 1. those which serve for exhibiting the penetrating power of microscopes; and 2. those which serve to exhibit their defining power. ‘The first of, these classes contain scales from the Lepisma saccharina, Morpho Menelaus, Alucita Pentadactylus, &c., Lycenz, Clothes’ moth, Pon- tia Brassica, Podura Plumbea, and Diamond Beetle. The second . class contains Mouse hair, Bat’s-hair, and Lycene Argus (the spotted feathers). In chapter 17, Mr. Pritchard treats of microscopic doublets and other compound magnifiers for microscopes, and of their illumination. The microscopic doublet, as our readers well know, was introduced by Dr. Wollaston *. © Mr. Pritchard has found that in such doublets “’ the distance of the lenses which gives the best effect is equal to the difference of the focal length of the two lenses, making a proper allow- ance for their thickness. The proportion of the foci may be varied at; pleasure : ‘All that is requisite in this respect,” says Mr. Pritchard,.,. “is, that the. difference must be greater than the thickness of the anterior lens, while it may be observed (in high powers), that the greater the difference between their two focal lengths, the more space will be Jeft in front ; and as this is of great practical importance, they should never be less than as one to three. I have made some very good ones, differing as much as one to six. Another advantage re- sulting from attending to this point is, that we do not lose so much * It is described in the Edinburgh Journal of Science, N.S. vol. i. p, 323. also in Phil. Mag. and Annals, N.S. vol. y. p. 300. Y2 164 Intelligence and Miscellantous Articles. magnifying power in such combinations as when the difference’ be- tween, the lenses is less.” det heactaciah, et Pe ee eee _-The.18th, and 19th chapters, which are written by Dr. Goring, treat of the verification of microscopic phenomena, and of the exact method of appreciating the quality of microscopes and engiscopes. These two chapters are of great. practical value, and will be read with much interest both by the naturalist and the optician. _, The last chapter of the volume is entitled Miscelluxeous Fragments, and contains many useful directions and methods, especially in refer- ence to the preparation and mounting of microscopic objects.” Such is a brief analysis of the work before us. We earnestly re- commend it both to the general and the scientific reader aS ‘an original, a valuable, and an ingenious work ; and we trust’ it will meet with such success as to disappoint the expectations of the author, who, in the following passage of his preface, has given a just though melan- choly picture of the present state of our scientific literature. “In the present forlorn state of scientific literature, it is rare that the author gets ‘a return of his outlay,’ and, indeed, very often loses one half, the demand for illustrated scientific books being less than for that of any other class : it is therefore in vain for an’ author ‘to expect pecuniary remuneration for his time and labour. All that is desired for this work is, that it may receive sufficient patronage to re- turn its expenses.” ere XXXV. Intelligence and Miscellaneous Articles. ON THE CAUSE OF THE PRODUCTION OF HEAT BY FRICTION AND PERCUSSION, AG oh To the Editors of the Philosophical Magazine and Journal. Gentlemen, b ber would much oblige me by explaining, in, your valuable L Journal, the ‘‘ cause. of heat from, friction. * , Iron laid upon an anvil and receiving violent blows, from, a ham- mer, will become red hot, partly from, the diminished volume of the iron, and still more, as it is supposed, from an electrical cause. May it not arise, and chiefly, from, the disengaged caloric latent in the particles of air which must intervene between the hammer or anvil, and the iron ? I am not aware of.any experiments having been. tried in vacuo. Should you, think this worthy of. insertion in, your Journal, you will oblige me. And I believe this idea has not occurred before to any one. I am, Gentlemen, your obedient Servant, gn PREPARATION. OF CHLORATE OF POTASH. M. Liebig proposes the following process for obtaining chlorate of oO A f=] potarh, Intelligence and, Miscellaneous Articles, 168 . Heat, chloride of lime till it ceases to destroy vegetable colours. In this case a mixture of chloride of calcium and chlorate ‘of potash is obtained. ., This is, to be dissolyed in hot water, and to the solution, concentrated by evaporation, chloride of potassium is to be added, and then. suffered to,cool,. After cooling, a quantity of crystals. of chlorate of potash is obtained, which are to be redissolved and erystallized again to purify them, , M. Liebig considers that this will be a cheap ptocess for obtaining chlorate of potash. From 12 ounces of chloride of.lime, of so bad quality that it left 65 per cent, of insoluble matter, he obtained an ounce of chlorate of potash, ; The only difficulty to overcome in this process is, that the chloride of lime is not so easily decomposed by heat as is generally supposed ; # solution of it may be kept boiling for an hour without losing its bleaching power. The best method is to form a thin paste with chlo- ride of lime and water, and then to evaporate it to dryness: if it be required to prepare it by passing chlorine into cream of lime, it is sadvantageous to keep it very hot. ve « The chlorate of potash, which separates from the solution by ery- stallization, has not the form of scales, waich it usually possesses, but is prismatic: whether this is occasioned by some admixture has not been ascertained; but on recrystallizing, it is obtained in the usual form. ' The solution ought not only to be suffered to cool in order to pro- cure crystals, for the crystallization is far from being terminated even after complete cooling ; crystals continue to be deposited for three or four days.—4nn, de Ch. et.de Phys. tom. xlix. p. 300. COMPOSITION OF CAFFEIN. MM. Pfaff and Liebig have given the following as the composition of Caffein :— Four atoms carbon .... 3-05750 Five atoms hydrogen .. 0°31199 Two atoms azote...... 1°77036 .....; 28°83 One atom oxygen .... 1°00000 ...... 16°30 613985. 100-00 At the request of MM. Pfaff and Liebi te g, the analysis was also per- _. formed by M. Wohler; and he obtained . Carbon .......... 49°93 ; t Hydrogen...... ao | D'43. oo Pas Azote PNP BITKS § 28°97" led, bon: Oxygen gi te +, 15°67 ———e 100-00 Ibid, p. 305. The following remarks, appended, by MM. Pfaff and Liebig to the results of their analysis, appear to me to constitute a perfect specimen ofthe manufactureof mystery and.confusion, which is likely, if anything can do so, to bring the atomic theory into discredit. 166 Intelligence and Miscellaneous Articles. « According to its theoretical composition, caffein may be consi+ dered a8 a compound of a cyanic acid, containing one half less oxygen: than the common acid, with ether analogous to cyanic ether. An zther formed of a problematical cyanous acid would be composed of Cg? £0 + (CH + OH?) = C* H® N? O; this formula is the same as that of caffein.” Now, among numerous other compounds, of which this compound may be supposed to be compounded, and for all that I see, with quite as much probability as those above stated, are One atom of bicarburetted hydrogen, One atom of ammonia, One atom of cyanogen, One atom of water. OER Py “EXPERIMENTS ON BEES’ WAX AND VEGETABLE WAX. M. Oppermann states that the vegetable wax from the East Indies is of a yellowish white colour, transparent at the edges, more brittle and greasy to the touch, but less compact than bees’ wax.) ' Its taste is rancid when it has been masticated for some time; its'sp. gr. 0°97; at 124° Fahr. it melts, remains fluid at 112°, and solidifies at 109°: . It is soluble both in spirit and in ether; the former solution solidi+ ~ fies in cooling, while the latter merely deposits light flocks.’ Japan” wax yielded by analysis, Carbon 6. sid ial. 70:9683 wom" Hydrogen .......0. 12:0728 AIR, SE RAW SENT 2 achancdeey eins 16:9589 oe 100-0000 Brazilian wax very closely resembles the foregoing’: their colour, 2, consistence and odour are almost the same ; the Brazilian is however distinguished by the yellowish brown pellicle with which it is covered ; it fuses at 120°, and solidifies at 13°. The spirituous and etherial solutions resemble those of the Japan wax. Brazilian wax gave by analysis, OE 17 sages 728788 Hydrogen ......++)12°0297 ORV PeUt aren pa on 15°0915 |, 100:0000 Bleached and purified bees’ wax is harder than the foregoing ;.but.—- the vegetable wax, dissolved in four parts of oil, gives a compound which is three times firmer than that obtainec with the same quantities of bees’ wax and oil; but the latter gives greater consistency to fat than the former. Alcohol, even when hot, dissolves bees’ wax with difficulty; the solution solidifies by cooling, and yields a white granular transparent ___ mass. JSther-when boiling forms a clear solution of bees’ wax, which becomes turbid by spontaneous evaporation; it afterwards thickens) © and the wax when separated appears to have suffered no change. fe fod ah HOM Parents. 167 Caustic’soda at first ‘merely softens bees’ wax, but afterwards converts it into soap, though not so readily as the vegetable wax... / By analysis, bees’ wax yielded t r : CAO 2 ogo eh NO ‘Hydresen’s...... Nk 14°07 26 _. Oxygen......... . 46364 100-0000 Ann. de Ch. et de Phys. xlix. p. 240. LIST OF NEW “PATENTS. To J. J: Jaquier, Castle-street, Leicester-square, merchant, for improvements in the machinery for making paper. Communicated by a foreigner.—Dated the 31st of August 1831.—6 months allowed to enrol specification. To H.G.Dyar, Panton-square, gentleman, for an improvement in tunneling, or method of executing subterraneous excavations. — —5th of September.--6 months. To G, Forrester, Vauxhall Foundry, Liverpool, civil engineer, for certain improvements in wheels for carriages and machinery, which improvements are applicable to other purposes.—5th of Sep- tember.—6 months, . To W. Bickford, Tuckingwill, Cornwall, leather-seller, for his invention of an instrument for igniting gunpowder, when used in the operation of blasting rocks and in mining.—6th of September. —6 months. To J. Neville, Great Dover-road, Surrey, engineer, for his im- proved apparatus for clarifying water and other fluids. —9th of September.—6 months. To G.H. Palmer, Manchester-street, Gray’s-Inn-road, civil en- gineer, for certain improvements in the steam-engines, boiler, and apparatus, or machinery connected therewith, applicable to pro- pelling vessels, carriages, and other purposes.—16th of September. —6 months. LUNAR OCCULTATIONS FOR AUGUST. Occultations of Planets and fixed Stars by the Meon, in August 1832. Computed for Greenwich, by Tuomas HenDeErson, Esq. ; and circulated by the Astronomical Society. a Immersions. 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[THIRD SERIES. ] SEPTEMBE BR 1832. XXXVII. On the Undulations excited in the Retina by the Action of Luminous Points and Lines. By Sin Davin Brewster, K.H. LL.D. F.RS. V.P.RS. Ed.* [X the theory of vision, the light which radiates from visible objects is supposed to act only on those parts of the retina upon which it directly falls. To this principle, however, there are some exceptions. Ifa white circle is placed upon a green ground of some extent, the colour of the circle will not ap- pear white but red, or the accidental colour of green. In like manner, if a narrow slip of white paper placed upon a green ground is viewed indirectly by the eye, it will vanish entirely as if it had been removed, and the space which it occupied will appear green. In both these cases the green light has acted upon a part of the retina upon which it did not fall, producing in the first case its accidental colour, and in the second case its own eolour. When the retina is under the influence of a very strong light, the colour of every object which is painted upon it is either changed, or diminished in intensity, although the image is not formed upon any part of the retina which is directly affected by the strong light. When light in the form of luminous lines in bright points acts upon the retina, a series of remarkable phenomena are ‘produced, which, in so far as I know, have not hitherto been noticed. In giving an account of the experiments which I have made on this subject, I shall begin with the simplest case of a line of light. * Read at the meeting of the British Association at Oxford, June 22, 1832. Third Series. Vol. 1. No. 3. Sept. 1832. Z 170 Sir D. Brewster on the Undulations excited in the Retina 1. If we look through a narrow aperture, about the 50th of an inch wide, at a bright part of the sky, or at the flame of a candle, we shal! observe the luminous ground covered with a great number of broken parallel lines alternately light and dark. These lines are always parallel to the narrow slit, and of course change their place as the slit is moved round before the eye. If we look through a number of parallel slits such as the teeth of a comb, the broken parallel lines are seen more distinctly; and if we give the comb a motion oblique to the direction of its teeth, the broken lines become more distinct, though less straight than before, arid new black lines appear lying in different directions as if they were detached portions of a number of dark ramifications. All these phanomena are seen more distinctly when we look at homogeneous light ; but I have not been able to perceive any marked difference of magnitude in the spaces between the broken lines when they are formed by differently coloured rays. _ If we use two systems of narrow slits and cross them at different angles, we shall perceive two systems of broken lines crossing each other at the same angles; and if when the lines of the two systems are parallel we give one of them a rapid alternating motion perpendicular to the direction of its slits, the parallel broken fringes are seen with peculiar distinct- ness. 2. Phenomena analogous to those now described, may be seen by looking at a number of parallel black lines drawn upon white paper, such as those which represent the sea in an engraved map, or by looking at the luminous interyals be- tween a number of parallel wires seen against the sky. If the eye looks at any of these objects steadily and continuously, the biack lines soon lose their straightness and their parallelism, and inclose Juminous spaces somewhat like the links of a number of parallel chains. When this change takes place, the eye which sees it experiences a good deal of uneasiness, an effect which is communicated also to the eye which is shut. When this dazzling effect takes place, the luminous spaces be- tween the broken lines become coloured, some with yellow, and others with green and blue light. The phenomena produced in these two experiments, are obviously owing to rectilineal undulations propagated across the retina; and the interference and crossing of the undula- tions, by which the dark lines are broken into detached pieces, and by which the colours are produced, arise from the un- steadiness of the head or the hand, which causes a want of parallelism in the successive undulations. 3. The action of small and bright points of light upon the by the Action of Luminous Points and Lines. 171 retina produces phenomena of a very interesting kind. If we look at the sun through a small aperture at a great distance from the eye; or, what is the same thing, if we look at the di- minutiye image of the sun formed by a convex lens or a con- cave mirror, or, seen in a convex surface, the light which falls upon the retina does not form a sharp and definite image of the luminous point, but it sends out in all directions an in- finity of radiations covering in some cases almost the whole retina. These radiations are extremely bright, and are ac- companied by mottled colours of great variety and beauty. The bright point of light propagates around it circular undu- lations, which are broken and coloured by interference, and which, being in constant motion from the centre of the retina in all directions, occasion the radiations which have been mentioned. 4. If we now look at the radiant image just described, through a narrow aperture, a very singular effect is produced. A vortex of circular rays appears on each side of the radiant point, and the rays have a rapid whirling motion. The line joining the centres of the two vortices is always perpendicular to the narrow aperture. This remarkable configuration of the rays is evidently produced by the union of a system of parallel undulations with a system of circular ones, the inter- sections of the parallel fringes and the diverging radiations forming the circular rays, as in the case of ordinary caustics. The preceding phzenomena, whatever be their true cause, clearly prove that light incident upon the retina exerts an action on parts of it upon which it does not directly fall, and that the same action renders other parts of the retina insensi- ble to the light which actually falls upon these parts. This remarkable effect is still more distinctly shown in the interesting experiment first described by Dr. Smith of Fochabers*. Upon looking with both eyes at a narrow slip of white paper, in such a manner as to see it double, he of | course saw two slips equally white; but upon,bringing a can- dle near one eye, the right one, for example, the image seen by the right eye became greenish, while that seen by the left eye was reddish white. Dr. Smith remarks that the two colours are complemen- tary, and form white light when the two images overlap each other, As the left eye was entirely protected from the light of the candle, and yet gave au image apparently complemen- ‘ tary in its colour to that given by the right eye, it was diffi- cult to resist the conclusion, that an influence was propagated from the right to the left eye through the medium of the optic * Edinburgh pata Science, vol. v. p. 42. Z 2 172 Sir D. Brewster on the Undulations excited in the Retina nerves*. «This conclusion; however, was the result of an'im- perfect| examination of the phenomena; and I am persuaded, from a number: of new experiments, that the following is the true explanation of the :colours which characterize the two images. ; -When the light of the candle held close to the right eye acts upon one part of the retina, it renders every other part of the retina insensible, in a greater or less degree, to all other luminous impressions. The insensibility isa maximum close to the illuminated spot, and diminishes with the distance from it. Objects moderately illuminated actually disappear in the vicinity of the highly excited portion, and bodies of brilliant colours are not only shorn of their spendour, but have their tints entirely changed. Dr. Smith observed that a light red slip of paper was seen of a deep red colour by the excited eye, and nearly white by the protected eye; while a faint green slip appeared a stronger green to the excited eye, and almost white to the protected one. If weuse a stick of red sealing-wax it becomes ofa dark, liver colour to the excited eye, and of a brilliant red to the other eye. All bright blue colours have their intensity diminished in the excited eye; but-those which are mixed with the less refrangible rays, or even with white light, be- come of a darker blue, that is, the depth of colour is increased, though the intensity of illumination is diminished. In the case of a compound red colour, such as that of red heat, the image seen by the excited eye is a decided yellow. From these results it is obvious, that when the retina is ex= _ cited by a strong light, the part of the membrane on which the light does not fall is rendered partially insensible to all colours, but in the greatest degree to red light. Hence it fol- lows, that the white slip of paper should appear of a bluish- green colour, the complementary colour of red light. The red tinge which affects the slip of paper seen by the protected eye is the natural colour of candle-light heightened by the contrast of the green slip. As there is tar less red in day-light than in candle-light, the slip seen by the protected eye is very much whiter in the former than in the latter. The sensibility of the illuminated part of the retina is affected in the very op- posite manner. It becomes first insensible to blue light, a fact which is clearly proved by the experiments of A‘|pinus and others. rit hie The influence of light on parts of the retina upon which it does not fall, is finely exhibited in an experiment which has * See Art. Accidental Colours, Edinburgh Encyclopadia, vol, i. by the Action of Luminous Points and Lines. 173 never been explained. . When a spectral:impression of any very luminous body has: become so weak that it'can no longer be seen on,a, white ground, it is instantly revived by ‘shutting the eye, and continues to be seen for a short ‘time when the eye is again opened. The obliteration of the spectral image arises fromthe white light around it, extending its influence to the part of the retina occupied by the image; and the mo- ment this action: is removed by shutting out the light the ori- ginal impression is revived, or rather is rendered visible by the removal of another impression which overpowered it. Connected with these views is a very remarkable experi- ment described by Dr. Purkinje of Breslau, and which has been communicated to me by Mr. Potter, who has frequently and successfully repeated it.—If a candle is held a foot or two before one eye in a room without any other light, and is viewed directly by the observer, a mass of reddish-brown light is seen around the candle, and on this light, as a ground, are seen the ramifying blood-vessels of the retina, the base of the optic nerve and the foramen centrale. Mr. Potter finds that this experiment succeeds best when the candle is held about a foot from the eye, making an angle of about 20° with the line of distinct vision. I have tried it repeatedly, and under all forms, but I can see nothing excepting the mass of brown light. . The prevailing explanation of this curious fact is, that the light which surrounds the candle is reflected back upon the retina, either by the inner concave surface of the crystal- line lens, or of the cornea; and that the objects are, somehow or other, magnified by these concave surfaces. ‘The moment I repeated this experiment, I recognised in the mass of nebu- Jous reddish light the very same phenomenon which I had long before described as seen round luminous objects viewed indirectly. I have no doubt, therefore, that this light is pro- pagated from the luminous image of the candle, and that though the retina, in. contact with the blood-vessels, is sensi- ble to direct light, it is insensible to propagated light, and therefore the blood-vessels must be delineated in obscure lines. As there is no retina across the foramen centrale, it will of course appear as a black spot; and owing to the obtuse vision of the optic nerve, it will appear less luminous than the sur- rounding retina. In referring to the phenomena of indirect vision, I cannot avoid noticing the fact, that a candle seen by continued in- direct vision appears more luminous than one seen directly. This led me to conceive the idea that it might be possible to generate, as it were, light by increasing its physiological action on the retina. Whenever we condense light for ceco- 174 Mr. Potter on anew Photometer by Comparison, and nomical purposes we merely change its direction, taking it away from one place and throwing it upon another; and in all such operations light is invariably lost: but if we can sti- mulate the retina and render it more sensible to a weak light by the mode of its application, we obtain the very same effect as if we had used a more powerful beam. ‘The experiments which I have made on this subject have been more successful than I could have expected; and I hope to be able on some early occasion to submit them to the Association. XXXVIII. On an Instrument for Photometry by Comparison, and on some Applications of it to important Optical Pha- nomena. By R. Porrer, Jun. Esq.* HEN engaged in examining the phaenomena of the co- lours of thin plates in the form of what are generally de- nominated Newton’s rings, I was surprised to find that the rings were so distinct in the transmitted light, and particularly when homogeneous light was used. These rings are now generally allowed to be produced, by the agency of the light which has been twice reflected at the surface of glass, under an incidence very nearly perpendicular, Photometry had taught me that most of the common sorts of glass reflect about ;\,th of the light incident upon them in this case ; and we should expect two reflections to give an in- tensity of 1th of .,th, or 53,th of the first intensity. Now it requires very little consideration to see, that the presence or absence of so small a quantity of light is quite beyond detec- tion by the eye, and experiments are easily executed by which it may be proved. The difficulty of accounting for so great an effect being produced in a pencil of light, by so small a proportion of it, renders almost equally inadmissible every hypothesis which has yet been proposed to account for the whole phanomena of thin plates. On the doctrine of fits of easy reflection and transmission, which many experiments, otherwise, show must be dispensed with, even in the theory that light is caused by an emitted matter, this difference of the intensity of the dark and bright rings in the transmitted light is not to be satisfactorily accounted for. The theory that light consists of undulations in a subtile ther, gives scarcely any more admissible reason for the whole appearances, than the other. For in this theory the intensity of the light being taken as the amount of vs viva in the vibrating molecules, the modification which could be intro- * Communicated by the Author. on some Applications of it to important Optical Phanomena.175 duced by the interference of 51,th part of the whole vis viva, of the transmitted light, must be allowed, on all mechanical considerations, to fall exceedingly below so distinct an effect as that which we witness. These considerations induced me to think upon the possibi- lity of determining the relative intensities of the light in these dark and bright rings. This is not so difficult a problem as it at first sight appears to be; for though we may perhaps never expect to measure the light in the rings directly, yet it will be seen that if we can form variable appearances where we know the intensities of the lights, we may so vary them that they may form a representation of the phenomena we are considering; and then the only difficulty to be encountered is that of the eye judging with sufficient precision and accuracy, when the artificial is a correct representation of the natural effect. In experiments of this sort the only resource is that of repeated practice, by which the eye acquires a power of jadging with an exactness far beyond what would be expected at the first trial. There are evidently many ways of producing appearances where the intensities of the illuminations may be subjected to measurement and calculation. ‘The instrument I have ex- ecuted for the particular purpose above mentioned, is very manageable, but can only be used in the day-time, and in a particular state of the sky; that is, when it is either misty or uniformly overcast with clouds, so that a uniform illumination may be afforded to a piece of pasteboard, which is an essential part of the instrument. The instrument I have used consists of a flat board of about 16 inches in length and 12 inches in breadth: on this board I fix edgewise a rectangular piece of pasteboard of about 232 inches in length and 33 inches in breadth. The edge of this pasteboard is fixed along a semicircle described on the board, as shown in the figure. In the centre of the cireular are is a pin, as at a, upon which turn the two arms aband ac. Attached to each of these arms is a piece of crown-glass, which has been ney flat and polished; and afterwards covered at the urther surface with black varnish to prevent reflection there. These pieces of glass are so fixed as when moving with the 176 Mr. Potter on a new Photometer by Comparison, and arms round the pivot, to remain always perpendicular to the plane of the board ; and hence, to an eye placed as at d, these glasses will reflect images of some portions of the surface of the pasteboard. Ifthis surface is everywhere equally illumi- nated, the brightness of the reflection in the glasses will de- pend only on their inclination to the visual rays: thus when either glass reflects to the eye, the light from the part of the pasteboard almost opposite, or from e, the reflection will be very strong, and it will be weakest when the incidence is nearly perpendicular, or when the glass shows to the eye the part near f. Having a fixed position for the eye, or a tube through which to view the glasses, we easily determine the angle at which the light entering the eye is incident on the glass, by having a quadrant round the pivot graduated, and showing the inclination of the arms to the direction of the light. “It will now be evident that to produce a representation of the transmitted rings, we may view two narrow stripes of the glasses, covering any superfluous parts with blackened paper, and move the arms carrying them until the relative intensities of the reflections are sensibly the same as the relative intensities in the rings. ‘Then knowing the angles of incidence upon the glasses, we can calculate the intensities of the light from a for- mula, which [ have deduced from experiments, and published in the Edinburgh Journal of Science. ‘The apparatus pro- ducing the rings with homogeneous light should also be at- tached to the board, or otherwise kept so conveniently that we may view them or their. representatives alternately without any considerable space of time intervening; and the paste- board should be coloured to the same tint as the homogeneous light made use of, to produce a more correct representation, and to prevent the eye from being deceived by any difference of colour. The lights I have used in these experiments are a good homogeneous green, produced by a solution of arsenite of cop- per (Scheele’s green) in muriatic acid, and a very perfectly homogeneous red, produced by a solution of iodine in hy- driodic acid; this last solution gives most probably a purer colour than can be obtained of equal intensity by any other medium. I keep the solutions in small cut-glass phials with flat sides. With the green light I found the rings produced by a lens of long focus* pressed upon a plane surface, to be represented * T do not know exactly the curvature of this lens, but believe it to be to a radius of 15 or 16 feet. on some Applications of it to important Optical Phenomena. 177 in the photometer at the incidences given in the first and se- cond columns of the following Table; the third and fourth give the quantities of light reflected; and the fifth the ratio of these quantities, the smaller one being taken as unity. Glass for the! Glass for the Ratio, the dark Ring | bright Ring | Dark Ring | Bright Ring | dark Ring being set at |requiresto be| contains: | contains: | being taken Incidence: | Incidence: as unity. 3°83 9°06 2°36 3°83 8°66 2°26 4°18 11°15 2°66 4°18 10°54 2°52 4°76 12°59 2°64 4°76 11°83 2°48 5°81 14°41 2°48 5'81 14°41] 2°48 » With the red light I obtained as in the next Table. The ratio of the intensities of the bright to the dark rings is here much greater than with the green light. I had expected it to be so in some degree, from the greater purity of the light, but not nearly to the extent which I found it. I repeated the first trials I made, very often, before I noted them down, and did not do so-until I found clearly that the eye was not satis- fied with any less difference. Ratio, the Bright Ring | dark Ring contains: | being taken Glass for the} Glass for the dark Ring | bright Ring | Dark Ring being set at |requires to be] contains: Incidence : | at Incidence: as unity. 70° 4°18 13°44 3°21 71 4°18 14°41] 3°44 73 4°76 16°74, 3°51 74 4°76 18°16 3°81 To calculate the intensity of the light in the third and fourth columns, I have used the formula which I have found for crown-glass in the essay above referred to; namely, of every: Cc rtbo—2, where a, b,c and r, are constant quantities, and x = 100, 4=2:73 6 = 1:04, and c? = 76; z being.variable, andthe sine of incidence to radius as 100. Third Series. Vol. 1. No. 3. Sept. 1832. yi 100 rays incident, those reflected are equal to’ a + 178 . Mr. Potter on a new Pholometer by Comparison, and The great difference in intensity between the dark and the bright rings which we here find, is certainly not to be ac- counted for on any principles of interference yet proposed ; and it furnishes a very strong argument against the undula- tory theory, in which the effects of interference are supposed to be perfectly determinate when we know the circumstances of the interfering pencils. Dr. Young and Sir John Herschel have each given for- mulze for this difference of intensity, which, it is important to know, nearly coincide; the slight difference between them arising only from the latter having introduced certain approxi- mations to simplify the expressions he used. Sir John Herschel has deduced his formula from the rules laid down by the late M. Fresnel; and he finds that the mini- mum of the light in the dark ring should be represented by the expression 1-—4.a, when the maximum of the light in the bright one is represented by 1*, and a is equal to the first re- flection, and the light incident equal to unity. Taking the value of a =,th, we have 1— 4,= 1'—"13 ="86 and ‘86: 1+:: 1+: 111538 or the intensity of the light in the bright rings should be to that in the dark ones, as 171538 to 1°, a result widely different from $°5 to 1‘, as we have found by experiment. The great effect which we find to be produced by the in- terference of a small portion of light, must be deducible from any theory which is proposed as representing the true law in nature ; and as a determined fact, it refutes an argument which M. Fresnel advanced against the hypothesis, that the fringes produced by the edges of bodies placed in a pencil of light diverging from a luminous point, are caused by the inter- ference of light which has suffered an evanescent reflection with that which has arrived directly from the luminous point. I have applied the photometer also, to repeating M. Arago’s experiment, by which he has demonstrated that if the reflected and transmitted rings could be superposed they would exhibit a sensibly uniform light. I find this to be undoubtedly the fact; and the experiment furnishes an excellent means of trying the suitableness of the weather for using the photome- ter, and also the fitness of the locality where we purpose to experiment. When I had completed the photometer, I found it very readily applicable to measuring the reflective powers of sub- stances, of which we could never expect to procure sufficient extent of surface to render the method of photometry by lamps available: it requires only a very small extent of plane sur- on some Applications of it to important Optical Phenomena. 179 face to perform an accurate experiment with the comparative photometer. For this purpose it is necessary to remove one of the pieces of crown-glass of the former experiment, and to place in lieu of it the substance to be examined, which has been before properly mounted, and then to find the incidence at which a similar surface on the piece of crown-glass gives an equal reflection. In this manner the larger facet of the diamond in a ring gave me the following results. The results in the first Table I obtained before the instrument was weil adapted to the purpose; those in the second, which were obtained after- wards, I consider to be more correct. II. Corre- .| Diamond Incidence} sponding | reflects of on Incidence | every 100 Diamond.| on Crown-| Rays glass. | incident. Corre- Diamond Incidence} sponding | reflects of on Incidence | every 100 Diamond. on Crown-| Rays incident. 63°48! 9°41 10 63 48 9°41 9°23 10°00 10°00 Pris 10°15 12°43 18°16 26°80 30°05 These results are important, as we may compare them with the formula which has the uniform approbation of those who adopt the undulatory theory of light. The unanimous con- clusion of Dr. Young, M. Poisson, and M. Fresnel, who have each investigated the subject, was, that the intensity of the perpendicular reflection, according to that theory, should be U 2 equal to teted) ; and knowing the value of p/, or the re- fractive index for diamond, we find that this reflection ought, if the undulatory theory were true, to be about the double of i iy: 180 =- Mr. Potter on a new Photometer by Comparison. 2°25 12°25 rays should be reflected of every 100 incident; whilst experi- ment shows it to be only somewhat more than 9°, and perhaps about 9°3. I have applied the photometer to a few other substances, and the results of my observations are given in the following Table. what it is in fact. Taking p! = 2°5, we find » or 18°36 Corresponding} Reflected of Substance examined. | Incidence. | Incidence on | _ every 100 Crown-glass. | Rays incident. 12 Po Re ee ah 205-40! 3°83 thatch acdinns powaine 5 19.9 3°80 Doi 4. . 20 25 30 4°01 LS Oe r-A0) 25. 0 Fy eee) IO, o2 ste ee 30 34 O 4°38 op Si rar Aas 30 39.0 4°43 Do.(another piece) 5 23 0 3°92 0 oa Sas . 5 19 70 3°80 Selenite ..... 3 ao 3°49 DDG} GR 68 was 5 10 O 3°60 G92 A Ste NP 45 45 O 5°20 Do.(another piece), 5 4 @ 3°52 Dept Bie wAyeHp 20 20 0 3°83 Iceland spar... 5 19 0 3°80 Dorvtieelaas 4 5 18 0 3°78 WGI My OBer'l s 5 1s 0 “o'70 DOO OE. 5 ‘ipa 3°75 Do.(another piece) 5 22 0 3°89 DO! Joke glsels P20. 5 22 0 3°89 Rock crystal. . . 0 14 0 3°68 DOU FSO 10) 14 0 3°68 Do! ARNG td 28.0 0 12 30 3°65 BPGR IE A) gs SIF 0 16 0 3°73 Do.(another piece) 5 12 0 3°64 DS) LOBOS lo rae 3°68 Amethyst ... 5 20 0 3°83 Doi Dyas ye, 5 "22 0 3°89 Emerald! 9 10 + Pea, 3°89 WDofOUSjOR IHL LY 10 24° 0 3°95 Desig % ibis 30 40 0 4°76 Delo2i3 PHBL 30 40 0 4°76 The natural surfaces, and as recent as possible for mica, selenite, and Iceland spar, were used in all the above, except- Mr. R. Warrington on Chemical Symbols. 181 ing in amethyst and emerald; and I have also less confidence in the measurements for these two substances than for the others. The mica, selenite, Iceland spar, and rock crystal, were covered with a varnish of black sealing- wax on their se- cond surfaces, to prevent reflection. Where it is said that the incidence on rock crystal was perpendicular, it must be understood that it was only so nearly so, that the natural un- evenness of the facet made it impossible to determine it. The reflection by selenite is so exceedingly nearly the same as that of crown-glass, that I found it impossible to state with certainty whether it was higher or lower: in one observation, however, I made it higher. With the other substances, and particularly with mica and Iceland spar, the difference is quite obvious at the first view. XXXIX. On the Establishment of some perfect System of Chemical Symbols; with Remarks on Professor Whewell’s Paper on that Sulject. By Mr. R. Warnineron*. [XN entering upon the consideration of the necessity of chemical symbols,—a necessity which becomes the more urgent from the rapid progress the science is continually making, and from the increasing number of new combina- tions which are daily brought before our notice, and the want of some system of symbols to facilitate our reasoning upon these and other combinations,—there are two great points to be kept in view; namely, brevity and clearness in the nature of the symbols themselves, and as perfect an approxi- mation to mathematical consistency and algebraic formulze as the nature of the subject will admit. Professor Whewell, in a paper upon this subject published in the 1st yolume of the Journal of the Royal Institution for May 1831, advocates the necessity of radically altering the symbolic system of Berzelius, on account of its total want of mathematical propriety, and fully demonstrates the advantages to be derived from the adoption of an arrangement founded on algebraic principles ‘t. The improprieties more particularly pointed out in Berze- lius’s system of notation are; first, the method adopted by him of connecting the elementary symbols together in representing compound bodies, as though, according to the notation made use of in algebraic reasoning, the constituents were multi- plied by 44 other; whereas the combination is effected by * Communicated by the Author. + In the Phil. Mag. and Annals, N.S., vol. x. p. 104, appeared a paper on Chemical Symbols and Notation by Mr, Prideaux, in reply to Professor Whewell, a brief rejoinder from whom will be found in the same volume. p- 405, note.—Ebir,. 182 Mr. R. Warrington on a System of Chemical Symbols, the simple union or addition of the elements. As for instance, in Sulphuret of Potassium, one proportion of sulphur is added and chemically united to one proportion of potassium (/alium), which should be indicated by S+K, Sulphur+ Kalium; but according to Berzelius’s arrangement it would be written SK, in which the components are apparently multiplied by each other; and this, to use Professor Whewell’s words (p. 441), “ violates all mathematical propriety so entirely, that it must always be disagreeable to see an example of it for any person who has acquired the first rudiments of algebra.” The next point of consequence commented on, is the man- ner of representing compounds which contain more than one proportion of an elementary or compound bedy, and to which the prefixes, Bis, Tris, Dis, &c. have been given. ‘The method pursued by Berzelius, is to place the numerals 2, 3, 4, &c. as indices over the symbol corresponding to the element, acid, or base: thus Bisulphuret of Iron, composed of two propor- tions of sulphur-+one of iron, would be written S* Fe; Bi- silicate of Alumina, S® A; Bisul phate of Copper, S* Cu; Disul- phate of the Peroxide of Iron, S Fer’. To obviate these in- congruities, and to lay before the chemical world a system formed on mathematical principles and consistent with alge- braic formula, appears to have been the object intended by Professor W hewell in his paper: but in this he appears to me to have failed, not for want of due consideration and ability, but from the subject having been taken up in a mineralogical rather than a chemical point of view; for the Professor him- self acknowledges, speaking of the proposed system (p. 448), that “‘ the preceding notation is intended principally for the purposes of mineralogy ;” and that “in the calculations of che- mistry it would be necessary to have some additional contri- vances. Thus it would be proper, as I have already observed, to indicate the mode in which both the oxides and the acids are formed from their bases by the addition of definite por- tions of oxygen.” On attentively reviewing this part of the subject, I cannot help forming the conclusion, that these con- tinual contrivances and contractions to suit different points of reasoning, must involve the subject in interminable confu- sion and difficulty. It would, I should consider, be far sim- pler to adopt one entire set of symbols applicable to all branches of chemical science, or to other sciences into which. chemical reasoning may enter. If some arrangement of this kind is not fixed upon, the subject will be continually open to variation, and the caprice of different persons according to their several ideas of symbolic notation. with Remarks on Prof. Whewell’s Views. 183 It is with the view of furthering the ultimate and, I hope, speedy establishment of some one systematic arrangement, that I have been induced to occupy a short space in your valuable Journal with the present paper, which, although the system promulgated in it should not be perfect, may yet be of service, as affording some useful hints to others more fitted for the final settlement of this most desirable and useful ob- ect. ; On the first consideration of this subject, I was led to ima- gine that abbreviations of the English nomenclature would be more simple to the English student, and would be more readily understood and applied by him; but upon further re- flection I was convinced that the Latin symbols, as selected by Berzelius, would be far preferable, on account of their having been in frequent use, more particularly among the Continental chemists and mineralogists, for some years, and also from their conciseness and simplicity. But (with one ex- ception, which will be stated hereafter,) nothing more, I think, of Berzelius’s system should be adopted, than the symbols of the elementary bodies. In the connection of these elements with each other, the methods generally adopted by Sir John F. W. Herschel, and subsequently followed by Professor Whewell in its principal features,—namely, the plus signs for the formation of compounds, and the use of brackets or ties, —must be taken to form the basis of a system with any claims to mathematical consistency:—an example will show more clearly the method according to which these are employed. Take, for instance, the octohedral copper pyrites, composed of two proportions of sul- phuret of copper and one proportion of sulphuret of iron; this will be indicated thus, 2 (S+Cu)+(S+Fe). Although this part of the subject has been cursorily alluded to in the former part of this paper, and the arguments used by Prof. Whewell briefly stated, yet I cannot avoid noticing in this place, that in a subsequent part of Professor Whewell’s essay, he appears to have entirely forgotten the severe strictures that he had passed on Berzelius as to the want of algebraic consistency; and also his own observation (page 442), that “the combinations of ingredients which make up compounds are clearly of the na- ture of additions, and never can have any analogy with the multiplication of the numbers expressing the components; they therefore ought by no means to be represented by that com- bination of symbols which denotes multiplication.” And again, at the 18th line of the same page, ‘there can be no doubt of the exceeding impropriety, I might say absurdity, of such a kind of symbols.” Now, in direct contradiction to these obser- vations, Professor Whewell proposes to represent the oxides of 184 Mr. R. Warrington on a System of Chemical Symbols, the metals (p. 44.9) * by repeating the second letter of the sym- bol for each additional atom of oxygen, and attaching s (semis- sis) for the half atom: thus, Mn, Mns, Mnn, are the Protox- ide, Deutoxide, and’ Peroxide of Manganese.” Again, in object- ing to the use of dots placed over the symbolic letters for the indication of the number of proportions of oxygen in any com- pound, it is admitted (p. 149) “that the notation is compact and simple,” but ‘that it is not consistent with algebraic rule, as far as the oxygen is concerned ;” and the writer argues, *‘that to be explicitly expressed, it should be done in the manner previously recommended, as fe+20, fe+30, Protoxide and Peroxide of Tron,” according to Berzelius’s view of those combinations. Now, on referring back to the preceding page, we find Pro- fessor Whewell urging the utility of representing the Acids commonly occurring in minerals, by an accent or dash placed over the bases of the acid: thus, for instance, S Sulphur, S/ Sulphuric Acid; C Carbon, C’ Carbonic Acid; Ar Arsenic, Ar’ Arsenic Acid; Cr Chromium, Cr! Chromic Acid; Cl Chlorine, Cl! Muriatic Acid; I Iodine, I' Hydriodic Acid. And at the concluding part of the paper this system is extended to other combinations of oxygen with the same bases, the accent being varied: as S‘ Sulphurous Acid, C’ CarbonicOxide, Ar’ Arsenious Acid. But in this arrangement no notice ap- pears to have been taken of acids the basis of which com- bines with both oxygen and hydrogen, as is the case with chlorine, iodine, bromine, fluorine, sulphur,&c. ‘The chloric acid must be indicated in the same way as the muriatic, the iodic as the hydriodic, sulphuretted hydrogen in combina- tion as.an acid the same as sulphuric acid, and so of the rest. Then we have also the perchloric acid, for which it would be necessary to form some other accent or distinguishing mark. Considering this subject impartially, it must be allowed, that Berzelius’s arrangement, with respect to the representing oxy- gen by dots, if examined even in an algebraic point of view, is more simple and correct than the various accents made use of by Professor Whewell, each of which represents oxygen or hydrogen quite as fully as the dots indicate oxygen alone; and that no clew is afforded by this method as to the elementary bodies or their proportions which enter into the composition of a compound, but simply, that it is a union of an acid witha base, &c., and that it may be sometimes even doubtful what the nature of that acid is,—whether the acidifying principle be oxy- gen or hygrogen. Besides these contractions, there are others introduced equally objectionable ; such as the representing the Metals by small letters, and their Oxides by the same letters, commencing with the large Roman character ; as 2'u Zine, Zn with Remarks on Prof: Whewell’s Views. 185 Oxideof Zinc; and alsothe indication of silica, alumina, and the other earths, by the symbolic letters of their individual bases, as S, A, &c.; and again with ammonia and water, they are re- spectively represented by the abbreviation Am, and the letter q: Professor Whewell states that these contrivances and con-' tractions are to be considered as mere abbreviations, yery con- venient, but not indispensably necessary. If not so, why are they introduced? But the strict reason I imagine to be, that from Prof. Whewell’s wishing to render the system perfectly mathematical, the different formule: must necessarily be very extended, and therefore inconvenient. I consider these abbre- viations uncalled for, however, and that they must add materi- ally to the rendering any system of symbolic notation intricate and confused. ‘The representation of oxygen by dots appears to simplify the subject, and render the formulz very brief; and it clearly shows at the first glance the number of proportions of oxygen which enter into combinations, without at all confu- sing the arrangement, or rendering other contractions for the representation of the oxides or oxacids necessary, and it has therefore been adopted in the present system. I also propose introducing other dashes or marks to represent chlorine, io- dine, bromine, fluorine, and nitrogen; for in the combinations of nitrogen with hydrogen and carbon, separately or con- Jointly,—as in ammonia, cyanogen, and their compounds,— this latter will be found of very great service. The wayin which I should introduce these would be as follows: H’ one propor- tion of Hydrogen and one of Oxygen will represent water, the dot, as in the system of Berzelius, indicating the oxygen ; H! Hydrochloric or Muriatic Acid, the vertical dash indicating Chlorine; H! Hydrobromic Acid, the«acute dash being Bro- mine; H’ Hydriodic Acid, the grave dash for Iodine; H Hy- drofluoric Acid, the horizontal stroke represen ting Fluorine:and (3 H). Ammonia, the dot beneath the symbols indicating Ni- trogen; but in case this formula should not appear applicable, the one 3H+n may be adopted. With respect to the half proportions, these may be readily and conveniently represented by making a fraction of the mark or accent thus: Fe, Fé, Fe= will be Iron, its Protoxide, and Peroxide. m., m‘, m'>, m* Manganese, its Protoxide, Deutoxide, and Peroxide. I fear that this introduction of accents and fractional ac: cents will be condemned by those who wish to establish a system on pure algebraic reasoning. But I doubt very much whether a system can be so established without rendering the formula very extended, and in fact superseding the use of Third Series. Vol. 1, No. 3. Sept. 1832, 2B 186 Mr. R. Warrington on Chemical Symbols, symbols altogether, the beauty of which must always consist in their simplicity, clearness, and brevity. I shall annex some examples of the three methods ; those of Berzelius, and Whe- well, and the one here proposed; and leave the subject, | hope to be established speedily, by some one fully equal to the task. O. Oxygen. G. Glucinum. W.. Tungsten, Wol- Cl. Chlorine. Y. Yttrium. framium. Br. Bromine. Th. Thorium. Cr. Cerium, J. Iodine. Zr. Zirconium. Ni. Nickel. F. Fluorine. Al. Aluminum. Co. Cobalt. N. Nitrogen. Si. Silicum. V. Vanadium. H. Hydrogen. M. Manganese. Cr. Chromium. C. Carbon. Fe. Iron, Ferrum. |Ta, Columbium, S. Sulphur. Zn. Zine. Tantalum. P. Phosphorus. Cd. Cadmium. Hg. Mercury, Hy- Se. Selenium. Sn. Tin, Stannum. drargyrum. B. Boron. [sium. |Sb. Antimony, Sti-/Ag. Silver, Argen- K. Kalium, Potas- |As. Arsenic. [bium. tum. Na. Natrium, So- /Bi. Bismuth. Au. Gold, Aurum. Li. Lithium, (dium. |Pb. Lead, Plumbum.'Pt. Platinum. Ba. Barium. Cu.Copper, Cuprum.'Pd. Palladium. Sr. Strontium. Te. Tellurium. [R. Rhodium, Ca. Calcium. Ti. Titanium. Ir. Iridium. Mg. Magnesium. Mo.Molybdenum, |Os. Osmium, Chloride of Sodium. Nitrate of Potash. Berzelins..ss..«: Cl Na NK Whewell......... cl+na (n+ 50) +(K+0) Proposed System N' N +K Nitrate of Ammonia. Muriate of Baryta. Berzelius........ NHN +H ClHBa+H Whewell...... (n+3n)+(n+50)+(h+o) (cl+h)+(ba+o)+(o+h) Proposed System (3H).+ N- +H H'+Ba+H Or the same in another view, Muriate of Baryta. Alum. Berzelius... CIB+2H KS + aS 34 25H Whewell(el+-b)+ %h+o0). K0+4+S+430)+ 3al+-0+8 $50)+4 25(04 hy Prop.Syst.Cl4+B+2H (K+S8)+3(al+S )+25H or, B+2H Difference of Level between the Sea and River Thames. 187 Hydrocyanate of Ammonia. Berzelius............ NHSHe°eN Whewell........000 (n+3H)+(2ce+ +h) Proposed System... (3H). + (2c). +H Persulphate of Iron and Potash. Berzelius...... 28 14 Fe + SK +25 H Whewell....,.. 205844504 fe+ 30)+(S+30-+4 Ka+ 0) +4 25(h+0) Proposed Syst. 2(14 oie Fe ) 48 4+Ka)+25 H Ferrocyanate of Potash. Cyanate of Lead. Berzelius... 2c? NK +c?N Fe+ 3H C2No P.b Whewell 2c-+n+K)+(2e+n+Fe)t+3(h+o) @c+n+0o) + (pb+o) Prop. Syst. 2((2c).+K)+((2c).+Fe)+3H (2C).+0+Pb- Ammoniacal Alum. Berzelius........ SalS +NH°S Whewell............ 3(al-o+s+30) +(n+3h+s +490) Proposed System... 3(al + S)+ ((3H). “F 5) 30, Church-street, Spitalfields, July 1832. ase XL. Tabular Abstract of the Results of Capt. Lloyd’s Leveling from the Sea near Sheerness to the River Thames at London Bridge. By B. Brvans, Esq. To the Editors of the Philosophical Magazine and Journal. Gentlemen, APT. LLOYD’s paper, as published in the Philosophical Transactions for 1831, which shows thatthe brass standard at the landing-place of New London Bridge is 2°3967 feet below an arbitrary mark at Sheerness, contains little information rela- tive to the longitudinal section of the river Thames itself, either as to the surface of the water at high, mean, or low state; and which, in a philosophical point of view, would have been very interesting*. Most tidal rivers have the high-water mark at the outlet considerably higher than at a distance of some miles up the river, particularly when the country is flat, or almost level, through which the river passes; whereas it appears by these * An abstract of Capt. Lloyd’s paper, including a brief account of the apparatus and methods employed, was given in Phil. Mag. and Annals, N.S., vol. ix, p. 357,—Epir. 2B2 188 Mr. Bevan’s Abstract of the Results of Capt. Lloyd’s levels that the surface of the water at London Bridge, at spring tide high water, is nearly two feet above the surface at Sheerness. It may be worth inquiring why the river Thames differs in this respect from other rivers. It-would not be very difficult to ascertain the nature of the curve formed by the surface of the water, both at spring and neap tides, by a simul- taneous registering of the height of the water every half-hour for one day, at the respective stages of the moon and tides. There appear to be about eight or nine points where the course of levelling came in contact with the river, where Capt. Lloyd, doubtless, left plain and conspicuous marks to enable any person hereafter to refer to. One person at each of these points for two days, would enable us to see the vari- ation of the surface of the water at the cardinal stages of the tide; and if such a development should be considered of suffi- cient interest, other periods of the tide might at an easy rate beadded. At present, it is to be regretted that we know scarcely anything of the physicalconstitution of the most important river in the United Kingdom; while almost half the inferior rivers have had their longitudinal and transverse sections procured, showing the depth and capacity of the channel, and the power of discharge at different states of the tides. The time will arrive when this knowledge will be impor- tant, and when an authentic record of the state of the river in times past will be of the greatest value. ' The following is an abstract of the result of Capt. Lloyd’s levelling, in reference to a natural zero of low water spring- tide. $°5300 Mean level of the sea. 17°6150 Mean spring-tide high-water mark at Sheerness. 15°7600 Mean high-water mark. 139160 Neap tide high water. 15°3159 Marshes of Queenborough. 50:4265 St. James’s standard. 19°0494 Boundary post of Hoo marshes. 15°7695 Marshes of St. Mary. 150455 Marshes of Higham. 24°1015 Three-mile stone on bank of Gravesend canal. 23°6849 Two-mile ditto, 22°8259 One-mile ditto. 22-2375 Iron clamp at second gate on Gravesend canal. 21:4983 Brass standard on pier at Gravesend. 18°7168 High water at Gravesend. 14°1922 Marshes at Northfleet. 16:9233 Boundary stone of Swanscomb. 12°8135 Marshes east of Dartford Creek. 11:9604 Marshes west of Ditto. Leveling from Sheerness to London Bridge. 189 2071142 Standard on Erith church. 11°5407 Marshes of Woolwich. 22-8830 Standard in arsenal, Woolwich. 23°2387 aN in corner stone near Officers’ garden. 23°3993 1) top of 43-mile post, in river. 23-6786 0 on stone at west end of Dockyard. 23°3356 Brass standard in Dockyard, east point of mast slip. 316786 4. on small north-east gate-way from main road, Greenwich. 162°3618 Small brass standard under transit instrument, Greenwich College. 26°7968 Little brass standard on plinth of statue of Geo. IL. Greenwich College. 23°5819 O oniron plate near south side of lock on City canal. 19°7373 City canal ea Trinity. 230617 High tide, City canal, 21st of November 18927. 22°9829 Brass standard, West India Docks. 20°6462 XXIII. Ditto. 24°1229 Brass standard at Regent’s canal. 21°8921 XXI. mark at Ditto. 20°1251 High-water mark on Ditto. 25°4381 Standard at London Docks, south-west pier. . _ HW 19°6699 XXIII. 18 feet = 7800 18:0029 Mean high water, London Docks. 19°6511 Spring tide high water, Ditto. 1°6489 Trinity. \ Spring tide low water, . Ditto. 1°6679 162739 Neap tide high water, _ Ditto. 10°5959 Mean level, Ditto. 37°7726 O on top of granite post near entrance from Rat- cliff Highway. fi 34°8457 on top of gun near eastern basin. 25°9954 Brass standard, St. Catherine’s Dock. HW 19°7391 XXVIII. TAG 22°9665 Standard at Traitors’ Arch, Tower. 19°5190 London Bridge, west side, shy 19°2844 New London Bridge, brass standard at lJanding- place. Trinity. Trinity. B. Bevan, “T1907 XLI. Description of a Species of Arachnida, hitherto uncha- racterized, belonging to the Family Araneide. By Joun Buackwat., F.L.S. &c.* Tribe, 'TuBiITeELz a Gate Dysdera, \ Latreille Dysdera Latreillit, PEs upper part of the cephalothorax is deep black, the under part being of a dark reddish-brown colour.. The abdomen is almost cylindrical, very soft, hairy, and of a pale livid brown colour, each extremity inclining to yellowish- white above; the four exterior mammulz or spinners are nearly equal in length. The legs, which are rather long, are marked with broad bands of brown and yellowish-white; the first pair is the longest, then the fourth, the third pair being the shortest; the two superior tarsal claws are deeply pecti- nated. ‘The eyes are seated in the anterior part of the head ; they are six in number, nearly equal in size, and form a small oval open in front, somewhat resembling a horse-shoe in figure. The mandibles are vertical; the maxillz are long and dilated at the base externally, where the palpi are inserted : the lip is elongated, and gradually decreases in breadth from the base to the apex. In the male of this species, the sexual organs are situated near the termination of the palpi, on their under side, and are bent abruptly backwards; they are of an oval form, and have a delicate curved process near their ex- tremity. Length, from the anterior part of the head to the extremity of the abdomen, 3th of an inch; length of the cephalothorax jth; greatest breadth of the cephalothorax about ;';th; length of an anterior leg 2ths. The above description is taken from a male spider; indeed, I have not yet been so fortunate as to procure a single speci- men of the other sex. The first individual I met with was in a hedge at Oaklands, about two miles south from Llanrwst, on the Denbighshire side of the vale of Conway, North Wales. I afterwards found two other specimens in the crevices of a stone wall inclosing the ornamental grounds immediately ad- joining Gwydir House, on the Caernarvonshire side of the same vale. The manners and ceconomy of this species are at present unknown to me, but I hope soon to have an opportu- nity of investigating them. I have carefully compared the new spider with a fine speci- men of a male Dysdera erythrina, captured in Manchester by * Communicated by the Author. Mr.B. Boddington on the Effects of a Stroke of Lightning. 191 my brother, Mr. Thomas Blackwall; and perceive that there is not only a great disparity in size, and a wide dissimilarity in colour between the two species, (circumstances which might be supposed to arise from a difference in age merely,) but that they likewise differ very decidedly in figure and structure ; thus clearly establishing the fact that they are specifically di- stinct. The former has the mandibles much less prominent, and the abdomen more nearly cylindrical than the latter ; its tarsi also are destitute of brushes, with which instruments those of Dysdera erythrina are provided. In adding another species to the solitary one at present constituting the genus Dysdera of M. Latreille, I avail myself of the opportunity to confer upon it the name of that illustrious naturalist, whose important researches have contributed so largely to the advancement of arachnology. Crumpsall Hall, Aug. 10, 1832. XLII. An accurate Statement of Facts relative to a Stroke of Lightning, which happened on the 13th of April 1832. By BensaMin Boppineton, Esg.* OX Friday, the 13th of April 1832, Mr. and Mrs. Thomas F. Boddington, having partaken of some refreshment at Tenbury, placed the servants inside their post-chariot, and mounted themselves the barouche seat behind, that they might enjoy the scenery on the road to Bromyard, through the ra- mifications of the Abberley Hills. It was about half-past three when they left, the sun shining, and the sky serene; but be- fore they had proceeded far, they observed a dark and singu- lar-looking cloud to arise, nearly in the direction of their route, and at the end of about three miles and a half a few drops of rain began to fall: they debated whether they should get inside the carriage, but agreed that the storm (for such it appeared to be) was passing off to the right, and that it would in all probability be only a slight shower, as the cloud in their immediate vicinity, though peculiarly dark and angry- looking, was of very small dimensions ;—at this time a clap of distant thunder was heard, but no lightning seen... Mr. Bod- dington put up an umbrella; but perceiving that it was an old one, somewhat torn, (belonging to one of the servants,) he gave it to his wife to hold over her bonnet, while he put up another ; when in the act of extending the latter, a flash of lightnin struck them both senseless, threw the horses on the ata and cast the post-boy to a considerable distance. ‘The ser- * Communicated by Mr, Faraday, 192 Mr. B..Boddingtomon the Effects ofa .. roke'of Lightning vants | inside were untouched, “and” indeed conscious of the real mature of the accident: the man’ says that he heard no previous thunder, but that a vivid flash of lightning, proceeding -as/he thought from the side of the road! next to which ‘he sat, was accompanied) by an instantaneous’ report, like the dis- charge of a highly loaded blunderbuss; and he concluded that some robber, or other mischievous person, had shot the horses. He acknowledges that he was so panic-struck that for a few seconds he sat still; but on recovering from the momentary alarm, he let down the side glass and looked ‘out to'see whether his master.and mistress were séifel athe was shocked to perceive the head of the former hanging over the seat, and apparently lifeless: he immediately jumped from the carriage, aud ascend- ing the:steps behind, raised his master’s‘ head, and found that his clothes were on fire; his mistress was standing up,’ tearing off her bonnet and shawls. Her account of the matter is this : —that she neither saw the flash nor heard the thunder, but her first consciousness was the feeling of suffocation, and that she was pulling off her things to obtain air; she felt, however, that they had been struck by lightning, and immediately com- menced assisting the servant to extinguish the fire that was still. consuming “the dress of her husband. . The passage of the electric fluid, as connected with Mrs. Boddington, was most distinctly to be traced: it struck the um- brella she had in her hand ;—it was, as I before stated, an old one, made of cotton, and had lost the ferule that is usually placed at the end of the stick; so that there was no point to attract the spark: it was literally shivered to pieces, both the springs in the handle forced out, the wires that extended the whalebone breken, and the cotton covering rent into a thousand shreds. From the wires of the umbrella the fluid passed to the wire that was attached to the edge of her bonnet, the cotton-thread that was twisted round that wire marking the place of en- trance over the left eye, by its being burnt off from that spot all round the right side, crossing the back of the head and down into the neck above the left shoulder; the hair that came in contact with it was also singed: it here made a hole through the handkerchief that was round her throat, and zigzagged along the skin of her neck to the steel busk of het stays, leaving a painful but not deep wound, and also affecting the hearing of the left ear. It entered the external surface’ of the busk :—this is clearly proved by the brown paper case in which it was inclosed being perforated on the outside, and the busk- itself fused for about a quarter of an inch on the upper sur- face, presenting ‘a blistered appearance. Its passage down: the'busk could not be ‘traced in any! way there’ w as 10 mark on some jersons sitting behind a Carriage, §c. 193 whatever on the;steel, nor was the paper that covered it dis- coloured or altered in the slightest degree ; its exit at the bot- tom, however, was as clearly indicated as its entrance at the top; the steel was fused in the same manner, and. the paper was perforated in the same way, but on the opposite side. The magnetic properties acquired by the busk are curious. Both ends attract strongly the south pole of the needle, the upper part for some considerable way down; it then begins to lose power over the south pole, and the point of northern attraction is at about one third of the length of the busk from the bottom; so that by far the greatest portion of the whole has acquired southern attraction. Perhaps it will be best ex- plained by the following sketch of the inside face of the steel, which is fourteen inches and a half long, by one inch and three-eighths wide. Mark from the lightning. ES : = = +] : Ps = fa Fee N 3 : S88 ss . ° : ss ais a) : : - - S$ s38 s : $ 3 : s3° FS sa, 3 : ; 5 37 2} - + . . — Mark fromthe Equal Point of — Equal on Southern attrac- Mark from lightning onthis onboth northern both poles, tion begins tobe the lightning, side only, and poles. attraction. strong, and con- much more not deep. tinues so to the on the other top. side. There were marks of burning on the gown and petticoat above the steel; and the inside of the stays, and all the gar- ments under the stays, were pierced by the passage of the fluid to her thighs, where it made wounds on both; but that on the left so deep, and so near the femoral artery, that the astonish- ment is, that she escaped with life;—even as it was, the he- morrhage was very great. Every article on which she sat was perforated to the cushion of the seat, the cloth of which was torn in a much more extensive way than the clothes: in most cases they were pierced by a hole not exceeding the size of half an inch in diameter, and even where the rgnts were larger they did not extend beyond an inch or two in any direction : but it is worthy of observation, that every article the electric fluid passed through had a singed appearance at the edges (and had a sulphureous smell, as I was informed by those who inspected them immediately after the accident: by the time I reached Tenbury, all trace of this smell had vanished). No ignition, however, took place beyond what occurred at the mo- ment of its passage, notwithstanding the inflammable nature of most of the articles; nor did any of Mrs. Boddington’s wounds present the appearance of burns. ‘The cushion of the barouche seat was stuffed with curled horse-hair, through which the Third Series, Vol. 1. No. 3. Sept. 1832. 2C 194 Mr. B. Boddington on the Effects of a Stroke of Lightning stream must have passed, though. no sign to indicate its. pas- sage was visible; the cloth edge of the cushion, however, im+ mediately behind where Mrs. Boddington sat, was torn out- wards, and the leather that covered the iron forced off in the same spot, clearly marking its egress at this place. As this same iron also received the charge that struck Mr. Boddington, I shall now state the effects of the lightning on him, before I trace its further progress. When first discovered by his servant, he was, as I have said, insensible, and he re- mained in that state for about the space of ten minutes, when he revived sufficiently to inquire where he was, but relates that he was perfectly unconscious of what had occurred; that he felt his eyesight affected, and pain all over him, but knew not from what cause these sensations arose. The umbrella in this case also was the conductor; it was made of silk, and was but little damaged, a small portion of the upper part only being torn where it joins the stick, and none of the springs or wires being displaced. The main force of the shock, how- ever, appears to have passed down the handle to his left arm, though a portion of it made a hole through the brim of his hat, and ‘burnt off all the hair that was below it, together with the eyebrows and eyelashes; the fragments of the burnt parts falling into the eyes deprived him nearly of sight for two or three days, but the eyes were not otherwise injured. The electric stream shattered the left hand, fused the gold shirt-buttons, and tore the clothes in a most extraordinary manner, forcing parts of them together with the buttons to a considerable distance; and a deep wound was inflicted un- der its position on the wrist. The arm was laid bare to the elbow, which is presumed to have been at the moment very near his left waistcoat-pocket, in which there was a knife; this also was forced from its situation, and found on the ground; a severe wound was made on his body, and every article of dress torn away as if it had been done by gunpowder. From the knife it passed to the iron of the seat, wounding his back, and setting fire to his clothes in its passage. Another portion descended to the right arm, which had hold of the lower part of the stick of the umbrella; was attracted by the sleeve-but- ton, where it made a wound, but slight as compared to that on the left, passed down the arm (which it merely discoloured, and broke the skin of in two small places,) to a gold pencil-case in the right waistcoat-pocket. ‘The great-coat he had on was an old navy watch-coat, commonly called a pea-jacket, and of great thickness; this was torn to pieces, and the coat. im- mediately above the waistcoat-pocket much rent; but) the waistcoat itself was merely perforated; on the external’ part, on some Persons sitting behind a Carriage, Sc. 195 where the discharge entered by a hole about the size of a pea, and on the inside by a similar hole at the other extremity of the pencil-case, where it passed out, setting fire to his trowsers and drawers, and inflicting a deep wound round his back, the whole of which was literally flayed. A very striking difference was observable in the wounds of Mr. and Mrs. Boddington : her’s, as I before stated, were frac- tures of the flesh; his, on the contrary, whether deep or shal- low, were all of them burns, and had a white and blistered appearance. The accumulation of force which the electricity acquired at this place deserves particular attention. I have observed that the shock on the right arm was nothing as compared to that on the left ; the shirt-button was unchanged, and unmoved from its position, and the passage of the fluid down the arm barely indicated; yet when it arrived at the pencil-case, the amount of its intensity was such as to meit one end of it, and displace a cornelian seal at the other ex- tremity, forcing it, I suppose, to some distance, as it has never since been found, though it was carefully sought after. It should seem that this accumulation of strength must have been derived either from the portion that passed over Mrs. Boddington, or from union with that which went down the left arm; in either case it appears to have been strangely diverted from its original course. The whole shock was now col- lected in the iron that formed the back of the barouche seat; the leather attached to it was torn off, and the iron itself broken in two, immediately opposite the spring, and the ends of the fractured parts bent forwards so as nearly to touch it: by this conveyance it is supposed to have diffused itself over the whole of the under carriage, and to have passed to the earth by the tires‘of the wheels, four holes being made in the road at the points they touched at the moment of the shock, ‘though the carriage was not standing in them at the time it stopped. The post-chariot was a new one, and the only in- jury it received, was the fracture and derangement of the barouche seat, as already stated, the removal of the japan in a line along the bulge behind, and the breaking of the poles the latter circumstance I conceive to have arisen, solely, from the fall of the horses, and to have been quite independent of the passage of the electric fluid. The horse the postilion rode was found to be dead; the other was evidently panic-struck, but unhurt, as he rose as soon as the harness was cleared from him; and though in a profuse sweat and trembling, he soon recovered, and not only was rode back for assistance, but returned again in the chaise that conveyed the poor sufferers to Tenbury, where they were detained at the inn for a month before it was thought safe to remove them, 2C2 196, Mr. B. Boddington.on the Effects of a Stroke of Lightning. _On inspecting the, dead horse no: wound was visible, nor any apparent cause for his death; the, brass front of the bridle was observed to be indented inwards, as if struck with a ham- mer; and when jhe was skinned, a. corresponding mark was found, on the bone of the head ; and from that spot to the ter- mination of the spine, the flesh was quite black and putrid for about the width of three inches, and there) were. diverging marks of the same nature on each side-of the: head, passing under the throat, and similar but much wider ones onthe flanks. The post-boy was thrown some, yards off, but» this I conceive to have been by the spring of the horse when ‘he was struck dead; and that spring doubtless jerked the car- riage beyond the holes where the lightning had. passed. into the earth. The boy was shaken by his fall, but in other respects perfectly unhurt. I inspected the spot nearly three weeks after the accident happened, found it was elevated ground, but by no means the summit of the surrounding country; on the con- trary, there were many higher hills in the neighbourhood: the road itself was so much hollowed out, that the banks must have been nearly equal to the height of the carriage; in a field to the right, within a few yards of the hedge, and exactly op- posite to where the shock took place, was a very high pear- tree,—it however bore no trace of injury. The carriage ap- pears to have been passing close to that side of the bank, as the holes I have before alluded to were still perfectly visible; indeed, the two to the right had undergone very little change, as they were nearly off the road; they were about fifteen inches in diameter, perfectly round, and nearly as deep as they were wide, the stones appearing to have been thrown out as if done by a miner’s blast. The collateral facts must now be mentioned. The landlord of the inn at Tenbury informed me that he was sitting in his parlour, talking to another person, when he saw the flash of lightning that must have caused the accident; he observed to his companion, that he had never before seen so singular a flash, as it appeared to divide into four parts when it came within about thirty yards of the earth;—this statement was confirmed by the person who was with him. It should seem, therefore, that they were not struck by a single discharge of electric matter, but were enveloped in a mass of electricity; aud this is the more probable, from the traces of the different’ strokes being so distinct, and yet taking such opposite direc- tions: the fluid seems to have pervaded the whole atmo- sphere, as many things were magnetized that were not in the line of any of the tracks that could be traced. For instance, Mr. Boddington’s watch was in his fob, and quite out of the line described by either of the shocks that passed over him: Mr. Daniell ‘ona New Register-Pyrometer. 197 after’ the accident, it ‘was’ found’ ‘necessary to ‘send it ‘to a watchmaker, and when taken to pieces, ‘parts’ of it’ were’ disco- vered to be highly magnetized, the balance-wheel in particular. This was shown to Mr. Faraday, when at Oxford, who set it afloat on a cork, ‘and found the poles to be so well defined, that I have since had it mounted as a compass. ‘Two pair of scissars also: that were in Mrs. Boddington’s work-box inside the carriage, were by mere accident, two months after the event, discovered to be magnetic. . » 1 certainly now very much regret that more minute re- searches were not made at the time as to these facts: but whoever has watched over the sick-bed of a beloved son, with but faint hopes of his recovery, will not be surprised that phi- losophical investigations were all absorbed in the deeper in- terest of the affections. Badger Hall, July 16, 1832. XLUI. Further Experiments with a new Register-Pyrometer for Measuring the Expansion of Solids. By J. FREDERICK ‘Danievr, Esq. F.BR.S. Professor of Chemistry in King’s Col- lege, London.* [N my former communication on a new Register-pyrometer, which has been honoured with a place in the Philosophical Transactions for 1830, I stated that I hoped, at some future period, to be able to lay before the Society the results of some experiments upon the dilatation of metals to their melting points; and I now purpose to redeem this pledge. My previous observations upon the subject of expansion, were (lirected chiefly to the object of establishing what degree of confidence might be reposed in the instrument as a mea- sure of temperature; and I was able, I trust, to exhibit such an accordance between the measures which it had afforded and those of the best experimenters, long previously obtained with various metals to the boiling point of water, as fully to establish its sufficient accuracy. ‘The comparison however which I most relied upon, was with the experiments of MM. Dulong and Petit, upon the expansion of platinum and iron to the high temperature of 572° Fahr.; and as this isa point of fundamental, importance, I shall still further strengthen it by a comparison with the results obtained by the same distin- * From the Philosophical, Transactions for 1831, Part ii.: this paper was read before the Royal Society, on the 16th of June in that year, Prof, Daniell’s former communication on the same subject will be found in the Phil. Mag. and Annals, vol. x, beginning at p, 191. 198 Mr. Daniell on @ New Register-Pyrometer guished philosophers with copper, ‘the only other solid metal to which they extended their inquiries. Previously to this, I trust it may not be thought tedious, if I briefly relate the results of some trials for obtaining registers of uniform composition, which might preclude the necessity of determining the rate of expansion in each individual instance. Exp. 23.—¥or this I had recourse to Wedgwood’s ware, of which [ obtained some bars carefully constructed and highly baked for the purpose. The expansion of these I found pre- cisely equal to that of platinum; so that when the register was immersed in boiling mercury, the index was found not to have moved. When a bar of iron was substituted for that of pla- tinum, the arc measured was 1° 7. With black-lead the same expansion gave a measure of 2°49', from which if we deduct the expansion of platinum in DIRGKSIGNG 55. 0000082200. Lesssastestee ates pcoteretE eS thie remainder’. .ccscc2..85s000 cares cites. Jewel salt te hatallols is sufficiently near to confirm the result. Exp. 24.—My next trial was with registers of black-lead of various and known mixtures of plumbago and Stourbridge clay. - Four-fifths proportion of the former to one-fifth of the latter produced a composition which was too tender for the purpose; but a mixture in the proportion of three-fourths to one-fourth formed a ware of a fine, even texture; whose ex- pansion was very equal, and not exceeding the least of those which I had formerly tried. Three different registers of this composition afforded me the following measures of the expansion of a platinum bar to the boiling point of mercury. 1° 45/ 1° 4,2/ 1° 38/. To which I may add a fourth, which gave for the expansion of an iron bar to the same point an arc of 2° 42’, which is equivalent to 1° 40! for a platinum bar.. For all common pur- poses, therefore, the mean expansion of 1° 42/ might have been adopted without any serious error in the final results. In investigations, however, which require the utmost precision, I still think it advisable to fix the expansion of each register by experiment. Exp. 25.—A bar of copper was adjusted in one of the re- gisters and exposed, in the manner formerly described, to boiling mercury; the arc measured on the scale was 4° 10’, equivalent to an expansion of *03633. ‘Let us now compare this result with the determination of MM. Dulong and Petit, as we formerly did the expansions of platinum and iron. Brae Sor Measuring the Expansion of Solids, 199 The expansion of Copper. Length of Bar, ids From. '32° to 212° = :0017182,.x6°5. .....%.. =) 01116830 From 392° to 572° "0018832 X\6°5)) .....003 F “01224080 *02340910 From 212° to 392° = Mean of the above...... = *01170455 Total expansion from 32° to 572° .......sseeeeee = °03511365 Add for the expansion from 572° to 660°, the temperature of boiling mercury, calculated at the highest rate :— 180° : 0018832 :: 88° : "00920675 ....... = "00920675 04432040 Deduct expansion for 32°, the experiment with the pyrometer having commenced at 64°.... = ‘00305457 Calculated at the lowest rate :— 180: °0017182: : 32°: *00305457 Real expansion of the bar by Dulong and Petit = -04126583 If from the real expansion thus obtained ............. *04126 we deduct the apparent expansion obtained by the PYTOMELEL.....cercercccevacrreccvccsvesccccesvescsecceces "03633 The remainder 00493 will be the expansion of the black-lead. SSS We thus obtain the expansion of 6°5 inches of black-lead ware, from 64° to 660° by platinum bar ............ ceseee “00421 Dy 1rOMbar .2....cdivederconcnences “OO4D7, by copper Dax} -n-dejynonepna stants, 0LO3 Mean -00457 in which the extreme results differ from the mean not -0004 inch, or one-fourteenth of the whole. _ When we take into consideration the great difference in the total expansion of these three metals, as well as the differences in their several rates of increase with the increasing tempera- ture, such an accordance appears to me to be perfectly deci- sive of the accuracy of the pyrometer. It will be unnecessary for me to trouble the Society with the details of the experiments by which I determined the ex- pansion of several other metals to the boiling point of mer- cury; it will be sufficient to state the results in a tabular form. [thought that it would add much to the interest of the de- 200 Mr. Daniell on a New Register-Pyrometer termination of the total expansion to the fusing points, to determine previously the expansion of each to the points of boiling water and boiling mercury; that any alteration in the rates of expansion between these points might be detected. I must, however, make a few observations upon the general method which I adopted to insure an accurate determination of the former. Exp. 26.—Judging from the action of the pyrometer at lower heats, I expected that the index would continue to be thrust forward by the progressive expansion of any bar of metal, till its cohesion gave way and it assumed the fluid form ; and consequently that a register would be obtained of its maxi- mum dilatation: but the difficulty consisted in applying the heat so equally that one part should not melt before another. The arrangement which I finally adopted to secure this pur- pose, and which was found to answer perfectly, was as follows, In the laboratory of the Royal Institution there is an excellent wind-furnance, from which proceeds a lateral horizontal flue, along which a flame may be drawn with any required degree of force. Into this flue open two muftle-holes, which give a complete view and command of the interior. From the equa- lity of the draught, regulated by a register, the whole of this chamber may be kept at a low red, or an intense white, heat, by a proper management of the fuel in the body of the fur- nace. : The registers of the pyrometer were prepared for the ex- periment by drilling three holes on their under sides, commu- nicating with the cavities in which the bars were placed; one at each extremity, and one in the centre. This was done for the purpose of allowing a vent for the melted metal, and to af- ford some criterion of the equality of the heat, by the time at which the metal ran from the different apertures. When the bar was properly adjusted in the register, it was carefully placed in the hot air-chamber, in a horizontal position, supported at each end by a small piece of brick, at a proper distance from the body of the fuel, accordingly as a greater or less degree of heat was required. The muffle-holes were then closed with their stoppers; all but a narrow slit, through which the pro- gress of the heating and the flow of the metal could be ob- served. The equality of the heat could be very accurately ascertained by the uniform colour of the register as it became red; and any irregularity could easily be corrected by ad- vancing one or other end more towards the fuel. In this manner I succeeded in obtaining very satisfactory results; except in the case of gold; and this metal requiring for its fusion rather more heat than I could at the time command in -~ Jor Measuring the Expansion of Solids. 201 the air-chamber, I laid the register upon the fuel in the body of the furnace, and it thus became only partially melted, and half the bar remained in the solid state. The amount of the expansion indicated is therefore evidently deficient, and must be discarded from the table. A similar accident happened once with brass; but this I have been able to rectify by sub- sequent trials. I shall now arrange the results of my experiments in two tables :—the first showing, in arcs of the scale, the expansion of pure metals from 62° Fahr. to 212°, 662° Fahr., and their respective melting points; and, the second exhibiting the expansion of certain alloys to the same points. The bars were in all cases of the same length of 6-5 inches. Taste XIII. Showing the progressive Expansion of the following pure Metals to their Melting Points. From 62° to 212° | to 662° | to Melting Point. ae not correct) of 2 30 6 17 8 44 3 45 6 0 7 51 9 47 TasLe XIV. Showing the progressive Expansion of the following Alloys to their Melting Points. From 62° to 212° | to 662° | to Melting Point. ° ° / Brass, -Common........- 0 54 4 42 (8 41 not correct) Brass. Copper 3, Zinc 4. Tao 451 | 13 39 Brass. Copper }, Zinc}. . 1, 27 Bo lt Lo, ae Bronze. Copper 3%, Tin »,.| 0 52 3 37 9 49 Bronze, Copper z, Tin 4 . 0 54 411 | 10 16 Bronze. Copper ?, Tin} ..| 0 58 444 | 10 55 ‘Bronze: Copper 3, Tin? ..| 1 0 | 4 7 | 4 7? Pewter. Lead 4, Tin + 2 PT BONNE 2 28 Type Metal. LeadandAntimony) 1 5 (| ...... 318 The first remark which I shall make upon these tables re- gards the fusing points of the pure metals. Having ascer- tained for each the expansion due to certain definite incre- ments of temperature, and the utmost expansion which they Third Series. Vol. 1. No. 3. Sept. 1832. 2D 202 Mr. Daniell’s Further Experiments undergo to their fiising points, it is clear that, had their ex- pansion been equal for equal increments, we might have de- termined the true temperature of their melting points from these data. As it is, even, knowing something of the limits of error introduccd into such a calculation by the increased rate of expansion at the upper part of the scale, and the di- rection in which it ought to affect the result, we may draw some important inferences with regard to the correctness of the determinations derived from other means. The follow- ing Table exhibits the results of such a calculation, compared with the melting points previously determined. TABLE XV. Fusing Points of Metals derived from their Expansions to 212° and 662° supposed cquable. From 212°| From 662° Real Temperature. rate. rate. 442 by Thermometer. 612 by Thermometer. 773 by Pyrometer. i 1873 by Pyrometer. Copper .. . y 1996 by Pyrometer. Cast iron .. 2786 by Pyrometer. Now by these results, the accuracy of the pyrometer may, again, be placed beyond doubt, in a manner which was per- fectly unforeseen at the time of instituting the experiments. In the first place we have two metals, tin and lead, whose melting points being within the temperature of boiling mer- cury, have been accurately determined by the common ther- mometer. Upon calculating the same points from their several expansions to boiling water, measured by the pyrometer, upon the supposition that they maintain the same rate to their points of fusion, the temperature of the first comes out 29°, and of the second 58°, higher: that is to say, the rate of expansion of these two metals increases with the increase of temperature, as has been found to be the case with platinum, iron and copper, by the experiments of MM. Dulong and Petit. It.is worthy of remark, that this increased rate in tin is equivalent to 29° in about 200°, and in lead to 58° in about 400°, above the boil- ing point of water. These results therefore indicate a very close agreement between the thermometer and pyrometer. 2ndly. The melting point of the next metal, zinc, is one’ of those which has been determined by immersion of the pyto~ meter into it, when it was in the act of fusion. Its tempera- ture, so determined, falls short of the same point, calculated with his New Register-Pyrometer. 203 from the expansion supposed equal, by 75°. This again in- dicates an expansion increasing at nearly the same rate (75° in 560°), as in the preceding instances of tin and lead. I pass over at present the result obtained by calculating from the expansion to the boiling point of mercury, as it presents an anomaly upon which I shall presently make some observa- tions. 3rdly. The melting point of silver, determined in the same way by immersion, differs from that calculated from expan- sion in the same direction; and the difference (286° in 1660°) is nearly in the same proportion. ‘The calculation from the rate of expansion to the boiling point of mercury comes much nearer to the melting point directly determined, and only dif- fers from it 176°: proving that the rate of expansion increases with the increasing temperature. ‘ 4thly. A similar comparison instituted with copper presents us with a rate of expansion increasing much more rapidly than in the preceding instances; so that the melting point, calculated from the expansion to boiling water, differs from the true melting point no less than 1266°. Taking the rate of expansion to boiling mercury, the difference is reduced to 370°. And here again I may refer to the experiments of MM. Dulong and Petit in confirmation of the result; for they found that the temperature indicated by the expansion of a rod of copper was 50° Fahr. higher than the true temperature at 572° Fahr. 5thly. The interesting nature of the results which I ob- tained with iron, and the peculiar difficulties in arranging the experiments from which they were derived, will, I trust, ex- cuse my entering more into their details than I have thought necessary in the preceding instances. I have already given the expansion of wrought-iron to the temperatures of boiling water and boiling mercury, and shown that the measures ob- tained with the pyrometer agree essentially with those deter- mined by very different means by MM. Dulong and Petit. I have also proved that the melting points of gold and silver, determined by the expansion of the same bar of iron, agreed very closely with the same points determined by the expan- sion of platinum. I was extremely anxious to complete this series of experiments by measuring the expansion of iron to its melting point. For this purpose I had a small bar of iron cast from the best gray iron, and afterwards cleaned of all oxide and reduced to the size of the other bars employed by filing. Upon measuring its expansion to the temperatures of boiling water and boiling mercury, I found the arcs upon the seale respectively 0° 29! and 2° 25'; and this being con- 2D2 204 Notices respecting New Books. siderably less than what I had obtained with the bar of wrought iron, I repeated the experiment with the latter in the same register that I had employed for the former, and ob- _ tained the measures of 0° 35! and 2° 44’—nearly agreeing with the previous determination: so that there can be no doubt that cast iron expands less than wrought iron, though the rate of increase for the higher temperature appears to be the same in both. [To be continued.] XLIV. Notices respecting New Books. Life Tables founded upon the Discovery of a Numerical Law regu- lating the, Existence of every Human Being, §c. By T. R. Ep- monDs, B.A., late of Trinity College, Cambridge. ps this work, of which we have been favoured with a copy, the author announces the discovery of a new law of mortality, which he has applied to the construction of a considerable number of an- nuity and other tables. The announcement in the title-page, that the tables are founded upon the discovery, instead of the law, is one of those inaccuracies of expression which occur in other parts of the book, and which bespeak carelessness at least on the part of the author, in the construction of his sentences. The new law is thus announced.—During the succession of years and moments of life, the continuous change in the force of mortality is subject to a very simple law, being that of geometric proportion. But instead of one uniform progression, there are three distinct or- ders, corresponding respectively to infancy, manhood, and old age. The common ratios of the three geometric series are, we are told, fined and immutable for all human life in all ages of the world. They are also said to be now first discovered : but it is not stated by what pro- cess, nor is it at allimportant to inquire; for they appear to be wholly empirical, and the tables founded upon them are of no practical value whatever. Indeed this is the opinion of the author himself. For in page xii. he says, with great truth, that “in all classes of a population the mortality is continuaily varying.” Hence the new fixed and immutable law cannot be applicable, except at some particular moment, to any of such classes. The author afterwards very justly remarks, that ‘to generalize from a single fact is absurd ; and it is an absurdity of this kind into which those people fall who would apply observations made on one kind of life to all kinds of life.” A remark which implies an egual absurdity in applying his own general law, which is fixed for all human life, to any one class or condition of mankind,—or in other words, to any one practical purpose. But although we concur with the author in the uselessness of his own tables, we dissent from most of his opinions relative to the com- parative value of others. Edmonds’s Life Tables. 205 In page xii.he appears to prefer the Northampton Table, chiefly 4e- cause it 1s supported by the name of Dr. Price. But the known incor- rectness of this table, or, as our author is pleased to express himself, the “slight inaccuracy of its adjustment of mortality to each age,” is not, in his judgement, of any “ sensible value in practice ;” yet he afterwards admits that “its applicability to the British population of the present day may fairly be questioned.” We believe that the Northampton Table is not capable of affording any accurate mea- sure of life contingencies of any kind ; in which respect it so much resembles our author’s own offspring, that we are not surprised at its having received from him a kind of fatherly affection. The Government Table, on the contrary, deduced from the lives of English annuitants, because, asthe author says, it ‘““opposesmy theory, as well as that of every other person”, incurs his severe displeasure. A clearly demonstrable fact opposed to a favourite theory is, we admit, vexatious enough, and more particularly so when the theory is one of our own invention, one of our first-born bantlings, and one upon which our hopes of reaping a full harvest of renown has been anx- iously founded. So harassing indeed has this opposition of the Government Table to our author’s theory been to his feelings, that he would hurl the Table and its author to perdition together, with per- haps the printer and his devils into the bargain. His method, however, of disposing of the author is not marked by that precision which we should have expected from a B.A. of Trinity College, Cambridge. He says, ‘‘ the reported mortality of English annuitants is not entitled to much confidence,” because it “ rests upon the authority of a person whose qualifications for the task un- dertaken are unknown to the public.” But the reported mortality is that which appears in the records preserved in the Government offices, and does not rest upon the authority of any person except as a transcriber, whose only requisite qualifications are, that heshould be able to read and write, and, as school-boys term it, do a sum in ‘Addition, We will, however, deal fairly with Mr. Edmonds, and not pin him down to his own loose expression, “ reported mortality,” but will help him to a phrase, which if any distinct meaning pervaded his mind when he wrote the passages we have just quoted, may per- haps represent that meaning. He possibly intended to say that the reported probability of life, among the English annuitants, is not en- titled to much confidence, because the qualifications. of the person deducing it are unknown to the public. Now, of all the reasons we have ever heard for discrediting the ‘ result of a rather complicated arithmetical process, this is the most futile and absurd :—because the qualifications of the author are un- known to the public. Why upon this principle, the Tables of Mr, Ed- monds might, even if they were really good for anything, flap their leaden wings to the end of time without attaining even the lowest degree of public confidence. For what do the public know of this gentleman’s qualifications ?_ But we will ask hin what he means by the public? We much suspect that in his vocabulary it signifies only the individual occupant of his own chambers. We shall, however, construe the phrase according to its ordinary acceptation, and shall — 206 Notices respecting New Books. suppose our public divided into three classes: the first consisting of those who from personal acquaintance with the author of the Govern- ment Tables have had an opportunity ofascertaining his qualifications for the task of framing them ; the second, those who have read his Report, printed by order of the House of Commons, March 31,1829, and are capable of forming a judgement of the author's fitness from that report; and the third, those who neither know nor care any thing about suchmatters. Now we have notthe least hesitation in affirming, that the first two of these classes do know the competency of the author to perform his task ; and in confirmation of this assertion, we shall quote an authority which we believe Mr. Edmonds himself will not dispute. Ina paper by Mr. Lubbock, in the third volume of the Cambridge Philosophical Transactions, and in p, 330, Mr. Edmonds will find the following passage: ‘‘ Mr. Finlaison has very recently published extensive tables of mortality, formed from theGovernment tontines and annuitants, which are rendered equally valuable ky the accuracy of the materials from which they have been deduced, and the very great care and attention which has been bestowed on them by the author.” After this, we apprehend we should only waste the time of our readers by pursuing this subject further. We have already expressed our dissent from many of the doctrines and opinions of this author : there are, however, some in which we readily concur; as those in which we are taught that ‘“ good air is as necessary to health as good food,” and that ‘the increase of a popu- lation has a great dependence upon the number of women at the child- bearing age,” and others equally conspicuous for their truth, and their beautiful simplicity, as general laws. We must now limit ourselves toa very few more observations. Our author says, p. xxi. ‘‘ The check on the exertion of the prolific power is scarcity of food.” We apprehend his meaning to have been, that scarcity of food abates the prolific power. But let him look to Ireland, with its scanty means of subsistence, and its overflowing population ; and he may also discover, when he sets about observing facts instead of building theories, that the largest families are upon an average produced by the poorest classes. We are told, p. xxx. that “ the circumstances most favourable to vitality consist in alternations of privation and saturation :”—to starve one day, and feed to repletion on the next. We, however, seriously recommend our author, and particularly at this time, not to trust his own vitality to such an experiment. And in p. viii. we have the comfortable doctrine announced, that «the hopes of an indefinite prolongation of the term of human life have now ceased to be visionary,” and this, we presume, without the assistance of the Hermetic philosophy. We suspect that “too much learning” has exercised an un- wholesome influence on the mind of our author, who is probably oung, with an active and uncurbed imagination, which he has per- mitted on this occasion to hurry him into as many scrapes as the wild steed of Mazeppa did his unwilling rider, But although we have thus amused ourselves, and perhaps our readers, at the author’s expense, we can assure him that we do not entertain the slightest un- Hodgkinson on Suspension Bridges and Iron Beams. 207 friendly feeling towards him; and although an entire stranger to us, we wish him every success in his laudable endeavour to build up an honourable reputation for himself: yet we earnestly counsel him not again to attempt the destruction of that of his neighbour; as it be- trays both bad taste and bad feeling, and may eventually convert into personal enemies those who might otherwise become useful friends. On Suspension Bridges; containing an Inquiry into the proper Forms of their Catenaries; with Remarks on ihe Menai Bridge, and that at Broughton ; as likewise some Account of the Failure of the latter. By Eaton Hopexinson, Manchester, 1831. In the eastern parts of the world, rope and chain bridges of large Span have for a long period been in use ; but in Europe the adoption of bridges of suspension is of comparatively modern date, and has opened a new and interesting field for inquiry and experiment, both for the engineer and the mathematician, and has rendered of practical importance the theery of the catenarian curve. During the last cen- tury, mathematicians investigated many of the properties of this curve; but the addition of the materials which are necessary to form the road- way, and to insure sufficient strength for the variable and large loads of transit, have added new data to the problem. Mr. Eaton Hodgkinson has, in the present treatise, given a very clear abstract of the properties of this curve under all the probable variations it is liable to in its application to bridges of suspension ; not only when the substance of the chain is of uniform strength, but also when the strength varies as the strain,—concluding with an ex- ample upon assumed data. The neat and elegant manner observed throughout renders the tract a desirable object in the library of the practical engineer. The second part of the work contains an account of the chain bridge at Broughton, near Manchester, with a particular estimate of the strain upon the various parts as compared with the strength, and also some important information on the form of the joints of the links ; to which are added some observations on high tests, and on defective welding of the bars. Next follow a few remarks on the Menai Bridge, showing that it possesses sufficient strength to support seven times its own weight. An Appendix is given, containing remarks and observations on the cause of failure of the bridge at Broughton, after standing some years, but which has since been repaired and made more secure *, Theoretical and Experimental Researches to ascertain the Strength and best Form of Iron Beams. By the same Author. The builder and engineer will find in this treatise many important experiments, conducted with great skill, and described with accuracy of detail. It should be read by every person who intends to use iron beams. The author bas long been known for his abilities as a mathe- matician, and his application of those abilities to practical purposes. * An account of the fall of the Broughton Suspension Bridge, with some Bava, of the causes of its failure, were given in Phil. Mag. and Annals, .S. vol. ix. p, 384, 208 Notices respecting New Books. The use of iron for beams has been lately much and deservedly re- sorted to. In the application of a new material it is to be expected that there will be occasional failures, partly owing to motives of ceco- nomy, and partly to want of skill in the builder. The price of iron renders it desirable that the smallest quantity should be used which is consistent with safety and durability. There are several popular treatises on the strength of iron and the form of beams ; but the rules contained in them are frequently at va- riance with experiments, and therefore mislead the practical man, who has not leisure or ability to investigate the principles upon which they are founded. In this tract, the author investigates the theory of strength, and of resistance to fracture and deflection, and supplies by judicious experi- ments the defective elementary data, giving the particulars at large of numerous experiments on iron of various forms and dimensions, so as to enable a practical builder to satisfy his own mind of the ground upon which the deductions are made. These experiments prove that the form recommended by the late Mr. Tredgold is in- ferior to others which have since been adopted, and also that the for- mula given by Mr, Tredgold for determining the strength is incorrect, and may lead to serious errors*. Much of the work is occupied by the subject of the transverse strength and strain, and some useful deductions are made on the ultimate de- flection,—a point which at present deserves further investigation. The author acknowledges his obligations to Messrs. Fairbairn and Lillie for the assistance they rendered him at their foundry, by which he was enabled to adopt a scale of dimensions seldom within the means of a theoretical investigator. Instances of liberality of this kind are frequently met with in this country, much to the honour of the persons who thus manifest themselves friends to their country and to science. The result of Mr. Hodgkinson’s experiments on cast iron beams hav- ing the bottom rib containing more than half the matter of the whole beam, shows that the breaking weight was proportionate to the area of the bottom rib, and to the full depth of the beam, and inversely as the length, subject to a constant factor depending on the position of the beam in the casting, the vertical castings being about sth stronger than the horizontal castings; the quality of the metal will also modify the factor in some degree. In such important experiments as these, the determination and statement of the specific gravity and hardness, together with the modulus of elasticity of the material, would add to their value, with very little additional burden to the operator. On the Economy of Machinery and Manufactures. By Cuarves Bas- BAGE, Esq. .4.M., Lucasian Professor of Mathematics in the Univer- sity of Cambridge, and Member of several Academies. London, 1832. Although the present volume does not properly come within the sphere of a scientific Journal, yet the principles which it discusses * Analyses of the first and second editions of Mr. Tredgold’s Essay on the Strength of Cast Iron, will be found in Phil. Mag. vol. Ix. p. 137; and vol. Ixiii, p. 52. Babbage’s Economy of Machinery and Manufactures. 209 are so intimately connected with the progress of the scientific arts, and the operations which it describes are so essential to the perfection of scientific instruments and scientific machinery, that we feel it a duty to make our readers acquainted with the merits of so remark- able a work. The name of the author, indeed, is sufficient to attract the attention of scientific men to any work which emanates from his pen; but those who are acquainted with Mr. Babbage’s merits as an inventor, and have acquired any knowledge of the nature and power of that extraordinary machinery which he has taught to perform the most complicated calculations, will turn with intense interest to a volume containing an account of the various resources of the mecha- nical arts which the author has himself studied in the different work- shops and factories of Europe, and a classification of the modes of action of tools and machines, and a generalization of the principles of their application to supersede the labour of the human arm. Mr. Babbage’s work is divided into two sections. The first section contains a view of the mechanical part of the subject, which occupies twelve chapters. The first chapter treats of the general sources from which the advantages of machinery are derived; and the nine follow- ing chapters treat of principles of a less general character, such as, Accumulating power,—Regulating power,—Increase and diminution of velocity,—Extending the time of action of forces,—Saving time in natural operations, —Exerting forces too great for human power, and executing operations too delicate for human limits,—Registering Operations,—CEconomy of materials employed,—and Of the identity of the work when it is of the same kind, and of its accuracy when of different kinds. ‘The eleventh chapter treats of Copying, and is di- vided into Printing from cavities,—Printing from surface,—Copying by casting,—Copying by moulding,— Copying by stamping,—Copy- ing by punching,—Copying with elongations,—and Copying with altered dimensions. This chapter, which is an exceedingly popular and interesting one, is full of the most curious practical information, and contains the first account that has yet appeared of Mr. John Bate’s ingenious art of Engraving from Medals. The twelfth chap- ter, which terminates the first section, treats of the method of ob- serving manufactures, and deserves the peculiar notice of the scien- tific traveller. The second section of the work begins with an introductory chapter on the difference between making and manufacturing’, and in eighteen succeeding chapters, contains a discussion of most of the questions and principles which belong to the political economy of manufactures, such as, The influence of verification on price,—The influence of durability on price,—On price as measured by money,—On raw materials,— On the division of labour,—On the division of mental Jabour,—On the separate cost of each process,—On the causes and consequences of large factories,—On the position of great factories,—On overma- nufacturing,—Inquiries previous to commencing any manufactory,— On contriving machinery,—On the application of machinery,—On the duration of machinery,—On combinations amongst masters or work- men against each other,—On combinations of masters against the Third Series, Vol. 1. No.3, Sept. 1832. 2E 210 Notices respecting New Books. public,—On the effect of taxes and local restrictions on manufactures; —and On the exportation of machinery. The work is then concluded by the thirty-second chapter, a piece of powerful and eloquent writing, which treats of the future prospects of manufactures as connected with science. Having thus given our readers a correct outline of the various sub- jects treated of by Mr. Babbage, we shall select some specimens of the interesting information which this volume contains. In treating of the inquiries which it is necessary for the projector of a new manufacture to make respecting the quantity of the article likely to be consumed, Mr. Babbage gives the following happy and interesting example, given in evidence before the House of Commons, by Mr. Osler, a manufacturer of glass beads and other toys of the same material, at Birmingham. «Eighteen years ago,” said Mr. Osler, ‘on my post journey to London, a respectable-looking man, in the City, asked me if I could supply him with dolls’ eyes. He took me into a room quite as wide, and perhaps twice the length of this, and we had just room to walk between stacks, from the floor to the ceiling, of parts of dolls. He said, ‘These are only the legs and arms; the trunks are below:’ but I saw enough to convince me that he wanted a great many eyes ; and as the article appeared quite in my own line of business, I said I would take an order by way of experiment; and he showed me several specimens. I copied the order. He ordered various quantities, and of various sizes and qualities. On returning to the Tavistock Hotel, I found that the order amounted to upwards of 5001. I went into the country and endeavoured to make them. I had some of the most ingenious glass toymakers in the kingdom in my service ; but when I showed it to them, they shook their heads, and said they had often seen the article before, but could not make it. I engaged them by presents to use their best exertions ; but after trying, and wasting a great deal of time for three or four weeks, I was obliged to relinquish the at- tempt. Soon afterwards I engaged in another branch of business (chandelier furniture), and took no more notice of it. About eighteen months ago I resumed the trinket trade, and then determined to think of the dolls’ eyes ; and about eight months since I accidentally met with a poor fellow who had impoverished himself by drinking, and who was dying of consumption, and in a state of great want. [ showed him ten sovereigns, and he said he would instruct me in the process. He was in such a state that he could not bear the effluvia of his own lamp; but though I was very conversant with the manual part of the business, and it related to things I was daily in the habit of seeing, I felt I could do nothing from his description. He took me into his garret, where the poor fellow had ceeconomized to such a degree, that he actually used the entrails and fat of poultry from Leadenhall Market to save oil. In an instant, before I had seen him make three, I felt competent to make a gross, and the difference be- tween his mode and that of my own workmen was so trifling, that I felt the utmost astonishment. “As it was eighteen years ago that I received the order I have men- Babbage’s Economy of Machinery and Manufactures. 211 tioned, I took the present reduced price of dolls’ eyes; and calculating that every child of this country not using a doll till éwo years old, and throwing it aside at seven, and having a new one annually, I satisfied myself that the eyes alone would produce a circulation of a great many thousand pounds. 1 mention this merely to show the importance of trifles, and to assign one reason amongst many for my conviction that nothing but personal communication can enable our manufactures to be transplanted.”—pp. 199—201. Mr. Babbage mentions a very instructive example of the difficulty of estimating the effects of a machine, and of the ingenious way in which the difficulty was overcome, In order to fix a proper toll for steam carriages, a Committee of the House of Commons endeavoured to ascertain, from competent persons, the injury done by the atmo- sphere to a well-constructed road, and then the proportional injury which the same road sustained from horses’ feet and from wheels. “Mr. Macneall,” says Mr. Babbage, ‘‘as superintendent, under Mr. Telford, of the Holyhead roads, proposed to estimate the relative injury from the comparative quantities of iron worn off from the shoes of the horses, and from the tire of the wheels. From the data he possessed respecting the consumption of iron for the tire of the wheels and for the shoes of the horses, of one of the Birmingham day coaches, he estimated the wear and tear of roads arising from the feet of the horses to be three times as great as that arising from the wheels. Supposing repairs amounting to 100I. to be required on a road tra- velled over by a fast coach at the rate of ten miles an hour, and the same amount of injury to occur on another road used only by wag- gons moving at the rate of three miles an hour, Mr. Macneall describes the injury in the following proportions : Fast Heavy Coach, Injury arising from Waggon. Atmospheric changes ..| 20 20 Wheels: iev.ad sou o. 20 35'S Total injury. .}| 100 | 100 One of the results of these experiments is, that every coach which travels from London to Birmingham distributes about eleven pounds of wrought iron along the line of road between these two places.”—pp. 201—203. In treating of the effect of taxes upon manufactures, Mr. Babbage has entered very briefly upon the subject of Patents,—a subject pe- culiarly connected with that of his work, and to which he should have allotted more space, and done greater justice. In the only paragraph which relates to the present state of the law of patents, Mr. Babbage remarks that “It is clearly of importance to preserve to each inventor the sole use of his invention, until he shall have been amply repaid for the risk 2E2 ee 212 Notices respecting New Books. and expense to which he has been exposed, as well as for the talent he has exerted. But the varieties in the degrees of merit are so nu- merous, and the difficulties of legislating upon the subject are so great, that it has been found almost impossible te frame a law which should not, practically, be open to the most serious objections.’’-—p. 289. The difficulty of framing a perfect law of patents, which shall recon- cile all opposing interests, is undoubtedly great ; but the present law is so disgraceful in its character, so injurious to the revenue of the country, so subversive of the rights, and so destructive of the property of inventors, that any change upon it must be an improvement. Let the reader only cast his eye over the following table of the expense and duration of patents in the different kingdoms of Europe and America, and then ask himself what he thinks of English legislation. Expense of Duration of } Countries. Patents. Patents. Great Britain and Colonies* .... 355 0 0 14 VATHELICR? Ji ieicnte) sighs. 6 SR AE ws 615 0O 14 (12 0 0 5 RGANCE LY Gass oie. stchtlete SEO, cle oc 32" 0100 10 60 0 O 15 INetherlandsinehie.w heel elles 61. to 301. 5, 10, 15 Aas triat. oiie creer seen site oye? V0). 26 15 spainginventor ites. 0. ie A ON Sor 15 Tmproreri oy ovis tet. 42 1 PQIND Cr7 10 Pmpoarter gssict sie) 1G, 92.1.9 10 22498 6 Great Britain thus robs every poor inventor of 355/. even if he never derive a farthing from his invention! Laws which thus tax genius, like those which tax knowledge, ought not to be allowed a single day’s existence. Although the few extracts which we have made from Mr. Bab- bage’s volume are in themselves highly interesting, yet they con- vey no idea of the multifarious and popular subjects which are treated of in the work before us, which may be read with as much pleasure as instruction by persons of all ages andall conditions in society. It is, indeed, one of those few works which are equally fitted for the perusal of the philosopher and the general reader. Mr. Babbage possesses the happy art of clothing the stores of his highly endowed mind with the richest drapery of language. In de- scription he is perspicuous, in argument he is concise, and in general views of the past, as wellas in his anticipations of the future, he rises into a strain of chaste eloquence, in which he has few rivals. The following beautiful passage, which concludes the book, will, we are sure, justify these observations. “ |S Ea) ES |'s ‘S =] 6 |6 |4 slam io] 4A [6 ee a [kad CE ——|}-—}— festa Poet Ciry or York, .... | 6,878] 23) 63/176|222) 3,601 512)1 113/495] 173 | 73 | 1,619 Arnstry of the same} 2,362/317|184/972| 6) 472), 79) 104/168) 60)15| 469 CITY OF YORK. Number of Males (Twenty years of Age) employed. SPECIFICATION. Animal Preserver ........+« cipnonst eo LOI pDASKETINGKET, | .5,.s0ccvascame Peete 16 Artificial Flower-maker ......... 1 | Blacksmith, (Horse-shoes) ..... + oo Auctioneer, or Appraiser ......... 13 INGHOR oecns-ceveocecenrareaeye ocat es ESTORET) feu tn esmnactt teatenat acess 14 | Boat-builder, Shipwright.......... Baker, Gingerbread, Fancy ...... 56 Cailker ose Reesaabs oop Barber, Hairdresser, Hair-dealer 47 Sail-maker........... web cesCeitge aemeegL Comparative Account : Population of Great Britain. 219 Bookbinder °siis.sis.cssceseeeceeees 31 Bookseller or Vender .«..+...+... . 24 Brass-worker, Tinker .-.....-....- 6 WCWET, bok oocn sh rsepadenss cad phecins an 29 Brush-maker ...., 1761 1690 Bronze. Copper %, Tint .. 1773 1534 Bronze. Copper 3, Tini .. 1755 1446 Pewter. Lead, Tiny ... 403 Type Metal. Lead and Antimony 507 I have not included in the foregoing Table the alloy of half copper and half tin, but have exhibited its expansion to the boiling point of mercury in Table XIV. This mixture was very hard and brittle, and resembled the speculum metal of reflecting telescopes. After it had been exposed to boiling mercury, it appeared as if it had undergone partial fusion; it was set fast in the cavity of the register, and had thickened towards the lower extremity. Iam inclined to think that it had nearly attained its melting point, but it was broken in re- moving it; and I had not an opportunity of trying any further experiment with it. With regard to these alloys, the experiments are not nu- for Measuring the Expansion of Solids. 265 merous enough to enable us to deduce with precision the general Jaws by which their expansions and points of fusion are governed ; but enough is discernible to show that the sub- ject is well worthy of further investigation. It appears Ist. That the expansion of the compounds is not the mean of the expansions of the simple metals of which they are com- posed, but bears some proportion to their relative quantities. Thus we may observe that the expansion of brass increases with the quantity of zinc which it contains, as does bronze or bell-metal with the quantity of tin. 2ndly. That the expansion of brass is in an increasing ratio to the increase of temperature till the quantity of zinc amounts to one half, when it seems to assume a decreasing rate, as we have reason to suppose is the case with pure zinc. On this account the melting points both of this mixture and zinc ap- pear to be higher when derived from their expansions to the boiling point of mercury, than when calculated from their ex- pansions to the boiling points of water. With this exception, there is great reason to suppose that the melting points of the alloys, from the higher rate of expansion, cannot be very far removed from the true temperatures. 3rdly. That the melting point of copper is reduced by an admixture of one fourth of zinc to nearly the average which results from the proportions of the two ingredients; but by an admixture of an equal quantity of tin it is reduced in a much greater proportion. ‘The temperature derived from the average with zinc would be 1690°, and the corresponding temperature in the Table is 1750°. The temperature derived from the average with tin would be 1607°, but the correspond- ing temperature is only 1446°. 4thly. That a similar power in tin to depress the melting point of another metal is exhibited in pewter; in which we may observe that a mixture of one fifth of tin with lead re- duces the melting point actually below that of either of the pure metals; and we may recall to recollection the fact, that an alloy of eight parts of bismuth, whose fusing point is 476°; five of lead, whose fusing point is 612°; and three of tin, whose fusing point is 442°,—liquefies at 212°. I shall here subjoin a Table, in the usual form, of the pro- gressive linear dilatation by heat of such solids as I have mea- sured with the pyrometer to the boiling point of water, the boiling point of mercury, and their respective melting points, where they have been ascertained. I have added to their ap- parent expansions by the register the corresponding expan~ sion of the black-lead; upon the assumption that the latter continues at an equal rate to temperatures above 662°; in Third Series, Vol, 1. No.4. Oct. 1832. 2M 266 Mr. Daniell on a New Register-Pyrometer which it is not probable, from the preceding observations, that there is any error of material importance. Taste XVII. Linear Dilatations of Solids by Heat. Dimensions which a bar takes whose length at 62° is 1-000000. At 212° At 662° (150°). (600°). At Point of Fusion. Black-lead ware ...| 1-000244 | 1-000703 Wedgwood ware...| 1:000735 | 1-002995 BISMNUM os cnsscec.- 1-000735 | 1:002995 | (1-009926 maximum, but not fused.) Iron (wrought) . ...} 1-000984 | 1-004483 | (1-018378 to the fusing point of cast iron.) Rear (CASt) ssi) vee 1-000893 | 1-003943 1-016389 (ald ks sonse Rte sand 1-001025 | 1-004238 Copper.......-.00ee+-| 1°001430 | 1-006347 1024376 Silver...........0. .-.| 1001626 | 1-006886 1-:020640 Pine $205 Ae 1-002480 | 1-008527 1:012621 Lead......... USsoene th 1-002323 be dtas ee 1:009072 BID soi seieacveceeus 1001472. Nusstetssoaah 1-:003798 Brass. Zinc 4......| 1:001787 | 1-007207 1-:021841 Bronze. Tin# ,..) 1001541 | 1-007053 | 1-016336 Pewter. Tin +t...| 1001696 | ....... At 1:003776 Type Metal......... 1-001696 | ......... 1:004830 The regularity of these several expansions is very striking. As long as the metal retains the solid form, the dilatation proceeds according to a fixed law, without any sudden starts or changes; till assuming the form of a liquid it doubtless is subject to a different mode of action. I shall conclude these observations with the results of some experiments which I made to determine, if possible, the cause of the singular change of texture in platinum, when intensely heated in the black-lead registers, which I described in my former paper*. Upon showing the bar so changed to those who were best acquainted with the working of this metal, they universally ascribed it to the action of sulphur: but nobody could explain to me why this action should require such a very intense heat; as up to the temperature of melting cast-iron, to which it had several times been exposed, no change took place; but the bar remained perfectly soft and malleable. In De Ferussac’s Bulletin for November 1830, there is an abstract of my paper on the Pyrometer, which the Editor concludes with the observation, that ‘ unfortunately I inclosed in the crucible which contained the register and the bar of platinum some pieces of iron, without being aware of the fact, which is known to all the workmen who manufacture pla- * See Phil. Mag. and Annals, yol. x. pp. 354, 355.—En1r. for Measuring the Expansion of Solids. 267 tinum, that the mere presence of iron is enough to communi- cate brittleness to that metal.” Upon inquiry amongst workmen in this country I cannot find that such a property has ever been observed in the course of their experience; and when I consider that the bar in the cavity of the register was perfectly preserved from contact with the iron nails; and moreover, that it had actually been plunged into melted iron without any change of properties; I cannot suppose that the alteration depended in any way upon this circumstance. To resolve these doubts I took 116 grains of the brittle platinum, which had been ground without difficulty to a fine powder in a steel mortar, and boiled them in nitro-muriatic acid till I had effected a complete solution ;—a little of this solution produced a scarcely perceptible cloudiness in a solu- tion of muriate of baryta. ‘This I have reason to think was owing to a slight impurity in the acids employed; I infer therefore that there was no sulphur in the metal. I proceeded to evaporate the solution; which towards the end of the pro- cess assumed a gelatinous appearance. When in this state, I poured alcohol upon it; and as the acid still remained in excess, a violent reaction took place with extrication of nitrous gas. I then evaporated to dryness and continued the heat; till the salt of platinum kindled spontaneously, and finally was left in a spongy state. This was again digested in nitro-mu- riatic acid, and the solution carefully evaporated to dryness, The muriate of platinum was then dissolved in water, and a sandy residue remained ; which, when well washed and heated to redness, was of a grayish-white colour, and had all the pro- perties of silica: it weighed 3°5 grains. ‘There can therefore, I think, be little doubt that at the high temperature to which it was exposed, platinum took up as much as 8 per cent. of silica ; or, more probably, a quantity of its base equivalent to that quantity of the earth, to which it owed all its change of character and properties. A temperature considerably above that of melting cast-iron appears to be necessary to this com- bination; which is analogous in many respects to the ab- sorption of carbon by iron in the process of making steel by cementation*. * The combination of platinum and the base of silica formed by Mr. Daniell, had before been noticed by Descotils and Chenevix ; but they con- sidered it to be a ccarburet of platinum. Boussingault, however, re-exa- mined it, and found it to be in reality a compound of the base of silica with that metal. Descotils and Chenevix obtained it by heating Pepe with charcoal, as Mr, Daniell has done by heating platinum with black-lead ware, Boussingault found that when the metal was heated with lamp-black this combination was not formed.—See Thomson’s Inorg. Chem. vol. i. p. 665.—Enpir, 2M2 L 268 J L. Notes on the History of English Geology. By Wi..1am Henry Firton, M.D. F.R.S. Sc. [Continued from p. 160.] But the most important observations, perhaps, that have ever yet appeared on the subject of stratification, are those of the Rev. Joun Micwe xt, in a paper ¢ On the Cause and Phenomena of Earthquakes,’ published in the Philosophical Transactions for 1760*; where the author not only describes the general appearance and structure of stratified countries, but explains most clearly the arrangement of the strata in En- gland :—and this, not as confined to Britain, but as exemplify- ing a general principle, which he supposes to hold universally in other parts of the globe. ‘ The earth,’ he says, ‘(as far as we can judge from the ‘ appearances,) is not composed of heaps of matter casually ‘ thrown together, but of regular and uniform strata. These ‘strata, though they frequently do not exceed a few feet, or ‘ perhaps a few inches in thickness, yet often extend in length ‘and breadth for many miles, and this without varying their ‘ thickness considerably. ‘The same stratum also preserves a ‘ uniform character throughout, though the strata immediately ‘next to each other are often totally different,’ The perpendicular fissures of the strata are then noticed, their bendings, and their position,which is stated to be, in a ge- neral view, horizontal.—* What is very remarkable, however, ‘in their situation is, that from most, if not all, large tracts of ‘ high and mountainous countries, the strata lie in a situation ‘more inclined to the horizon than the country itself, the ‘ mountainous countries being generally, if not always, formed ‘ out of the lower strata of earth. This situation of the strata ‘ may be not unaptly represented in the following manner: ‘ Let a number of leaves of paper, of several different sorts * of colours, be pasted upon one another; then bending them ‘ up together into a ridge in the middle, conceive them to be ‘reduced again to a level surface by a plane, so passing ‘ through them as to cut off all the part that had been raised; ‘let the middle now be again raised a little, and this will be ‘a good general representation of most, if not of all, large * Vol. li. Part ii. Sections 37 to 49, p. 566, &c.—Mr. Farey states that Mr. Michell was appointed Woodwardian Professor at Cambridge, about 1762; an office which he held, we believe, for about eight years. He was then, unfortunately for Geology, transferred to the Rectory of Thornhill, near Wakefield, in Yorkshire; and died on the 21st of April 1793. Mr. Michell was the author also of some excellent Astronomical papers in the Philosophical Transactions. ——— . ; f Dr. Fitton’s Notes on the History of EnglishGeology. 269 ‘ tracts of mountainous countries, together with the parts ad- ¢ jacent, throughout the whole world*. ‘ From this formation of the earth, it will follow, that we ‘ ought to meet with the same kinds of earths, stones, and mi- ‘ nerals, appearing at the surface, in long narrow slips, and ‘ lying parallel to the greatest rise of any long ridges of moun- € tains; and so, in fact, we find them. ‘The Andes, in South ¢ America, has a chain of volcanos that extend in length above ¢ 5000 miles: these volcanos, in all probability, are all de- ‘rived from the same stratum. Parallel to the Andes is the ‘ Sierra, another long ridge of mountains, that run between ‘the Andes and the sea:’ and ‘ these two ridges of moun- ‘tains run within sight of one another, and almost equally : ‘ for above a thousand leagues together + being each at a me- ‘ dium above twenty leagues wide. ‘ The same thing is found to obtain in North America also. ‘ The great lakes, which give rise to the river St. Lawrence, ‘are kept up by a long ridge of mountains, that run nearly ‘ parallel to the eastern coast. In descending from these to- ¢ wards the sea, the same sets of strata, and in the same order, ‘ are generally met with throughout the greatest part of their * length. ita ‘ In Great Britain we have another instance to the same pur- ‘ pose, where the direction of the ridge varies about a point from © due north and south, lying nearly from N. by E. to 8. by WS ‘ There are many more instances of this to be met with in the ‘world, if we may judge from circumstances, which make ‘it highly probable that it obtains in a great number of places; ‘ and in several they seem to put it almost out of doubt. ‘ The reader is not to suppose, however, that, in any in- * stances, the highest rise of the ridge, and the inclination © of the strata from thence to the countries on each side, is ‘ perfectly uniform, for they have frequently very considerable * inequalities, and these inequalities are sometimes so great ‘that the strata are bent, for some small distance, even the contrary way from the general inclination of them. This ¢ often makes it difficult to trace the appearance I have been re- § lating, which, without a general knowledge of the fossil bodies * of alarge tract of country, it is hardly possible to do. * At considerable distances from large ridges of.mountains, ‘ the strata, for the most part, assume a situation nearly level; * © Fig. 3. (Plate IL.) represents a section of a set of strata, lying in the * situation just described. The section is supposed to be made at right ‘angles to the leugth of the ridge, and perpendicular to the horizon.’ + ‘See Acosta’s Natural History of the Indies.’ } ‘ See Lewis Evans’s Map, and Account of North America.’ § ‘ Of this,’ Mr. Michell adds in a note, ‘ I could give many undoubted proofs, if it would not too far exceed the limits of my present design,’ 270 Dr. Fitton’s Notes on the History of English Geology. ‘and as the mountainous countries are generally formed out ‘ of the lower strata, so the more level countries are generally ‘ formed out of the upper strata of the earth. ‘ Hence it comes to pass that, in countries of this kind, the ‘ same strata are found to extend themselves a great way, as ‘ well in breadth as in length. We have an instance of this in ¢ the chalky and flinty countries of England and France, which ‘(excepting the interruption of the Channel, and the clays, ‘ sands, &c. of a few counties,) compose a tract of about three ‘hundred miles each way.’ The account of the districts in America, above referred to, has been confirmed, we believe, in general, by more recent ob- servations: and nothing can be more clear than Mr. Michell’s exposition of the principle of the stratification of England. That he was acquainted with the detail also, is proved by a memorandum discovered in 1810, among the papers of Mr. Smeaton, then in the hands of Sir Joseph Banks; in which are enumerated several of the principal beds, from the chalk down to the coal ; detached portions, several miles distant from each other, being, in two instances, associated under the same name.— This paper is as follows* : ¢ Mr. Michell’s Account of the South of England Strata. Yards of Thickness. Present Names. OW alates scr a ee Pens) an eitey 6 120 Chalk. CASTE ARCH atpe Fone | he RDO NS car ars 50 Gault. : t Woburn Sands, — Sand of Bedfordshire. ..... 10 to 20 ; [Lower Green-saind.] ‘ Northamptonshire lime, and Portland lime—lying in 100 } erie itt and other several strata........ aks 1 OMyaRStlAtan) ool stelle) sus Loee sale 70 to 100} Lias. ©Sand of Newark........ about 30 ? * Mey 1 of ‘Tuxford, Bon 100 New-red-sand-stone. * Sherwood Forest, pebbles an 50 usecael Probably superficial Piavelses fs pars tat se. , 4 Gravel. © Very fine white sand....... uncertain ? j \ * Roche Abbey and Brotherton limes. 100 ee a Lime. * Coal strata of Yorkshire” ..... Coal-measures ? It is extraordinary that the very remarkable paper in the Philosophical Transactions from which the forégoing extracts * We are indebted to the late Mr. Farey for the publication of this valuable document, in the Philosophical Magazine, vol. xxxvi. p. 102, &c. ; and the list of modern names above given has been adopted from him. The thickness of most of the strata, he justly observes, is greatly underrated. —The list was found, in Mr. Smeaton’s writing, on a part of the back of a letter bearing the London post-mark of November 21, 1788. Smeaton himself died in September 1792. ee sae Dr. Fitton’s Notes on the History of English Geology. 271 have been taken, embracing general principles of such im- portance, does not appear to have been mentioned, or al- luded to by any writer on geology, either in this country or upon the Continent, during a subsequent period of more than fifty years. This may, perhaps, be accounted for, in some degree, by the title and immediate subject of the paper itself; but it must be ascribed principally to the very languid state of inquiry as to the structure of the earth, in England, for a long time after its appearance*. [A still more interesting question is,—Whether by the words “fossil bodies,” without a general knowledge of which ‘in a large tract of country,’ Mr. Michell states, ‘it is hardly ‘ possible to trace the appearances he has been relating’—he intended to signify the organized remains included in the strata :—For, if that were his meaning, there would really be very little in the doctrines of modern geology, in which, as to principle, he did not take the lead. ‘This, however, does not appear to have been the case. Mr. Sedgwick has very justly stated}, that no part of the Woodwardian Collection, which was for some years under Mr. Michell’s immediate superin- tendance is stratigraphically arranged ; and that, not only in the works and catalogues of Woodward, but in the language of other English naturalists of the last century, every mineral substance was designated under the general term ‘fossil ;’ organic remains almost always distinguished by the name of ‘ extraneous fossils, organic fossils,’ &c. Nor is there any rea- son to suppose, that Mr. Michell’s arrangement of the British strata was made public till the accidental discovery of the slight document above mentioned, many years after Mr. Smith’s inquiries had begun; indeed, at a period when his Map of England was far advanced towards publication.] ‘The next author of note is Wui1reaurst, whose Inquiry into the Original State and Formation of the Earth was first pub- lished in the year 1778, and reprinted, with considerable im- provements, in 1786. A great part of this «book is infected with that taste for cosmogony which had misled so many of the author’s predecessors; but if the reader be not repelled by the formidable chapters ‘ Of the component parts of chaos whether homogeneous or heterogeneous,’ and ‘ Of the period of human life before and after the Flood, he will find some excel- lent remarks upon organized fossils; and in the latter part * After the first publication of Dr. Fitton’s article in the Edinburgh Re- view, Mr. Michell’s paper on Earthquakes was reprinted in full, in Phil. Mag. vol. lii. beginning at p. 186.—Ebprr. + Address to the Geological Society, at the Anniversary, February 1831. Proceedings, p. 274 (or Phil. Mag. and Annals, N.S. vol. ix, p. 275,—Enrr.) 272 Dr. Fitton’s Notes on the History of English Geology. of the volume, especially the chapter ‘on the Structure of Derbyshire and other parts of England,’ abundant. proofs of the author’s acuteness and fidelity as an observer. His state- ments, indeed, concur precisely with those of Mr. Michell; ‘ the arrangement of the strata being such,’ he tells us, ¢ that ‘ they invariably follow each other, as it were, in alphabetical ‘ order, or as a series of numbers. J do not mean to insinuate ‘ that the strata are alike in all the different regions of the ‘ earth, with respect to thickness or quality—for experience shows ‘ the contrary; but that in each particular part, how much so- ‘ ever they may differ, yet they follow each other in a regular * succession*.’—‘ It was my intention,’ he says in another place, ‘to have deposited specimens of each stratum, with its pro- € ductions, in the British Museum, arranged in the same order € above each other as they are in the earth; being persuaded ‘that such a plan would convey a more perfect idea of sub- * terraneous geography, and of the various bodies inclosed in ¢ the earth, than words or lines can possibly express +.’ But it is remarkable that Whitehurst, at the close of his work, appears to dwell with much more pleasure on that part which relates to the early ages of the world, and the condition of its antediluvian inhabitants, ‘ who slept away their time in sweet ‘ repose upon the ever verdant turf,’ than upon the truly im- portant and substantial part of his performance. The most direct instance that we have met with, of the ac- tual tracing the course of any of thestrata in England, before the commencement of Mr. Smith’s investigations, occurs in the ce- lebrated work of Smeaton on the Eddystone Lighthouse ¢; and it affords an excellent proof of the practical benefit to be de- rived from geological inquiries. Mr. Smeaton was in want of lime which possessed the property of forming a good cement for works exposed to the sea; and finding the lime afforded by the lias limestone at Aberthaw, on the coast of Glamor- ganshire, to answer his purpose §, he was led to seek for stone of the same qualities in other places. This he found, in the first instance at Watchet, on the Somersetshire coast, ‘ where ‘ all agreed, that they were the very same stratum of lias lime- * Whitehurst, Second Edition, pp. 178, 179. + Pages 204, 205.—This project has since been executed’; Government having, in 1806, purchased, for the British Museum, Mr. Smith’s collection of fossils, arranged according to the order of the strata:—an acquisition certainly of the highest interest in the scientific annals of our country, and deserving a most distinguished place in a great national repository. { London, folio, 1791. Sections 168-190, &c. In the Introduction it is stated that the book was printed in 1786. ; § The best cement was found to be a compound of equal parts of blue- lias lime and puzzolano, mina! | 7 } « Dr. Fitton’s Notes on the History of English Geology. 273 ‘stone, that were found on each side the Channel, though at ‘the distance of twenty miles.’ He went accordingly, to Watchet, and examined the situation of the beds there, which he has very well described ; and he subsequently traced the pro- gress of the lias, through Monmouthshire and the intermediate counties, as far north as Newark in Nottinghamshire; a course which corresponds precisely with the results of more recent investigation. He mentions likewise, that Mr. Cavendish and Dr. Blagden had assured him of its existence at Lyme, on the coast of Dorsetshire; which is the more remarkable, as a con- siderable mass of other strata intervenes, upon the surface, between that place and those which Mr. Smeaton had ex- amined himself. It is not however improbable, that Smeaton’s inquiries upon this subject may have been connected with some previous communication with Mr. Michell; since he appears to have received from that gentleman, the list of the strata to which we have already referred, before the publication of his own work on the Lighthouse. It is difficult to trace the history of WrrNneEr’s doctrines; the most important of his tenets having been delivered only in the form of lectures; while the writings of his pupils, who confessedly borrowed from their master, are generally di- luted with large additions of their own. In England espe- cially, a correct view of Werner’s geological system was not obtained till long after its promulgation: it was not indeed ac- cessible to persons unacquainted with the German language, till the publication of Mr. Jameson’s volume of Geognosy, in 1808 ; and was very imperfectly appreciated for a considerable time afterwards; the controversy between the Wernerian and Huttonian schools, having called off the attention of those en- gaged in the study of Geology, to the speculative department of their subject, from the more solid occupation of inquiry into the actual structure of the globe. The Kiirze Klassifikation of Werner, a brief but valuable arrangement and description of rocks, published by himself in 1787*, has no allusion nor hint at the doctrine of Formations, the terrh not once occur- ring in that work. Nor was the distinction of the transi- tion from the floetz class introduced into his arrangement for some years afterwards; grey-wacké being placed, in the list of 1787, among the flats sand-stones. ‘The opinions of Werner, as to the origin of the basaltic rocks, were formed after his examination of the Scheibenberg in 1787+. The * Kiirze Klassifikation und Beschreibung den verschiedenen Gebirgsarten. Von A. G. Werner, &c. Dresden, 1787. 4to, pp. 28. + Bergmiinnisches Journal, 1788, vol. ii. p. 845. Third Series. Vol. 1. No. 4. Oct. 1832. 2N 274 Dr. Fitton’s Notes on the History of English Geology. doctrine of formations was delivered in his lectures only, and may be dated as of 1790 or 1791; that of the ¢ransztion-class not until 1795 or i796. But his theoretic views, as to the depo- sition of rocks in general, and the configuration of the earth’s surface,—which, after all, (if what relates to the overlying for- mations be excepted,) are little more than a selection from the doctrines of preceding writers,—may be collected from his work on Veins, first published in November 1791; at which time it is certain that he was acquainted with the works of Whitehurst, for they are quoted in the book last mentioned. The true merit of Werner, on which it is probable his reputation as a naturalist will ultimately rest, appears to con- sist, in his having drawn the attention of geologists, expli- citly, to the Order of succession which the various natural roups of rocks are found in general to present ; and in having himself developed that order, to a certain extent, with a de- gree of accuracy which before was scarcely attainable, from the want of sufficient methods of discriminating minerals and their compounds. He was, we believe, the first to observe, or the first to diffuse the doctrine, that the masses or strata, con- stituting the surface of the globe, present themselves 7 groups or assemblages, the members of which are generally associated wherever they occur, and are so connected as to exhibit a cer- tain unity of character. ‘To such assemblages Werner gave the name of Formations; and his doctrine (or hypothesis, if this latter term be preferred,) was, that the exterior of the earth consists of a series of these formations, laid over each other in a certain determinate order. Not that the whole series is anywhere complete; but that the relative place of its members is never departed from. Thus in the ascending series A, B, C, D, it may happen that B or C, or both, may be occasionally wanting, and consequently D be found imme- diately above A; but the succession is never violated, nor the order inverted, by the discovery of A above the formations B; or C, or D, nor of B above those that follow it, &c.* A very important exception, however, to this regularity of arrangement, is found in the position of that great class of _ compound rocks, which includes all those of the trap family, the porphyries, syenites, and some at least of the granites of Werner. The compounds of this tribe, in general, agree, not only in possessing the characters of crystallization, and in being wholly destitute of organic remains, but in exhi- biting, at their junction with the stratified substances, the [* The substance of this and the following paragraphs, is taken from a preceding article in the Edinburgh Review, by the author of the present paper; Vol. xxix. Nov. 1817, p. 71.] a ke Se a eS Mr. Haworth on the Narcissinezx. 275 most obvious marks of violent derangement; and the trap rocks, in the form of large and numerous veins, are found to traverse, indiscriminately, all the other formations. It is im- possible, then, to believe, that the same laws have governed the disposition, both of these compounds, and of the strata which contain organic remains, and exhibit greater uniformity of structure; and every arrangement which assigns to both a common origin, or attempts to include the trap, and other similar formations, in the general series of rocks, must be de~- fective, and radically inconsistent. ‘The capital mistake of Werner (to which he was led, no doubt, by an erroneous theory), was, that he attempted such a combination, and neg- lected those demonstrations of violence and disturbance. In England, although the greater part of the country wants the more striking features of the primitive tracts, it fortunately happens that the series of secondary strata is nearly complete ; and, when our great extent of coast is taken into the account, few countries present a field for geological observation in which the phanomena are at once so varied and so well displayed. It will soon be perceived that the inferences from Mr. Smith’s examination of this country, coincide, to a great extent, with those of Werner: and this coincidence, between the results obtained by two independent observers, through channels of inquiry so different, is no small confirmation, both of the fidelity of their observations, and of the correctness of their deductions from them. [To be continued.] LI. Observationes quedam ad Narcisstni:as spectantes ; Autore A. H. Haworrtn, Soc. Linn. Lond.—Soc. Horticult. Lond.— Soc. Cas. Nat. Curios. Mosc.—Soc. Reg. Horticult. Belgic.—necnon Bot. Reg. Ratisb., Socius : §c. Fe. Lo the Editors of the Philosophical Magazine and Journal. Gentlemen, N this my thirty-second communication to your valuable and scientific Journal, a few material alterations and amend- ments, together with some novelties towards the improvement of my Narcissinéarum Monographia, may be acceptable to your readers; made from the living plants during the blooming season of the fine spring of 1832, during great part of which time the fragrant Narcissinea were very ornamental, and I think finer than, up to that time, I ever beheld them. But there are nevertheless many dubious points I am not even yet able completely to clear up respecting these intricate 2N2 276 Mr. Haworth’s Additions to and Amendments plants; so that the motto of the Monograph remains in force;— « Multum adhuc restat, multumque restabit.” - At the end I have added, by way of postscript, a few other amendments and observations on kindred bulbous plants; and remain, Gentlemen, yours, &c. A. H. Hawortu. Observationes quedam ad NanrcissinEAs spectantes. Obs. In the generic character of Corbularia the seeds are quadrifariously, rather than bifariously inserted as stated in Narcis. Monog. ed. 2.; but I have not yet been able to examine more than one species. Obs. To Corbularia Bulbocodium add, as synonymiay, Lob, Ic. 119. 2.—Bauh, Hist. 2. 559. f. 2. ' Obs. To Corbularia lobulata add: Narcissus tenui- folius Redout. Lill. 486. Obs. To Corbularia serotina add, Affinium Folia, longiora et dupld validiora, decumbenti- humifusa, valdé flexuosa, vel quasi serpentina. Ex eodem bulbo scapi subindé tres, si optimé culto.—Query: Is Nar- cissus infundibulum of Lamarck a species of Corbu- laria. Obs. In the genus Ajax the seeds are from 2- to 4- fariously inserted. Obs. Ajax minor of Narc. Monog. is N. minor Re- dout. Lill. t. 480. maximus. Ajax. (The largest yellow): Obs.—Folia latiora quam in A. majore, minus torta. Corolle lacinize magis ex- pansz, seu feré horizontales. Corona preegrandis pa- tens, lobis longé indistinctioribus vel potius plicatim multi- et magni-serratis, serrisque ad oras reflexis. Flos paulld saturatior flavus, feré 3 uncias longus, et 4 une. latus. In A. majore, corolle lacinize semierecte, lobis subrecurvis. Flos 34 une. lat., 24 long. anceps. A. (light green-leaved): corolle laciniis albis, corona leeté luted, foliis loratis obtusis latiusculis leeté viridi- bus, scapo compresso ancipiti. Ajax lorifolius 6. Narcis. Monog. ed. 2. p. 8. Florebat in horto amici Dom. Sweet, Aprili mense A.D. 1832, post A. lorifolium Nob. Distinguitur optimé ab affinibus proximis, laté viridibus foliis, florum albis laciniis, scapoque valdé compresso. Ante Ayacem bico- lorem certé locarem, propter albas lacinias, tempusque florendi; sed satis ab eo in foliis angustioribus et non glaucis differt. of his Narcissinéarum Monographia. 277 propinguus 8. A. (The paler yellow): Ajyacem Telamoneum si- mulat, sed Jacinize longissimé saturatiores cum corona latiore et breviore similitér lutea, lobis plus dupld ma- joribus. Affinior forsan Ajace majori, 4 quo differt luteo flore, (nec aurantio-luteo seu flavo,) duploque minore, corona minus expansa lobis minus circularibus, et foliis minus flexuoso-tortis. Obs.—Stigma antheras, in nostro solitario exemplo, subhumilius, qui non est in A. maximo, majore, telamo- nio, vel propinquo a sed cum his omnibus habet mag- nam affinitatem. los 2 unc.; 4 lin. long., 3 unc. lat. Observationes ulteriores—Lacinie ovato-lanceolatze semiexpanse leté luteze varié tortule coronam bre- viores. Corona paullo magis lutea plicatula, ore parim expanso alté et distincté 6-lobato, lobis magnis sub- semuncialibus plusquam semicircularibus przplicatis et obsolete irregularitér crenulatis. Obs. Communicavit amicus Dom. Penny, A.D. 1832. Fortassé propria species. Obs.—Itius, Haw. Narciss. Monog. ed. 2. p. 10. triandrus. 1. (The snowy white-flowered) : 1—5-florus: corol- lx nivex, laciniis lanceolatis corona integra dupld longioribus, stylo exserto. Narcissus triandrus Linn. Sp. Pl.416.9.—Narcissus juncifolius flore albo reflexo, Park. Par. t. 93. 2. Obs. Corolla tota nivea. Linn. 1. c.—‘ Bearing out of a skinny husk three or four or more snow-white flowers.” Park. 1. c.— Swertius Florileg. t: 29. f.4? Forté species major minus reflexa, stylo incluso. cernuus. I. (The pale yellow): corollz ochroleucz laciniis planis lanceolatis oris albis corona integra saturatiore sesquilongioribus, stylo incluso, scapo teretiusculo. Ganymedes cernuus Salish. Prod. 223.—Haw. Nar- ciss. Monog. ed. 2. p. 10, 1. Narcissus triandrus Bot. Mag. 48. nec Linn. N. coronatus Sch. Syst. Veg. 7. p. 986.—Swertius Florileg. t. 65. f: 7. 8. Stylo excluso. An idem ? albus. 1. (The tortuose white): corollz alba laciniis lanceo- lato-linearibus tortis corona integra dupld longioribus, stylo longé exserto, scapo compresso. Ganymedes albus Haw. Narciss. Revis. in Pl. Suce. p. 208.—Illus triandrus Haw. Narciss. Monog. ed. 2. p. 10. nee. Linnai N. triandrus. Obs. N. Coornei. Ted. Lill. v. 8. ad finem, ct Rudb, 278 Mr. Haworth’s Additions to and Amendments Elys. t. 65. f: 2-—Moris. 8. p. 4. t. 23. fig. penult. addito bulbo.—Chabr. Sciagr. 217. f.2. Lob. adv. alt. 498. ic.—Bauh. Hist. 2. 599 fortassé est imperfecta et casualis (ex mala cultura vel transplantatione) vari- etas hujus speciei, et indé imperfecta, redacta, quoque tortiles flores. f orientalis. ScHizaANTHES, Narciss. Monog. ed. 2. p. 12. Obs. Varietatem flore pleno sive semipleno vidi cres- centem in horto Dom. Young, apud Epsomam, Aprili mense A.D. 1832. major. JONQUILLA. Variat fl. pleno, media, JONQuUILLA. Variat fl. pleno, minor, JONQUILLA. Variat fl. pleno. Genus Hermione. Sectio GRANDIFLORE. solaris. HErMIoNnE, Narciss. Monog. ed. 2. p. 15. Est solum planta debilis sive immatura, vel ex mala cultura, Herm, cupularis, corollis paucis, cum laciniis depau- peratis omnino angustioribus et distinctioribus quam in H. cupulari: propterea e systemate expurgandam est. grandiflora. H. (great orange-bordered): sub-6-flora: corollz amplissime rotularis laciniis albis, corona patula plica- tim crenulaté primd superné aurantiaca, demum tota lutea, foliis glauculis. H. grandiflora Synops. Succ. app. p. 330.—Narciss. Trewianus Bot. Mag. t. 940. (castigandis synonymis), medio etati floris representatus.—H. Trewianus Nar- ciss. Monog. p. 16, excluso synonymo Trewit et Sweetit. 6. fissicorona (The cloven-cupped): subtriflora: co- ronda majore patenti trilobatim fissa lobis magnis1—4- relobulatis truncatis. flexiflora. H. (great yellow-cupped) 3—S-flora: corolla am- plissimze rotularis laciniis horizontalibus albis primo planis mox varié flexis, corona patula plicatim crenu- lata semper tota lutea, foliis glauculis. H. flexiflora Narciss. Monog. p. 16.—Bazleman ma- jor Trew. Fl. Imag. Narciss. 1. t. 23. H. Trewiana. Sw. Fl. Gard. 118. subcrenata. H. (middle yellow-cupped) 3—8-flora: corolla laciniis subreflectentibus albis, corona patula plicatu- latim crenulata luted 3-plo longioribus, foliis loratis an- gustioribus glauculis. H. subcrenata Narciss. Monog. ed. 2. p. 16. Bazle- man minor Trew. Fl. Imag. Narciss. 2. t. 60.° Obs. Corone ipse margo subinde in prima florescen- of his Narcissinéarum Monographia. 279 tia, cum aurantiaco aliquantillim gaudet, citiis eva- nescente. Prioribus duabus omnino minor. crenulata. H. (lesser saffron-bordered) 3—8-flora: corollz laciniis subreflexis albis, corona patula luted croceo alté marginata plicatulatim crenulaté 2—3-pl0 longi- oribus, foliis loratis angustioribus glauculis. H. crenulata Narciss. Monog. p. 16, excluso synonymo Trewti, quod praecedentem pertinet. viridifolia. H. (narrow green-leaved) 2—3-flora: corollz. la- ciniis semireflexis albis, corona parva patula luted, croceo primo paululim marginata plicatulatim crenu- lata 2—3-plo longioribus, foliis lineari-loratis praean- gustis superné debilitér varié flexuoso-recurvis viridi- bus. Nova species, quam prioribus duabus bulbo et flori- bus minor, foliis longé angustioribus, et certé viridiori- bus sesquipedalibus 5 lin. lat. concavo-inflexis, subtus convexis striatis. Florebat in hortulo nostro cum dua- bus ultimis, ubi per multos annos colui. Sectio nova: REFLEXIFOR®. Corolla \aciniis plusquam semireflexis, reflexisve. refleca. TH. (white reflexed) sub-5-flora: corolla secundz la- ciniis semi-plusve-reflexis ovatis imbricatis varié flex- ulis, corona cupulari ore contracto aurantiaco subdu- plo longioribus. Nova species, ultima feré dupld minor. Communica- vit amicus Dom. Penny. Habitat in Europa australiori. Floret Aprili. Obs. Folia lorato-attenuata pedalia sub-semunciam lata, carinata glaucescentia. Scapus ancipite-teres striis elevatis, foliis cavo-canaliculatis florendi temp. paulld altior. Pedunculi graciles 3-angulares elevato-striatuli. Corolle \acinise demum horizontalese Corona integra vel subindé subundulata. Anthere rubro-aurantiace, 3, extra tubum exserte. neglecta. Hi. (slender white reflexed) sub-4-flora: corolle la- ciniis lineari-lanceolatis reflexis distinctis niveis, co- rona subcupulari lutea 3—4-pld longioribus, foliis me- diocribus erectis lorato-attenuatis carinulatis. Obs. Sub nomine Narcissi neglecti, ex Neapoli ac- cepit amicus Dom, Rob, Sweet, et in ejus horto florebat A.D. 1832, Aprili mense. Obs. Quam priore gracilior, glaucior. Corolla laci- 280 Mr. Haworth’s Additions to and Amendments niz magis reflexe graciliores. Corona brevior ore non contracto. Anthere lutez nec aurantiace, 3 ex- tra tubum ut ined. Folia 11 unc. iong. florendi temp. et scapo breviora. Subsectio, corona acetabuliformi. craterina. 1. (open-cupped yellow) sub-7-flora: corolla la- ciniis luteis subincurvulis, corona perlutea_crateri- formi ore subrecto, plus duplo longioribus. Nova species. Patriam nescio. Florebat medio Aprilis A.D. 1832 in hortulo meo. Obs. Floris tubus luteus, basi virescens, laciniis longior. Folza florendi temp. vix semunciam lata ensi- formi-lorata, superné seepé flaccidé recurvula glaucula striatula, inter breviora et planiora. Scapus vix com- pressus teretiusculus striatulus glaucus. Pone H. aperticoronam mihi, locarem. Per mul- tos aunos colui. Sectio CrrRocoRONE. Obs.— Hermione floribunda Narciss. Monog. ed. 2. p.17. was a Dutch specimen given me by Mr. Sabine, from the Chiswick Garden, by the name of *¢ The Grand Monarque,” and is well preserved in my Herbarium, with 16 flowers in one spathe. And I have this year seen it from Holland, in Mr. Dennis’s fine collection in his Nursery in the King’s Road, Chelsea, also with 16 flowers on one scape, but named “ The Grand Primo Citroniére,” which I am assured is its proper florist’s name. It has perhaps the broadest leaves of all the genus, measuring when adult, in my garden, 24 feet long, and 14 inch broad, on a plant which had onl 14 flowers in one spathe. Mr. Dennis had likewise The Grand Monarque from Holland ; and he has seen 18 flowers on its scape, but their laciniz are far more acute, and may be characterized in the following manner : acuminata. H. (The acute-flowered Nosegay) 8—18-flora: corolle magne laciniis albis saepé productim ovato- acuminatis subreflexo-incurvulis, corona ampla citrina suberecta integra 3—4-plolon gioribus. The Grand Monarque, Hortulanorum. Obs. Cxtera cum H, floribundé Nob. (The Grand Primo Citroniére of the Dutch) concordat, sed saepius, non semper, minor foliis minoribus floribus seepé pau- cioribus. of his Narcissinéarum Monographia. 281 Along with these fine-grown plants at Mr. Dennis’s I saw an Hermione with 23 flowers on one scape ; and another with « proliferous spathe, from the centre of which arose a sort of second scape above the primary flowers, bearing 4 peduncles, each having an open flower upon it. I never saw a proliferous scape before in this genus; but it is represented, and recopied in several of the works of the elder botanists. I likewise saw at the same time Hermione deflexicaulis, and others, with 21 flowers ; and A. polyantha Loisel. with 19 flowers on separate scapes each. In my own garden, several scapes also bore 21 flowers; Queltia aurantia bore 2 flowers in one spathe, which I have seen only once before : and Corbularia serotina Nob. in Mr.Sweet’s garden bore 2 flowers on one scape; and a monstrous union, or casual coalescence of two such scapes bearing together 4 flowers, I have examined in the Herbarium of the late Sir James Smith. decora. H. Narciss. Monog. ed. 2. p. 17. Obs. Under this species 1 now place the following var., rather than where it stands in my Monograph. My plant bore 9 flowers in a head, whose segments were about twice as long as their cup. 8. major, foliis adultis 13 unc. latis, floribus preecoci- oribus. H. polyantha 8. Narciss. Monog. p. 18. polyantha. HH. Loisel.: 3—20-flora: corona sulphurascente subcrateriformi plicatulatim crenulaté mox alba, co- roll laciniis ovatis niveis sesquidupl6 breviore, foliis prelatis perviridibus planiusculis. Obs. Bulbus inter maximos, Varietates belgice plures in hortis coluntur. Folia inter erectiores, seepé unciam lata. Tuna. H. 3—4- raritis 5-flora: corolla laciniis niveis imbri- catis, corona primo pallidissimé citrina mox alba ses- antic longioribus, foliis ensiformi-loratis perviri- ibus planis. H. Luna Nob. Narciss. Revis. p. 143. Obs. Folia seepé 8 lin. lata superné debilitér flexu- oso-recurva. Flores et bulbus minores quam in pre- cedente. Sectio ANCIPITEs. chrysantha. UU. Narciss. Monog. ed. 2. p. 18. Obs. The plant described in the place cited was in Third Series. Vol. 1. No. 4. Oct. 1832. 20 282 Mr. Haworth’s Additions to and Amendments a weak state, and has since produced 5 flowers in a spathe, with a less compressed scape, and the floral segments only 3 or 4 times longer than the crown: wherefore it should be removed from this section, and placed in, and arranged at the head of, the Section Fia- VIFLORE. Its presumed Italian origin is given up. dubia. H. (The lesser white): scapo sub-9-floro ancipiti, co- rollz laciniis brevibus ovatis incurvis imbricatis hori- zontalibus tubo brevioribus coronaque cyathiformi un- dulatim subintegra subtriplo longioribus. Narcissus dubius Gowan et Willd. Herm. dubia Narciss. Monog. p. 19. Communicavit florentem amicus Dom. Penny, Apr. 10, A.D. 1832. Obs. Scapus valdé compressus et acuté anceps, grossé vel subangulatim striatus virescens, humilior quam H. jasmined, et tota planta longé minor. Folia subvirescentia eusiformi-lorata, paululum torta cari- nata obtusiuscula, basin versus intus inflexo-canalicu- lata, scapo florendi temp. parum altiora, dodrantalia, et 7 lineas lata. Spatha albida ad oras quasi exusta. Pedunculi breves subunciales angulatim subsemicy- lindrici. Flores nivei concolores unciam lati et confertim quasi imbricati. Tubus basi virescens obtuse angulatus. Genitalia nivea, exceptis solim aurantiacis polliniferis antheris, harum 3, extra fubum, sed stigma trilobum humiliores. jasminea, H. (The jasmine-like) sub-5—9-flora: corollz elegantissimz nivee laciniis lanceolatis stellatis basi subimbricantibus, corona erosulé sub-5-plo longiori- bus. Hermione papyratia 6. jasminea Nob. in Narciss. Revis. p. 143. A.D. 1819. et H. jasminea Nod. in Phil. Mag. 1830, p. 133, et Narciss. Monog. ed. 2. p. 19. —Narcissus niveus Loisel., et Schultes Syst. Veg. v.'7. - 976. r Obs. I believe these synonyma to be correct, but have never been able to procure a sight of the work of Loiseleur, and cannot at present determine which is the elder name. All these pure white-flowered plants were well known to and figured by the elder botanists; but I cannot take up the valuable space in the pages of the Philosophical Magazine, which it would require, to unravel their synonyma. of his Narcissinéarum Monographia. 283 trifida. Hermione. sub-3-flora: corolla laciniis subochroleu- cis corona subaurantiaca cupulari erecta, seu subcam- panulata trifida, (lobis bifidis,) 2—3-plo longioribus, foliis loratis 9 lineas latis planioribus obtusis glaucis. Genus Narcissus Linn., et Nob. Narciss. Monog. ed. 2. p. 20. brevitubatus. Narcissus. (The short-tubed small-crown): co- rolle laciniis niveis preeimbricatis ovatis logitudinaliter subplicatulis tubo subduplo longioribus, corona erecta parva intensé luted croceo tenuissime cincta. Obs. Corolle \aciniz basi ad oras demum reflexe, sed superné varié flexee et ad oras inflexee. Obs. This description was made from a single living specimen, without leaves, which was grown in Mrs. Marriot’s rich garden on Wimbledon Common, and given to me, at the end of April 1832, by my friend Mr. E. D. Smith, the able artist of Sweet’s Brit. £1. Garden. The characters above given are very strong, and sufficient, if constant; but may they not have arisen from some imperfect state of cultivation, or un- timely transplantation of the root, or from being kept too long out of the ground? It seems to be a dwarf species close to N. angustifolius of Bot. Mag. t. 193. Obs. ulteriores.—N. angustifolio affinis, sed minor, et differt scapo compresso ancipiti striato crassiore dodrantali, et forsin pallidiore : coroll@ laciniis latiori- bus minus stellantibus; coroné minore, erecta, nec patula vel patellari, et potissimim tubo laciniis duplo breviore, nec lacinias eequante; ovario feré oblongo nec ovali, ut in N. angustifolio. Fortasse est Nar- cissus odorus circulo rubello, \Rudb. Elys. t. 44. cum icone. Genus PurLoGyNE. Obs. Much yet remains to be cleared up in this genus.—Philog. Campernelli was described in Narciss. Monog. from imported roots, and had flowers lower than the leaves. Others exactly similar, but from Bury Botanic Garden, and kept in the ground all the year, had florigerous scapes higher than the leaves at the time of flowering; so the difference of relative altitude is thus accounted for: but the leaves in P. Campernelli were much paler, especially at the base, than those of P. odorus, and the flowers had little or no scent. I had only one specimen of P. odorus to compare with many of P.Campernelli, in the blooming season of the present year, 202 284 Mr. Haworth’s Additions to and Amendments Pu. Curtisit. Narciss. Monog. ed. 2. p. 12.—This was described from a single specimen in Mr. Sweet’s garden, and has not since bloomed; but he joined me in thinking it had more deep and distinct lobes on its ample and not rugulose, but crisped crown, than Ph. interjectus; and time may prove it. From Phil. triloba it differs in the larger propor- tions of its crown. POSTSCRIPT. Genus Morium mihi. Atuium Linn., Treviran., Don, &c. Spatha 2—8-loba, marcescens. Stamina subulata, basi dilatata, plana, connata. Scapz nudi, centrales. Folia radicalia lorato-attenuata ecarinulata. Obs. The genus Moly of Theophrastus, Dioscorides, &c., and all the higher divisions of my friend Mr. Geo. Don’s very excellent Monograph on Allium, are good and sufficient genera, or subgenera, of the great family of Alliean plants; and the very characters he has there laid down are sufficient and satisfactory. In the present place I have not leisure to dwell further upon this point, than merely to describe, as a distinct species of Molium, (sent to me as an Ornithogalum,) which Mr. Don, at the time of printing his elaborate Mono- graph, had no opportunity of separatng from Molium nigrum of Linnzeus,—the Allium multibulbosum of Jacq. Austr. t. 10., and which by way of contrast may be called, paucibulbosum. Mo.rum (pale blush-coloured) inodorum: bulbo principi magno simplicitér dichotomo sub-ebul- billoso, foliis erecto-incurvis glauculis, stylis 3—4, toti- demque ovarii loculis. Allium bicorne, latifolium, flore magno dilute pur- purascente, Rudb. EHlys. 11. p. 160. f- 21. M. indicum flore purpureo, Swert. Florileg. t. 61, Jigura centralis. M. montanum latifolium purpurascens Hispanicum, Park. Parad. p. 144? Moly latifolium hispanicum, Bauh. Pin. p.75.n. 111. Obs. Planta inodora autumno quiescens¥’. Radix bulbosus magnus sine feré bulbillis. Folia radicalia suberecto-incurva pedalia et ultra, 2 uncias lata, lan- ceolato-lorata, glabra, incurvo-canaliculata, et indé basin versus precipué canaliculata, ad oras in lente of his Narcissinéarum Monographia. 285 albo-marginulata et minutissimé asperiuscula. Scapus teres solidus plus quam 2-pedalis laevis aphyllus viridis. Spatha multiflora membranacea persistens et recurva lobulata. Flores capitatim umbellati numerosissimi con- ferti aibi, sed mox dilute erubescentes. Pedicelli 1—1}- unciales teretes virides. Perigonium 6-petaloideum. Petala oblongo-lanceolata dorsali linea viridi, horizon- talitér expansa obtusa vel partum incurvula, Stamina patula, filamenta subulata superne plus minus erube- scentia, antheris ordinariis. Ovarium leté perviride obtusé 3—4—5-gonum, totidem loculis. Stylz itidem 3—5 erecti subulati, sublineam longi albi, stigmatibus feré nullis. Proximum est A. multibulbosum Jacq., sed differt in bulbo, foliis, floribusque; et potissimum in stylorum numero, loculisque ovarii viridissimi. In the course of composing my MS. Hortus (sub dio) bulbosus, 1 have found that Zephyranthes grandi- flora of Bot. Mag. tab. 902. is the same plant as Ha- branthus robustus ef Herbert, figured in Sweet’s Brit. Fil. Gard. ser. 2. tab. 14, This may be useful for all botanists, bulb-growing collectors, and gardeners to know, as will also be the following remarks. plumbea. Sciiua. Bot. Reg. tab. 1355, is the same as Scilla hyacinthoides Linn. and Bot. Mag. tab. 1140. esculenta. Scitua. Missouri Squill or Quamash, Bot. Mag. tab. 1574, must be very different, and not even of the same genus, as the Camassia esculenta (Eatable Quamash) of Bot. Reg. tab. 1486; and I think I have seen a smaller kind (perhaps only a weaker specimen,) of the former, which is a true species of Sczdla. Under the same useful views I may remark, that Scilla untfolia Linn.—Lowd. Hort. Brit. and Scilla pumila Brot. (monophylla Link) and Sc. pumila Bot. Mag. t. 3023. are the same plant. I have long had in my garden two species of Scilla, that [am not aware of having been distinguished in print from each other ; viz. peruviana. Scitia. Linn. Sp. Pl. 442. et ejus Herb.: foliis lorato-lanceolatis, thyrso multifloro conferto, bracteis, pedunculo imo longé brevioribus. Scilla steilaris boeticus major sive peruanus, Park. Parad. tab, 125. f. 7. 8. minor, floribus albis. 286 Mr. Haworth on the Genera Molium and Muscari. prebracteata. Scirus (long bracted): foliis Jorato-lanceolatis, thyrso multifloro conferto, bracteis imis pedunculo valdé longioribus. Scilla peruviana Bot. Mag. tab. 749. Genus Muscat Clus., Tournef. Hyacintuus Linn. &c. Obs. Under the name of Hyacinthus botryoides, and its varieties, have been confounded two distinct species, which I separate and endeavour to establish as follows: botryoides. Muscarit (The grape - flowered): corollis race- mosis confertis globosis uniformibus, pedicellis flori- geris subnullis, longioribus, foliis loratis inflexo-cana- liculatis erectis, bulbillis radicalibus numerosis. Hyacinthus botryoides. Linn. Sp. Pl. 455. Muscari botryoides. Sw. Brit. Fl. Gard. tab. 15 8. azureum (bright blue). Sw. 7. c. . 15. f. a.—Hy. muscari y. coeruleum majus Linn. Hort. Clif. 126. et Herb. Linn. y- pallidum (pale blue). Sw. /. c.f c.—Hy. Muse. a. exalbidum Linn. Hort. Clif. l. c. 8. carneum (pale blush). Hy. Muscari B. carneum minus Linn. Hort. Cl. 1.c. Hy. botryoides flore albo-. rubente Park. Par. p. 115. z. album (white). Sw. l.c. f/b.—Park. l. c. t. 113 f. 6. fi ¢. ramosum (the branched). Park. Parad. t.113.f. +- Obs. The last very remarkable variety, and the blush-coloured one, I have never seen; but they cannot depend better than on the fidelity of Linnzeus and Park- inson. peduncularis. M. (The sub-blotched sky-blue): corollis laxius racemosis paucioribus, globosis uniformibus imis pe- dicellis brevioribus, foliis patulis lineari-loratis inflexo- canaliculatis, bulbillis radicalibus numerosissimis. Hyacinthus botryoides Curt. Bot. Mag. t. 157. nec Linn. vel Sweet.—Hy. botryoides coeruleus amoenus (The sky-coloured grape flower). Park. Par, 114. t. 113. f. 5. cum optima descriptione et , figura. Obs. Priori minus et longé rarits floret, nisi bulbilli innumeri removendi sunt, in quolibet anno. Chelsea, July 1, 1882. { 287 ] LII. Notice of some recent Observations of Encke’s Comet, and of Gambart’s Comet of July 19;—extracted from a Letter Jrom Professor Schumacher of Altona, to the Rev. T. J. Hussey*. NCKE’S comet has been but twice observed this year (at least I have received no more observations), and that not in Europe, but by M. Mossotti at Buenos Ayres. It was un- commonly faint, and even there scarcely visible. Of the comet discovered July 19 by M. Gambart, one of my assistants, Mr. Peters, has calculated the following ele- ments, which he is now about to correct by the whole of the observations. They are founded upon Gambart’s observations, July 19; our own here, August 4; and Nicolai’s, August 21. Passage .. 1832. Sept. 25°62887 mean Berlin time. Perihelion . . 227°50! 2! \ counted from the apparent Bias auiets -) 72 28 16 Equ®™ July 29. OE es 43 20 20 logg...-+.+ 0:0728427 Retrograde. They represent the observations as follows : Diff. in Long. _ in Latit. July 19, Marseilles —4" — i" August 4, Altona +1 sh) ly! —21, Manheim +2 + 1 Altona, Sept. 3, 1832. LIII. On Periodical Variations in the Quantities of Water af~ Jorded by Springs ;—in a Letter to Sir Charles Lemon, Bart. M.P.F.R.S. By W.J. HEenwoon, Deputy Assay-Master of the Duchy of Cornwall, F.G.S. Hon. M.Y. P.S. To the Editors of the Philosophical Magazine and Journal. Gentlemen, PTHE only publications pretending to bring this subject to numerical accuracy, with which I am acquainted, are Mr. Bland’st and my own{. ‘The information contained in both these, is of a very similar character; but I will now en- * Communicated by Mr. Hussey. + Phil. Mag. and Annals, N.S. vol. xi. p, 88: Read to the Geological Society, December 14th, 1831. } Phil. Mag. and Annals, N.S. vol. ix. p. 170. Read to the Royal So- ciety some time in February or March 1830. A typographical error, dates this in the Phil. Mag. January 28th, 1831, instead of January 28th, 1830, which it should have been. 288 Mr. Henwood on Periodical Variations deavour, as briefly as I can, to supply other matter, which I was prevented from giving in that paper, by circumstances not under my own control. The observations to which I now venture to solicit your attention, extend through seven years ; from 1823 to 1829 both inclusive. The first inquiry seems to be, *“* For the same mine the depth being constant, what is the variation in the quantity of water delivered, for corresponding months of various years?” The examples I select, are the United Mines, situated in slate, depth from which the water is drawn 98 fathoms; Dolcoath, of which the surface is slate, and the bottom granite, water drawn from 222 fathoms deep; and Huel Damsel, situated in granite, depth 202 fathoms. For further details of the depth, and mode of estimating the water, I refer to my former paper*. The following Table I. represents the mean of the average monthly quantities of water pumped out of these mines, in cubic feet, and the monthly averages of rain in inches for the same periods. Taste I. Mines. January. February. March, | April. May. June. ~~. | eubie feet. | cubic feet. | cubic feet. | cubic feet. | cubic feet. | cubic feet. | United Mines} 4723799 5857656 | 4895049 | 5466032 | 4394400 1782565 880608 | 807545} 840111] 839807 3577 : 3007 | 2-522 Sept. 3436863 | 3435319 | 3510144 | 3330284 1400135 | 1436790 | 1422857 | 1750345 683521} 669309| 653564) 780149 3-934 4-194 5-543 Taking the foregoing means respectively as standards of com- arison, we shall see how the monthly averages in the follow- ing Table II. vary therefrom. * Phil. Mag. and Annals, N.S, vol. ix. p. 171. Surface above Bottom Of the bottom sea-level. below sea. full of water. United Mines... 48 fathoms. 160 fathoms. 120 fathoms. Dolcoath......... G25 i... tod.-% ieee. 4. tes 05% QO Geiteee Huel Damsel.... 59 ......0. 143 in the Quantities of Water afforded by Springs. United Mines. § 1822, Dec. 1823. Jan, Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. Taste IT. Huel | Damsel. 765,677| 819,741 800,609 893,625 793,119 731,815 | Dolcoath. 1,894,762 1,691,011 1,836,030 1,922,201 1,567,337 1,611,828 1,608,971 1,431,062 658,345 1 1553,293, 577,427 1,529,559) 565,321 1 609,139, 598,025) 1,710,348) 644,470 1,979,536 675, 959) 9: 728,529) 6- United | Mines. Pelgonth "12,205,913 nese 1,223,887 3,892,417 1,271,191 . |3,419,060 1,152,142 pt. |2,872,736 1,237,470 2,759,297 1,567,249 . |2,424,979 1,094,771 « [3,636,077 . |2,462,892 1,470,081 3,316,010 1,714,405 1,090,749 i 4, 710, 403 1,752,665 4,350, 3152, 091,307 3,763,764 1,815,024 Hu Damsel. Rain. 0-66 1:24 2115 4315 2:84 4:28 44 4°42 662,709 626,789 588,744 431,676 538,701 590,235 683,331 603.554/1-6 740,237|5:265 721,023)1:36 859,77815°315 727:7762°16 July. |3,726,0561,515,085 Aug. |3,369,586 1,418,579 Sept. |2,899,215'1,135,286 Oct. |2,704,164 1,167,132 Novy. |2,552,262 1,245,571 Dec. 13,354,116 1,828,735 1828. | Jan. |6,109,5112,346,045 Feb. {7,793,133 2,081,595 Mar. |6,355.808/2,050, 179) April 5,193,102|* May |5,910,392/2,155,227 June 5,874,4312,180,986| 962,159)1- July |5,306,100)1,501,722| 933,176\4: Aug. |4,481,789/1,466,902|1,004,299\4- 1,505,560) 758,924| 2°7 | Sept. |3,722,706} * 974,995)|3" 1,612,661) 836, 711) 3°61 Oct. |3,672,149/1,560,404) 958,115/3- 3705,725)| 735,568) 1° Noy. |3,496,458)1,381,751 & 1,459,578 711,555, Dec. 4,173,845}1,609,129 1,406,288) 687,904' 1-8 | 1829. 1,472,770) 695,021| 0°31 | Jan. |4,745,878 1,386,542) 642,376 3°14 | Feb. * 1,244,851) 585,315) 2°73 | Mar. |5,071,161 1,244,948 577; 089 Be 09 April 4,579,744 1,284,167] 555,002) 5°82 | May 5,328,338 1,597,410 085,556 5:285 . Ene 14,327,238 uly 1,806,884] 804,716 3:075] Aug. 1,856,601) 741,670 5:295} Sept. 1,435,500) 889,283 2°31 | Oct. 1,772,190|'787, 555) 11k Nov. 1,722,006} 776, 638 0-6 689, 101\2:25 687,798)2:865 633,469/2:82 649,128 6- 644,479 3: 804,390)7- 941,755)7° 880,487 4: 914,075)3: 871,083)7- 992,297)3° 1824. Jan. Feb. Mar. April May June July Aug. Sept. Oct. Novy. | Dec. | 1825. Jan, Feb. 34 Mar. April(3, 755, 247\1 6,464,158 5,800,654 5,135,800 1,808,211 1,570,986 1,714,520 1,815,507 1,576,255 1,561,641 1,635,458 1,551,167 1,367,813 1,401,820 1,537,290 1,872,764 785,731 709,011 729,649 729,621) 2: 698,081 653,738 714,421 705,689, 652,500 639,811 730,284 857,628 1,852,679] 866,815} 3°375 3 1,029,02616: 1,843,533 1,523,075 1,910,332 * 1,572,507 1,415,462 4,067,023)1,461,774 3,732,569|1,341,428 3,811,897 )1,885,834 4.295,97 11,506,842 4,344,319|1,706,102 1,154,831 fi * - 14,433,788 - 13,877,763 - 13,745,016 . 4,732,704 1,164,264)1- 1,014,850)5: 1,110,616): 940,224'4- 705,383/5°615 774,412/5°515 784,308)6:'82 831,217|3°035 808,451/1°645 * + 14,917,809) April |6,236,749 May 5,276,957 § My observations on this mine are not comparable with one another further k than April 1825. _ * No observations recorded for the months thus distinguished. Third Series. Vol. 1. No. 4. Oct. 1832. P 290 Mr. Henwood on Periodical Variations Collecting the annual results of this Table, itis found that the cubic feet of water drawn, and rain in inches, are, Taste III. Year. |United Mines| 1 Dolcoath. | Huel Damsel. Rain. 1823 * | 19,965,691| 8,524,133] 53°705 1824 ~ | 19,5 20,204) 8,477,065| 51°355 1825 sd 18,048,533, 8,510,008} 40°135 1826 |49,477,875 | 18,090,219| 8,757,924) 33°125 1827 | 42,039,201 | 18,798,449| 8,229,909| 41°725 1828 | 61,269,695 | 21,676,376| 10,890,395| 54°97 1829 | 53,914,548 | 19,558,583) 11,123,222) 46:995 From Table I. it is obvious that for the seven years under consideration, the maximum of rain has been in December, and the minimum in Junet. Greatest} Months |Smallest |} Months | Max. of Water Wines. Quantity| after |Quantity| after | drawn, exceeds of Max. of Min. Min. of the Water. | Rain. | Water.| Rain. mean by. United Mines} March} 3 | Dec. 6 O°574 Dolcoath .....| Jan. 1 | Sept. 3 0°288 Huel Damsel | March 3 | Nov. 5 0°295 I do not think any of the foregoing Tables afford informa-. tion on which we can build, of the effects of rain on springs rising at great depths; for in Table III. an inverse ratio be- tween them seems to obtain about as frequently as a direct one. Nor does this appear to proceed from any extraordinary drought or flood towards the termination of a preceding year. The second point to be investigated is, Jn a given mine, what periodical variation in the quantity of water obtains for any determinate increase of depth? Seeing the difficulties with * For these unreported months, I have, to complete Table III., interpo- lated from Table I. SE Mr. Giddy, from whose register the rain is taken, gives the minimum rain for 1821, 1822, 1823, 1824, 1825, 1826, 1827 in April, Phil. Mag. and Annals, N.S. vol. iii. p- 181. The difference between the mean temperature of the years of these ob- servations are : 1823 mean it 1827 mean 51-5 1824 — 515 1828 — 52:2 1825 — 52 1829 — 50. 1826 — 53°5 Giddy, Phil. Mag. and Annals, N.S. vol. iii. p. 182. . in the Quantities of Water afforded by Springs. 291 which we had to contend, in the first part of this inquiry, it is obvious that the present one presents many others, some of which are to me insurmountable. I take as examples situated in clay slate, Huel Rose, surface 35? fathoms above the sea ; Huel Hope, surface 50? fathoms above that level; and Poldice, surface from 28 to 40 fathoms above the sea- In granite the only case I shall adduce is Huel Reeth, of which the surface is about 66 fathoms above sea markt. Tasie IV. j{ Huel Rose. | Huel Hope. Huel Rose. Water, Cub. Ft. 1,565,187] ... .-- 12,646,157] ... +++ |2,341,190) ... +++ |2;333,533) --. 2,250,359) -- ... {1,879,489 1,735,859 . 11,610,751 1,555,045 »-» {1,615,076 ... +++ 11,346,398 w+» {1,637,411 + {1,851,747 ««. {2,296,465 - |2,039,894 .. 12,459,984) ... ”. |1;913,890} ... * w+» 11,859,413} ... Soo psp tet he) eas eee {1,751,822) ... »-+ |1,682,792! ... 85 |1,835,665] ... * «(2,414,911 * 79 |2,168,204] ... 84 |1,711,032| ... whe “4 - 13,362,051 Huel Hope.§ Water, Cub. Ft. 1,679,843 1,482,723 1,459,652 1,335,605 1,369,297 2,066,255 2,428,149 2,123,209 2,562,010 2,309,617 2,092,514 * 1,766,160 1,677,752 1,584,818 1,669,365 * 2,699,121 2,530,137 _May | 91 June} 9 July | ... |: Aug.! ... Sept. cel i: 1,854,494 ie Nov. | ... Dec: | ... f 1828. Jan. | 85 |3,174,525) .. Feb. | 90 Marsal f. April |100 May | ... June | 95 July |100 Aug. | 95 |2,530,456)1 Sept. | ... Oct. Nov. Dec. 1829, Jan. Feb. Mar. Water, Cub. Ft. 3,073,158 ... |2,873,097 ws. {2,899,681 ... 2,833,634 w-. 2,503,753 . |2,273,581 +. |2,225,924 . {2,309,194 2,984,186 | * 3,292,749 . \3,125,796 4 wo. [2,872,231 . {2,874,119 | 2,629,117 ..- 2,662,792 12 |2,501,831 dee |2,264,919 we. 2,281,205 ..., {2,146,405 . |2,388,458 .-. [2,889,535 - 2,748,953 2,788,771 April} 104 {2,692,850} 112|2,659,448 May June Aug. Sept. Oct. Nov. + Phil. Mag. and Annals, N.S. vol. ix. p. 171. t I make two Tables, [V. and IV*. because it appeared that the first two and the second two formed series very distinct, so far as depth, at least. The rain having been given in Tables L. and IL, 1 do not repeat it. § Phil. Mag. and Annals, N.S. vol. ix. p.172. ‘The columns mean, depth of the mine, in fathoms; and quantity of water drawn out, in cubic feet. 2 P2 July | 113 |2,525,173| 128 |2,285,164 2,231,667 we. [2,242,170 wes [2,621,985 ves |2,489,828 292 Mr. Henwood on Periodical Variations Tasre IV?. Poldice. Huel Reeth, Poldice. Huel Reeth. a po] . Go aS Water. aS Water. ae Water ae Water. Q=|Cub. Ft. Ge |Cub. Ft. Ar | Cub. Ft. 4 o |Cub. Ft. 1822, |—— rae tT LeZos pis epinaspaael Dee. | 135 i 125| 880,663} June | 157 |2,660,942) 169 | 304,203 1825. July | 162 |2,682,468) ... 262,885 Jan. | ... |3,327,107| ... | 629,219 Aug. |. |2,342,342) ... 225,141 Feb. | ... [4,924,641] ... | 915,563 Sept. | ... |2.025,384) ... 209,518 Mar. | 139 |3,940,670| ... | 738,615] Oct. | ... |2,153,458] ... | 206,009 April 3,303,934 429,341] Nov. | ... |2,123,368) ... | 198,651 May | 141 |3,033,058/ 127 | 342,207] Dec. | ... |2,479,338) .. | 478,529 June | 142 |2,716,302) 135 | 273,723] 1827. July | 144 |2,521,868) ... | 216,365} Jan, | ... {2,319,208} ... | 489,605 Aug. | 145 |2,501,825} ... | 302,189] Feb, | ... |2,579,821) ... | 467,429 t Sept. | 146 |2,437,174] ... | 379,582] Mar. | ... |3,187,412) ... | 721,001 Oct. | 147 |2:530,667) 145 | 523,531] April] ... 2,961,881] ... | 433,656 ‘ wee [2,679,540] ... | 575,191] May | .. [3,185,067] ... | 524,469 u Nov. Dee, | ... |2;961,414) 149| 661,269] June | ... |2,921,629| ... | 420,608 A 1824, July | ... |2;717,207| ... | 334,130 Jan. |... 13)244,887| ... | 584,321] ‘Aug, | ... |2,723,087] ... [241,958] 9 Feb. | ... |2,943,396) ... | 405,159] Sept. | ... |2,255,414) ... | 257,111 i Mar. | -.. |3,359,807| ... | 571,395] Oct. | ... |2,591,115] ... | 332,998 ; April] ... |5,151,160| ... | 376,196] Noy. | ... |2,668,019) ... | 498,538 ; May | «-. |3,162,396| ... | 374,940] Dec. | ... |2,887,534) ... | 824,990 June | ... |2,862,492] ... | 342,268] 1898. ; July eee 3,095,589 nee 420,928 Jan. ees 4,192,716 eee 999,368 LY Aug. | «++ |2,737,222| ... | 303,117] Feb. | ... 13,597,390) ... * : Sept. | «+. |2,594,766] ... | 263,169} Mar. | ... |3,499,163| ... | 488,384 Oct. | «-. |2,836,271] ... | 401,328] April] ... 13,206,197] ... | 533,962 Nov. | --. |2,781,280) ... | 536,512] May | ... 13,330,326] .. | 459,621 Dec. wee 3,499,641 oe 842,607 June | ... * eee 406,112 1825. July | ... |3,303,130} ... | 339,984 Jan. | 142 |3,640,529} ... | 633,158] Aug.| ... |3,160,195| ... | 378,825 £ Feb. | «-. |3,274,633| ... | 610,574] Sept. | ... |2,814,212] ... | 323,576 | Mar. | -.. |3,481,963] ... | 557,904] Oct. | ... |2,756,998] ... | 363,892 : April/151 |3,243,756] ... | 345,880] Nov, | 166 |2,308,730] ... | 428,613 May |152 |3,383,893] ... | 339,126] Dec. | 167 |2,871,306) ... | 598,067 June} ... |3,256,043) ... | 288,918] 1829, July | ... |2,728,108] ... | 259,408] Jan. | ... * |... | 484,343 Aug, | ... |2,318,724] ... | 213,110] Feb. | ... |2,801,183) ... | 426,356 Sept. | ... |2,242,829) ... | 193,304] Mar. | ... * «-- | 435,451 Oct. | ... |2,438,833] ... | 208,976] April} 171 |2,921,596, 189 | 433,665 Nov. | ... |2,262,912) ... | 326,315] May | ... 3,222,374] ... | 413,624 Dee. | 157 |2,700,186| 169 | 563,006] June | ... |2,875,565| ... | 333,116 1826. July | ... |2,921,754! ... | 373,325 Jan. | ... |2,763,869| ... | 503,617] Aug. | 172 |2,651,104) ... | 443,614 Feb, | ... |2,612,800| ... | 605,474} Sept. | ... |2,801,815] ... | 629,729 Mar. | ... 13,560,152) ... | 579,844] Oct. | ... 13,258,694) ... |557,110 April| ... |2,504,400} ... | 360,055] Nov. | ... 13,199,579) ... | 442,601 May | ...|2,781,242| ... | 282,815 The results of Tables IV. and IV’. afford the basis for the following monthly mean for the various mines, * No observations recorded for the months thus distinguished. in the Quantities of Water afforded by Springs. 293 Taste V. | Mean | | Mines. (Depth. ‘Fath’ Huel Rose! 86 |2,934,372!2,555,207|2,979,034 2,773,150|2,922,359|2,389,601 Huel Hope| 90 |2,672,268'2,658,524|2,976,395 2,728,614|2,657,176|2,481,20 Poldice.....| 156 |3,248,052)3,233,662|3,519,752 3,041,846)3, 156,908/2,882,16 Huel Reeth; 160 617,661) 559,848 600,701) 416,108) 390,972 338,421 January.|February.| March. | April. May.,| June. Oct. Nov. Dec. Huel Rose 86 |2,220,861 1,982,410)2,012,454 2,056,895/2,183,835 2,954,85 Huel Hope} 90 |2,206,094 2,084,932 1,940,218|2,033,555|2,972,956 2,463,44 Poldice....| 156 |2'852.875 2,633,499 2.453,085|2, 652,291/2,574,775 2,809.90 Huel Reeth] 160, "315,289 301,136, 522,284)” 370,549 429,489 \ July. | August. | Sept. From Tables IV. and IV*. we also obtain the annual re- sults contained in Tasie VI.+ Water. 1823) * 5 ic * 141 |37,361,088] 132 |6,206,189|53-705 1824, * * * i 147 |35,721,680) 149 |5,240,602/51-355 1825} 70 |24,717,645| * * 149 |35,772,864| 149 |4,819,280/40-135 1826) 77 |23,561,261| 74 |24,050,960) 159 |30,910,611| 169 |4,301,218)33-125 1827) 90 25,717,144] 77 |32,054,242) 162 |32,589,198] 169 |5,200,032/41-725 1828) 95 |33,487,188] 107 |32,645,018| 162 |38,185,210| 169 |6,193,176|54-97 1829) 108 31,808,118} 119 |30,851,118) 170 hraeeed | 182 |5,571,001/46-995 These results are obviously dependent on two causes of va- riation ;—first, the variable quantity of rain; and, second, the difference in depth at various times. , Having already discussed the former, we are enabled to use the data obtained in Table III., having nothing better to apply. Huel Rose and Huel Hope are compared, so far as possible, with United Mines, being in the same stratum; and where the observations on the latter do not extend, I make the comparison between the former and Dolcoath. Poldice is also brought to the standard of Dolcoath. Huel Reeth (in granite) is reduced to the ratio of Huel Damsel. + To complete this, 1 have been compelled to interpolate from Tables IV. 1V%, and V. 294 Tasie VII.* Mr. Henwood on the Variation of Springs. 1825 1824 1825 1826 1827 1828 Huel Rose. 1829 | 182 Dentt Galculates Quan. Difference} pt, ety ee Dath due to Increase] Water given ST yin Depa 4:, THEIL 70 | 24717,.645| |... 24,717,645 77 | 24,774,734 | —1,213,473 | 23,561,261 90 | 20,018,979 | +5,698,165 | 25,717,144 95 | 33,462,300] + 24.888] 33,487,188 108 25,673,994 | +6,134,124 31,808,118 103,930,007 |+-10,643,704 | 114,573,711 Huel Hope. 74 | 24,050,960 bes 24,050,960 i 21,001,506 |+ 11,052,736 32,054,242 107 30,608,477 |+ 2,036,541 32,645,018 119 | 26,934,069 |+ 3,917,049 | 30,851,118 78,544,052 |+-17,006,326 95,550,378 Poldice. 14] 37;361;088" [~~ “se. ee2 37,361,088 147 36,527,464 | — 805,784 35,721,680 149 | 33,773,533 | +1,999,331 | 35,772,864 159 33,851,539 | —2,940,928 30,910,611 162 35,176,823 | —2,587,625 32,589,198 162 40,562,178 | —2,376,965 38,185,210 170 36,599,233 | — 32,317 36,566,916 216,490,770 —6,744,291 209,746,479 Huel Reeth. 132 GO ZOG 189s! | VANE: | 6,206,189 149 6,171,920 — 931,318 5,240,602 149 6,195,905 — 1,376,625 4,819,280 169 6,376,406 —2,075,188 4,301,218 169 | 5,991,972 — 791,940 5,200,082 169 7,928,999 —1,735,823 6,193,176 8,098,514 = 2)527:513 | 5,571,001 40,763,716 —9,438,407 31,325,309 * For want of better information, I have assumed the effects of rain at all depths to be uniform ;—an assumption which | make without any in- tention to advance such an opinion, and which we have at present no sufficient knowledge either to confirm or disprove. in all the nines in this Table (VIL.), the whole of the first year’s results de- pend on rain, and no part thereof on rain.—T'his also is merely taken for granted, in order to compare the other values with one another. + When the observed quantities eaceed the calculated, I prefix the + It is also assumed that Mr. T. Andrews’s Chemical Researches on Cholera Blood. 295 The before-mentioned mines are selected merely because they afforded examples of the various results in the different strata of our mining districts. They appear to show, For Mines of which the Depths are constant : 1. That although the rain falling appears to exert, after a certain time, some influence on the quantity of water drawn out of mines, yet the amount of this effect is not in a direct simple proportion. 2. That although great differences in the quantity of rain appear to modify the quantity of water in mines, yet the va- riations so induced, sometimes disappear when the differences of rain falling are small. 3. The times elapsing between the maxima and minima of rain, and those between the maxima and minima of water in the mines, are often not identical; nor are they always the same for different mines. For Mines increasing in Depth: 4. From Tables IV. IV*. V. VI. and VII. it would appear; that in mines from 70 to 120 fathoms deep, the quantity of water is increased as the depth is augmented; but that in others of from 130 to 180 fathoms in depth, an augmented depth induces a diminution in the quantity of water. It is not my intention to insist on the universality of these inferences, which further investigations may, perhaps, show to be of but limited application. I regret that more pressing engagements at present forbid my entering further on the sub- ject, to which however I hope on another occasion to return, with other matter, which is now in a state of preparation. I have the honour to be, Your most grateful humble Servant, Perran Wharf near W. J. Henwoop. Truro, June 5, 1832. LIV. Chemical Researches on the Blood of Cholera Patients. By Tuomas Anprews, Esq*. (THE discordancies in the various analyses which have been published of the cholera blood, rendering it desirable that the subject should be again investigated with precision, I availed myself of the opportunity afforded by the prevalence of the epidemic in Belfast, to institute a new set of experiments. The first analysis of cholera blood that appeared in this sign to the numbers in this column; when the excess is on the othier side, the — sign. * Communicated by the Author. 296 Mr. T. Andrews’s Chemical Researches country is Dr. Clanny’s; from which, and a corresponding analysis of the blood in nesitn he inferred, that the water, as well as the albumen and fibrin, are deficient in quantity;. that the colouring matter, and what he denominates free carbon, are greatly in excess, and that the saline constituents are entirely wanting. Dr. O’Shaughnessy is the next chemist who turned his attention to the subject; but he seems_to, have confined himself principally to the serum, of which he has published a very elaborate examination. He found. its specific gravity increased in consequence of the deficiency of water, the animal matter considerably in excess, but a diminution of the salts, especially of the carbonate of soda,. which in one case was ene the serum being devoid of ac- tion on test paper. But the latest, and by far the most yalua- ble researches on cholera blood are those of Dr..Thomson, which, although they do not exhibit its true composition, yet furnish data from which it may be nearly calculated. He agrees with Dr. Clanny in the excess of colouring matter and deficiency of water, albumen and fibrin (but he confesses that the deficiency of the latter may be doubted) in the blood; while in the serum he found the albumen increased, but the. salts normal in amount and composition*. A few of these different results may have arisen from va- riations in the composition of the specimens of blood which were subjected to analysis; others can be referred only to errors of experiment ; but the principal source of them is the diversity of the modes of analysis which were followed. _ It is for this latter reason that I shall enter with more minuteness than might otherwise be necessary into the details of the fol- lowing experiments. Specimen 1. Cholera Hospital, Belfast——'This was ob- | tained from a rapid case of cholera; but I know nothing more of its history. The blood was taken from the vena cava immediately after death, and introduced into a vial, in which it afterwards coagulated. The serum was slightly tinged red, but perfectly transparent; the crassamentum was not in this case darker than it often appears in healthy blood. Their relative pro- portions were DPT MUM Eis ee ata “cht odbed mee 41°6 Crassamentum ...... 58°4 100:0 * An abstract of Dr. O’Shaughnessy’s results will be found in Phil, Mag... and Annals, N.S. vol. xi. p. 469: Dr. Thomson’s researches’ on cholera | fn blood were ‘published i in the same volume, p. 347. Eprt. ree on the Blood of Cholera Patients. 297 But as the serum was merely drawn off, these proportions do not admit of comparison with the healthy ratio of Berzelius. Serum.—Specific gravity 1038; had an alkaline reaction. $2°518 grammes of it were evaporated to dryness; and after being reduced to a coarse powder, dried till they ceased to lose weight on a warm bath, the temperature being prevented from rising too high by placing some shreds of cotton beneath the capsule containing the albumen. The dried mass weighed 4°078 grammes. This was now incinerated and washed re- peatedly with boiling water, which was evaporated to dryness, and the saline matter thus obtained calcined, and found to weigh *243 gramme, to which, adding :027 (obtained, as we shall hereafter mention), we have the saline matter soluble in water equal to ‘27 gramme. About ‘02 gr. of this matter was carefully examined to de- termine its nature. By spontaneous evaporation it yielded a set of crystals, which, examined by a microscope, proved to be principally cubes intersected by others of an acicular form. Two or three of the largest and purest of these cubes were dis- solved in water ; the solution had a strongly alkaline reaction, and was precipitated by nitrate of silver, the precipitate being soluble in ammonia. ‘The rest of the crystals were now dis- solved in a drop of water: pure ammonia was added to a mi- nute portion of it, and a faint cloud appeared, indicating the presence of phosphoric acid. The remainder of the solution was divided into two portions; to one of which tartaric acid was added, and to the other chloride of platinum. Evolution of gas took place in both cases; and in the one solution, nu- merous clusters of crystals (whose shape was a six-sided prism) appeared in a few seconds; while in the other a gra- nular deposit of octohedral crystals was soon formed. To the remaining *25 gr. of saline matter, chloride of bari- um was added in excess: a white precipitate fell, but the so- lution continued alkaline, and by evaporating it to dryness, a portion of insoluble matter remained, which had principally arisen during the evaporation, forming a thick crust on the surface of the liquid. The solution still continued slightly alkaline, and became opake on the surface. These experiments indicate the presence of uncombined alkali. The carbonate of baryta weighed and estimated for the whole saline matter was equal to ‘0972 gramme, equivalent to ‘0525 carbonate of soda. It dissolved with effervescence in nitric acid, leaving a residue of ‘012 of sulphate of baryta, equivalent to ‘008 of sulphate of potash. ‘The nitric acid solution was precipitated by ammonia, and prussiate of potash occasioned a faint white cloud. Third Series. Vol. 1. No. 4. Oct, 1832. 2Q 298 Mr. T. Andrews’s Chemical Researches In order to obtain the remainder of the saline matter from the incinerated mass, it was boiled in acidulated water, ‘050 gr. of saline matter was obtained, of which °027 gr. dissolved in water. ‘The remainder was dissolved in nitric acid and pre- cipitated by ammonia of a slightly red colour, then redissolved in nitric acid and precipitated by oxalate of ammonia; but I could not detect any magnesia in it, probably from the minute scale on which the experiment was performed. The serum therefore contained, VU REOR hoecta rey erterie eye hepato afer e thot! S 74959 AAbumen. 6% O%. we NeGeaday HM -~- 11640 Chlorides of sodium and _ potassium 6-69 with uncombined alkali. ..... ‘} Carbonate and phosphate of soda . . 1°36 Sulphate of potash. ....... Sb ‘25 Phosphate of lime... ....-... “71 1000°00 Crassamentum.—23'49 grammes were dried in the same manner as the albumen; they lost 16-472 gr. of water. ‘This water arose from the serum in the crassamentum, and must have been united, by its analysis, to 2°360 gr. of albumen and salts. Hence the crassamentum consisted of 18°832 serum, and 4°658 red globules and fibrin. 58°58 grammes of the same crassamentum were washed to separate the fibrin, but the process was very tedious; and after persevering for above a week, I did not succeed in ren- dering the fibrin perfectly colourless. It was dried at the same temperature as the albumen and crassamentum. It weighed °52 gr. and was of a dirty green colour. From these experiments the composition of the blood was, Water i i/9\s. She Rel BMS Albumen and salts ... 10°00 Red globules ...... 11°06 Bibb Ge BEA ca 51 100°00 Specimen 2. Cholera Hospital, Ballymacarrett.—This spe- cimen of blood was taken from a male patient (zt. 50), who had been seized with cholera the same morning, and died early on the following day. From the commencement of the attack he had passed involuntary stools, and vomited co- piously. The pulse was perceptible before he was bled, but afterwards became very faint and irregular. The blood flowed with difficulty, and was of a very dark colour and viscid consistence. It coagulated perfectly, the serum was on the Blood of Cholera Patients. 299 yellow and pure, and the crassamentum much darker and more bulky than usual*. Serum.—Sp. gravity 1:045; alkaline reaction ; taste saline, similar to healthy serum. 14°377 grammes of it were analysed in precisely the same manner as the preceding specimen. Its constituents were, Water 2 yldndenr cia Sieenttiwte vats 847°02 Albumen) pions. ea sremitos esos 144°36 Chlorides of sodium and potassium, 5-96 with fréealkaln’. S800 2. Meas Carbonate and phosphate of soda . . 162 Sulphate of potash. ........ “3 “22 Phosphate of lime with a trace of iron 82 1000:00 Crassamentum.—The blood weighed 77°94 grammes, and the crassamentum, with a considerable portion cf impure se- rum, 58:27 gr. The latter contained 47°604 gr. of serum, and 231 gr. of fibrin, of a buff colour and pretty pure. The composition of the blood was therefore, Water so 4,0¥) 46 ersiese 978K Albumen and salts ... 13°21 Red globules ...... 13°38 Fibrin... .. .,ailedit tie 2 *30 100:00 Specimen 3. Lunatic Asylum, near Belfast—This was taken from a female patient (at. 20) in the state of collapse, the radial pulse not being perceptible when the blood was drawn. It flowed in a continuous stream for a few seconds, but afterwards trickled with extreme difficulty. The patient died next day. The blood was black and thick; it coagulated as usual. Serum.—Sp. gravity 1040; of a pure yellow colour; 4°811 gr. left, by desiccation, *636 gr. of albumen,and salts. It con- tained therefore, WWater 2 6 6 SE One, 865'95 Albumen and salts... 134°05 1000:00 The saline matter was not weighed, but its solution was alka- line, and effervesced with acids. * In this, as well as in all the following cases, the blood was received into a vial, which was immediately closed. This precaution was necessary, as serum exposed to the air evaporates with great rapidity. 2Q2 300 Mr. T. Andrews’s Chemical Reseas‘ches Crassamentum.—The proportion of serum to craSsamentum was, M4 : 4 ’ Tah ht epracennay ae biipses 5 4OX TOR Crassamentum . » 595 100°0 But the same observation applies to this as to the former de- termination. The crassamentum contained 68°55 per cent. of water; it contained also ‘075 gr. of pure fibrin, equivalent to *26 per cent., the blood weighing 28°937 gr. Hence it consisted of, WV aCr a eee oe, ». 74°98 Albumen and salts ... 11°60 Red globules ...... 13°21 Lod es ae ear 26 100°00 Specimen 4. Lunatic Asylum.—This blood was drawn from the jugular vein of a female patient (at. 20), who had rallied from collapse for about a day by artificial excitement, the blueness having disappeared, and the natural warmth having been restored. The blood was obtained six hours after death. It did not coagulate, but the red globules subsided, leaving the serum yellow and pure. Serum.—Sp. gravity 1:040. 9°940 grammes of it were sub- jected to analysis, and found to contain, WV AEEY sci's.t. Seek 2S 986672 Albumen and salts. . . 133°28 1000°00 The saline matter was found to be about 1:2 per cent., but the experiment was not made with much precision: its solution in water was alkaline, effervesced with acids, and contained both potash and soda. The blood was found to contain, Wrater’: . % 0.7%. Pge 76:07 Albumen and salts ... 11°69 Red globules ...... 12°24. 100°00 There was no fibrin present. Having thus ascertained the composition of the blood in the severer stages of the complaint, I next proceeded to exa- mine it in the incipient stages. Two of the first specimens I procured were from the Cho- lera Hospital, taken from patients affected with diarrheea and on the Blood of Cholera Patients. 301 vomiting, but who afterwards recovered. I did not see them myself, and therefore cannot be certain whether they were real cases of cholera or not: the specimens resembled in every respect healthy blood. The sp. gravity of the serum of one was 1:0243, and of that of the other 1:0232. The latter was subjected to analysis ; it contained, Water cmts ot eseilevere cris 21999 Albumen’. (keine. - 71°62 Slaltsys rps maven ar-traes eens 8°39 1000°00 The serum was to the crassamentum in the ratio of 51:3 and 48°7, and the latter contained 74 per cent. of serum. Hence the blood was composed of, ALOT aie | Sion ag ie te, | s 80°35 Albumen and salts ... 6°99 Redjglobules ...». - 12°66 100°00 Specimen 6. Ballymacarrett Hospital—This was taken from a female (zt. 45), who had been affected with violent purging and vomiting. The pulse was feeble when the blood was drawn, but she did not fall into collapse. The blood co- agulated as usual. Serum.—Sp. gravity 1:031; very pure. It consisted of, Water igs iajeye apt, vee 2° B91 69 Albumen and salts... 108°31 1000:00 Crassamentum.—The fibrin in this case was determined by agitating a separate portion of the blood with a network of iron wire, and was thus readily obtained pure, and found to be 296 per cent. The blood contained, oh ge mt ein oY ef Albumen: . .vnganieiid dries 245 Bed globules ...... +. 12°34 OUD TID 15a nies sa B oni out *30 100°00 In three other cases of incipient cholera the serum was found to have the following specific gravities, Sp. gravity . 1:027 1°030 1°033 The last. was from a very well marked case. These experi- ments on the blood of incipient cases, though less numerous 302 Mr. T. Andrews’s Chemical Researches than I should have wished, seem to me to warrant the general conclusion, that the composition of the blood does not differ from the normal state during the early stages of the disease. | In order to show more clearly the changes induced in the blood by cholera, I shall collate the results of my own experi- ments with those obtained in the analysis of healthy blood. SERUM. Health. Cholera. Sp. gravity|Sp. gravity|Sp. gravity} ° 1°029. 1°038. 1°045. SE ec Ne arn el Ve tn oes eRe as 900°00| 874°59| 847°02 Albamen'? ss... - sonia Yad eet (a 90°80} 116°40| 144°36 Chlorides of sodium & potassium 6°60} 6°69} 5°96 Carbonate & phosphate of soda .| 1°65 1-36} '1*62 Sulphate of potash. ....... “35 “25 22 Earthy phosphates........ “60 71 "82 1000°00 |1000°00 |1000°00 The analysis of healthy blood is Dr. Marcet’s, which closely agrees with those of Berzelius and Lecanu. A glance at this table is sufficient to show that in the serum of cholera blood, the albumen is in great excess, but that the salts are both qualitatively and quantitatively the same, the minute differ- ences in their proportions being less than analysts have found in healthy blood*. Buioop. Incipient Cholera. Cholera. -—_—_-— 73:43 | 73°11| 74:93) 76:07} 80°35) 77:93 Albumen and salts} 10:00; 13°21} 11°60} 11°69} 699) 9:43 Red globules . . .| 11°06] 13°38} 13:21) 12:24) 12:66) 12°34 51 30 “26 30 * It may not be uninteresting to obstrve here, the striking analogy be- tween these conclusions and those of Dr. Marcet; who found in the ana- lysis of dropsical fluids, that however great the variation of albumen, the proportion of salts was invariably the same as in the serum of blood, on the Blood of Cholera Patients. $03 I shall venture to give one other table, because I believe its results have not been published in any English work, and they are essential to a correct knowledge of the composition of the blood. Female. Min. Max. Min. 85°31 79:04 80°53 77°36 Albumen and salts 8°74 6°72 9°23 6°68 Red globules and fibrin . .| 13:00 6°83 14°84 11°58 The variation in cholera blood from the healthy standard is not so great as is generally supposed. The water is not only in every case below the mean of healthy blood, but below the minimum in the experiments of Lecanu, and the albumen is proportionally increased. In the analyses of Prevost and Dumas and of Lecanu, the fibrin was not sepa- rated from the red globules, nor do I know of any experiment worthy of confidence on the amount of the former consti- tuent in healthy blood; it is generally estimated at about five per cent., but I am inclined to believe that it is not one tenth of that quantity. Indeed it is with diffidence that I publish the results I have obtained from cholera blood, as I am satis- fied that the process suggested by Dr. O’Shaughnessy is the only one susceptible of precision. It was, however, followed in the last experiment, and the results agreed with those ob- tained by the other method. Another source of fallacy is this; —that the temperature at which fibrin is decomposed seems much lower than that necessary to decompose other animal principles: but further experiments are necessary to elucidate this point. I shall only further observe, that in the heart from which the specimen No. 1. was taken, scarcely a vestige of fibrin could be discovered. But the most interesting and important fact derived from these investigations is, that, contrary to the conclusions of former experimenters, and apparently in direct opposition to the evidence of the senses, the colouring particles in black cholera blood exist in the same proportion as in the blood of health, varying not more than a half per cent. from the normal standard; and as a much greater diversity is found in the blood of different individuals in health, we must conclude that these slight variations are independent of, and unconnected with, its diseased state. These results differ very much from preceding analyses, but it will not be difficult to reconcile them with the experi- 304 Mr. T. Andrews’s Chemical Researches ments of Dr. Thomson. In order to separate the globules, * he merely washed the crassamentum (drained of its serum), and evaporated the solution thus obtained; but it is evident that in this way “a portion of serum containing albumen,” which could never be appreciated, varying with the bulk of the coagulum, “ would be added to the colouring matter, and have the effect of apparently increasing its quantity.” In one experiment, he found in this way the red globules to be 27-4 per cent.; while the albumen and salts only amounted to 5-9 per cent.: in another the red globules were 232 per cent., and the albumen 7°5. Fortunately, however, he has stated the water in the crassamentum, as well as its proportion to the serum, from which, and the composition of the serum, the re- lative proportion of the constituents of the specimens of blood which he analysed may readily be calculated as follows: Water “bo. 2s0a% oie o's 70°76). + 67:96 Albumen and salts... 13°53 . . 15°83 Red globules... ... 15°33 . . 14°87 PION) os 22% 1..0e) sisal Te SB.) 5°t US4 100°00 100:00 These results do not perfectly agree with my own experi- ments, but the coincidence is sufficient to confirm the deduc- tions which I have made from them. ‘The analysis of the se- rum by Dr. Thomson proves also that the salts are in every respect normal; and I cannot therefore avoid concluding that the experiments of Dr. O’Shaughnessy are inexact. Unless Dr. Clanny will publish with more detail the methods he has followed in analysing both healthy and diseased blood, it will be difficult to understand how he has arrived at his conclusions. It may be right, however, to observe, that the amount of re- sidual carbon obtained by calcining albumen, globules, or any proximate principle, will not depend on the organic matter itself, but on the salts, and especially on the phosphates which may be present; for these by fusing protect the carbon from combustion; but if they are previously removed, then. the ‘* free carbon ” of Dr. Clanny will speedily disappear by cal- cination even in a covered crucible. If these experiments and those of Dr. Thomson can be re- lied upon, the principles upon which the saline treatment is founded are evidently false. ‘To introduce a small quantity of inert saline matter into the stomach will certainly be as ineffi- cacious in the cure of diseases, as it is innocuous: but it is a question of very great importance to determine, whether the addition of a large portion of salts to the blood by infusion into the veins (introduced with an intention of supplying a on the Blood of Cholera Patients. 305 ‘deficiency, but in reality occasioning an excess,) may not only be not beneficial, but positively injurious. It is not improbable, that since so great a uniformity exists in the amount of saline ingredients in every variety of serous fluid, this quantity in the serum of blood may be essential to the due discharge of the functions of that fluid. An accurate examination of the blood in sea-scurvy might throw light on this obscure subject;. for either the exhibition of saline remedies is an absurdity, or the serum of a scurvy patient is overcharged with salts. In dropsy the blood is drained of a fluid containing a much larger quan-. tity of salts than the cholera evacuations (if the experiments of Dr. O’Shaughnessy on the latter be exact) ;—yet who will pre- tend to discover in such patients or in their blood any of those marvellous effects which have been attributed to the absence of these matters? The evacuations in cholera, containing little more than half the saline matter of the serum, ought to increase instead of diminishing its saline contents: but I do not doubt that if these evacuations could be obtained in the same state in which they are separated from the serum, and unmixed with other fluids, they would contain nearly the same proportion of salts which is found in it. There is one circumstance in- deed which renders it improbable that even if a deficiency of salts could occur, it would produce any very injurious effect : the serum of a bullock, resembling in every other respect that of man, contains (according to Berzelius) less than half its saline ingredients ; yet it is neither darker nor more diffi- cult of arterialization. But we must not hence draw a hasty conclusion, that either a deficiency or excess of salts in the blood would be harmless. The following are the general conclusions that appear to follow from these researches. That the only difference between the blood of cholera and of health consists in a deficiency of water in the serum, and a consequent excess of albumen. That the saline ingredients of the serum are the same as in healthy blood. That the red globules, and probably the fibrin also, are normal, That the want of fluidity in the blood, the darkness of its colour, and the bulk of the crassamentum, are simple effects of the increased viscidity of the serum. I am at present engaged in further researches connected with this subject; but conceiving these results to be of some immediate interest, I have been induced to publish them in this detached state. Third Series. Vol. 1. No, 4. Oct. 1832. oR [ 306 ] LV. Notice of the great Meteor seen on June 29th. By R. Epmonps, Jun. To the Editors of the Philosophical Magazine and Journal. Gentlemen, Ts E meteor of June 29th is spoken of by all in this neigh- bourhood who saw it, as by far the most sublime spectacle they have ever beheld. The weather for the last two or three days had been very sultry, with little or no winds or clouds. On the night of the 29th the sky was cloudless, and the air, in the lower regions of the atmosphere, almost motionless, the vane pointing nearly east. At eleven o’clock, while walking towards the west, in an open place near this town, a bright light suddenly shone around me. I instantly turned to my left, and at S.E. by S., at an elevation of between 30° and 40°, I beheld an intensely white ball of fire, nearly as large as the meridian moon, and taper- ing upwards into a tremulous or vibratory tail, eight or ten times longer than its greatest transverse diameter. The me- teor seemed to have no horizontal motion, but to be descend- ing very slowly and majestically in a perpendicular direction to the earth, at the distance of only a few hundred feet. Words can convey no idea of its sublimity. It was visible for ten or twelve seconds, and then disappeared, hidden, no doubt, behind an eminence about a mile from me. I conti- nued out for half an hour afterwards, but heard no report or sound of any kind proceeding from the meteor. Although the nights are now less dark than in any other part of the year, the eye could scarcely endure the excessive splendour. A gentleman, who happened to be looking in the direction of the meteor when it first appeared, and who was then tra- velling on a coach, twenty-five miles east of this place, over a plain bounded only by the horizon, and who consequently saw ita second or more both before and after myself, informed me, that at its first appearance it was in the direction already stated, at an elevation of about 40°; that it appeared very near, and to descend very slowly, without any horizontal mo- tion; that it was first of an intense blue colour, and of the size and form of an egg, with its smal] end upwards, accom- panied with a long luminous train, extending also upwards, and perfectly similar to the train of an ordinary shooting-star; that it soon lost the train, and became a vivid white ball of fire; that it then seemed to burst, or to expand into a round- ish but irregular form of a reddish hue, four or five feet in diameter; and finally disappeared, as if it had fallen to the earth, within the limits of the horizon. The gentleman with- Mr. J. Prideaux on the Meteor of June 29th. 307 drew his eyes for a second or two from the meteor, to observe the degree of illumination which it diffused, and he saw the wheel-tracks and little stones on the road, and the country around, as clearly as they could be seen by daylight. I consider the light shed by the phenomenon over this neighbourhood equal to that of a cloudless noon in December. From the above description, I conclude that the meteor must first have appeared in the S.E. by S., and have moved towards that point until it sank beneath the horizon; its ap- parent increase of size, and its redness en approaching the horizon, being explicable on the same principle that the moon seems so very large and red when near the horizon, compared with her appearance when southing. I find that the meteor has been seen in France. Iam, &c., Redruth, July 14th, 1832. Rp. Epmonps, Jun. LVI. Notice of the Meteor of June 29th ; and Inquiries rela- tive to certain Points in Magneto-Electricity. By Mr. Joun PRIDEAUX. _ To the Editors of the Philosophical Magazine and Journal. Gentlemen, (THE great meteor which appeared on the 29th ultimo, having been very differently represented from different quarters, and having excited attention through a wide range, 1 have collected as many particulars as could be gained, from a considerable number of observers in our own neighbourhood, and from the crews of vessels who saw more or less of it in their passage hither both from the east and the west. These particulars are transmitted to you, in the hope, that, making your Journal the focus, we may obtain a complete account of it; particularly of its descent, which must have been far to the southward, probably in the Bay of Biscay, if it cleared the French coast. On the day named, Friday the 29th ult., a large star ap- peared near the zenith, having extreme brilliancy, its light resembling that of lime under the oxy-hydrogen blowpipe. It passed quickly southward, enlarging as it proceeded, to a cir- cular disc approaching the full moon in size, and the sun in splendour, until within about 5° of the horizon, when ii ap- peared to expand till lost by extenuation, without sound. _ Its course was marked by a continuous train of light, dilating _ with its expansion, and generally about five or six times its diameter. ‘The entire form of this train is described as pyra- 2RY 308 Mr. J. Prideaux on the Meteor of June 29th; and on midal, or rather as resembling that of a long and narrow pa- per kite, with its tail completely inverted, so that the end of the tail was uppermost. ‘The time of its appearance was probably five or six seconds, though some persons estimate it to have been much longer. Many persons assert they saw it fall into the sea, with the production of vapour, bubbling, and a hissing noise. Three of these I have met with : one describing it as in Hamoaze; another just outside the Breakwater; and the third near the Lizard Point ;—a range of fifty miles. And as each declares it fell quite near him, their account is evidently re- ferrible either to alarm or to imagination. Here, and by vessels to the eastward, the point of its ap- proach to the horizon seems to have been observed nearly due south, some giving it easterly, some westerly declination. But none of those who saw it from about the Lizard, attribute to it any easterly declination. In such observations, casually made, and without instruments, we can put no confidence as to accuracy ; but being generally obtained from sailors, they are, I think, enough to justify the inference, that it was at a considerable distance to the southward. ‘The most complete view of it that has been reported to me, occurred to Captain Tozer, of the Navy, which has served to correct the exagge- rated statements of others, whose alarm or imagination was excited on witnessing only the latter part of its course. The Falmouth Packet newspaper says it was seen from the Scilly Islands to Melksham (Wilts). I have traced its ap- pearance from Buckfastleigh by land, and east of the Start by sea, to the Lizard Point; and, on the authority of Mr. Harris, northward to Barnstaple. You will probably find accounts of its having been observed much further in every direction. Its greatest splendour seems to have been at sea, where many were obliged to cover their eyes with their hands; and one man, east of the Start, thought his ship was on fire. Yours, &c., Plymouth, July 9th, 1832. JoHn PrIDEAUX. P.S. There is another subject on which I am still more de- sirous of information. It is stated, at sections 99, 100, 121 of Dr. Faraday’s Ex- perimental Researches, &c., just published in the Phil. Trans. Roy. Soc., that If the marked pole of a magnet be placed above a copper disc (fig. 15, 27), or the unmarked pole below it, or both, and the disc be rotated screw fashion (or with the sun, as it is expressed by sailors), currents of positive electri- city set off from the central parts in the general direction of the radii, by the pole, to the parts of the circumference on the certain Points in Magneto- Electricity. 309 other side of that pole: and these statements are corroborated by others. (Sect. 101, &c.) But Mr. Sturgeon’s plate, in your Number for July (fig. 16, 17), gives this current reversed, the other circumstances being the same; and the current the same, the rotation being re- versed. It is also shown by Dr. Faraday Sect. 220, 222), that a magnet held in the direction of the earth’s axis, unmarked pole up, and rotated with the earth, or unscrew, yields posi- tive electricity at its extremities, and negative at the centre; - and that a copper cylinder revolving round the magnet pro- duces the same result; and that the rotation being reversed, the electricities are also reversed. But in a plate of Mr. Sturgeon’s very commodious electro- magnetic apparatus (Ann. Phil. N.S. No. 12, p. 359), with an explanation, it appears that a magnet, unmarked* pole up (fig. 1), subjected to positive electricity at the centre (for in a single pair with a liquid the copper pole is so), and ne- gative electricity at the poles, immediately rotates screw or with the sun. And this is confirmed by fig. 8. of the same plate, where a copper cylinder, on the same pole, subjected to positive electricity at the pole, and negative below, rotates unscrew, or with the earth. Now according to the statement above, this rotation produces positive electricity at the pole; and the rotation of the magnet just described determines po- sitive electricity to the equator. In all other cases positive electricity repels positive and attracts negative; but here it produces, in both cases, those motions by which electricity of the same name is brought to the same point, instead of those which, by determining the opposite electrical state there, would have satisfied this attractive property. Even the repulsion pro- duced by the first few turns would seem likely to stop and revert the motion, yet no such thing occurs. If these cases have cost others of your readers so much per- plexity as they have me, a rationale from either Dr. Faraday or Mr. Sturgeon is a desideratum. . To the former gentleman I would also suggest the expedi- ency of creating a few new words, expressive of the various conditions of electro-magnetic circulation. There has seldom occurred a case in which they are more needed; and I need not point out to him geological and mineralogical synonymy as a vocabulary which has a great many to spare. * In that partieular magnet neither pole is marked; but the letter N being affixed to the marked and S to the unmarked pole of a horseshoe magnet on the same plate (fig. 8), there can be no doubt about their meaning in the figure in question, [ slo | LVII. On certain Irregularities in the Vibrations of the Magnetic Needle produced by partial Warmth; and some Remarks on the Electro-Magnetism of the Earth. By Rosert WERE Fox*. [\ prosecuting some inquiries relative to the intensity of the terrestrial magnetism, I have been not a little perplexed by the anomalous results which the vibrating needle afforded, especially when it was removed from one station to another ; and in order to ascertain the cause of these discrepancies, I instituted a series of experiments, some of which I shall ven- ture briefly to mention. I had a box made of sheet copper, leaving one side open, which was afterwards covered with glass for the purpose of observing the vibrations of a magnetic needle delicately sus- pended in it by unspun silk. This box, the glass side ex~ cepted, was inclosed in a copper case of much larger dimen- sions, with sufficient space between them to admit of my sur- rounding the former with water at any given temperature. The needle I employed was six inches long, and vibrated as follows :—With water at the temperature of 130°, it made 40 vibra. in 163’. Commenced with an arc of 90°, and ended with one of 28° 85 dee do. 163 do. 90% do. 30°5° 54 vee do. 163 do. 90 dos 4i31?, These results appeared to me to be at variance with the prevailing opinions of the influence of temperature on the vi- brations of a magnetic needle, and induced me to enter into further investigations of this subject. I next placed a wooden box, containing a needle ten inches long, on a heated block of granite, a thermometer having been put into the box to ascertain the temperature. At the tem- perature of 95°, it made 80 vib. in 510"-5. Arc at first 90°, & ended with24° 72 eye: OG +Dt pies 90 see 24 55 aan se 509 eve 90 +e 26'5 A box of slate containing a light needle, ten inches long, upon heated granite also. At the temperature of 85°, it made 30 vib. in 176"*5. Arc at first 40°, & ended with 9° 60 aes do. Lin ose pee lOs wee 13 A box of slate containing a heavier needle, nine inches and a half long, under similar circumstances. At the tempera- ture of * Communicated by the Author. : x d ! h é Mr. Fox on Irregularities in the Magnetic Needle. 311 120°, it made 80 vib. in 641". Arc at first 90°,&ended with16°5 104 ... do. 641°5 ee do. 2h 18 So IA dS: 641°5 at. do. AF 18 gare 3." ‘de: G44°25 vee do. ooo S4 A warm blanket was then thrown over the slate box in order to communicate warmth to its top and sides, the sup- porting granite being at 52°. At the temperature of 60°, it made 80 vibrations in 645!*5. Arc at first 90°, and ended with 38°. After the needle had been held a short time in the hand, in order to warm it, It made 80 vibrations in 642-2. Arc at first 92°, and ended with 22°. In these experiments it appears that the number of vibra- tions was mostly rather increased, and the ares diminished, when the bottom of the box, or the needle only, had its tem- perature augmented. When merely the sides of the box were warmed, the result was different; and when the heat was ap- plied as uniformly as possible to all parts of the box, the irre- gularities of the vibrations were less considerable than when the bottom of it only was heated; and merely touching the latter with the hand for a short time frequently produced con- siderable derangement in the action of the needle. The effects, however, were often so different when all circumstances ap- peared to be alike, that it seemed desirable to investigate the subject further. For this; purpose I suspended a very slender needle in a copper case, and placed the latter on supports in a basin, into which I poured warm water till it reached the bottom of the case. An extraordinary agitation of the needle then took place, its vibrations sometimes amounting to ten or fifteen degrees on each side of the meridian, occasionally stopping, and then starting again, and frequently shifting its centre of vibration backwards and forwards on either side of zero; and this mo- tion continued more or less, till the water’ had approximated to the temperature of the room. At first I fancied the agita- tion of the needle might be owing to electricity, but subse- quent observations have induced me to attribute it to currents of air, rapidly rising and descending in the box containing it. These effects were produced by any heated substances put under the needle, and at the distance of several inches, or even a foot, when the heated body was large; but when it was held above the box containing the needle, the influence was com- paratively inconsiderable. In the course of these experiments the needle was suspended in close boxes of metal, slate, and 312 Ps Mr. Fox’s Remarks on the Electro-Magnetism — paper, and in every instance it became affected as soon as the warmth had in any degree penetrated through the bottom of the respective boxes. When other substances, such as slen- der copper wire, paper, &c. were suspended like the needle, they also were agitated by slight changes of temperature ; but when the needle was inclosed in an exhausted receiver, it did not appear to be much, if at all, affected by heat. Hence it becomes manifest that the anomalies so often com- plained of in making experiments on the vibrations of the needle, may probably have arisen from the box having been partially affected by changes of temperature, produced, per- haps, by having been held in the hand, or by some slight change of position affecting the temperature of the box; and when observations are made in the open air, it is evident that the vibrations may be sensibly disturbed by solar heat, cold wind, and other causes. Indeed, I have found from repeated experiments, that when the needle is vibrated in the sun, the arcs become rapidly diminished, and the vibrations conse- quently increased in number; but in all cases of exposure to warmth, it appears that the vibrations and arcs are very ano- malous, depending, no doubt, on the direction in which the excited aérial currents act on, or strike the needle :—hence the discrepancies which occurred in my experiments above stated. It is therefore obviously important that the magnetic needle should be exposed as little as possible to fluctuations of tem- perature, and that it should be contained ina box made of wood, or of some other imperfect conductor of heat ; and for the same reason there would be an advantage in having the glass doubled. The needle itself should not be too light, and the cylindrical form will least expose it to being disturbed by currents of air. It is, however, evident, that no remedy can be so effectual as exhausting the air, which, when it can be con- veniently done, will add much to the value of experiments with the vibrating needle, and render all observations on the compass, in which great accuracy is required, more deserving of confidence*. It might, however, be unnecessary to exhaust the air, if the needle were suspended in a vessel surrounded with water, or nearly so, at a given temperature. Indeed it might sufficiently answer the purpose to have the top and bottom of the vessel or box, furnished with a double metallic * It seems that my friend W. S. Harris has for some time past been in the habit of using a vibrating magnetic needle suspended in an exhausted receiver; and I have very recently seen his apparatus, which appeared to me to be admirably adapted for making experiments on the terrestrial in- tensity. and Thermo-Magnetism of the Earth. 313 case to contain water, the sides being surrounded witha bad conductor of heat, except a space left to be covered with double glass, for the purpose of observation; for it appears from my experiments that the needle is not much affected by a change of temperature at the sides of the box only. It has till within a very recent period been generally as- sumed that the earth’s magnetism is owing to a central mag- net, notwithstanding the incongruity of many facts with such an hypothesis. Indeed, if we admit the existence of intense heat in the interior of the globe, we have every reason to be- lieve that magnetism cannot exist there; since it appears, that neither the loadstone nor steel can retain it at a high tem- perature, and that iron at a white heat loses its power of at- tracting the needle. The discoveries of Oersted and Seebeck have, however, laid the foundation of juster views of this interesting subject, and many difficulties vanish when the phenomena of the earth’s magnetism are referred to the circulation of electrical currents around it. This hypothesis, which was first suggested by Ampere, appeared to me to derive strong confirmation from the stratification of rocks, the arrangement of metallic and other veins, the high temperature which in a greater or less degree prevails under the surface of the earth, and its rota- tion on its axis, possessing as they seemed to do, many ana- logies to electro-magnetic, and thermo-electric combinations. I was consequently led to suspect the existence of free electri- city in metalliferous veins, and was not disappointed *. If we take a glance at the map of the world, we perceive that it consists of two grand divisions of land, and two of water, alternating with each other, from east to west. This curious arrangement seems to bear on the point in question, as well as the difference of temperature found generally to exist between the eastern and western sides of great conti- nents; the lines of minimum temperature may possibly coin- cide with those of no variation; at least this point seems to deserve investigation when opportunities, occur. The direction of the electrical currents under the earth’s surface may be greatly diversified; this may be inferred from ‘my experiments on the electricity of metallic veins+. But the facts I have referred to, especially the rotation of our planet from west to east, and the solar rays acting in a contrary di- rection, would induce us to suppose that the currents, taken col- * In some lead-mives in Flintshire, where the temperature is low, I could not detect any free electricity. Was this fact owing to their being situated in horizontal strata ? + See Phil. Trans. 1830, p. 400, &c. Third Series. Vol. 1. No. 4. Oct. 1832. 25 814 Mr. R. Brown’s Remarks on the Structure lectively, must have a prevailing tendency; and it follows from the direction of the needle, that this tendency, as it respects the positive currents, must be from the east, more or less towards the west. i It appears that the ores themselves, in some instances, possess opposite thermo-electric properties. The sulphurets of lead and of copper, for example, when partially heated in a very moderate degree, yielded positive electricity to the less heated part; whereas in the case of sulphuret of iron, it was yielded from the latter to the former. When two of these ores were respectively placed in contact with each other at different temperatures, the sulphuret of lead was always po- sitive with respect to the other two, whether it was at a higher or lower temperature than they were; and the sulphuret of copper was, when heated, positive with regard to iron pyrites, but negative when the temperature of the latter was the greater. In some instances the nature of the electricity be- came reversed before the heated ore had entirely cooled; this occurred when lead or copper ore was placed in contact with iron pyrites at an inferior temperature. These different thermo-electric properties of metallic sub- stances seem to throw some light on the cause of opposite currents in mineral veins, and are, perhaps, connected with the periodical variation of the needle. Several observations have been made in the mines of Corn- wall on the intensity of the earth’s magnetism, from which it is to be inferred, that if at the greatest accessible depths it differ at all from the intensity at the surface, the difference is very inconsiderable, and that therefore the principal source, or cause of the terrestrial magnetism, must be far removed from us, so far indeed as to require powerful electrical cur- rents to produce the effects observable at the surface. LVIIL. Remarks on the Structure and Affinities of Cephalotus. By Rozert Brown, Esq. FBS. Sc. * N the Botanical Appendix of Captain Flinders’s Voyage to Terra Australis, a figure and description of Cephalotus fol- licularis are given, in some respects more complete than those of M. Labillardiére, by whom this remarkable plant, a native of the south-west coast of New. Holland, was first published. Both accounts, however, are equally imperfect with regard to the fruit; and my principal object in the present communica- tion is to supply that deficiency. My earliest knowledge of the ripe fruit of Cephalotus was * Communicated by the Author. and Affinities of Cephalotus. 315 obtained from a single specimen, sent in 1815 by M. Le- chenault, who had found the plant in February 1803 near the shores of King George’s Sound, where I had gathered it in a less advanced state in the beginning of January 1802. I have, however, more recently, received numerous speci- mens with ripe seeds from Mr. William Baxter, who collect- ed them also at King George’s Sound in 1829, Cephalotus was introduced in 1823 from the same place by Capt. King, into His Majesty’s Botanic Garden at Kew, where it flowered repeatedly, and ripened seeds from which several plants have been raised. A figure of one of these with expanded flowers, but still without fruit, has lately been pub- lished by Dr. Hooker in the Botanical Magazine ; and a plant brought also from King George’s Sound in 1829 by Mr. Wil- liam Baxter is now in flower in Mr. Knight’s nursery. The following account of the ripe fruit will serve as a sup- plement to the description of the plant which I have given in the work referred to. AKENIa membranacea, insecta parva alis conniventibus quo- dammodo referentia, perianthio partim aucto staminibusque persistentibus cincta, iisque sesquilongiora, feré distincta, ipsa basi, ubi receptaculo communi inserta, post separationem in- tus aperta ibique € membrana simplici crassiusculd imberbi nitente formata; supra clausa et é duplici membrana conflata; barum exterior densé barbata, pilis longis, strictis, acutis, de- flexis, stylo persistenti brevi arcte reflexo rostrata: membrana seu lamella interior tenuis, intts quandoque dehiscens. SEMEN unicum (rarissimé duo), basi cavitatis membrane interioris insertum, oblongo-ovale, teres, funiculo umbilicali brevi juxta basin affixum. Jntegumentum duplex : Testa mem- branacea laxiuscula, raphe tenui laterali et apice chalazd parva insignita: Membrana interior tenuis separabilis. Albumen semini conforme, album, carnosum, subfriabile, ¢@ materia oleosa cum granulis minutis mixta constans. Empryo parvus, in basi axeos albuminis, teretiusculus, al- bus, rectus, albumine 4—5ies brevibr. Cotyledones breves, plano-convexee. adicula teres, basin seminis attingens. RecerpracuLUM COMMUNE fructus: tuberculum centrale, parvum, brevissimum, subcylindraceum, cujus lateribus bases apertee akeniorum adnate sunt, apice convexiusculo barbato. From this description, especially of the embryo, it is evident that Cephalotus must be removed from Rosacez, to which it had been referred by M. Labillardi¢re; and also, though not with much confidence, in the account which I published in 1814. M. de Jussieu, indeed, in 1818, proposed to exclude 202 316 Mr. R. Brown’s Remarks on the Structure it from Rosacez and append it to Crassulacez ; and the struc- ture of the seed, as well as of the folliculi or akenia, and even their insertion on the minute central receptacle or axis, may seem to confirm the correctness of this approximation. Cephalotus, however, still appears to me sufficiently remote from every natural order at present established, to entitle it (like Philydrum * and Brunonia+), now that its structure is completely known, to rank as a distinct family which may be called CePHALOTE®, and which may be placed between Cras- sulacee and Francoacee ; differing from both in being apeta- lous, in the valvate zestivation of the perianthium, and in many characters of inferior importance: from Crassulaceze also in its minute embryo and more copious albumen; and from Francoacez in the absence of barren stamina and in the pis- tilla being monospermous and apparently distinct. The most striking peculiarity of Cephalotus consists in the conversion of a portion of its radical leaves into Ascidia or pitchers. But as ascidia in all cases are manifestly formed from or belong to leaves, and as the various parts of the flower in Phzenogamous plants are now generally regarded as modifications of the same organs, the question is naturally suggested, how far the form and arrangement of the parts of fructification agree in those plants whose leaves are capable of producing ascidia or pitchers. ‘The four principal, and in- deed the only genera in which pitchers occur, are Nepenthes, Cephalotus, Sarracenia, and Dischidia, and the few other somewhat analogous cases, consisting of the conversion of bracteze or floral leaves into open cuculli, are found in Marc- gravia and two other genera of the same natural family. The only thing common to all these plants is, that they are Dicotyledonous. It may also be remarked, that in those genera in which the Ascidia have an operculum, namely Nepenthes, Cephalotus, and Sarracenia, they exist in every known species of each ge- nus, and the structure of these genera is so peculiar that they form three distinct natural families ; while in Dischidia, whose pitchers are formed without opercula, these organs are neither found in every species of the genus, nor in any other genus of the extensive natural order to which it belongs. The striking resemblance in most points of the Ascidia of — Cephalotus to those of Nepenthes, leads to a comparison in the first place of these two genera. But although both are apetalous, and in the parts of the flower deviate from the qui- nary or prevailing number in Dicotyledones, yet they differ * Flinders’s Voyage, vol. ii. p. 578. ¢ Transact. Linn, Soc. yol. xii, p. 132. _ ae ‘ : ; and Affinities of Cephalotus. 317 in so many other important characters that they cannot be considered as nearly related. The place of Nepenthes in the natural series I have long since*, in my account of RafHlesia, suggested to be near Ari- stolochiz or Asarinz, without, however, intending to include it in that family. This approximation was adopted by M. Ad. Brongniart, who, however, went further, having absolutely referred Nepen- thes to Cytinez. The union of plants so utterly unlike in appearance and ceconomy, and so different, it may be added, in many of their most important characters, seems to have been generally re- garded as somewhat paradoxical ; and accordingly Professor Link, in 1829, has established. Nepenthes as a section or tribe of Aristolochiz, and Dr. Bartling and Mr. Lindley, in 1830, have considered it as forming a distinct natural family. To the numerous and obvious distinctions between Cytinez and Nepenthes may be added the no less important differences in their internal structure. For while Cytinew, like most, perhaps all, other plants parasitical on roots, are destitute of spiral vessels, Nepenthes exhibits these vessels in the greatest degree of development and abundance, and also produces them in parts in which they are hardly to be met with in any other dicotyledonous plant. Thus, in addition to the dense circle or stratum of spiral vessels existing in the stem between the outer parenchyma and the wood, they are found also singly or scattered in the pith, in the loose parenchyma situated between the wood and the bark, if it may be so called, even in the fibres of the root, and everywhere in the substance of the leaves, the pitchers, calyx and capsules. And between these solitary or scattered spiral vessels, which are often of considerable length, and those forming the stratum or circle externally bounding the wood and existing in the veins of the leaves, no essential difference in structure will I believe be found. In these points there is little resemblance between Nepenthes and Cephalotus, in the internal structure of which last there is nothing unusual. Between the parts of fructification of Nepenthes or Cepha- lotus and Sarracenia, there is still less analogy, and it is ob- viously unnecessary to compare in this respect any of these genera with Dischidia. September 25th, 1832. * Transact. Linn. Soc. vol, xiii. p, 219. f 318 J LIX. Account of an Experiment in which part of the infextok of the Eye is exhibited by Reflection in the Lye-glass of a Telescope*. raya ue account of Dr. Purkinje’s experiment in the Septem- ber Number of the Philosophical Magazine has induced me to record the following fact, which bears some analogy to it, and which has been too often remarked and too carefully examined to admit of any doubt as to the circumstances. - Being in the habit of occasionally looking at the sun through a very fine and powerful achromatic telescope, I have fre- quently been unable to distinguish the spots, being per- plexed by what appeared the reflection of some part of my own eye, interposed between it and the sun; and this, whe- ther the eye approached the telescope as closely as possible, or was withdrawn to some little distance. I could not believe that it arose from the eye becoming dazzled by the light, because it was capable of bearing a much intenser application and far stronger glare without fatigue, and of looking immediat-ly from the object in question to the white paper on which I delineated it. On reading the passage in Sir D. Brewster’s communication, as above, p. 173, I immediately recollected, that though three differently coloured glasses had been used for the sun, it was * Communicated by the Rey. T. J. Hussey. Intelligence and Miscellaneous Articles. 319 only with one transmitting a reddish brown orange tint that I had been annoyed by this reflection; to render the descrip- tion of which more intelligible, I have made the sketch from several distinct observations taken for the purpose. The number of the reflections never varied; there were five appa- rent, one behind the other, the one in front, and the upper part of the second, being the brightest, the others growing gradually more indistinct: they were perfectly circular, except at the upper edge to the left, where the outline was rather broken by two dark spots. Instead of appearing dark relieved by the light as a ground, they were exactly vice versd, looking like a bright film composed of silver ramifications*, the dark spots seeming like holes with strongly illuminated margins; and the pattern of the ramifications never changing. It was not till I had been induced to scrutinize the appear- ance more attentively, in order if possible to ascertain what it was I really did see, that I perceived in advance of the five bright circles a sixth, like a small dusky cloud+. I could never distinguish any ramifications upon it; indeed the very outline was so slightly defined that I did not attempt to represent it on paper; but there it always was, only disappearing when I looked against the side of the tube: this the bright ones did not do immediately,—they faded gradually away. ‘These reflec- tions were most visible when the whole field was filled with the sun; when only a small part of the disc was in it, they disappeared, or nearly so. The orange-brown tint always shone through the silvery films, or rather between the ramifications of the network. A.M. H. Hayes, Sept. 1832. LX. Intelligence and Miscellaneous Articles. ON THE TRUE SOURCE OF THE AMNIOTIC ACID OF VAUQUELIN (ALLANTOIC ACID OF LASSAIGNE): AND ON THE IMPORTANCE OF OBTAINING COMPARATIVE ANALYSES OF THE ALLANTOIC FLUID, AND THE URINE OF THE YOUNG ANIMAL AFTER BIRTH. a8 Dr. Thomson's Inorganic Chemistry (vol. ii. p. 167), the Am- niotic acid of Vauquelin and Buniva is described under the appellation of Allantoic acid, upon the authority of Lassaigne. The chemist last named, it appears, examined, three successive times, * The dark outline of course did not appear; it is merely used in ‘the drawing because the circles could not otherwise be defined. The drawing supposes the whole field of the telescope filled with the sun. + The bright ones showing through it. ‘320 Intelligence and Miscellaneous Articles. the fluids contained inthe amnios and allantois of the cow; and al- ways found the acid in question in the fluid of the latter membrane, but never,in that of the former. He concluded from these results, that the allantoic fluid had been given for analysis to Vauquelin and Buniva: instead of the amniotic, and changed the name of, the acid accordingly.. At present, therefore, our knowledge of the true source of this acid rests upon the authority of Lassaigne alone. But it is always desirable that new facts should not rest upon the testimony of a single observer, however deservedly high may be his reputation; and as the existence of strong independent, though partial evidence, in favour of Lassaigne’s conclusions, has apparently been overlooked by that chemist (as well as by Dr. Thomson, though published in the journal formerly conducted by himself), it may be useful to draw the attention of chemists tothe subject. This seems the more requisite, because the authority of Dr. Prout, by whom the confirmatory evidence has been furnished, is so valuable upon a point of this nature, on account of his minute acquaintance with the animal fluids, and his practical skill in their examination; and because, also, the authors of several of our systematic treatises on ‘Chemistry (Dr. Henry and Dr. Turner for example,) have not no- ticed Lassaigne’s revision of the subject, but have retained the amniotic acid, as such, in the sections on animal chemistry of their respective works. In 18]5 Dr. Prout published, in the Annals of Philosophy (First Series, vol, v. p. 416), an account of his examination of the dzquor amnii of a cow. His attention, he states, in this examination, was particularly directed to the principle found in that fluid by Vau- quelin and Buniva, and called by them amniotic acid, but that he could not, however, discover the least traces of a similar principle. This negative result, therefore, confirms those of Lassaigne, who, as above stated, could never find the acid in the fluid of the amnios. Further evidence, however, is derivable from Dr. Prout’s paper, in confirmation of Lassaigne’s opinion that the fluid examined by Vauquelin and Buniva was truly that of the allantois. Dr. Prout states that the fluid he examined differed very considerably from that described by them, in its sensible qualities, as well as in its chemical ones; and although he ascribes this dissimilarity to the circumstance that his was taken from an animal slaughtered in an early period of her gestation, while theirs, most likely, he observes, was procured at, the full period, it is evident that the existence of differences so great is far better explained, by the supposition, that Vauquelin and Buniva in reality examined a different fluid, or at least one which did not wholly consist of liquor amnii. A com- parison of the results obtained by Vauquelin and Buniva with those of Dr. Prout, tends rather to indicate that the fluid examined by them consisted of the mixed fluids of the amnios and allantois, than that it was the allantoic fluid alone, as supposed by Lassaigne. Thus, the liquor amnii examined by Dr. P., as well as the fluid examined by the former chemists, gave a copious white preci- _ pitate with muriate of barytes ; both contained an organic sub- _ stance soluble in alcohol, and both also yielded a substance pre- Intelligence and Miscellaneous Articles. $21 cipitable by alcohol. The mixture of the fluids might easily occur from the rupture of the membranes. I give this opinion, however, without being aware how far the examination of the allantoic fluid by Lassaigne, (except as to its containing the acid, ) may agree with that of the supposed amniotic fluid by Vauquelin and Buniva. Again: the agreement between the results of Dr. Prout’s ‘analysis of the Ziguor amnii of the cow, and those of Vauquelin and Buniva’s analysis of the corresponding fluid of the human subject (respect- ing the origin of which, of course, no mistake could have occurred), may be adduced in support of Lassaigne’s opinion. According to these analyses, the two fluids agree in the following circumstances (in which, at the same time, they both differ from the alleged am- niotic fluid of the cow examined by Vauquelin and Buniva): In colour, smell, and taste, they evidently belong to the same class of fluids ; their differences, in those respects, being no greater than always exist between the corresponding products of animals ge- nerically different; while they agree in containing minute float- ing particles apparently caseous, in foaming when shaken, in partial coagulation by heat, in the action of acids, and in containing albumen and salts of soda: Dr. Prout, likewise, found sugar of milk in the fluid of the cow; while Vauquelin and Buniva observed that alcohol threw down from that of the human subject a light precipitate, which, when dry, became brittle and transparent like glue,—characters which would be assumed by slightly impure sugar of milk, in this mode of operating. Another corroboration of Lassaigne’s results may be deduced from the situation and functions, respectively, of the amnios and the allan- tois. The latter, receiving the urine of the foetus, would more proba- bly contain a fluid of an acid nature than the former; indeed, it would seem that the contents of the allantois could not but be acid ; while there is no apparent reason why (in animals provided with the latter membrane) the Auid of the amnios should have any considerable degree of acidity. The analogies (which are considerable) connecting the allantoic with the uric acid, seem further to corroborate the same view of the subject : the urine of the cow, like that of other herbivorous Mammalia, does not contain uric, but benzoic acid; but the urine of the foetal calf, however, we might reasonably expect, since the nourishment it re- ceives is altogether animalized, (though produced from the vegetable food of the cow,) would contain some principle analogous to uric acid. If this notion be correct, we should expect to find allantoic acid in the urine of the calf while it receives nourishment by sucking, and perhaps that the benzoic acid (since the milk is devoid of that princi- ple) would not appear until it begins to graze. It may be requisite here to anticipate an objection which might aise, on the ground that the urine of the Mammalia taking animal food ex- clusively, does not contain uric acid. That fact might be supposed to invalidate the inference, that the urine of the foetal and of the sucking calf (since the animal, in those states, receives animalized nutriment alone,) ought to contain some principle analogous to uric acid. But among the Mammalia, those species only appear to secrete uric acid Third Series, Vol. 1. No, 4. Oct. 1832. 2T 322 Intelligence and Miscellaneous Articles. which are omnivorous, or at least such as take food of a mixed nature ; and this exactly accords with the nature of the calf's nutriment, as derived from the slightly animalized fluids of an exclusively herbivo- rous animal, either as supplied to the foetus, or in the form of milk. If the. above reasoning be correct, and if the allantoic acid be really derived from the foetal urine, the subject appears to acquire a degree of importance which has not hitherto attached toit. It would be very desirable to ascertain whether the acid is also contained in the urine of the young animal after birth; and a series of compa- rative experiments on the allantoic fluid, and on the urine of the young animal, while sucking only, while it both sucks and grazes, and after lactation has entirely ceased, ia all the Mammalia in which the allantois exists, might lead to important results, relative to the functions of the foetal urinary system, and perhaps also to the qua- lity. and process of formation of the foetal blood. It may be remarked, in relation to this subject, that great additional benefits would be con- ferred upon physiology, if the attention of the Committee of Science of the Zoological Society,—the investigation of the comparative ana- tomy of various animals by whom, has already thrown so much light on the relations of tneir minute anatomical structure to their re- spective stations in nature, as well as on their physiology in general, —were extended to the performance of experiments on the contents of the animal fluids. The cow, the mare, and the ewe, iz all which the allantois is found, are readily accessible ; but the collection of the Zoological Society consists, principally, of animals, which not being ebjects of rural or commercial ceconomy, cannot often furnish sub- jects for investigation by the animal chemist, but peculiar facilities for researches on which are presented by that Society’s establish- ment. With respect to the source of what has hitherto been called am- niotic acid, it may be said, perhaps, that the repeated experiments of Lassaigne are amply sufficient to determine the point ; but as it would appear, from the silence on the subject of Mr. Brande, Dr. Henry, and Dr. Turner, that his results are not generally received or attended to by chemists in this country, the foregoing remarks upon it may not be superfluous. Sept. 22, 1832. E.W.B. OBSERVATIONS OF THE TRANSIT OF MERCURY, ON MAY 5, 1832, MADE AT HULL, BY MR. J. D. SOLLITT. External ingress, or beginning of the transit, . . 4% 20" 59™ 1s BhtemalAngressychios od) ..76) HyTSR UAT RO Horry vDy ogra At 22" it became thick and rainy, and remained so during the rest of the day. The above observations are for Mean Time at Hull. Latitude of the place of observation, . . . . 53° 45" 57'N. Longitudetin'time 's.° 2) Jenn oy Cre. 1! OT OW. Hull, June 26th, 1832. Be Biter Intelligence and Miscellaneous Articles. 323 AN EPHEMERIS OF THE STARS PROPER TO BE OBSERVED WITH MARS, AT THE ENSUING OPPOSITION OF THAT PLANET. [We transfer the following to our pages, from the Supplement to No. 11. of the Monthly Notices of the Astronomical Society, on ac- count of the importance of the object contemplated by the Astronomer Royal at the Cape, and in order to give additional publicity to the Ephemeris itself. The latter is now given from October 11th to November 7th; and the corresponding portions for November and December will appear in our Numbers for those months. } Previous to Mr. Henderson’s departure for the Observatory at the Cape of Good Hope, (to which he has recently been appointed Astro- nomer, in the room of the late Rev. Fearon Fallows) *, he expressed a wish that a selection might be made of such stars as would be proper and convenient to be observed with Mars, at his ensuing opposition in November next ; with a view to the determination of the parallax of that planet; and that a list of the same should be circulated amongst different astronomers in various parts of the world, for the purpose of obtaining corresponding observations, Mr. Sheepshanks having furnished the apparent places of Mars (together with the semidiameter and horizontal parallax) for each day during the requisite period, Mr. Baily selected the stars agreeably to Mr. Henderson's wishes: and the Council of this Society, desirous of promoting, as much as lies in their power, an object which, if actively and properly followed up, may be attended with much advantage to the science of astronomy, have caused the same to be printed and circulated. The positions of Mars are the apparent geocentric places (cor- rected for aberration) at mean midnight at Berlin; deduced from the Berlin Ephemeris, using 5th differences in the computation. The positions of the stars also are their apparent places on the day of transit: Mr. Sheepshanks having furnished the daily corrections for precession, aberration, and nutation. These stars are selected in such manner that there may always be a sufficient interval of time between the transit of the star and the planet, to enable the observer to read off the divisions of the circle or micrometer; except in a few cases when they are both in the field of the telescope at the same time, or so nearly on the same parallel that one setting of the instru- ment will be sufficient for both observations, with the aid of a mi- crometer. Mr. Henderson requests that, when both limbs of Mars. cannot be conveniently observed on the same day, the northern limb should be observed on the odd days, and the southern limb on the even days of the month: as a guide to the observer, this is denoted by the letters. N and S inserted in the column of magnitudes. Also, that the transit of the second limb should be observed prior to the day of opposition, and the transit of the first limb after that day: this is denoted by the figures 1 and 2 annexed to Mars. * See our Number for September, pp. 237, 242.—Enir. zi"? 324 Intelligence and Miscellaneous Articles. Aldebaran should be observed on every night when the planet is observed. Those astronomers, who are possessed of good equatorial instru- ments, may take repeated measures of the difference of declination between the selected star and the planet on the same night: noting, however, the times at which the observations were made, a The Ephemeris is extended from October 11th to December 25th, for the purpose of including the stationary points of Mars, both in right ascension and declination. The star (38) 4rietis is to be found in Piazzi’s catalogue: the small stars (a) (6) (c) are taken from Lalande’s Histoire Céleste, page 33. The star (4) is the brightest, the most northerly, and the second of two stars that are distant from each other about 2' in de- clination; and between which Mars will pass on November 17th. For this, and for two or three other proximate stars, the wire micro- meter might be advantageously used in determining the difference of declination. The places of the larger stars are taken from the cata- logue of this Society, and the constants there given are used in the reductions. The following are the assumed mean places, on January 1, 1832, of the 10 stars selected for the comparisons ; viz. Star. | Mag.| Mean AR. |Mean D. Noth. } | | | h m s ot a a (38) Arietis 8 /3 11 12,37 | 19 53 50,48 65 6 14 44,87 | 20 12 9,87 * Tauri (a) 9 29 15,55 | 20 21 45,62 F! 67 2 38,01 | 19 9 23,82 32 —— 6 46 56,77 | 21 59 18,00 si (4)| 8 47 20,25 | 20 49 44,88 Al —— 5 54 46,12 | 21 36 55,94 51 —— 7 \|4 8 26,98 | 21 9 43,42 53 —— 6-7 9 32,03 | 20 43 44,60 * (c)| 8 16 21,2 21 4 53,84 Other quantities, used in the computations, are the following : viz. Sun's horizontal parallax = 8",578 Mean semidiameter of Mars = 4 ,790 Constant of aberration —=b493°,|2 Berlin, East of Paris = 44™ 1256 —#—— of Greenwich = 53 34,1 *.* Mr. Henderson was also desirous that some stars should be — selected for observing the parallax of Mars in right ascension; agree- — ably to the method pointed out by Lalande, in his Astronomie, vol. ii. — page 281: since Mars will be favourably situated, at the ensuing opposition, for such observations in the northern hemisphere, But there are no stars, near the path of the planet at that time, of sufficient — magnitude for such purpose. * Intelligence and Miscellaneous ‘Articles. 325° Apparent Place. Semidiameter. |, ini 1 1832. Stars. Mag.) Raf { Right Ascens. | Declin. North.| In time.| In arc. |. h mos Oi} Ane ; wid Oct. 1153 Tauri 6.7\4 9 34,69 |20 43 48,0 * (c)) 8 16 23,9021. 4 56,7 = +: i Mars? N 29 59,23 |20 36 55,1 | 0586 8,22 14,71. , 1253 Tauri 6.7|4 9 34,71|20 43 48,1 B 3 * (c))..8 16 23,92 |\2b 4 56,8 F Mars? iS) 22 59,00 |20 39 22.5) .590 8,28 | 14,82 fe 1353 Tauri | 6.7/4. 9 34,74|20 43 48,1 : is (e)| 8 16 23,95 |21 4 56.8 Mars? N 22 59,07 |20 41 44,0) -594 | 834 | 14,92 1453 Tauri 6.7 |\4: 9 34,7620 43 48,2 4 (c)) 8 16 23,97 |21 4 56,8 Mars? 8 22 55,40 |20 43 59,6} -599 | 8,40 15,03 } 1553 Tauri 6.7 |4 9 34,78 120 43 48,2 i (c)| 8 16 23,99|21 4 56,9 Mars? N 22 47,94|20 46 9,3| -603 | 8,46 | 15,14 1653 Tauri 6.7 |4 9 34,81 |20 43 48,3 * (e)} 8 16 24,02/21 4 57,0 Mars? Ss) 22 36,66 |20 48 12,9) 607 | 8,51 15,24 17/53 Tauri 6.7|4 9 34,83 |20 43 48,3 ig (c)} 8 16 24,04|21 4 57,0 Mars? N 22 21,55 120 50 10,4) °612 | 8.57 | 15,34 1853 Tauri 6.7 |4 9 34,85 |20 43 48,4 id (c)| 8 16 24,07 |21 4 57,1 Mars? NS) 22 2,59|20 52 1,7) 616 | 8,63 | 15,44 1953 Tauri 6.7|4 9 34,87 |20 43 48,4 ‘a (c)| 8 16 24,09 |21 4 57,1 Mars? N 21 39,77 |20 53 46,2) -620 | 8,69 | 15,54 20.53 Tauri 6.7|4 9 34,90 |20 43 48,5 * (c)} 8 16 24,11 /21 4 57,2 Mars? Ss 21 13,09 (20 55 24,0) -624 | 8,74 | 15,63 21153 Tauri 6.7|4 9 34,92|20 483 48,5 * (c)| 8 16 2414/21 4 57,2 Mars? N 20 42,55 |20 56 55,0} 628 | 8,79 | 15,73 2253 Tauri 6.7|4 9 34,94 |20 43 48,6 * (c)) 8 16 24,16/21 4 57,3 Mars? Ss 20 8,18/20 58 19,1] -632 | 8,84 | 15,83 23.53 Tauri 6.7|4 9 34,96 |20 43 48,6 * 8 16 24,18 /21 4 57,3 Mars? N 19 30,01 |20 59 36,3] ‘636 | 8,90 | 15,93 2453 Tauri 6.7|4 9 34,98 |20 43 48,7 * (c)| 8 16 2420/21 4 57,4 Mars? Ss 18 48,06 |21 0 46,3) +640 | 8,95 | 16,02 25\53 Tauri 6.7|4 9 35,00 /20 43 48,7 lad (c)} 8 16 24,22/21 4 57,4 Mars? N 18 2,39/21 1 49,1} :643 |} 9,00 | 16,12 326 Intelligence and Miscellaneous Articles. | eae abe ee Apparent Place. Semidiameter. Hor, | Right Ascens. | Declin. North. | In time. | In are. : heim eta ° Les aike/) Oct. 26,51 Tauri 6.7/4 8 29,99/21 9 47,6 * (c)) 8 16 24,25|21 4 57,4 é My i} Mars? S 17 13,06/22 2 44,4) 0°647.| 9,05 | 16,20 27/5) Tauri 6.7/4 8 30,01/21 9 47,6 Mars? N 16 20,15 |21 3 32,1} +650 | 9,10 | 16,28 * Tauri (c)} 8 16 24,27 |21 4 57,5 2851 Tauri 6.7/4 8 30,03|21 9 47,6 Mars? Ss 15 23,73 /21 4 11,9} +653 | 9,14 | 16,35 * Tauri (c)| 8 16 24,29|}21 4 57,5 29/51 Tauri 6.7/4 8 30,05|21 9 47,7 Mars? N 14 23,89 |21 4 43,9] -656 | 9,18 | 16,42 * Tauri (¢)|, 8 16 24.31/21 4 57,6 3051 Tauri 6.7\4 8 30,07|21 9 47,8 . Mars? Ss 13 20,74/21 5 7,8] 659 | 9,22 | 16,49 * Tauri (c)| 8 16 2433/21 4 57,6 31/51 Tauri 6.7\4 8 30,09|21 9 47,8 Mars? N 12 14.38/21 5 23,8) -661 | 9,26 |16,56 Nov. 1 }A! Tauri 5 [3 54 49,28 /21 37 1,3 Mars? N 4 11 4,93/21 5 31,7| -664.| 9,29 | 16,62 Y} 2)A2 Tauri 5 |3 54 49.30/21 37 1,4 Mars? S j4 9 52.50/21 5 31,4} -666 | 9,32 | 16,67 3)/A) Tauri 5 |3 54 49.31/21 37 1,4 Mars? N 4 8 37,25121 | 5 22.9) “668 | 9,35 |'16,72 4A? Tauri 5 |3 54 49,33|/21 37 1,5 Mars? S |4 7 19,30)21 5 6,2} -670 | 9,38 | 16,77 5A? Tauri 5 |3 54 49,35 /21 37 1,5 Mars? N /4 5 58,81|21 4 41,2) 671 | 9,41 | 16,81 6)A! Tauri 5 |3 54 49,36/21 37 1,6 Mars? S (4 4 35,92|21 4 7,8} 673 | 9;43°116,84 7|A) Tauri 5 |3 54 49.38/21 37 1,6 Mars? N |4 3 10,81/21 3 26,3] -674 | 9,45 | 16,87 53 Tauri 6.7 9 35,25 |20 43 49,2 SEPARATION OF THE OXIDES OF LEAD AND BISMUTH. BY M. LIEBIG. When nitrate of lead or of bismuth is boiled with carbonate of lime, magnesia, or barytes, these salts are decomposed, and the oxides are so completely precipitated that hydrosulphuret of ammonia shows no traces of them in the solution. Carbonate of lime, when added to a cold solution of these metals, precipitates only the oxide of bismuth. Several methods have been proposed for separating the Jead which is contained in the bismuth of commerce ;_but carbonate of lime, used in the mode now stated, is preferable to them.—Ann., de Chim. et de Phys. tom, xlviii, p. 290. Intelligence and Miscellaneous Articles. $27 OCCULTATION OF SATURN, OBSERVED AT GENEVA. This phenomenon, which tock, place on the 8th of May, was ob- served by M. Gautier with the Dollond’s telescope described in the last Number of Phil. Mag. p. 246. The same clock was used, but it was now only three seconds and a half fast. hm s Entrance of ring behind the moon.... 9 44 20 First contact of the planet’s disc... ... 9 44 34 End of the planet’s entrance ........ 9 45 28 End of the ring’s entrance.....-.... 9 45 58°5 End of the emersion .............. 10 47 10 At the end of the emersion, M. Gautier observed that the light of Saturn was then singularly pale and of a grayish-green colour, ** from the effect of the lustre of the illuminated limb from which the planet emerged.” — Bzbl. Univ. April 1832. NEW PROCESS FOR OBTAINING MORPHIA, M. Ant. Galvani has proposed a new method of obtaining mor- phia directly from opium, free from narcotine :—Evaporate to the consistence of an extract a spirituous solution of opium ; then, by successive solutions and filtrations, separate all the resinous matter of the extract, which separates the narcotine from the morphia: long ebullition with calcined magnesia,—a series of filtrations, and wash- ings and dryings, yield very pure morphia, free from narcotine. When the resinous matter is dissolved in dilute sulphuric acid, and the solution decomposed by potash, the narcotine is precipitated, which is purified by a fresh solution in sulphuric acid and precipi- tation by ammonia, and this often, after filtration, washing and re- dissolving in alcohol of 0-903, crystallizes. A pound of opium yielded by this process 8 drachms of perfectly pure white crystal - lized morphia.— Ann. de Chim. et de Phys. tom. xlviii. p. 297. LUNAR OCCULTATIONS FOR OCTOBER. 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LONDON ann EDINBURGH PHILOSOPHICAL MAGAZINE AND JOURNAL OF SCIENCE. [THIRD SERIES. ] NOVEMBER 1832. LXI. Observations on some remarkable Optical Phenomena seen in Switzerland; and on an Optical Phenomenon which occurs on viewing a Figure of a Crystal or geometrical Solid. By L. A. Necker, Esq. Professor of Mineralogy at Geneva. 5 In a Letter to Str Davip Brewster. 1 My Dear Sir, Pi - ] MUST not delay any further fulfilling my promise of : writing to you, respecting the subjects of our conversation ' in the too short moments I had the very great pleasure and _ good fortune of seeing you in London. Iam the more bound to write soon, as my first object must be to correct a wrong ' statement in the date of my observation of the parhelia, as __ stated in my letter to Mr. Forbes (Edinb. Journal of Science, ‘ No. 12. p.251.). As this mistake, into which I was led by __ trusting too much to my memory, and to some wrong infer- ences, has had the effect of weakening some circumstances ' which were in favour of your explanation, I am the more an- | xious to do it all justice, so that you may be in time to ans nounce in your next Number the consequences of this mis- _take, for which I beg leave to apologize to you, to Mr. Forbes, and to your readers, whom I have unwillingly led into error. The true date of the day when I saw the parhelia, was the 1st of June 1830, as I observe by the little memorandum I kept of this remarkable, and to me entirely new pheenomenon,—and not the middle of July, as I stated in my letter, written from memory in Edinburgh. Here I transcribe the whole note, together with the little sketch which it contains. Third Series. Vol. 1. No. 5. Nov. 1832. 7U wee Se ee ' Vo! 33 OR A-0¢ v 330 Prof. Necker’s Observations on some remarkable Parhelia seen the Ist of June 1830, from 53 o’clock p.m. till sunset at 74 o’clock, represented in the most complete state, as I saw it at 6 o’clock :—S is the sun; EADC the inner halo, which was much the brightest; C and E the two lu- minous images or mock suns; FG the outer halo, which was Jura Mountain. Hill of Pregny. weak, and seen only for a few moments, as well as the inverted arch H. All the various points of these arches were not equally distinct at the same moment as they are represented here. On the contrary, when the image or mock sun at the right hand, C, was strong, the one at the left hand, EK, was pale, or did not appear; such was the case at the beginning of the apparition. At the end, the left image, E, was very lu- minous and coloured, shining with prismatic colours; while the right image C was less visible, and sometimes altogether wanting. ‘The strength of illumination of the various parts of the halo was constantly variable. Often certain portions, sometimes very considerable, entirely disappeared, and af- terwards reappeared again. A little before the sun had set, the only part visible was that between A and B, and it was vividly lighted and coloured, and reflected by the lake; at the same time the single point C was also shining brilliantly, coloured with iridescent colours. At the moment of sunset, there remained nothing but a small arch in D. The phe- nomenon ended almost immediately after the sun had disap- peared behind the Jura at 7" 20". All this time the parts Optical Phenomena seen in Switzerland. $51 of the sky situated to the west and north-west were hazy, and with some little clouds; while the eastern and southern parts were perfectly pure and clear, and the chain of the Alps quite pure and bright. The very rough and inaccurate sketch is a copy of the one which I made rapidly at the time, to preserve the memory of the fact. I well know that the halos and arches must be por- tions of perfect circles, and parallel to each other; but it be- ing easy to make this correction in the mind, I preferred giving the thing as I sketched it in haste two years ago. Iam happy now to be able to give accurate information about the state of the atmosphere in the day itself of the phzenomenon, and in the days preceding it, by referring to the meteorological tables of the Bzbliotheque Universelle, to which you may look for more particular details. I see that on the 24th of May 1830, the thermometer of Reaumur had stood be- tween 10° minimum and 20°8 maximum; then came rain ; and by my notes I see that snow fell on the 25th on the Jura, which was melted on the 26th. On the St. Bernard (1278 toises above the level of the sea), the 24th of May, the temperature was between +2° R. minimum, and +8° R. maximum, when rain fell, and the thermometer on the 25th of May descended to —0°2 R. minimum, and +4°5 R. maximum. On the 27th and 28th of May, snow fell on the St. Bernard, and the tem- perature decreased till the 29th of May, when it was so low as to reach —6°1 R. minimum, and +4°°5 maximum. On the 30th of May it had risen again to —4°8 R. minimum, and +5°-4 maximum; and on the $lst to —1°1l minimum, and +5°*7 maximum: so much for the temperature of the high parts of the atmosphere at the St. Bernard. During the same time, in the lowland at Geneva, since the rain of the 25th of May, the thermometer had gradually lowered till the 30th of May, when it had attained +3°-2 R. minimum, and +15°4 R. maximum. On the 31st of May it had already risen to + 10° R. minimum, and +14°4 R. maximum. Now on the Ist of June 1830, the day of the parhelia, the thermometer at Geneva was between + 3°°5 R. minimum, and +17°3 R. maximum. The last must have been nearly the tem- perature during the phenomenon in the plain. At the St. Bernard on the same day, the thermometer was between —$°6 KR. minimum and +9° R. maximum. ‘This last temperature may give an idea of that of the atmospheric strata at 1000 toises above Geneva, at the time of the parhelia. The whole day was serene and cloudless at the St. Bernard. At Geneva it was likewise so, except in the afternoon, when a thin mist or haze, and some light clouds, appeared in the west. 2U2 332 Prof. Necker’s Observations on some remarkable From the combination of all these circumstances, it remains not unlikely, nay, even probable, that icy particles may have been floating in those light mists which gave rise to the par- helia, if we suppose their height to exceed a good deal that of 1000 toises above Geneva, or 1280 toises above the level of the sea. Although mistaken in my former statement of the epoch on which the parhelia took place, considering that June, though not the hottest, as I said of July, is at least a hot month of our summer, that the occurrence of a parhelion in that season, and in such a latitude as ours (46° 12! N, lat.), is a very rare thing, and that by the knowledge we have been able to get of the meteorological circumstances attending such a phzeno- menon (circumstances which I do not believe have been men- tioned in similar accounts of parhelia),—we are able to form an idea at least of the minimum of height at which the refracting medium causing the parhelia must have been placed. I do not regret to have drawn your attention to this fact, which, instead of militating against, will rather tend to corroborate your ideas as to the necessity of supposing minute crystals of ice to explain the phenomenon. I now come to the point which you particularly wished me to describe to you: I mean the luminous appearance of trees, shrubs and birds when seen from the foot of a mountain, a little before sun-rise. The wish I had to see again the pha- nomenon before attempting to describe it, made me detain this letter, a few days, till I had a fine day to go to see it at the Mont Saleve; so yesterday I went there and studied the fact, in elucidation of which I made a little drawing, of which I give you here a copy: it will, with the explanation and the annexed diagram, impart to you, l hope, a correct idea of the pheenome- non. You must conceive the observer placed at the foot of a hill interposed between him and the place where the sun is rising, and thus entirely in the shade; the upper margin of the mountain is covered with woods, or detached trees and shrubs, which are projected as dark objects upon a very bright and clear sky, except at the very place where the sun is just going to rise; for there all the trees and shrubs bordering the mar- gin are entirely, branches, leaves, stem, and all, of a pure and brilliant white, appearing extremely bright and luminous, although projected on a most brilliant and luminous sky, as that part of it which surrounds the sun always is. All the mi- nutest details, leaves, twigs, &c. are most delicately preserved, and you would fancy you saw these trees and forests made of the purest silver, with all the skill of the most expert work- man. The swallows and other birds flying in those parti- ee i eT Rs i ee nee ee ‘Optical Phenomena seen in Switzerland. 333 cular spots appear like sparks of the most brilliant white*. Unfortunately all these details, which add so much to the beauty of this splendid phenomenon, cannot be represented in Fig. 2. such small sketches. Neither the hour of the day, nor the angle which the object makes with the observer, appears to have any effect ; for on some occasions I have seen the phenomenon to take place at a very early hour in the morning. Yesterday it was 10 o'clock a.m., when I saw it as represented in fig. 1. I saw it again on the same day at 5 o’clock p.M., at a different place of the same mountain, for which the sun was just setting. At one time the angle of elevation of the lighted white shrubs above the horizon of the spectator was about 20°; while at another place it was only 15°. But the extent of the field illuminated is variable, according to the distance at which the spectator is placed from it. When the object behind which the sun is going to rise, or has just been setting, is very near, no such effect takes place. In the case represented, fig. 1, the distance was about 194 metres, or 636 English feet, from the spectator, in a direct line; the height above his level being 60 metres, or 197 English feet, and the horizontal line drawn trom him to the horizontal projection of these points on the plane of his horizon being 160 metres, or 525 English feet, as will be seen in the following diagram, fig. 3. In this case only small [* This appearance seems to be connected with that assumed by flying birds when seen, under certain circumstances, through a telescope, during observations on the sun, and which, it has been alleged, has occasionally been mistaken for that of small meteors seen_in the day-time: see the next two pages.—Epir.] 334 Prof. Necker’s Observations on some remarkable shrubs, and the lower half of the stem of a tree, are illumina- ted white, and the horizontal extent of this effect is also com= paratively small; while at other places when I was nearer the edge behind which the sun was going to rise, no such effect took place. But, on the contrary, when I have wit- O S 5 8 = RX, hy gi. feet Ae o YY YYyYy Yyy YY act \ & Yj YD iif, zs A [Mn mntbintiasaican =S 1000 metres, or 3281 Engl. feet. S. Apparent place of the sun. T. Tree illuminated white. M. Spectator. nessed the phenomenon at a greater distance and at a greater height, as L have seen it other times in the same and in other mountains of the Alps, large tracts of forests and immense spruce firs were illuminated white throughout their whole length, as I have attempted to represent in fig. 2. and the corresponding diagram, fig. 4. Nothing can be finer than these silver-looking spruce forests. At the same time, though at a distance of more than a thousand metres, a vast number of large swallows or swifts (Cypselus alpinus), who inhabit those high rocks, were seen in the shape of small brilliant stars or sparks moving rapidly in the air. " From these facts, it appears to me obvious that the extent of the illuminated spots varies in a direct ratio of their distance; but at the same time that there must be a constant angular space, corresponding, probably, to the zone, a few minutes of a degree wide, around the sun’s disk, which is a limit to the occurrence of the appearance: this would explain how the real extent which it occupies on the earth’s surface varies with the relative distance of the spot from the eye of the observer, and accounts also for the phanome- non being never seen in the low country, where I have often looked for it in vain. Now that you are acquainted with the circumstances of the fact, I have no doubt that you will easily observe it in some part or other of your Scotch hills: it may a en ee eae Optical Phenomena seen in Switzerland. 835 be, some long heaths or furze will play the part of our alpine forests; and I would advise you to try to place a bee-hive in the required position, and it would perfectly represent our swallows, sparks or stars. I now only wonder that such a phenomenon, which must necessarily take place in every mountain of the earth, every day and at every hour of the day when the sun shines, should never have been noticed before. I now come to another subject which you also desired me to mention: I mean the varying colours exhibited by Mont Blanc during and after sunset. Lord Minto was perfectly right in the account he gave you of these appearances. But he may have omitted some circumstances which will assist in leading us to an explanation of these varying appearances. I shall here state the facts in the order in which they appear. When the sun is near setting, and the weather is serene, all the mountains of the Alps, facing the west, are tinged with a fine purplish hue, which on Mont Blanc, on account of its bright covering of snow, takes a tinge more verging towards a light orange. When the sun has set for the plain, these mountains appear more vivid and more illuminated, by the effect of contrast. When, some minutes after, the lower mountains are in the shade, their purple hue is changed into a dark blueish tinge, the contrast between their shaded parts and those that were lighted by the sun has disappeared, and an almost uniform grayish blue shade covers them all; at this time Mont Blanc remains the only terrestrial object still lighted by the rays of the sun, and that circumstance causes its immense mass of snow to appear more bright, and its yel- lowish orange colour more vivid: at the same time the con-~ trast between the projected and other shadows and the lighted arts is at its maximum (I have two or three times seen pe Blanc at that moment, and when dark clouds were be- hind it, look almost as bright and red as a live coal). When, however, the sun has set for Mont Blanc, which happens about a quarter of an hour after it has set for the plain round Geneva, then the whole of Mont Blanc assumes a dull blueish white hue, and a flattened appearance, owing to the absence of contrast from the once shaded parts with those that were lighted. And so its new aspect is to that which it offered afew minutes before, like that of a dead body to a living and healthy one. ‘This pale and, as it were, morbid appearance of the mountain is owing to the fact, that above it exists still a wide zone of atmosphere loaded with thin and light vapours, for which the sun has not yet set, and which on that account are still lighted vividly, and coloured with a purple hue. When, 336 ~—- Prof. Necker on an apparent Change of Position however, the sun has also been setting for these higher re- gions of the atmosphere, the contrast between their illumina- tion and the shade existing all over Mont Blanc, to which was owing that blueish and deadly colour assumed by the eternal snows, having ceased to take place, the Mont Blanc assumes once more, but in a much fainter and darker manner, its orange yellow colour; and the lower and nearer moun- tains recover their purplish hue. All the objects then being uniformly and altogether illuminated by the much paler and less powerful light of the twilight, as they were before all lighted at once by the brighter, but equally uniformly spread, light of the sun; so that every thing being placed in the same relative quantity and quality of illumination as before, an analogous aspect is seen in both cases, though much darker under the latter than under the former circumstances. Hence it appears to me that the whole of the phanomenon is most naturally and easily explained by contrast. The object I have now to call your attention to, is an ob- servation which is also of an optical nature, and which has often occurred to me while examining figures and engraved plates of crystalline forms: I mean a sudden and involuntary change in the apparent position of a crystal or solid repre- sented in an engraved figure. What I mean will be more easily understood from the figure annexed. The rhomboid AX is drawn so that the solid angle A should be seen the nearest to the spectator, and the solid angle X the furthest from him, and that the face ACBD should be the foremost, while the face X DC is behind. But in looking repeatedly at the same figure, you will perceive that at times the apparent position of the rhomboid is so changed that the solid angle X will appear the nearest, and the solid angle A the furthest; and that the face ACDB will recede behind the face XDG, which will come forward; which Wa Ds effect gives to the whole solid a quite con- /| trary apparent inclination. I have been Ly / a long time at a loss to understand the reason of the apparently accidental and involuntary change which I always witnessed in all sorts of forms in books of crystallography. The only thing I could observe was, that at the time the change took place, a parti- cular sensation was felt in the eye (for it takes place as well when seen with only one eye, as with both eyes), which proved to me that it was an optical, and not merely as I had at first thought a mental, operation which was performed. After, how- ever, a more attentive analysis of the fact, it occurred to me, that it was owing to an involuntary change in the adjustment B D = in a Drawing or engraved Figure of a Crystal. BEI of the eye for obtaining distinct vision. And that whenever the point of distinct vision on the retina was directed on the angle A, for instance, this angle seen more distinctly than the others was naturally supposed to be nearer and _fore- most; while the other angles seen indistinctly were supposed to be further, and behind. ‘The reverse took place when the point of distinct vision was brought to bear upon the angle X. This solution being found, I proved that it was the real one by three different ways. Ist, By being able at my will to see the solid in which posi- tion I chose, and to make this position vary at pleasure, in looking alternately, with fixed attention, either to the angle A, or to the angle X. 2ndly, While looking steadfastly to the angle A, and seeing the rhomboid in its proper position with the angle A fore- most, if without moving either the eye or the figure, I made a convex lens (such as is used in spectacles for long-sighied- ness,) pass gently from below upwards between the eye and the figure, at the instant when the figure was visible through the glass, the change had taken place, and the solid had assu- med the apparent position in which the angle X was the fore- most, and that only because, owing to the refraction through the glass, the image of the angle X had come to take the place of the real angle A, and so the point of distinct vision, with- out being at all moved, had by this means come to bear on the angle X, or rather on its image. 3rdly, If through a hole made with a pin ina card you look at the figure in such a manner that either the angle A or the angle X be hidden, the visible angle will determine the appa- rent position of the solid, so that this angle will always appear the nearest; it will be impossible to see it in any other way, and consequently there will be no change. What I have said of the solid angles is equally true of the edges,—those edges upon which the axis of the eye or the central hole of the retina are directed will always appear for- ward; so that now it appears to me certain that this little, at first so puzzling, phenomenon, depends upon the law of di- stinct vision. You surely will draw from all the above communications, many consequences which my ignorance of the subject pre- vents me from anticipating. You may do what you think most proper with all these observations. I remain, my dear Sir, with the kindest regard, Eyer most sincerely yours, Geneva, May 24, 1832. L. A. NEcCKER. Third Series. Vol. 1. No. 5. Nov. 1832. 2X [ 338 j LXII. Some Facts which appear to be at Variance with the Igneous Hypothesis of Geologists. By Roperr W. Fox*. say speculations respecting the origin of rocks, and the confidence with which their existing arrangements are sometimes attributed to the agency of fire, induced me to en- deavour to ascertain their expansion when heated; and the following are the results of the few experiments I have made. Pieces of granite increased in bulk when raised to a dull red heat between ,jth and ,4th part; and contracted on cooling to their original dimensions. I did not detect any difference in these respects whether the granite was measured in the direc- tion of its cleavage, or at right angles to it. At a full red heat decomposition commenced, and vitrification at a white heat. Porphyritic felspar, from an “ elvan course,” heated to red- ness, expanded =, to ;1, of its original dimensions; to which it again contracted on cooling. Different specimens of clay-slate were augmented in size, in the direction of their cleavage, 3; to ;4, by a heat scarcely visible in the dark in some instances, and by a full red in others; and when cooled, some of them were found to be per- manently enlarged to nearly one half of the extent of the ex- pansion the heat had produced. I could not clearly ascertain the expansion of slate at right angles to its cleavage, from its liability to split, but I think it was less considerable. Greenstone, at a red heat just visible, increased ,, or there- abouts, and contracted back to nearly its previous bulk when cooled. Serpentine, however, underwent no expansion in any direction that I could appreciate, even when the heat was raised to a full red. If, then, any of the rocks which are expanded so much by great heat, had their origin from irruptions of matter in igneous fusion, ought they not to abound with fissures in every direction, or at least to afford evidence of their having once existed in them, independently of other contiguous rocks ? ‘This consequence seems to follow from their different expanding and contract- ing properties, even without adopting the hypothesis of various epochs of formation. Such evidences, however, do not exist in Cornwall at least; but, on the contrary, our mineral veins, as is well known, traverse all the rocks without any necessary change in their size or direction. There are, it is true, frequent in- stances of the thickness, and other characters of veins being altered in passing from rocks of any given denomination into those of another ; but if in some cases they become enlarged, in others it is the reverse, so that no rule can be laid down in this respect. Besides, there is far too great a conformity in the * Communicated by the Author. Facts at Variance with the Igneous Hypothesis of Geologists. 339 direction of the veins containing similar substances, in any given district, to admit of their being referred to the con- traction of the rocks which inclose ‘them. ‘The large * elvan courses,” or porphyritic dykes, which abound in Cornwall, are even more remarkable than the veins for a considerable de- gree of parallelism; and their inclination from the perpendi- cular in descending is greater and more uniform, it being mostly towards the N.W. Mineral veins having, however, the closest affinity to each other, as it respects their contents and horizontal bearing, are very commonly found to separate widely in descending at angles of 30° or 40°, and upwards; whereas other veins which cross them at large angles at the surface, and consequently in their descent also, for the most part differ entirely in their contents. ‘These well-ascertained points are scarcely less op- posed to the hypothesis of veins having originated from fissures resulting from the shrinking of the rocks, which would in- volve their contemporaneous formation in the same rock, than the indisputable fact I have heretofore referred to,—that the contents of veins change with the rocks they traverse. It may, moreoyer, be well to mention that veins commonly possess the same general appearances in valleys as in the contiguous hills ; and not only do they not exhibit symptoms of having over- flowed, but in both situations the metalliferous veins are in general equally furnished with “ gossan,” or other foreign matter overlying the ore*. It has been urged, that mineral substances do not suffer de- composition or vitrification by heat when under great pres- sure. It is not necessary to inquire whether there be sufficient proof to establish the correctness of this conclusion, because it can hardly be asserted that such great pressure could have existed at or near the surface, or in the fissures resulting from the contraction of the rocks. Open fissures, or cavities, are frequently found in some me- talliferous veins, and very rarely in others of equal or greater thickness. The yellow sulphuret of copper, crystallized oxide of tin, and other metallic, as well as earthy combinations, which are found in these cavities, and are easily affected by heat, give no indications of its having ever existed even ina slight degree. Other facts and arguments might be adduced. But are not those I have alluded to sufficiently decided to show that the hypothesis of the igneous origin of rocks cannot be maintained * How does this fact accord with the assumed denudation of the valleys? [Is not this query too general ? Surely it is demonstrable that some valleys 1ave been formed by the process of denudation, however true it may be that that mode of formation has been ascribed to others by assumption merely,—Epir, } 2X2 340 Mr. Nixon on a Repeating Circle, by which any Multiple without creating greater difficulties than it tends to explain? If so, surely it ought to be discarded from the science of geo- logy, although no other hypothesis may be substituted for it. Geologists have sometimes carried their speculations so far as to refer the spheroidal form of the earth to its having once been a mass of plastic matter in igneous fusion or aqueous so-~ lution, its present shape being due simply to the operation of mechanical principles. But these appear rather to militate against the assumption, because the rocks, instead of being parallel to the equator, have their prevailing stratification at considerable angles to it in various parts of the world: more- over, the proportion of land to the water between the tropics exceeds that which is near the poles, and the specific gravity of the rocks is equally great; whereas, on mere mechanical principles, the most fluid and lightest matter ought to accu- mulate near the equator, and the heaviest near the poles. If their arguments be founded on the adaptation of the earth’s form to the rate of its daily revolution,—in which of the works of the great Creator is there not the most perfect and wonderful adaptation to the end designed? And if it can- not be denied that in the beginning it existed in things the most minute, I see no ground for imagining that this great globe, with which the existence of animal and vegetable life is so in- dispensably connected, should present a solitary exception. Many of the operations in nature, and the laws which re- gulate them, may, to a certain extent, be comprehended by man; and the more they become developed, the more beauti- ful and harmonious they appear: but we cannot find laws to apply to the original organization of the earth, or the things which it contains. The distinction is important in every point of view; and it is surely more useful and instructive to accumulate facts and observations upon the actual state of things and their mutual relations, and to deduce from them such conclusions as expe- rience and analogy may justify, than to hazard conjectures, and puzzle ourselves about questions which probably are, and ever will be, out of our reach. LXIII. Description of a Repeating Circle, by which any Mul- tiple of an Altitude may be measured from one Observation by the Telescope. By Joun Nixon, Esq.* GEVERAL years ago the late Mr. James Allan constructed for me a repeating circle, designed originally for the mea- surement of (oblique) terrestrial angles, which, when mounted * Communicated by the Author. ee, ae oe of an Altitude may be measured by one Observation. 341 with an additional level, and fixed in a vertical position, would serve not only to take an altitude, but also to obtain, after the completion of one, single observation, any multiple of the angle. With the aid of the front view of the circle, fig. 1., and the horizontal section through its axis (fig. 2.), its con- struction, and the method of using it, may be briefly described. W is an eleven-inch wheel, furnished with an axis D, which projects about three inches beyond each surface of the wheel C, a ten-inch graduated circle, of which the hollow axis E moves about the front part of the axis of the wheel. H, H are two opposite verniers, fixed on the wheel, by which the divi- sions of the circle are read off to 10". P is an immoveable seule) plate, twelve inches in diameter, having a hollow axis *, in which the back part of the axis of the wheel is fitted and revolves. The two-foot achromatic telescope T, carrying a spirit-leyel U, rests with its cylindrical rings within two Ys, 342 Mr. Nixon’s Description of a Repeating Circle, G, G, fixed to the divided circle. When the instrument is placed in a horizontal position, the line of collimation of the telescope can be rendered level (in the usual manner) by the adjustments of the level and those of the cross-wires. It will also be parallel to the plane of contact of the wheel to the circle in case the latter can be moved half-round in azimuth without disturbing the bubble (of the telescope). The circle C and the wheel W have their circumferences cut into teeth. One pinion J (fixed to the wheel) serves to move the circle, and the other L (fixed to the immoveable plate) turns the wheel and circle, clamped together by the nut K. The wheel and plate are secured together by the nut M. Supposing the instrument fixed by the plate P to the side of a vertical wall, or mounted as a French repeating circle, with a movement in azimuth; the circle and wheel, clamped together with the zero lines of the divisions of the circle coinci- dent with those of their respective verniers, are moved together by the pinion L, until the middle of the bubble is brought to its reversing point. The line of collimation of the adjusted telescope will now point level; and if we wish to take the alti- tude of a nearly horizontal star, we must disengage the circle from the wheel, and direct the telescope exactly at the star by turning the pinion J. Having clamped the circle to the wheel, the angle of elevation is finally read off by the two verniers. In the event of the subsequent obscuration of the star, note the position of the bubble, and having freed the wheel from the fixed plate, depress the telescope by the pinion L until the bubble attains the reversing point, or that degree of its scale at which the line of sight points level. Clamp once more the wheel to the plate, and having disengaged the circle from the wheel, elevate the telescope (and with it the divided circle) by means of the pinion J, until the bubble reverts to the two points of its scale between which it stood when the telescope bisected the star. The angle now to be read off will, it is evident, be double the altitude of the star; and by continuing the same process of measurement, a multiple of the angle, suffi- cient to obviate the errors of graduation and reading off, may be procured leisurely and accurately. When the altitude of the object is beyond the range of the scale of the level, recourse must be had to the additional level Z mounted on a toothed wheel V, which can be moved by the pinion U about a short horizontal axis projecting from the divided circle, or fixed by the opposite clamps X,Y. Having pointed the telescope parallel to the horizon, and af- terwards on the elevated star precisely after the manner above indicated, clamp together the circle C and wheel W, and then Mr. T. Smith on certain Phenomena of Vision. 343 bring the bubble of the additional level by means of its pinion exactly to between the two marks drawn across its tube*. Continue thus successively to depress the telescope by the pinion L until its bubble stands at the reversing point, and afterwards to elevate it by the pinion J until the bubble of the additional level comes to between its marks; and when the repetition has been carried far enough, the altitude may be found by dividing the mean of the two readings by the num- ber of observations. Apparently, there would be no difficulty in obtaining any multiple of the double zenith distance of a celestial object pro- cured precisely as by the French circle. Zwo additional levels, both fixed to the divided circle, would then be indis- pensable; one to be Jevelled when the instrument had been turned half round in azimuth, and the other when the tele- scope had been pointed. the second time at the star. By means of the two additional levels, the difference of zenith distance of two objects might be measured at. once, without obtaining the absolute zenith distance of either. Leeds, Sept. 4, 1832. J. Nrxon. Erratum.—Page 108, line 1, for 11” read 11’. LXIV. Investigation of certain remarkable and unexplained Phenomena of Vision, in which they are traced to Functional Actions of the Brain. By Mr. Tuomas Smitu, Surgeon, Fochabers. [Concluded from p. 258.] AVING thus ascertained the precise nature of the effects, the next step I took was to investigate the true nature of the exciting cause. In all the experiments in which I had hi- therto observed the phenomena, the light which appeared to excite them was more or less whzte; for the bright object was either a lamp or candle, or the direct rays of the sun, or the sun’s light reflected from snow or the like. In addition to this circumstance, the bright object had always been so situated in relation to the point P, to which the eyes were accommodated, that its image on the retina must have been formed either * It would be preferable to have both levels fitted up with accurate scales, and to note the position of their bubbles rather than to attempt to bring them always to one fixed mark. From the register of the deviations of the bubble of the telescope from its reversing point, and those of the bubble of the additional level from the point at which it stood when the telescope pointed at the star, it can be ascertained,;how many seconds are to be added to or subtracted from the final reading, 344% Mr. T. Smith’s Investigation of certain Phenomena of before or behind the true focal point. Now, as in the inves- tigation of new phaenomena, with the principles of which we are, as in the present case, utterly unacquainted, every com- bination of the circumstances ought, as far as possible, to be tried till we arrive at the most simple which is capable of pro- ducing the results; so it appeared proper to try if any one kind of light, or any one position of it, was more efficacious than another in exciting the appearances. The following ex- periment, repeated often with the utmost care, convinced me that an zmperfect image of the bright object was required to fall on the retina in order to produce the phenomena. Exp.8. I placed a strong bright light at the nearest distance to which my vision could adapt itself, and directing both eyes to it, I caused a screen to be interposed between one of them and the light; so that one of my eyes only was exposed to the bright light, and the image of it was formed perfectly distinct on the retina. A slip of white paper, illuminated from behind me, was held so near my eyes as to appear double; the result was very remarkable. Of the two images, that which was seen by the exposed eye appeared darker than that which was seen by the shaded eye; but both appeared distinctly white, without any tinge whatever of green or red. In performing this expe- riment, great caution is required that the exposed eye be adapted correctly to the distinct vision of the flame; for by much observation I have found that a small error in this re- spect, such as occurs when the eye becomes dazzled, is suffi- cient to excite those changes in the sensibility to red light, which have been proved to be the causes of the green and red appearances of the white paper. The difference of brightness observed in the two images in this experiment is undoubtedly owing to the operation of the affection of sight, mentioned in Note *, p. 255, &c. as may be proved by shading or exposing both eyes, by turns. When the images appear unequally bright, by shading both eyes, the darker image acquires the same luminousness as the brighter one; and by exposing both, the bright image becomes of the same shade as the dark one. Having thus ascertained that bright light failed in eliciting the phenomena when it formed a distinct image on the retina, it remained to try the effects of different kinds of light. The results of numerous observations carefully made with the diffe- rent primary colours, are shown in the following experiment. Exp. 9. 1 raised a broad yellow flame in the manner recom- mended by Sir David Brewster for the construction of a mo- nochromatic lamp: this I placed in the position F, fig. 1, near my right eye, and applied a tube, blackened within, to my Vision, tracing them to Functional Actions of the Brain. 345 ‘other eye, to prevent the result from being disturbed by any stronger light entering my left eye. A lighted candle was placed in a dark lantern behind me, with only a small open- ing in it to permit a stream of white light to fall on the slip of white paper S, which was placed so as to be visible to both eyes when they were directed to a distant point P. The ex- periments, with the other primary colours, were made with narrow tubes of thin coloured paper. One of the tubes being applied to the right eye, was strongly illuminated by means of lights placed near its sides; and a black tube was applied to the left eye, to insure that inequality of the action of the co- loured light on the two eyes, which, even in a more moderate degree, had been found sufficient with white light to produce the phenomena: the results in all these trials were striking and uniform. The image of S, seen by the eye exposed to the primary coloured light, was constantly of the colour that was complementary to that of the tube or light employed,—an ap- pearance manifestly referrible to the affection of sight mention- ed in Note *, p. 255, &c.; but the image of S that was seen through the black tube was uniformly whzte, being never in the smallest perceptible degree changed by the affection of the other eye. From these observations we learn that no excess of any primary coloured light entering one of the eyes is able to pro- duce the affection which we have been investigating; hence it follows that white light only is capable of exciting it. But the 8th experiment proves that white light also fails to produce it, when it forms a distinct image on the retina. It is not the action of the white light, therefore, but the indzstinctness of the white image, that constitutes the true exciting cause. This conclusion leads us to remark, that the affection of vision now under investigation, as well as that which is dis- closed under Notes * and +, p.255 and 257, are both produced by the same exciting cause, or at least by causes of the very same nature. Before inquiring, therefore, into the intimate causes or seat of these analogous affections, it may be of use to compare the indistinct images in both with one another, and with their respective effects, in order to detect, if possible, any physical differences between them and their distinct images that may serve to account for the phanomena they produce. When rays of light from a primary coloured object are in- tercepted by the retina before they reach their focal point, the image is rendered indistinct by the diffusion and mixing of rays from single points of the object over many points of the retina. Rays from a white object similarly intercepted, have, in addition to this cause of indistinctness, another, arising from Third Series. Vol. 1. No. 5. Nov, 1832. oY 346 Mr. T. Smith’s Investigation of certain Phenomena of the chromatic aberration ; for every white image falling on the retina before or behind its true focal point is surrounded by a red or violet border, which, as well as the other cause, inter- feres with its distinctness. Now it is certainly a very extra- ordinary circumstance, that diminished sensibility to red light around the white image should occur then, and then only, when it is surrounded by this red or violet border. A distinct red border around a distinct bright object produces no such effects, as I have proved by experiments carefully made: it follows, therefore, incontrovertibly, that it is not the physical difference between a distinct and an indistinct white image that excites those changes in the sensibility which have been proved to occur. In regard to a primary coloured image, the difference between it when distinct and when indistinct, consists in that diffusion and mixing of the rays in the latter which has been noticed above, and which not only obscure the outline, but the whole surface. If these scattered rays, therefore, pro- duce the changes in the sensibility that take place in these circumstances, we must be compelled to acknowledge that the same physical cause produces directly contrary effects at the same time; for, if this be true, the scattered rays that obscure the surface of the primary coloured image, increase the sen- sibility, in a remarkable degree, to the same kind of light, and the scattered rays that obscure the outline, diminish, in the same degree, the sensibility to the same kind of light. The supposition is manifestly absurd, and therefore we return with increased confidence to our first conclusions, that indistinctness _ of a white image is the true exciting cause of the diminished sensibility to red light that takes place around it in the exposed eye, and of the zucreased sensibility to red light that occurs in the other eye at the same time; and that zndistinctness of a primary coloured image is the real exciting cause of the in- creased sensibility to that colour which ensues to the image itself, and the diminished sensibility to the same colour that occurs for some considerable space around the image. The nature of the effects and the true exciting causes of these remarkable affections of sight being ascertained, it only remains to investigate the seat and nature of the actions ex- cited by the indistinctness of the image on the retina. In the first place, then, the retina, though it has been cus- tomary to consider it as the seat of any changes in the senst- bility to light, cannot, in these cases, be regarded as the seat of either of these affections in the exposed eye ; for it is incon- ceivable that undulatory motions, extending from the part of the retina on which the bright light falls, to all parts around it, can be produced by an zndistinct image, when a distinct Vision, tracing them to Functional Actions of the Brain. 347 image of equal or superior brilliancy produces no such effect : besides, it has been shown above, that to ascribe the state of the sensibility in and around the part of the retina where the bright light falls, to the physical impulse of the difference be- tween a distinct and an indistinct image, would be to assert a physical absurdity; it follows unavoidably, therefore, that the changes in the sensibility in the exposed eye arise from actions ab interno. With regard to the state of the sensibility in the un- exposed eye in one of these affections, there cannot be two opi- nions: it must be produced by an action from within; and though we are not yet prepared to say in what manner, or by what medium, an action of the brain can affect the sensibility to light, yet the fact is a most important one; and the perfectly correct manner in which the defect of sensibility in the exposed eye is balanced by an excess of sensibility in the unexposed eye, not only affords an additional argument for their common origin, but seems to open a path, which, if duly followed, may lead to interesting discoveries in this obscure department of physiology. In the other affection of sight, though the changes in the sensibility are confined to the exposed eye only, yet the same correct balance of excess and defect is found to exist,—a circumstance that strongly corroborates the conclusion, that both of these remarkable affections of vision are produced by one common principle, and arise from one common seat. But, in the second place, the exciting causes of these affections are of such a nature, I should humbly submit, as to render them totally incapable of producing any but functional actions pre- organized for the occasion. Indistinctness of image (disregard- ing its physical causes, which have been shown to be inade- quate to the effects,) is a purely negative quality, and can have no effects beyond the simple perception of it, except in so far as distinct vision is the end to which the mechanism of its several organs, viz. the eye, optic nerve, and brain, has been adapted: that of these three the brain is the directing organ in another highly interesting function of vision, which is also excited into action by indistinctness of image, admits of another kind of proof: the function I mean is that by which the eyesare accommodated to the different distances of objects. Suppose, after looking at a distant object, that we wish to view one near at hand, what we do in this case is to direct the two eyes so as to make their axes meet in the object to be viewed. If the former accommodation of the eyes continued, the object now viewed would be indistinct ; but to prevent this, an action of the brain produces a change in the eye not yet sufficiently un- derstood, by which a correct image of the object is formed on the retina. That the unknown change here mentioned is pro- q¥ 2 348 Mr. T. Smith on certain Phenomena of Vision. duced by a function of the brain will not, I believe, be dis- puted, since injury of the brain by mechanical compression, &e. destroys the function, and the contractions and dilatations of the iris that are observed to accompany its exercise. In this case, therefore, distinct vision is the end for which a cer- tain function of the brain, as well as a certain mechanism of the eye, is provided; and the following considerations, sug- gested by the effects on the objects produced by the affections we are investigating, lead to similar conclusions in regard to the end or purpose of them. It is well known that the vision cannot be adapted in the common way to more than one di- stance at once. Now when the eyes are adapted in this way _to objects at one distance, objects that are nearer or further off than that distance, are actually made more distinct than they would otherwise be by the operation of the two affections we have been examining. By one of these the indistinctness of a brighter object is lessened by the sensibility being in- creased to the colour of the object itself, and diminished to the same colour in less luminous objects around it, thus making the principal object brighter and better defined by a double contrast. By the other, the indistinctness arising from the chromatic aberration is removed by insensibility to the red.or violet rays bordering the image; and as that insensibility ex- tends over a wider space than the red or violet border occu- pies, the false vision thus occasioned is corrected by the sen- sibility to red light in the other eye being increased, in exactly the same degree as it is diminished. in the exposed eye. Both affections, therefore, have the characters of perfect functions admirably contrived, it must be acknowledged, and as well adapted to produce distinct vision as can well be imagined in the circumstances. Having thus given, in as compressed a form as I could adopt in justice to the subject, a full account of this investigation, I forbear, for the present, from making any observations on the singular nature of the cerebral functions thus detected, or on the perhaps still more singular nature of their exezting causes, thinking it due to truth, ina case that appears to involve prin- ciples entirely new, to wait the observations of competent inquirers, with whom it remains to confirm or refute, by an impartial scrutiny, the results which I have obtained. I shall, therefore, conclude with a short summary of those results. lst. Besides the well-known function by which the eyes are adapted, by turns, to different distances, ¢wo other functions, hitherto unknown, are occasionally called to the aid.of vision. 2nd. Both of these newly observed functions are excited by Mr. J. Phillips on the Lower Coal Series of Yorkshire. 349 éndistinctness of vision; the one, when the indistinctness arises from undue scattering of the rays of light,—the other, when it is owing to the chromatic aberration of white light. 3rd. The organ excited in both cases is the drain; but whether, being thus excited, it does not also excite some other auxiliary organ, as in the case of the adaptation to different distances, does not yet appear. 4th. The actions excited are directed to the effect of remov- ing, more or less, the exciting cause, and producing distinct vision. Fochabers, 20th June, 1832. Note.—An investigation of the remarkable phenomena de- scribed in the preceding ingenious paper, but leading to results different from those obtained by the author, will be published in the next Number of this Journal.—D. B. LXV. On the Lower or Ganister Coal Series of Yorkshire. By Joun Purxurrs, #.G.S., Sec. Y. P.S., Assist. Sec. Brit. Association, &c.* J (bees lowest portion of the Yorkshire coal strata resting upon the millstone grit, produces comparatively but a small quantity of coal, and this, in general, not of a good quality. But no part of the coal-field is more curious in its geological relations, or more worthy of close study by those who desire to penetrate into the history of the production of coal. We may define this lowest coal series very simply, by saying that it is included between the millstone grit of Bram- ley beneath, and the flagstone of Elland above, having a thickness of about 120 or 150 yards, and inclosing near the bottom two thin seams of coal, one or both of them workable, and several other layers scattered through its mass, too thin to be worth working. ‘The most regular and continuous of all these coal seams’ reaches, in a few places, the thickness of 27 or 30 inches, but is generally only about 16 inches. It is worked at Yeadon, Rawdon, and Horsforth, near Leeds’; at Baildon, and Heaton, near Bradford; Catharine Sluck, and Swan Banks, near Halifax; Bullhouses, near Penistone; and at several points about Sheffield. It would have been impossible to have traced so thin a seam of coal along so extensive a range without some peculiar facili- ties,—some points of reference more distinct than the varying Saad of the coal, and the still more irregular fluctuations of the sandstones and shales. This coal seam is covered by a roof unlike that of any other coal bed, above the mountain * Read before the Yorkshire Philosophical Society, October 2, 1832; and communicated by the Council of that Society. $50 Mr. J. Phillips on the Lower or Ganister limestone, in the British Islands; for, instead of containing only the remains of plants or fresh-water shells, it is filled with a considerable diversity of marine shells, belonging to the genera Pecten and Ammonites; and in one locality, near Halifax, specimens of Orthocera, Ostrea °, and scaly fish have been obtained from certain nodular argillo-calcareous concre- tions, called Baum Pots, lying over it. ‘The uniform occur- rence of the Pectens and Ammonites through so wide a range over one particular thin bed of coal, while ‘they are not found in any other part of the coal strata, is one of the most curious phenomena yet observed concerning the distribution of or- ganic remains, and will undoubtedly be found of the highest importance in all deductions relating to the circumstances which attended the production of coal. The following sections will convey a good idea of the general character of the whole of this lowest coal series. The first is a section of Swan Banks Colliery near Halifax; furnished to me by its friendly proprietor, Christopher Raw- son, Esq., President of the Literary and Philosophical Society of Halifax, whose remarkable zeal and diligence in exploring the phenomena presented by his underground works, have not only produced the discovery of many new and curious animal remains in the baum pots, but added some very im- portant facts to the general history of the coal-field. Yds. Ft. In. Ragstone, (the lower part of the flagstone rock). . 27 0 O Blames shale’... :.:.seib dere'net = cos yeteetls Sea panwiaus 40 0 0 Coal:(80 yards band coal)... 4...2.25+.. 0 0 6G Ra FE in cin ie: sadetre(yo spre ia bby coir olbeY ratiet yey» haart 4 0 0O Pla tle cttette A ohuan chi ce saver avn eaceysen ied AE 28 0 0 tioal (48 vards band, coal)» jes<::<%)<) pysiveileieh his 0 011 MCA, SAMS 4 5, 0) ores spy pipntre fs sis Soke seer 0 '2'0 PAE SBR akties sabe bn ait asivi sacybusist tien a Dirt band (black tough clay) ..........-. OX ONS Balak Shige si cae cs gstreneges ate ay sdoaaed Hes leptons 4 1 6 Coal (36 yards coal band) ...........- ONG RAT ict oiiKd. at por inrs sh ide as: | Heese eeho io beee eeeat en 1: OMng Black shaleicas si). Wr Sof bl Mattie inten 12 \/0.4@ Rag) and: shale: sono. so,0ie) ent odeedtuas aur hewsdle Yoie 13 0 0 Black shale, jog rpdueih dered) om binaueuehstadnilpicays 70/0 Shale and ironstone (called Haxd Band), flat og” gg Day. NOtSofeim thug sitiwadl eles (1a) 6 pots . = Gray shale (called WhiteEarth), with small r ‘ound ee a baum pots containing Ostree? ...... p g Concretions (called Baum Pots), with Ammonites,xc. 6 1 — Coo Black shale (called Moon Bassett), with Pectens 0 Coal Series of Yorkshire. 354 soa} Yds. Ft. In. Coal (the hard band coal) worked ....-- Peat Oi ease Seatstone .. 2. ee eee tee cree ee eee 0 1 0 Seat earth (white clay), with vegetable fossils... 2 0 0 Gray shale... 6 eee ee eee eee 5 0 0 Bitle shale gay ate isife Sty sis ees aol oe ake 4's bn G Coal (middle band coal). ..+-+-+-+-> Meira mri srk rt Middle band stone... -- +++ eee ee eee 1s oR 59 Black shales. {sa sd) sf Bree la ee ee 8 0 0 Layer of fresh-water shells (Unio) .....+--. 0 1 0 Black shale .. 2.2.0 eee eee ere erers + ieee Nee | Meme!) ie 1 MPU Slee epee 0 0” ee Black shale... . 22s eee eee ARV Sisde ci Dy haem Coal (the soft bed coal) workable... - +--+ Oj hie Upper millstone grit, on which Halifax stands. The following section of Horsforth Colliery was communi- cated to me by my most valued and lamented friend the late E. S. George, Esq., of Leeds, whose researches into the minuter history of the Yorkshire coal strata were equally accurate and well directed; and I hope that some of their results will soon be brought before the public. Yds. Ft. In. I oe cada stint) icine tN LPT eee 2 0 0 Galliard of Headingley Moor.....-+.-++-- 0 2 6 Galliard in thin beds ...- e+ +e ee eees pete Wea Coal (sometimes thickened by stone GOdl)g.2\.)s), On Open Sandstone with partings....--++++++e+:: 4 0 0 Blue-brown rag «+--+ sees teeter ees 4 0 0 Lifts or beds of sandstone, about 14 inches thick, cued with 2-inch partings of shale. ..-..-+- 0 TT IRTIAIE neces, <5. *, 22, =, 44° ehierP ie ea 6 0 0 o ofgl ye adlies ne lienaint Stee iphay RA ae ere anata ees, On Eels nace ms elise a 5) shaitcts tach iets 18 0 0 Blue shale, with Ammonites Listert ..++++> 0 0.3 Blue shale, with Pecten papyraceus ».++++-+> 0. Deld in sia iee io com Si Wein RE ee Oo 1 4 Seat of coal (White Earth) .....-+-+++--: 2 0 0 Measures of stone and shale, with a seam ofironstone 8 0 0 ois an mn ots: rel tc se naked ER Ons. 0 Various measures occur below to the thickness of 20 or 30 yards, and then the millstone grit of Bramley appears. In these sections, we may observe, besides the very re- markable layers of marine shells, several occurrences of a eculiar hard siliceous sandstone, called Galliards, Ganister, or Seatstone (according to local custom, or slight differences), 852 Mr. J. Phillips on the Lower or Ganister which in fact is the same thing as the ‘ crowstone” of the mountain limestone district in the north-west of Yorkshire, and like that contains in abundance the remains of plants, particularly of the genus Stigmaria, Brongn. By the extreme abundance of plants of this kind, indeed, the galliard beds may almost always be recognised throughout their range in Yorkshire. . This stone, in some cases, forms the floor or sill of the coal seams,—a circumstance never observed in the upper coal strata, amongst which, indeed, galliard never occurs in. its true character. Hence this whole group of strata may be appropriately called the Galliard or Ganister coal series. The Ammonites and Pectens which lie above one of the seams of coal, and still more the Orthocere which sometimes accompany them, are remarkably analogous to fossils of the mountain limestone. The galliard is likewise to be compared with similar stones in the mountain limestone series, and therefore the ganister coal series might without impropriety be associated with the upper-mountain-limestone series of the Penine chain, or with the millstone grit and limestone shale of Derbyshire, and thus the flagstone of Elland would appear to be the lower limit of the true coal-measures. But a short examination of the neighbourhood of Halifax, in Oc- tober 1831, has shown me another order of phaenomena and another set of shells, which connect this same series with the upper or true coal-measures. In the upper coal series of Northumberland, Durham, York- shire, and Derbyshire, are several most extensive layers of bivalve shells, commonly called Muscle bands, and referred to the genus Unio, from which the fresh-water origin of those coal deposits has been inferred. It was therefore with extreme gratification that I found, in passing through Mr. Rawson’s colliery at Swan Banks, in the midst of this series of ganister coals, two layers of these shells, one of them about the middle of the series, considerably above the Pecten coal, the other near the bottom, and considerably below that coal. No shells of this kind have ever been met with in the moun- tain limestone group, which there is every reason to consider as of decidedly marine origin ;—not one of all the zoophytie, testaceous, or crustaceous reliquiz of this limestone has ever been found in the upper coal series: this opposition of zoo- logical characters would appear to be fully explained, if the coal deposits were admitted to have been accumulated in fresh water, and this opinion is, perhaps, generally adopted. We find, then, in the lowest coal series, which is placed on the line of transition between the marine and fresh-water de- Se Coal Series of Yorkshire. 353° posits, zoological and mineralogical characters common to both. Examined in detail, we find these characters not mixed, but alternating in such a manner as if there had been one periodical return of the marine element into its ancient re- ceptacle, after that had been for some time occupied by fresh water and its few inhabitants. ‘The effects of this irruption having, as it were, worn out, the zoological characters of fresh- water deposits are again manifested at intervals in the muscle bands, till the whole carboniferous system is entirely ended, and marine exuvis reappear in the magnesian limestone, If, from whatever cause, we could witness the effects of a general irruption of sea-water into a modern lake of great extent and considerable depth, it is probable that the result- ing phenomena would be perfectly analogous in kind to those described above. But this irruption of the ancient ocean into the coal-basin of Yorkshire was probably not produced by any violent convulsion in that basin,—for there is no uncon= Jormity between the supposed marine and supposed fresh-water deposits,—but by some disturbing causes originating at a di- stance. As the elevation of the Western Alps has probably occasioned the dispersion of boulders in Dauphiné and Pro- vence, and as the uplifting of the Scandinavian chain has been followed by diluvial currents in Germany, without affecting the position of the strata in those countries, so may the York- shire coal district have felt the transient shock of some distant convulsion. The periodical revolution in the nature of the waters which operated the deposition of the lower coal strata in Yorkshire, bears so remarkable an analogy to some of the phenomena of the marino-lacustrine tertiary deposits, that the same prin- ciples will probably serve for a basis for the explanation of both cases. In both instances we have a decidedly marine deposit below; and a decidedly lacustrine deposit above; the intermediate ground is not exactly neutral, but sometimes shows gradations from the one tothe other, and sometimes periodical alternations,—accompanied, however, by so entire a parallelism of strata, thatin seeking for the cause of these changes, we are compelled to have recourse to agency at a distance,—to the blocking up of the outlet of some estuary, or to irruptions of the sea arising from subterranean distur- bances in a different quarter. In a future communication to the Society, I shall describe in detail all the species of animal remains which have been obtained from this interesting part of the Yorkshire coal strata. Third Series. Vol. 1. No. 5. Nov. 1882. Na / {[ 354 ] LXVI. Official Documents respecting the Health of theWorkmen employed in Cleansing the Public Sewers of Westminster, as affected or not by their Employment, and also during the existence of Malignant Cholera in the Metropolis; together with authenticated Statements relative to the Health of other Workmen exposed*to putrid Effluvia. Communicated in a Letter from Sir Antuony Canuisiz, F.R.S. &c. Sc. To the Editors of the Philosophical Magazine and Journal. Gentlemen, "BRE accompanying documents have been for some time in my possession, but I deemed it proper to reserve them from public notice until the heated contentions about Indian cholera were abated. In the capacity of a Commissioner of Sewers for Westminster, I requested authenticated informa- tion respecting the effects of putrid substances on the health of persons employed for the longest time under the orders of the Commissioners ; and especially whether they were parti- cularly affected by putrid fevers or by bowel complaints. The tabulated report now submitted for publication is left to be used at my discretion ; and the facts appearing in many in- stances contrary to general opinion, yet unquestionably accu- rate, I think them well deserving the notice of medical philo- sophers, and of other scientific men. A similar report was obtained by Commissioners appointed by the Council of Health at Paris, in 1826, to inquire into the effects of putrescence in certain French manufactures of cat- gut and other strings made from animal intestines, with a view to ascertain the antiseptic influence of chlorides. The several results, published by order of the French Commis- sioners, have been translated and published, with many addi- tions, by M. Labarraque and the translator, in 1827, under the title of an Essay on the Use of the Chlorurets of Soda and Lime, &c. &c. by Thomas Alcock, Surgeon. Printed for Bur- gess and Hill. Since the report above mentioned was received, I have thought it needful to make inquiries also respecting the effects of the late prevailing malignant cholera among the labourers in the sewers of Westminster ; and I now send you the official returns, which appear to me of much public importance. I cannot imagine that any person will regard the publica- tion of these facts, so impartial and genuine, as an encourage- ment of filthiness; since they are entirely and specially di- rected to discover whether any connection subsists between the origin or propagation of malignant cholera, and the most offensive and varied kinds of putrid vapours. Tam, Gentlemen, your obliged Servant, Langham Place, Oct. 6, 1832. ANTHONY CARLISLE. ain Health of the Workmen cleansing the Westminster Sewers. 355 Report on the Health of the Workmen employed in Cleansing the Public Sewers of Westminster, Sc.: transmitted to Sir A. Caruiste, by Mr. J. Houseman, Clerk to the Commis- sioners of Sewers for Westminster ; and dated December 10, 1831. Wounded 2 Bruker Burnt by | Burnt by g. fe UW speek Foul Air. Slight Colds ; Pains in the + Bowels, Loins, and Limbs: tles in the as. Sewer. No. of Years employed. ia) i=] 5. a flee | one | rea Often pains in the bowels without (jaa 1. Labourer] GO | 92 | ...< | being relaxed ; eye Se took spiritsto re- | 7.2 2s ess lieve him. yp ose rae 3 6a ENA o&e3 ss Often pains in the | 22 2 h ICES . an — a . Ditto...] 52] 92} - bowels and limbs |< $ > ag mo from cold caught | ee $5 2 ict oe standinginsewers.| | 2 5 9 meee SPP she o 25 2 [55s eye Often pains in the | 2 eee j H ifs Te 3. Ditto...| 49 is) bowels and limbs Baste 42 | 21 from cold caught Fea Nee 3 = 32 5 standing in sewers. 2 El Wee h = hy A Often, once very Bee y 4. Ditto...} 50 | 20 | ---4| severely, has had | } Often. g5o5 an apoplectic fit. ESSE 5. 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C1 1-0€ & 8£9-66 “THN | “Xe *uopuo'y | O c ghl-6z 1 ‘3dag ‘OS8I *y UO] | yo sktgy | Moray THE LONDON ann EDINBURGH PHILOSOPHICAL MAGAZINE ¢ AND JOURNAL OF SCIENCE. SS = [THIRD SERIES. ] DECEMBER 1832. LXX. On the Variations which Temperature produces in the Double Refraction of Crystals. By Freprerick RupBere, Professor of Physics in the University of Upsal*. HE researches of M. Mitscherlich having demonstrated that the angles of crystals which do not belong to the regular system, change their magnitude with the temperature, and that the dilatation is consequently different, according to the principal directions of these bodies, or according to their axes of crystallization, there was reason to believe that the double refraction also would vary with the temperature. The existence of this variation was afterwards established by ul- terior researches, which M. Mitscherlich, in a manner as simple as it was ingenious, made by the method of interferences, by observing the compensation effected by crossing plates of cry- stals at different temperatures. By this method, however, we obtain only the ratio between the mean double refraction of the crystal in a cold and in a heated state, without being able to determine how much the refraction of each of the two rays into which the light divides itself, has separately varied with the difference of temperature. In order to decide this question, we must obviously determine directly the refraction at a high temperature ; and the following are the results of such an in- quiry, made with rock crystal, calcureous spar, and arragonite. The experiments were made in the same place, and by means of the same instruments and the same prisms, as my former experimentst on the refraction of the same minerals at the temperature of the air; and for this reason I do not * Communicated by the Author. + See our present volume, p. 1, and 136.—Eprr, Third Series. Vol. 1. No.6. Dec. 1832. 3G 410 Prof. Rudberg on the Variations which Temperature here compare them with these. In order to maintain a con- stant temperature during the whole time that an experiment lasted, it was necessary to have a particular apparatus, of which I shall first give a description. A box, of the form of a parallelopiped, was made of white iron, and so strong that four of its faces were double, and formed with each other a shut-up space, which communi- cated only at one side, and beneath one surface, with a small steam boiler; and at the other side, above a second surface, with the external air. The other two surfaces were formed with plates of mica, so that there was an inclosed space which contained only air, and which, when the prism was placed in it, was heated by the steam, which, surrounding the four sides, circulated only in the space between the four double surfaces, without being permitted to mix with the interior ‘air. The temperature of this space was indicated by a thermome- ter put into a cork, which was introduced into a tube passing through the two upper surfaces of the box, and which com- pletely closed the tube, in order to prevent the heated air from escaping upwards. A similar tube passing through the two lower surfaces of the box formed a free communication between the interior and the exterior air, so that their elasti- city remained always the same. In the middle of this tube, without touching its sides, there rose from the centre of the repeating circle a vertical copper rod, carrying on its summit a plate, upon which the crystal was placed. ‘This rod was attached below to another plate of copper, which, instead of produces in the Double Refraction of Crystals. 411 the plate of ground-glass, upon which the prism was placed in my former experiments, rested on the ring of copper, which having teeth upon its circumference could be put in motion by a screw. By this arrangement, which allowed me to turn the prism, it was as easy as formerly, when the prism re- mained in the open air, to perform all the operations neces- sary for the exact determination of the refraction, without being obstructed by the heating apparatus, which being on one side united with the boiler by a tube, was on the other side attached to a rod of iron, rising from the masonry on which the repeating circle rested. The temperature of the interior of the box remained, by this means, perfectly invariable during the time occupied by each experiment. From the temperature, however, of the external air, of which the extremes were on different days +12° and + 20°, it varied from day to day between + 76° and +84°; so that there was almost a constant difference of 64°. With respect to the experiments themselves, I ought to re- mark, that no change in the dispersion could be observed, and that for this reason, I determined the ratio of refraction only for the single ray F* of the spectrum. At the beginning of each experiment the prism being at the temperature of the external air, and being turned till the ray F was at its mini- mum deviation, the variation in the deviation produced by heating was measured in this position of the prism. For cry- stals with one optic axis this determination was the only one to be made, because the edge of the prism being parallel to the axis of crystallization, the refracting angle did not change with the temperature. But for crystals with two optic axes, it was necessary, besides this, to determine the change which the difference of temperature produced in the refracting an- gle, which, as the following results will show, was very con- siderable. With respect to the calculation of the index of refraction, it must be observed that the refracting power of the air sur- rounding the prism being diminished, the deviation becomes at first directly increased, But at the passage of the ray through the last plate of mica, it is, on the contrary, somewhat dimi- nished. ‘These two corrections must be determined separately. According to the experiments of MM. Biot and Arago, the index of refraction of air at 0°, and at a barometrical pressure = h, is _ [9000588767 "tT ¥ 7-40:00875¢ * 0™76" * This ray or dark line is nearly the boundary between the green and the blue space.—Enrr, 8G2 412 Prof. Rudberg on the Variations which Temperature The elasticity of the internal and the external air being the’ same; and almost equal to 0™°76, we have when ¢ the mean temperature of the external air is +16°, the index of refraction = /1+0°000554, and at 4-80°, or the mean temperature of the internal air, the index will be ) = /1+0°0004529 Whence, if » is the ratio between these two elasticities, y = 1000051. If A is the deviation produced by the prism, and 6A the small angle through which the ray deviates still more in pass- ing through the plate of mica, we have Sin A = v.sin(A—®A), or —1l tA = i which correction ought always to be added to the observed deviation. Calling, in short, +dA the variation produced in the deviation corrected by ¢A, and putting «= the re- fracting angle of the prism + de = the variation of this angle, and 2 = the index of refraction, we shall have with a suffi- cient approximation, for crystals with one optic axis, sin $(A+dA +8) y.sinte and for crystals with two optic axes, sind (A+dA+e+de) 2S. y.sin 3 (¢+ de) . tang A > The results of the observations were as follows: 1. Calcareous Spar.—Refracting angle of prism = 59° 55! 9". a. The Ordinary Spectrum.—For this spectrum I found the remarkable property, that the crossed wires of the telescope be- ing placed in the ray ¥, at a low temperature, they always re- mained fixed there at the highest temperature, notwithstanding a difference of 64°. The variation which sometimes presented itself during’ the repetition of the observation was too small to be measured. It is besides evident that the slightest change in the refract- ing power, would have produced a remarkable change in the deviation, which was = 52° 53°43’. This apparent in- variability of the deviation proves a small decrease in the re- fracting power; because if the latter had been perfectly con- stant, the observation would have shown an augmentation of produces in the Double Refraction of Crystals. 413 the deviation, for the density of the surrounding air had be- come less. Itis easy to calculate how much this augmenta- tion would have been. . The index of the ray F being at the ordinary temperature = 1°66802, the deviation A calculated by the formula sin 3 (A +e) = 1000051. +1°66802. sin 2 becomes = 52° 54! 14”, or greater by, 32” than 52° 53! 43". 0 000051 From these 31" we must subtract ——___ te 2° 53/=14" n e e must subtrac 1000051 tang 52° 53 =14", or the angle which the ray deviates at the plate of mica, so that there will remain only 17". Though this quantity is the least which I could directly measure with the repeating circle, I have no reason to believe that if it did occur, it would have escaped me. Whence we may conclude, that the re- Jractive power of calcareous spar for the ordinary ray, either does not change at all with the temperature, or decreases with it by a quantity extremely small. b. The Extraordinary Spectrum.—The deviation of the ray F was found to be augmented by a difference of temperature of 64°, a quantity = 9! 96", If we add to this the correction for the passage of the light ‘ < si 0:000051 ., brs £2, F " through the plate of mica = 7.599951 “7S 36°. 18! 26 = g!-0, the total augmentation produced by the temperature an the deviation of the extraordinary ray becomes = 2! 34! The calculation gives the index = 1°49118, whereas at the ordinary temperature it was = 149075. Hence it follows, that a difference of temperature of 64° produces in the index of refraction of the extraordinary ray of calcareous spar, an in- crease of +0°00043. During my stay at Berlin in the month of May, of the pre- sent year (1832), I had fortunately an opportunity of confirm- ing, at the house of M. Mitscherlich, and in his presence, this remarkable property of calcareous spar,—that the deviation of the ordinary ray does not ‘change, at least not in an appreci- able manner, with the temperature; while, on the contrary, that of the extraordinary ray increases considerably with the tem- perature. ‘This property is in a certain manner connected with the discovery of M. Mitscherlich,—that calcareous spar, when the temperature rises, dilates itself in the direction of the axis of crystallization, but undergoes in a direction penpen- dicular to the axis a contraction extremely small. The crystal thus approaches to a cube with an increase of temperature, and the double refraction ought, consequently, to diminish, as 414 Prof Rudberg on the Variations which Temperature my observations prove. But, on the other hand, it:appears singular, that while the dilatation of bodies commonly dimi+ nishes their refractive power, the extraordinary ray, though the crystal is dilated in the direction of its axis, becomes never- theless less refracted, and that the refraction of the ordinary ray, notwithstanding the contraction of the crystal in a di- rection perpendicular to its axis,.does not change, cr dimi- nishes if there is any variation. An analogous phenomenon, however, has already been observed by M. Arago in water™, in which refraction always goes on increasing from the tempera- ture of the maximum density to the point of congelation. 2. Rock Crystal.— Refracting angle of the prism = 45° 20! 5". In both spectra a decrease of the deviation, was observed, which was also sensibly the same; viz. = 48!"0 0000051 1000051 = 6-0, it follows that the total diminution of the deviations in both spectra is whence, on account of the correction = tang 28° 15/ ==742"50. The indices calculated for the ray F become in the extra- ordinary spectrum =1°55868, or 000028 less than at the or- dinary temperature; and in the ordinary spectrum, = 154944, or 0°00026 less. 3. Arragonite.— The experiments were made with the prisms A, No. 1; A, No.2; B, No.2; and C, No.2.¢ In all of them I found for the spectrum polarized perpendicular to the axis of crystallization a diminution, of the deviation pro- duced by an increase of temperature. J also observed a change in the refracting angle of the prisms, with the exception of prism A, No.1; with which, in this respect, on account of thie magnitude of the refracting angle, no experiment with the heating apparatus could be made. The following were the observed results : ahe A, No. 1. A, ‘No, 2. B, No.2. ONO. 2: Variation of the _ sig! 1! 6g! —a! gi _ 9! 5gil deviation... 4 Variation of re- { not mea- as piel re fracting iat tired: Va16 0 —1' 53 —A8'"6 If we correct these values for the deviation of the plate of mica, we obtain * See Edinb. Encyclopedia, Art. Expansion, vol. ix. p. 257; and also the observations in the next page.—Eprr, + See present volume, p. 139.—Eprr. produces in the Double Refraction of Crystals. 415 A, No. 2. B, No. 2. ©: No. 2. Real variation of deviation —1/ 47" —3! 57! 2! 5a" Real variation of rei 430-9 | 1 44" Koll ing angle 7 1a ily oasis Whence we obtain the following indices of refraction : A, No. 2. B, No. 2. G,’No.'2. 1°53416 1°69421 1°68976 At the ordinary temperature of the air they were 1°53478 1°69510 1:69058 Thus the diminutions which an increase of temperature of 64° has produced in the indices of refraction in the spectra polarized perpendicular to the axes of crystallization, are A. B C —0:00062 — 000089 —0:00082 The double refraction of arragonite thus appears to decrease a little with the temperature, because the refracting power in the direction of the axis A has diminished in a smaller ratio than that according to the axes Band C. Jn other respects arragonite comports itself quite differently from calcareous spar: the axis A of arragonite obviously corresponds with the axis of crystallization of the spar; but notwithstanding this, the refracting power in this direction diminishes in the former, and, on the contrary, increases in the latter ; besides that in the direction perpendicular to the axis A, the refract- ing power diminishes considerably in arragonite, whilst, on the contrary, it undergoes almost no change in Iceland spar. Observations on the preceding Paper. The optical readers of this Journal will, we are sure, join with us in expressing our obligations to Professor Rudberg, for the accurate and valuable observations contained in the preceding communication, which he has been so kind as to transmit to us. The subject is entirely new, and we trust that he will extend his researches to other minerals, and also to artificial salts... The influence of heat in modifying the re- fractive power of uncrystallized solids, such as glass, gums, &e.; of fluids, such as water, oil, &c.; of fluids with circular polarization, such as oil of turpentine, &c. ; and of minerals, &c. belonging to the tessular system, such as rock salt, alum, &c.—merit the attention of Professor Rudberg. In reference to the important observation of M. Arago, that the refractive power of water gradually increases while it passes from that of its maximum density to that of congela- tion, we beg leave to quote the following observations*. « When the writer of this article had the pleasure of seeing * Art. Expansion, Edinb. Encyclopedia, yol, ix. p. 257. 416 Sir D. Brewster on Prof. Rudberg’s Results. M. Arago at Paris, in the course of last summer (1814), he mentioned to him a series of experiments on the refractive power of water at different temperatures, in order to deter- mine if its maximum density was above 32°. He filled a prism with water at the temperature of 32°, and observed the angle of deviation produced by refraction, while its tempera- ture rose from 32° to 212°. The angle of deviation was greatest at 32°, and it gradually diminished to 212°, exhibit- ing no marks whatever of a variation of refractive power at 40°, or at any point between 32° and 212°. Hence M. Arago concluded, that since the refractive power always increases with the density, the density of water must be a maximum at 32°, * * * Tt is assumed in this reasoning, that the refractive power of bodies increases with their density,—a doctrine which requires to be established by direct experiment, before it can be admitted as a valid argument in favour of any other posi- tion. Nay, it has actually been proved by Albert Euler, from numerous experiments, that the refractive power of glass is encreased by heat. An augmentation of temperature of 60° of Reaumur diminished the focal length jth part, and an aug- mentation of 33° produced a diminution of j>th. M. Euler concludes, without sufficient evidence, that the refractive power of finids is increased with heat.” Looking at all these facts together, the action of heat is very anomalous : Heat increases the refractive power of glass. Heat diminishes the refractive power of water, oils, &c. Heut increases the extraordinary refractive power of cal- careous spar. Heat diminishes the extraordinary refractive power of quartz. Heat does not affect the ordinary refractive power of cal< careous spar. Heat diminishes the ordinary refractive power of quartz. Hence there is reason to infer that heat produces some other change in the state of a body than a mere change in the relative distance of its particles. The difference between the action of heat on calcareous Spar and quartz is very extraordinary. ‘The primitive form of each is a rhomb ; and they differ only in the former having negative, and the latter positive double refraction. It will, therefore, be of importance to examine other negative and positive crystals; and if the difference of effect is not found to depend upon this circumstance, it may possibly arise from the peculiar structure of quartz in reference to circular pola- rization, Sir D. Brewster on the Action of Heat on Glauberite. 417 Among the other crystals which M. Rudberg will doubt- less examine, we trust he will not omit sulphate of lime and glauberite, on the doubly refracting structure of which, heat produces such extraordinary effects.—D. B. LXXI. On the Action of Heat in changing the Number and Nature of the Optical or resultant Axes of Glauberite. By Sir Davin Brewster, K.H. LL.D. F.R.S. V.P.R.S. Ed. EVERAL years ago Prof. Mitscherlich made the beauti- ful discovery, “that the ordinary sulphate of lime or gyp- sum which, at common temperatures, has two optic axes in the plane of its laminz inclined at 60° to each other, under- goes a great change by elevation of temperature; the axes gradually approaching each other, collapsing into one, and (when yet further heated) actually opening out again in a plane at right angles to the lamine.” Sir John Herschel, in whose words we have described this remarkable experiment, goes on to observe, “ This singular result we cite from memory, having in vain searched for the original source of our information; but it might have been expected, from the low temperature at which the chemical con- stitution of this crystal is subverted by the disengagement of its water, that the changes in its optical relations by heat would be much more striking than in more indestructible bodies. We have not, at this moment, an opportunity of fully verifying the fact; but we observe that the tints developed by a plate of sulphate of lime, now before us, exposed as usual to po- larized light, rise rapidly in the scale when the plate is mo- derately warmed by the heat of a candle held at some distance ’ below it, and sink again when the heat is withdrawn, which, so far as it goes, is in conformity with the result above stated. Mica, on the contrary, similarly treated, undergoes no appa- rent change in the position of its axes or in the size of its rings, though heated nearly to ignition*.” In repeating this important experiment, I made use of one of the specimens described in the Phil. Trans. for 1818, in which I discovered one of the resultant axes of this mineral. It was about |} inch thick in the plane of the laming, and the system of rings which surrounded this axis was exceedingly minute, with the usual black brush at each end of them. The other system of rings could not be seen in this specimen, owing to the manner in which it was cut. Having brought the crystal to a considerable heat, and exposed it to polarized light, it * Treatise on Light, Encyclop. Metrop. p. 568. Third Series. Vol. 1. No. 6. Dec. 1832. Oma 418 Sir D. Brewster on the Action of Heat in changing the was a singular sight to see the system of rings travelling along towards the Jine which bisects the optic axes, like a celestial body passing through the field of a telescope, and changing their form and size as they advanced. The specimen did not permit me to see the two systems unite, and still less to see them open out again in a plane at right angles to the Jaminz; but from the degree of heat which I used, and which drove off the water of crystallization from part of the specimen, I presume that the complete phznomenon cannot be developed without destroying the constitution of the crystal; that is, that after the two systems of rings have opened out in a new plane, they wilk not return by cooling, through their state of union, into their primitive inclination of 60° in the plane of the lamine. A property of a similar kind, but perhaps a still more ex- ° traordinary one, I discovered some years ago, subsequent to Professor Mitscherlich’s discovery; and I have slightly noticed it in a paper on Glauberite, published in the Edinburgh Transactions*. This interesting mineral has at ordinary tem- peratures the curious property of two axes of double refraction for red light, and only one axis for violet light. If we apply heat to it, the two optic axes for red light gradually close, and, at a temperature which the hand can endure, the two systems of rings for red light have united into one system, so that the crystal has now only one axis of double refraction for red light. By continuing to increase the heat the two axes se- parated, and the single system of rings opened out into two systems lying in a plane at right angles to that in which they were placed at first. The heat was now less than that of boiling water. By increasing it, the inclination of the optic axes gradually increased. I now applied artificial cold to a crystal of glauberite at the ordinary temperature of the atmosphere. The inclination of the optic axes for red light increased, as might have been predicted; but, what was very unexpected, a new axis was created for violet light, the plane of the two violet axes being coincident with the plane of the two red optic axes at and below the ordinary temperature. An increase of cold in- creased the inclination of the optic axes for all the colours of the spectrum; the inclination of the axes being /eas¢ for the most refrangible, and greatest for the least refrangible rays. These results appear very complicated when we begin with the effects at an ordinary temperature, and view them in the manner in which they were observed; but if we commence the experiments at a low temperature, such ‘as the freezing * Edinb. Phil. Trans. vol. xi. Part ii. p. 273. Number and Nature of the Optical Axes of Glauberite. 419 point, the order and connexion of the phenomena will be more easily understood. At 32° glauberite has two axes of double refraction for rays of all colours, the inclination of the axes for the violet rays being least, and that for the red the greatest. As the temperature rises, the optic axes for all colours gradually ap- proach, and the axes for violet first unite into one. At this time the crystal has two axes for all the other colours; but as the heat increases, all the other pairs of axes unite in suc- cession, and form a single system of rings. But before this has taken place, the axes for violet rays have opened up again in a plane at right angles to that in which they originally lay, and they are followed by all the other pairs of axes; so that at a temperature much below that of boiling water, each pair of axes appears with different inclinations arranged in a new direction. During all the changes which have been described above, the crystal has preserved its constitution, and by abstracting the heat, the phenomena are all repeated in an inverse order. If the crystal should happen to be observed at that tempe- rature, which very often occurs, when the greenish-yellow or most luminous rays have the optic axes corresponding to them united, or form a single system of rings, then the blue rays will have two systems of rings lying in one plane, and the red rays also two systems of rings in a plane at right angles to this. In two rectangular positions, namely, when the planes of the double axes coincide with, or are at right angles to, the plane of primitive polarization, the black cross will be very distinct, but in intermediate positions it will be much less so, and the uniaxal system of rings which predominates, from the greater intensity of their light, will have that indistinctness of character which, whenever it occurs, indicates a peculiar action of the doubly refracting force on the differently-coloured rays. When the black cross is perfect and equally distinct in all positions, while the colours of the rings deviate from those of Newton’s scale, then the axes for all colours are obviously coincident, and the peculiarity in the colour of the rings is owing to an irrationality in the action of the doubly-refracting forces on the differently-coloured rays. This deviation from the tints of Newton’s scale, I have found in many crystals which have only one axis of double refraction. It is extremely common in crystals with two axes. I have elsewhere described the construction of a chromatic thermometer, in which the temperature is indicated by the polarized tints transiently developed by heat in a number of plates of glass;—but it is obvious that a plate of glauberite $2 420 - Capt. Luetke’s Account of Experiments with an may be made a thermometer which will indicate by its change of tint very slight changes of temperature. The temperature at which a ray of definite refrangibility has the optic axes corresponding to it united, so as to form a single system of rings, is a point as well fixed as that of boiling water, and every different inclination of the optic axes of definite rays indicates two different temperatures in the scale of heat, equidistant from those other points at which the same rays have their axes united. The accurate measurement of these angles would no doubt be difficult, but an instrument might be made to show them by inspection. ‘The temperatures, however, might be more simply indicated by the great variety of tints successively de- veloped by heat; and as each tint has a numerical value in the scale of colours, its accuracy would not be much less than that of the other method. Allerly, Nov. 3rd, 1832. LXXII. An Account of Experiments with an Invariable Pendulum, during a Russian Scientific Voyage. By Captain LUETKE*. HE observations of the invariable pendulum occupied the first place amongst the scientific researches to which our attention was directed during the circumnavigation of the Séniavine. All these observations are already calculated: but, as I have not yet been able to give them the form in which they will ultimately appear before the public, and asa new appointment confines me at present to other duties, I trust that a summary account of these observations and their re- sults will be acceptable to the Imperial Academy of Sciences, as well as to the scientific world in general. The apparatus, which we made use of in these experiments, is the same as that which had been previously adopted by Capt. Basil Hall, at the several stations in South America. It is, in fact, the same in construction as that which was em- ployed by Capt. Sabine in his voyage to Spitzbergen. Before quitting England, a series of experiments was made at the Observatory at Greenwich: and again on our return. The second series gave a result, which differed from the first, about ,f;tlis of a vibration, in excess; which I attribute to a slight wearing of the knife edge. This difference ought perhaps to be distributed over the whole interval, in arithmetical pro- * Translated from the Bulletin Scientifique, page xi., attached to the Memoirs of the Imp. Acad. of Sciences at St. Petersburgh. Series vi. vol. i. (1830). Invariable Pendulum, during a Russian Scientific Voyage. 421 gression : but I shall content myself, for the present, by taking the mean of the two results. } The other stations were Valparaiso, Sitka, Petropaulouski ; the islands of Ualan, Guam, Bonine and St. Helena; and lastly, the Observatory of St. Petersburgh. Here the experi- ments had for their object, as much the length of the pendu- lum, as the change of length from temperature. The two series (one of which was made at the mean temperature of 31°°5 Fahr., and the other at 82°5) showed a difference of 0°458 vibration in a mean solar day, for each degree of the scale. This result is 0:033 greater than that found by Capt. Sabine, from a similar process; although the two pendulums were made of the same kind of metal (bell-metal*), and were nearly of the same dimensions. But, I do not find, in our ex- periments, any thing that should cause this difference, unless it be the smaller density of the metal of which our pendulum is composed. In voyages of this kind, the stay at each port is generally very short; and the time which we can give to each species of observation naturally very limited. It is evident therefore that we depend much on accidental circumstances, which ma influence the success of our labours very considerably. Hence it happens that, although we have always paid the same at- tention to every thing that could contribute to the accuracy of the experiments, yet they are not all of the same value. Those which deserve the greatest confidence are those that were made at Greenwich, St. Petersburgh, Petropaulouski, Valparaiso, and the Bonine isles. At these five stations, I think I can answer for ;!,th of a vibration. Then come Sitka, and the island of Ualan; where the mean result may be un- certain to ith of a vibration. ‘The experiments, which are the least to be depended upon, are those made at the islands of Guam and St. Helena; where I do not pretend to a precision greater than } a vibration. The latitudes were determined by circum-meridian alti- tudes of the sun and stars, observed with a sextant and a cir- cle, each by Troughton, and with a reflecting repeating circle by Dollond. We had not an astronomical repeating circle: but, we endeavoured, by multiplying the observations, and varying the circumstances, to make the above-mentioned in- struments serve the same purpose. I now come to the results; which are contained in the fol- lowing Table: where the $rd column contains the number of * We suspect that Capt. Luetke is wrong in designating the pendulum as made of bell-metal; as we believe they are all made of brass.—Kp1?. 422 Capt. Luetke’s Account of Experiments with an vibrations made by the pendulum, at each station, in a mean solar day, reduced to the standard temperature of 62° Fahr., to a vacuum, and to the level of the sea. The 4th column contains the corresponding length of the seconds pendulum (in English inches), founded on that determined by Captain Kater in London. For this purpose we ought to reduce the experiments at Greenwich to the station at Portland Place, by the difference in the number of vibrations, found to exist be- tween these two places, by Capt. Sabine. Number of Length of the Stations. Latitudes. Vibrations. |Seconds Pendulum UA Soo 16" N. 86112-83 39-02756 GrliaNlsec cts conse le 2er2r ON: 117-98 -03242 St. Helena...... 15 54 59S. 125-63 -03933 Bonin ds. ssc . ; Lastly, if we exclude also the Bonine islands, where it appears there is a great degree of attraction, we shall have x = 39°023923, y = 0°192535, and z — a And this is the result to which we have at length come, as best repre- senting the whole of our experiments in the Northern hemi- sphere. In this case the differences of the partial results from the calculation will be as follow: viz. | j Stations. Experiments. |Calculations.| Difference. RS EATs We... Sees 39-02765 | 39-02560 + -00205 Gaiam’. 23.4000 .4 03242 03442 — 00200 St. Helena...... 03933 03840 + -00093 London ......... -13929 14191 — 00262 Petropaulouski 14838 14677 + -00161 SEK oceseonacess -15810 -15950 — -00140 St. Petersburgh -16950 16816 + -00134 The compressions which we have deduced are almost iden- tical with the mean results of the experiments made by Cap- tains Freycinet and Duperrey: but they are greater thau those of Capt. Sabine. In order to determine whether these dis- cordancies are to be attributed to local causes, to an irregu- larity in the form of the spheroid, or to errors of observation, it would be necessary to make other combinations by uniting the experiments not only of the navigators above mentioned, but also those of Captains Parry, Kotzebue and Hall: an undertaking which would exceed the bounds which I have prescribed to myself here, and which is reserved for the de- tailed account of our labours. LXXIII. On the Power possessed by Spiders to cscape from an isolated Situation. By Grorcr Fairucime, Lsg.* AVING observed, in a late Number of the Philosophical . Magazine (August 1832), an article by Mr. Blackwall, in which a doubt appears to be expressed of the power of spiders to escape from an isolated situation by means of a projected thread, I beg leave to mention a few observations on that subject which were made by me some years ago, while *- Communicated by the Author. to escape from an isolated Situation. 425 ‘residing in Switzerland, and which will place the matter be- yond adoubt, in as far, at least, as it relates to one of the species, though not with respect to the Aranea domestica, or common house spider. While residing on the shores of the Lake of Thoun, in the summer of 1828, I was frequently in the habit of spending some hours on the water, in a small boat, near a low part of the shore, where there was abundance of reeds growing in the water, and where those reeds gradually became more widely scattered, as the depth of the water increased, until at length they entirely disappeared. I had frequently had occasion to remark, amongst the thick- er crop of reeds, the singular manner in which the tops and stems of the plants were bound together by cobwebs of such strength and elasticity as to resist the action of the most powerful winds. But baving observed that even the most di- stant and completely isolated plants were equally furnished with spiders and cobwebs, it became an interesting inquiry how the communication with these more distant objects was brought about, and what means of escape the little colonists had within their power; as I had never observed an instance of their passing along the surface of the water. On taking, therefore, one of these spiders in my hand, I was not long in discovering their mode of operation. For when placed on the point of my finger, in an elevated po- sition, I observed that a fine thread was proceeding in a ra- pid course, from the /oom, and was carried by the wind to leeward, where it became attached to the first object with which it came in contact; and a communication was thus ef- fected, by means of which the little captive was not long in making his escape. Having thus discovered their general mode of operation, 1 had subsequently many opportunities of amusing myself and my friends, by more particular remarks and experiments on the powers of these curious insects. I have more than once taken spiders out into the lake, to endeavour to ascertain to what length this projected thread might be extended. In these experiments, tried in situations where a dark shade, as a back ground, enabled me to follow the course of the thread with my eye to some distance, it was always carried in about half a minute beyond my powers of vision, or to a distance of about twenty-five or thirty yards; and as no object intervened to which it could become attached, I have reason to think it might extend considerably further. On one occasion, I was enabled distinctly to trace the whole process, and the eventual escape of the spider to an object fully twenty yards distant. Third Series. Vol. 1. No.6. Dec. 1832. $.J 426 Mr. Fairholme on the Escape of Spiders. I placed him on my finger, and with a microscope I ob- served the valves in the abdomen to open, by several distinct apertures, from each of which a fine thread of gummy liquid issued, all of which threads became united into one strong cord, which continued flowing until (carried by a gentle breeze to leeward) it became attached to the branch of a tree, about twenty yards distant. It was highly interesting to observe the proceedings of the insect during the operation. He had previously, by simply bringing the lower extremity of his body in contact with my finger, attached the gummy thread firmly to it; and while it was flowing, which was distinctly visible by occasional en- largements in the thread (probably occasioned by dusty par~ ticles adhering to it as it flowed) he remained nearly still, except when making an occasional trial with one claw, to dis- cover if it was yet fixed to any object. These trials strongly reminded me of those of a rope-dancer, while the assistants are screwing up his rope to the necessary degree of tension. At length he seemed to have found the desired resistance, though I was not then aware of the object to which the line had become fixed. But a most singular operation now com- menced, and was performed with extraordinary celerity. For by a rapid movement of his hooked claws, he “ hauled in the slack of the rope,” tightening it to the necessary degree; and when he had thus collected a confused mass of tangled thread, he swallowed it, and again fixing the tightened end of the cord to my finger, he lost no time in proceeding along the line towards the desired point. I now brought the cobweb in contact with a fixed object, near which I stood, and follow- ing the traveller (who was rocked by the breeze in a manner he would not have been if left to his own ingenuity, for in fixing the cord I had not attended with sufficient care to the degree of tightness to which he had himself arranged it), I saw him reach in safety the branch of a tree, fully twenty yards distant, to which | now found the projected thread had become fixed. From the above observations, it is therefore clear that in some instances spiders are endowed with this remarkable power of escape; but whether this instinct is confined to those species which, from their abode near water, would appear most to require it, my observations do not enable me to de- cide. But it seems to me nearly certain that the gossamer which is scen floating in long threads in the summer air, is of the same niuture as these projected cobwebs ; and also that those innumerable and minute threads, which are often seen to cover the ploughed fields, and the hedges, in a horizontal tal Prof. Kupffer on the Mean Temperatuve of Sitka,in America. 427 position, and which become so visible in the slight frost of an autumnal morning, partake of the same character. Mr. Temple, in his amusing and interesting account of his travels in Peru, and while describing the first indications of the approach to the end of his voyage across the Atlantic, has the following passage, from which it would appear that in- stances similar to that which I have just described, may pro- bably be found in various other parts of the world, and that the power of projecting a web of great length is possessed by more than one of the species. ¢ We weighed anchor, and made all sail up the stupend- ous, but wholly uninteresting river Plate, which is 120 niles wide at its mouth, and not less than from 20 to SO, for up- wards of 150 miles inland. In the course of the day, the rigging of the ship, from top to bottom, was literally covered with long fine cobwebs, that had been blown off the shore, having attached to them their insect manufacturers, who dis- persed themselves in thousands over our deck.”—Travels in Peru, vol. i. p. 49. I have frequently endeavoured to ascertain to what length one of these spiders had the power of spinning a thread. By letting the insect drop from an object of known dimensions held in the hand, and by winding out the thread, while tarn- ing the object, I thought it possible to form some idea of its length. But from the unnatural position of the spider, and the occasional force necessary to make him work, I have never been able to come to any definite conclusion on this point. But it appears to me probable, that from 30 to 40 yards is as much as can be produced at one time, without a degree of compulsion, or exhaustion, which makes him roll himself up, and become motionless for some time. It seems certain that the substance from which the cobweb is composed is a gummy liquid while in the body of the insect, but becomes dry and elastic in the open air, in the same man- ner as threads of any other gummy substance when do drawn out in a half moist state. Ramsgate, Oct. 5, 1832. * LX XIV. Note on the Mean Temperature and BarometricHeight of Sitka, on the North-west Coast of America. By Professor M. A. Kuprrer, of the Imperial Academy of Sciences of St. Petersburgh*. THE following meteorological observations have been com- municated tome by M. Lutke. ‘They will afford at least on approximate idea of the climate of Sitka. * Communicated by the Author. 312 428 Prof. Kupffer on the Mean Temperature of Sitka, in America. Table containing the Maxima and Minima of the Barometric Height and Temperature Jor each Month of the Year 1828 ( Old Style). Barometer in English Inches. Max. Min. Max. Min. Reaumur’s Thermometer. Months. January ......] 29°80 29°20 = a —— sie February ..... 29°83 29:23 6 1 March........ 30°44 29°06 8 — 2 April....s.....| 30°27 | 29°3 134 +" Mays Ji.ccues 30°12 29°57 12 54 June .......+..| 30°20 29°45 16 ‘0 Julyesis.e 30°20 29°75 18 9 August .......| 30°17 29°34 15 | 5 September...| 30°20 | 29-20 a BS October ...... 30°01 28°78 10 Ree | November ...} 30°10 28°66 6 2 December ...| 30°57 £8°72 + 64 —10 Mean ....| 30°16 | 29-20 +10°7 If we take for Jloulouk the mean of the maxima and minima of the barometric heights of all the months of the year 1828 (see the second table of the following article), we shall find Engl. Inches. Mean of maxima for Jlonlouk ...... 29:92 Mean of minima. ....... it PE ease 28°80 Means. tu e' 29°36 To which, adding 0°32; that is to say, the error of thebarometer, which g gave the preceding means,— __ Inches. WAM» occ. 6 flat bm a, ate he oe tee ehene tae 29°68. If we make the same align for Sitka, we shall PUGAMTAN TAs 2. eke Eo tea samen ltd. «met epepiste conan 29°68. That is to say, exactly the same value. ‘This agreement gives a greater weight to the observations than might otherwise be attributed to them. It is easily seen that for Jloulouk the mean of the maxima and minima of all the months is greatly different from the true mean barometric height. With regard to the thermometrical observations, we know also that the mean temperature of the year does not differ much from the mean of the maxima and minima of all the months. The mean of these maxima and minima for Sitka, for the year 1828, as we see by the preceding table, is +5°°8 Reaum. Oh ee Rete on esac dae: aah eatin kes Sane bor pr ecayt 45°05. Fahr. It is not, howeek: without difidence that I communicate this result. [ 429 J] LXXV. Note on the Mean Temperature and Mean Barometric Height of Jloulouk, in the Island of Ounalachka. By Pro- Jessor M. A. Kuprrer, of the Imperial Academy of Sciences of St. Petersburgh*. LUTKE has communicated to me some meteorolo- e gical observations which have been sent to him from Ounalachka. Though these observations do not yet contain a very great space of time, I have no doubt that the interest which they possess will be received as an excuse for the hurry in which I have published them. The following Tables contain the mean barometric heights, expressed in English inches, and the indications of a thermo- meter of Reaumur placed in the shade, and towards the north, in a hollow cylinder of white iron, open at both ends. The observations were made three times a day, about 8" a.m., 1" p.m., and 9" p.m. The duties of the service did not always permit the observer to keep exactly to these hours; the ob- servations were sometimes made half an hour sooner or later: but such is the slowness with which the temperature varies in this climate, that this irregularity does not sensibly affect the accuracy of the mean results. Table 1.—Containing the Mean Temperature of each Month of 1828, and part of the Years 1827 and 1829 (Old Style). Mean Temperature. | Mean Temperature. | Mean Temperature. Reaumur. Reaumur. Reaumur. ° io) ° Me 7 Och 1°7 1828. May sede] i1'S2S.Decs—3"1 Nov. 2°0 June 6°6 | 1829. Jan. = 1°5 Dec... (1°35 July 8°4: Feb. —0-4 1828. Jan. +3°7 Aug. 11:0 Mar. +0°1 Heb, Ory Sept. 6:2 April 0°8 Mar. —0°1 Oetact 2:9 May 41 April+2°1 Nov. — 0°1 June +6°6 Mean of the first twelve months... 4°°0 Mean of the year 1828 .......++00 3°5 Mean of the last twelve months ... 3:0 General mean .....cecceceeeeeeceeeeee 3°5 Or 39°875 Fahr. According to the observations made at Leith Firth in Scotland, and communicated by Sir D. Brewster, the mean observation made at 8" a.v., 1" p.m, and 9" pM., will exceed the true temperature of the place by 0°-2 of Reaumur. Hence the corrected mean temperature of Jloulouk will be 3°: 7 Reaumur, or 40° 325 Fahrenheit. * Communicated by the Author. nA 430 Prof. Kupffer on the Mean Temperature of Jloulouk. Table IIl.—Containing the Mean Height of the Barometer, and the Extent of its Variations, for each Month of the Year 1828 and part of 1827 and 1829 (Old Style). Mean Barome- Months. i i i Maximum, Minimum. Differences of Engush ice Max. and Min 1827 Oct. 29-33 29-85 29-01 0-84 Nov. 29-44 30-08 28-60 1:48 Dec. 29-65 30°26 28-87 1-39 1828. Jan. 29-47 29-94 28-77 1:17 Feb. 29:17 29-84 28-35 1-49 March 29-42 30-08 28:72 1:36 April 29-32 29-74 28-98 0-76 May 29-50 30-06 28-94 1-12 June 29-44 29-78 28:96 0-82 July 29-56 29-82 29-18 0-64 August] 29-65 30-00 29-20 0:80 Sept. | 29-41 29-77 28:74 1-0: Oct. 29-16 29-82 28-45 1:37 Nov. 29-20 29-85 28-66 1-19 Dec. 29°83 30:38 28-71 1-67 1829. Jan. 29-29 29-73 28:36 1:37 Feb. 29-20 29-69 28°55 ]-14 March 29-08 29-98 28-51 1-47 April 29-55 30°24 28-44 1:80 May 29-43 30-11 28-80 1-31 June 29-55 29-89 29-05 0-84 Mean ... 29-41 29-95 28-75 119 The barometer used in the preceding observations was compared with that of M. Lutke. He found that the former constantly indicated a height 0°32 inch less than the latter. The barometer of M. Lutke having been compared with that . of the observatory of Copenhagen, its indications may be re- garded as exact. i Adding 0°32 to the above mean, we find for the mean baro- metric height of Jloulouk* 29°73. The temperature of the mercury was unfortunately not observed. We may, however, without falling into a great error, regard the above barometric height as reduced to +14° Reaum. This result confirms are- mark made by M. Erman, jun., on the barometric heieht of the sea of Okhosk. See Poggendorf’s Annalen 1829, No. 10. * See the preceding article Note on the Temperature, &c. of Sitka.—Eprr. Sir D. Brewster on certain Isothermal Lines in America. 431 Table I1I1.—Showing the State of the Winds observed thrice a day. During the past year there were, 92 North winds| 85 West 170 South | 23 East 49 NNW 45 WSW | 34 SSE 6 ENE 59 NW 106 SW 49 SE 42 NE 32 WNW 41 SSW 15 ESE 21 NNE. Hence we see that the prevailing winds are those of the south and the south-west. LXXVI. Observations on the Isothermal Lines on the North- west Coast of America, as deduced from the Results in the two preceding Articles. By Str Davin Brewster, LL.D. F.R.S. &c. N determining the inflexions of the isothermal lines round the pole of maximum cold in the Arctic regions to the North of America, I employed the valuable observations of Mr. Scoresby ; a long and valuable series of observations made on the west coast of Greenland, and communicated to me by Sir Charles Giesecke ; together with observations made in Iceland, and in different parts of Canada. I sought in vain, however, for measures of mean temperatures in those parts of the Arctic regions which are placed in a meridian nearly opposite to our own; and it is therefore a source of great satisfaction to me to have received from M. Kupffer the valuable observations contained in the two preceding papers. ‘These observations indeed have been yet made for too short a period to give us a very accurate measure of mean temperature; but the ap- proximate results which they afford will be of some use, till we obtain a larger series. In order to compare the observed mean temperatures of Jloulouk and Sitka with those calculated from the formula Mean temperature = (86°°3 sin D) —31, D being the distance of the place of observation from the North American pole of maximum cold, which is situated in north latitude 80°, and west longitude 100°. Professor Kupffer has not given us the longitude and lati- tude of Jloulouk and Sitka. ‘The position of Ounalachka, however, according to the observations of English naviga- tors, is between 168° 40’ and 168° of west longitude, and be- tween 53° 45’ and 54° of north latitude. We shall take, there- 4.32 Sir D. Brewster on certain Isothermal Lines in America. fore, the position of Jloulouk at 168° 20' west longitude, and 53° 53’ of north latitude; and from these data we shall find. . . . Sst). coer eon, 3 D = 33°23! And the calculated mean temperature of Jloulouk 43°-980 Observed mean temperature ...... Here BA Terk. a Sa Difference .... +3°655 This difference between the formula and observation is much greater than usual; but we shall presently see that it must arise either from the observations not affording a correct mean, or from the temperature of the place being affected by local causes. I presume that Sitka is the same place as the Isle of Sitka, iu the Great Northern Ocean, where Dr. Erman made his magnetical observations. The following extract from Dr. Erman’s table, given in his letter to the academician M. Wis- niewsky, and published in the Bulletin Scientifique, will enable us to approximate to the position of Sitka. North Lat. | West Long. Nov. 4. In the Great Northern Ocean 56° 54!*20 223° 53':20 — 12. Atthe Isle of Sitka..... STi 22 — 20. Inthe Great NorthernOcean 54 26°50 221 22°80 As Dr. Erman has omitted to give the longitude of Sitka, we may infer from the preceding table that it cannot be far from 222°. Hence we obtain D = 25° 38’, and The calculated mean temperature of Sitka .. 33°84 Fahr. Observed mean temperature .......65+55 45°05 Difference.....- ot deat This difference is so extraordinary, that we must either have mistaken the locality of Sitka, or there must be some singular source of heat in the island, or some inexplicable error in the observations. The reader will observe, that the difference is now —, whereas it was + in the case of Jloulouk. Without taking the formula as our guide, we have only to consider that Jloulouk, in latitude 53° 53, has only a tempera- ture of 40°; while Sitka, in latitude 57° 3', has a temperature of 45°! in order to be convinced that the formula will not be found to be in fault.. We must wait, therefore, for other observations from these regions before we can explain the cause of this singular discrepancy. - 1 7 Agnic rip Te 6? hi fF 433 J LXXVII. Further Remarks on Experiments relative to the Interference of Light. Bythe Rev. BaprEn Powe, M.A., F.R.S., Savilian Professor of Geometry, Oxford*. [* a paper which appeared in the Philosophical Magazine and Annals, N.S. for January 1832, I described a few ex- periments, having in view the fuller illustration of the prin- ciple of interferences, and of the undulatory theory of light. Those remarks claim no higher character than that of at- tempts to simplify some points in the inquiry, and facilitate the diffusion of elementary knowledge on this most beautiful and interesting branch of science; and it is with no other ob- ject that the present paper has been drawn up. There are, in fact, few parts of science (especially consider- ing the experimental and popular form of which it is suscep- tible,) which have excited less general attention than that to which the name of physical optics has been applied. And I would observe, in passing, that as the distinction implied in this designation between the properties of interference, polari- zation, &c., and those of ordinary reflexion and refraction is wholly arbitrary,—these last being just as much physical pro- petties as the former,—it would surely be better to restrict the term “‘ physical optics” to a sense analogous to “‘ physical astro- nomy,” viz. to the theory of those motions and forces which shall account for the observed effects on dynamical principles. This is quite independent of the facts. Nor is the distinction merely verbal, for I believe that an imagined inseparable con- nexion between the facts of the coloured rings, polarization, &c. and the physical theory, has tended in no small degree to create a reluctance in many persons to enter upon a subject which was supposed to be identified with a doubtful, abstruse, and difficult hypothesis. In this point of view, therefore, the distinction may be by no means unimportant. Long since, indeed, those who were most profoundly versed in the subject were not backward in their attempts to dispel such misconceptions. The present Lord Chancellor Brougham, in his highly acute and original papers * On the Reflexion, Inflexion, and Colours of Light,” in the Philosophical Transactions for 1796-97, insisted strenuously on the distinction between the facts of Newton’s experiments (which he pursued and extended) and the theories whether of fits or waves; and though he rejected both for a simpler theory of his own, this was at a period when the real nature of either was as yet undemonstrated. And when the singu~ lar fact of interference was unequivocally established by Dr. * Communicated by the Author. Third Series. Vol. 1. No.6, Dec. 1832. 8K 434 Prof. Powell’s Further Remarks on Experiments Young, it is surprising that his lectures and writings did not produce a general impression in favour of a branch of science, which his researches had successfully reduced to a form not less philosophically comprehensive, than experimentally simple and striking. More lately Fraunhofer, in his elaborate re- searches, has carefully pointed out the distinction that these “intervals” have a real existence, whatever theoretical view we may take of their nature. The publication of Sir J. Her- schel’s Treatise on Light forms an epoch in the history of the science, and has given a material impulse to the study of it: and there are only wanting further endeavours to sim- plify and facilitate the investigations, and to bring them more within the reach of the generality of students, in order to dif- fuse a knowledge of the subject as widely as its beauty and importance demand. The only point which continued to be a matter of ques- tion, viz. the application of interferences to the colours of thin plates, having now been decisively settled by Professor Airy’s experimentum crucis (Phil. Mag. and Annals, August 1831), the language of comparison between the theories which was legitimately used before, has ceased to be admissible. But the sagacity with which Newton detected the existence of these intervals, as well as the accuracy with which he mea- sured them, only continues to be enhanced in our estimation by the more recent explanation of their nature. He observed that at certain thicknesses no sensation of light reached the eye: it was therefore a natural and unavoidable conclusion, that none was reflected,—when as yet neither the paradoxical fact that two reflexions might destroy each other, nor the equally essential point that in this case there were two re- flexions concerned, had been established. Next to the fact of the existence of the intervals, that of their diminution in more refractive media is of fundamental importance to the theory. ‘The fact is indeed involved in a variety of phenomena: but as I have not happened to meet with any detailed account of the method of showing it ex- perimentally, except mixed up with other considerations, I will here offer a few remarks upon the subject. In the first place it is evident, that if we employ the inclined reflectors for the interference-stripes*, and they be immersed ‘in a transparent fluid, the surface of the liquid medium being so arranged that the rays are incident perpendicularly, and if the eye-lens be placed in such a manner as to receive the rays * * The experiments, as well as the formula here referred to, are those de- seribed in my former paper.—Phil. Mag, and Annals, N.S. vol. xi. p. 4, &c. relative to the Interference of Light. 435% immediately from the liquid, the stripes will be seen as formed at its focus within the liquid. This will be immediately un- derstood on recollecting that the stripes seen by a lens, under any circumstances, are those formed at its focus, and are to be regarded simply as an optical image situated there. | Hence also, if the lens have not its surface in contact with the liquid, but be placed at any distance from the surface less than its focal length, it will still exhibit the stripes as formed within the liquid. In this way the stripes will be seen narrower, or having less values of c than in air: and from the equation, Xr = agg SOUB: or A = 2c tan 4, it follows, that since § remains the same, A must be diminish- ed within the medium. If the obtuse prism be employed, or the interference be produced by refraction, it will be manifest that, owing to the less difference in refractive power between the glass and the liquid, than between the glass and air, the rays will cross at a smaller angle; and if Aremain the same, c ought therefore to be greater; but in point of fact the stripes are observed unaltered, or c remains the same: hence it fol- lows that A must really be diminished. The diminution of § is evidently due to the difference of refractive power between the liquid and air; and if m be the relative index (calling the angle in the liquid 6), we have sin § = m sin 4; and since in such very small angles we may substitute the sine for the tan- gent, the formula gives, in air, A = 2c sin§ : es ts in the liquid, aA, = 2c = Sin 6, Or A, is a value diminished exactly in the ratio of the refractive powers. Either of these experiments is, however, very trou- blesome to manage; and it is very difficult to compare satis- factorily the breadth of the stripes in the two cases. The following is much easier, and has the additional advantage of being applicable to solid transparent bodies as well as to liquids. : If a mass of a solid transparent body with plane parallel surfaces, or of a fluid bounded by parallel plates of glass, be simply placed between the prism or reflector and the eye- lens, the latter having its focus within the medium as before, then the rays on entering the medium, as they emerge from the prism inclined to each other at an angle 24, that angle will now be diminished to 2 4, and hence, as before, the stripes formed within the medium ought to become wider; but in point of fact they are seen ea : they may in this case be 3 KZ 436 Prof. Powell’s Further Remarks on Experiments easily compared with the stripes formed in air by arranging the lens so that one half of it is exposed to the direct rays, the other to those passing through the medium. The two portions of the stripes thus seen are, in fact, continued exactly in the same straight lines; and the eye would be well able to judge of the smallest deviation in such extremely delicate and well-defined lines, did any exist. The stripes, however, are precisely of the same breadth, or the values of c the same, whether with or without the interposition of the medium: hence, as before, A must be diminished exactly in proportion as m isincreased. But these experiments refer only to the fact, that along the length of what we term a ray of light, there : A 5 : occur at intervals equal to the value of —, points at which the ray is in some way affected with a different character, such that the concurrence of two rays at a point of like affection shall produce light, but at one of opposite affection, darkness ; this character evidently changing gradually from one condition to the other. All this, however, may consist with the notion of these different affections occurring simply at successive fixed points equidistant along the ray, which are merely more crowded together in a denser medium. It is then a’separate conclusion, established by distinct evidence, that these intervals are propagated along the line which represents the ray with a definite velocity, diminished in proportion to the refractive power of the medium. The simple fact of the diminution of the intervals is, however, usually presented mixed up with the consideration of this progressive propagation, or rather of its retardation in denser media, in explaining the shifting of the stripes, as in the experiments referred to in my former paper, and to which the method I have suggested by means of a thin prism, offers a convenient auxiliary process; showing at once the existence of the effect and its amount. Connected with this subject, some curious researches were given by Mr. Potter, in a paper read before the British Association for the Advancement of Science, at the Oxford meeting in June last, to the publication of which I look with great interest, espe- cially as they were founded on my experiment just alluded to, and as their tendency appeared to be somewhat at vari- ance with the received views on this point*. There are many students to whom it is an important object to know what is the least possible amount of apparatus in- dispensable for carrying on their experiments. It may be desirable to mention, therefore, that in order to perform the * Mr. Potter’s paper here alluded to will appear in our next Number.—Eb. relative to the Interference of Light. 4.37 interference-experiments, although it is most convenient to have an apparatus like that of a solar microscope for sending the sun’s rays horizontally into a dark room, and concentra- ting them by a small lens, whilst the mirror is capable of fol- lowing the motion of the sun,—yet all these conditions are not absolutely essential. A completely darkened room is far from indispensable, and the apparatus may be perhaps more con- veniently fixed in a screen, which may at any moment. be placed in the sun’s rays in any situation, and the effect ob- served at some feet distance. But the place of such an appa- ratus may be quite sufficiently supplied from materials every- where at hand, by merely adjusting a common plane mirror in a proper position, and receiving the rays either through a small lens, or even a minute aperture in a screen; the sole essen- tial being an origin of light, which is as nearly as possible an absolute point. Or, again,‘we may use still simpler means; for if we have only a small convex mirror, such as the bulb of a thermometer, a globule of mercury, a polished metallic but- ton, &c. simply placed in the sun’s rays, this gives an image of the sun diminished nearly to a point; and if the light from other sources be screened, the diverging beam thus formed will suffice for showing the stripes either with the obtuse prism, or by two reflecting surfaces, not indeed with the same bril- liancy and distinctness, but sufficiently to verify the facts. This method is also successfully applicable to the fringes of edges and apertures, and the internal stripes of shadows for- merly called Diffraction. And mentioning these phenomena, I may observe, by the way, that the simple property on which the explanation of these fringes is founded, viz. the tendency of light to diverge from a new origin whenever an obstacle is presented,—which is a real exception, as far as it goes, to the primary law of the rectilinear propagation of light,—does not appear to me (except, perhaps, in one passage in Sir J. Her- schel’s treatise,) to have been placed in that prominent point of view in which it should be stated in the elementary exposi- tion of the nature and propagation of light. There are also some other remarkable facts apparently dependent on it, which I am engaged in investigating. One of the most singular experiments connected with the coloured fringes is that in which the centre of the shadow of a small circular disk appears a bright point. This experiment is difficult to perform satisfactorily; since even when such a disk is cut with the utmost care, each of the minute inequali- ties in its edge is magnified, and accompanied with fringes, which mix and cross in such a manner as totally to confuse the whole appearance,. I have succeeded by taking up a 438 Sir D. Brewster’s Account of a Chinese Mirror; which reflects small quantity of thick ink on the point of a pin, and drop- ping it on a clear plate of glass, by which means a sufficiently even circular edge is produced, the disk being about 5th inch diameter. . Oxford, Nov. 4, 1832. LXXVIII. Account of a curious Chinese Mirror, which re- flects from its polished Face the Figures embossed upon its Back. By Sir D. Brewster, K.H. LL.D. &c. WE have just received, through the kindness of George Swinton, Esq. of Calcutta, whose zeal for the promotion of science is never relaxed, an account of a curious metallic mirror, which had been recently brought from China to Cal- cutta, and which was then amusing the dilettanti and per- plexing the philosophers of our Eastern metropolis. This mirror has a circular form, and is about five inches in diameter. It has a knob in the centre of the back, by which it can be held, and on the rest of the back are stamped, in re- lief, certain circles with a kind of Grecian border. Its po- lished face has that degree of convexity which gives an image of the face half its natural size; and its remarkable property is, that when you reflect the rays of the sun from the polished surface, the image of the ornamental border, and circles stamp- ed upon the back, is seen (we presume in shadow) distinctly re- flected on the wall. The metal of which the mirror is made, appears to be what is called Chinese silver, a composition of tin and copper, like the metal for the specula of reflecting telescopes. ‘The metal is very sonorous. The mirror has a rim of about jth or ¢th of an inch broad, and the inner part, upon which the figures are stamped, is considerably thinner. Mr. Swinton states, that no person he has met with has either seen or heard of anything similar to this mirror. The gentleman who brought it from China, says that they are very uncommon in that country; and that this one, with a few others, was brought by a Dutch ship from Japan several years ago. On the back of one of these was a dragon, which was most distinctly reflected from the polished side. Mr. Swinton also mentions that he has seen another Chinese cir- cular mirror, which is curiously embossed on the back. It is eight inches in diameter; but as its polish is rubbed off, he has not yet been able, by replacing it, to ascertain if it reflects a picture similar to the figures stamped upon its back. | Mr. Swinton adds, that the original mirror first described, is to be” — from its Face the Figures embossed upon tts Back, 439 sent to England, either to Sir John Herschel, or to the writer. of this notice; and in the mean time he proposes to us the question, ** How are these strange optical effects produced ?” Mr. Swinton himself ingeniously conjectures that the phe- nomena may have their origin in a difference of density in different parts of the metal, occasioned by the stamping of the figures on the back, the light being reflected more or less strongly from parts that have been more or less compressed. If metals were absolutely opaque, and if the light which they reflect never entered their substance, as in the case of re- flexions from transparent bodies, then the only possible way by which they could give a picture of the figures stamped be- hind would be that which Mr. Swinton suggests *. I believe, however, on the authority of the phenomena of elliptical polarization, that in silver nearly one half of the reflected light has entered the metal, and in other metals a less portion; so that we may consider the surface of every metal as transparent to a certain depth,—a fact which is proved also by the transparency of gold and silver leaf. Now this thin film having its parts of variable density in consequence of the stamping of the figure, might reproduce the figure by re+ flexion. It is well known that silyer polished by hammering, acts differently upon light from silver that has received a spe- cular polish; and 1 have elsewheret+ expressed the opinion that a parabolic reflector of silvered copper polished by ham- mering, will, from the difference of density of different parts of the reflecting film, produce at the distance of many miles a perceptible scattering of the reflected rays similar to what takes place in a transparent fluid or solid, or gaseous medium. J am satisfied, however, that, at the distance of a few inches from the Chinese mirror, this evanescent effect will be alto- gether imperceptible, and that we must seek for another cause of the phetiomenon under consideration. Some years ago I had occasion to observe the light of the sun reflected upon paper from a new and highly-polished gilt button, and I made a drawing at the time of the figure which appeared in the spectruin. It consisted of radiations exactly like the spokes of a carriage-wheel, the radiations being stateen * A series of very pretty deceptions might be made on the same principle, by painting (with thin transparent varnishes laid on in narrow lines) a figure on the back surface of a plate of glass. The figure would be seen by reflecting the light of the sun upon a wall, in consequence of the reflexion being destroyed, or nearly so, at those parts of the back surface which are covered with the varnish, and of the light being scattered at the outer sur- face of the varnish. In ordinary lights the lines would not be visible, but they would distinctly appear in the reflected rays of the sun. + Ediub. Trans, vol. xi. pi47. 440 Sir D. Brewster’s Account of a curious Chinese Mirror. in number, and a little confused in the centre opposite the eye of the button. On the back of this button several words were deeply stamped, but these words did not appear in the reflected image. I have since examined several varieties of such buttons, and I find that they almost all give either radia- tions or great numbers of narrow concentric rings, (and some- times both), whose centre is the centre of the button, and the smallest one of which is always like a dimple in the centre. Upon examining the surface of these buttons in the sun’s light and at the edge of a shadow*, I have invariably been able to see the same rings excavated in the polished face that appeared in the luminous image, which it reflected. They obviously arise from the button being finished in a turning lathe, and the rings are produced by the action of the polish- ing powder, or probably, in some cases, they may be the grooves of the turning tool, which have not been obliterated by the subsequent processes+. These facts will, I presume, furnish us with the secret of the Chinese mirror. Like all other conjurors, the artist has contrived to make the observer deceive himself. ‘(he stamped figures on the back are used for this purpose. ‘The spectrum in the luminous area zs not an image of the figures on the back. The figures are a copy of the picture which the artist has drawn on the face of the mirror, and so concealed by polishing, that it is invisible in ordinary lights, and can be brought out only in the sun’s rays. ented Let it be required, for example, to produce the dragon de- scribed by Mr. Swinton, as exhibited by one of the Chinese mirrors. When the surface of the mirror is ready for polish- ing, the figure of the dragon may be delineated upon it in ex- tremely shallow lines, or it may be eaten out by an acid much diluted, so as to remove the smallest possible portion of the metal. The surface must then be highly polished, not upon pitch, like glass and specula, because this would polish away the figure, but upon cloth, in the way that lenses are some- times polished. In this way the sunk part of the shallow lines will be as highly polished as the rest, and the figure will only be visible in very strong lights by reflecting the sun’s rays from the metallic surface. When the space occupied by the figure is covered by lines or by etching, the figure will appear zm shade on the wall, but * By this method the figure in the Chinese mirror could be rendered visible beneath its polish. + In polished steel buttons the reflected light is crowded with lines run- ning at right angles to each other, and clearly indicating the cross strokes by which they have been ground and polished. Prof. Botto on the Chemical Action of Magneto-electricity. 441 if this space is left untouched, and the parts round it be co- vered by lines or etching, the figure will appear most lumi- nous. We would recommend this subject to the notice of the op- tician, as likely to furnish him with a lucrative article of trade. Allerly, Nov. 8, 1832. LXXIX. Notice on the Chemical Action of the Magneto- electric Currents. By Professor Borro, of Turin*. AMONGST the characters which it is important to de- termine with reference to the knowledge of the nature of the magneto-electric currents discovered by Faraday, is that of their chemical action. As decisive of this point, I will state the results I have recently obtained, limiting myself for the present to a mere announcement ; since they makepart of other results belonging to a series of careful experimental inquiries, intended to clear up certain points of the theory of electro- magnetism, which will be published in due time. The apparatus which I used to examine the chemical effi- cacy of the Faradian currents [Faradiane correnti| consisted principally of an artificial horse-shoe magnet, and a bar of soft iron surrounded in the middle by a magneto-electric spiral. The extremities of such a bar may, by help of a very simple arrangement, be separated at will from the poles of the magnet, and restored again to their first position with any re- quired degree of rapidity. The apparatus is inclosed within a wooden box, and is put into activity by an external handle. ‘The box is surmounted by two rods, so connected (moveably) with the internal me- chanism as by means of it to interrupt or re-establish the current, at pleasure, and at the moment most favourable to the production of a spark. When the spark is to be obtained, it is only necessary to connect these rods with the .extre- mities of the magneto-electric spiral. When the apparatus is to be adjusted for chemical decomposition, the extremities are to be otherwise arranged, and so that the substance to be decomposed enters into the circuit. Water, sulphate of copper, acetate of lead, and other salts in solution were thus submitted to trial. At first, minute gramuties of the substances were acted upon, because of the eeble power of the apparatus (the magnet scarcely lifting six pounds, Piedmontese), and the presumed relative tenuity of the current: but I was not long in ascertaining that such was * Communicated by the Author. Third Series. Vol. 1. No. 6. Dec. 1832. 3L 442 Dr. Fitton’s Notes on the History of English Geology. the senergy of the latter, that I could act with success on larger quantities. Two platinum wires as conductors were fixed by cement in two holes made in the side of a small glass; the latter was then filled with water, made a better conductor by a few drops of solution of soda, and inverted in a vessel filled with the same fluid... The communication was then completed, between the platinum conductors, and the extremities of the rods connected with» the magneto-electric spiral, and the apparatus was worked. So soon as the successive detaching and attaching action began, the divellent forces of the platinum poles became evident, and an infinity of gaseous bubbles rose from them in the form and appearance of two columns of vapour: in a short time these being collected in the top of the glass, produced a portion of oxygen and hydrogen capable of causing a sensi- ble detonation. The phenomena became even more interesting, when the evolution of the two gases was observed through a powerful lens; the bubbles succeeding each other the more vigorously as the alternate action of the magneto-electrometer is more rapid.» My colleague Professor Michelotte, to whom I com- municated these results, wished me to produce them at the Cabinet of Philosophy in the University, where the experi- ment was repeated under his own eyes. I shall refrain from describing at present other results ob- tained by attempting the solutions of various metallic salts : in general the analogy between the effects produced and those of the hydro-electric currents appeared perfect; at least when due regard was given to the continuity of these, and to the intermitting and fugacious nature of the magneto-electric currents ;—to the constant direction of the former, and the al- ternate opposition of the latter. At present it is not easy to predict by what the means of exciting and increasing the chemical efficacy of the magneto-electric powers will be li- mited; but it is certain that such a character, highly inter- esting as it is in the philosophy of imponderable agents, de- serves to fix the attention of men of science. Turin, Oct, 12,1832. LXXX. Notes on the History of English Geology. By . Wituam Henry Firron, M.D. F.R.S. &c. a BS {Continued from p. 275. ] A gs this enumeration of authors, which we haye now brought down to the, period when Geology, asa branch of inductive science, may be said to have had its birth in England, we have Dr. Fitton’s Notes on the History of English Geology. 443 omitted to notice the greater number of an extensive class of writers, the older British ‘Topographers; who»contributed to the progress of the subject rather by supplying detached facts and local information, than by connected views of the struc- ture of the country: and hence, although their works may’ be consulted with advantage by those who are employed in in- vestigating local details, they do not claim particular notice, where general principles are the chief objects of inquiry. There is one, however, among the topographic antiquaries, who ought, perhaps, to have been mentioned at the very:com- mencement of this paper; and who deserves to be had in:re- membrance, as the Patriarch of English Geologists ;—though his work remained unknown for more than two hundred years. Gerorce Owen of Henllys in Pembrokeshire, Lord of Cemaes or Kemes, was the author of a History of that county; the manuscript of which bears the date of 1595, during the reign of Elizabeth;—perhaps more than a century before any thought of tracing the strata of England or of the globe, had been acted upon, or even mentioned in this country: but the work«re- mained in manuscript till 1799, when it was published in the Cambrian Register*. ‘The author enters largely and with great intelligence, into topographical and statistical detail; and in one of his chapters, treating of the ‘natural helpes, ‘ which is in the countrey to better the lande’—of which he reckons ‘ lyme’ to be the ‘ chiefest,’—* First,’ he says, § you ‘shall understand, that the lymestone is a vayne of stones ‘running his course, for the most part right east and west, ‘although sometimes the same is found to approach to the ‘north and south,— Of this lymestone there is found of an- ‘ cient, two veynes, the one small and of no great account; ‘ and not of bredth above a butt length, or stones cast; and ‘ therefore whosoever seeketh southward or northward over the ‘ bredth misseth it.’-—'The course of this ¢ veyne’ is then traced to a considerable distance eastward, out of Pembrokeshire. ‘ The other vayne of limestone, and chiefest of the two, is about ‘ seven miles distant from the former, more southerly then it, ‘and soe or neare they continue together as shall be de- § clared ;’—and its course is in like manner traced towards the east, to where ‘ it taketh water,’ and passing under the sea,— ‘ as reason and the course thereof leadeth us to think,’ isagain * «AHistory of Pembrokeshire, from a manuscript of George Owen, ‘ Esq. of Henllys, Lord of Kemes, &c.—now first published by his great- ‘grandson Richard Fenten, Esq.’ Cambrian Register for 1796, vol. i. p. 52. London, 1799.—An extract from this History, containing what re- lates to Coal, has been printed also in Fenton's Historical Tour through Pembrokeshire,—Appendix, p. 54. $L2 444 Dr. Fitton’s Notes on the History of English Geology. resumed in the land;—and it is followed in detail to Chepstowe, and for some distance beyond that place. ‘ This digression,’ he adds, ‘ concerning these two vaynes ‘of limestone, taking their original here in Pembrokeshire, ‘ | have thought good to insert in this place; for at the re- ‘quest of a dear friend of myne, and famous for his learning, ‘1 took some paynes about it,—finding the natural course ‘ thereof to be as before a thing perchance not so well noticed ‘as fitt to be known; and being noted and knowne, it may be ‘a guide to some parties to seek the lymestone where it yet ‘lyeth hidd, and may save labour to others in seeking it, ‘where there is no possibility to finde it.’ A third § veyne of lymestone,’ is also noticed, more northerly than the other two,—(probably one of the subordinate beds of the transition series),—which is correctly distinguished from those above mentioned, and likewise traced, as far as the author’s acquaintance with the country extended. ‘ For the veyne of coales—which is found between these ‘two vaynes of lymestone, as a benefit of Nature, without ‘ which the profit of the lymestone were neare lost :—betweene ‘the sayd two vaynes from the beginning to the ending, ‘there is a vayne (if not several vaynes) of coles, that fol- ‘loweth those of the lymestone, — ‘This vayne of cole in ‘ some partes joineth close to the first lymestone vayne, as in ¢ Pembrokeshire, and Carmarthenshire; and in some partes ‘it is found close by the other vayne of lymestone, as in Gla- ‘morgan, Monmouth, and Somersetshires. ‘Therefore,’ it is ‘ cautiously added, ‘ whether I shall say that there are two ‘vaynes of coles to be found betweene these two vaynes of ‘lymestone, or to imagine that the cole should wreathe or ‘ turne itself, in some places to one, in other places to the ‘ other; or to think that all the land betweene these two vaynes ‘ should be stored with coles,—I leave to the judgement of ‘ the skilfull miners, or to those which with deep knowledge ‘ have entered into these hidden secrettes.’ Now these ‘two vaynes of lymestone’ are in fact the boun- daries, on the north and south, of the great coal-tract of South Wales; and if the reader will compare Mr.Owen’s descriptions, or even our brief abstract, with a good map, and with the ac- count of that tract since published by Mr. Martin *, he will be surprised, perhaps, at the coincidence, and will regret that a work so valuable remained so.long unknown and unproduc- tive ;—since it would be difficult to produce, even at the pre- sent time, a better specimen of geological investigation. * Philos. Trans, 1806, vol. xcvi. p. 342. Dr. Fitton’s Notes on the History of English Geology. 445 Another class of authors, still less deserving of specific notice than the topographers, and fortunately of much more frequent appearance during the seventeenth and the beginning of the last centuries, than of later years, is composed of those who min- gled Scriptural history with speculative or ideal geology, and weakly fancied that they maintained the authority of the Scrip- tures, and promoted the cause of truth,—by seeking for traces of the Deluge in all the appearances of the earth, and warping into accordance with the Mosaic account of the Creation, their own scanty and inaccurate notions of the structure of the globe. Of these writers the greater number appear to have forgotten the danger which attended their presumptuous attempts; since if they had succeeded in establishing the connexion of their own views with the sacred writings, the fall of their opinions (and, one after another, they have all passed away,) must necessarily have been accompanied by that of Scriptural authority. An instance of the ill effects of this mode of proceeding has been already noticed, in the history of organic remains; and it would be easy to multiply quotations, which might perhaps surprise our readers of the present day*. ‘There are, however, some very honourable exceptions to these general remarks. The works more especially of Catcott+, in the last century, and more recently of Mr.’Townsend }, whom we have already men- tioned, afford in many instances correct views of the operations of nature, and valuable statements of fact; notwithstanding their erroneous notions, as to the objects of geology, and the mode of conducting inquiry in this as in every other depart- ment of scientific research. In that part of Mr. Catcott’s work which goes to demon- strate, to use the language of Cuvier, ‘ that the earth has been ‘ recently overwhelmed by the waters of a transient deluge,’ there are many excellent observations: but in attempting to include the solid strata within the range of that operation, and ascribing to it the presence of the fossils which they contain, the author shares the fate of all those who before him had in- dulged in similar speculations: and his Diagram,—‘ repre- ‘ senting the internal structure of the terraqueous globe, from ‘ the centre to the circumference,’ is the result of suppositions not less visionary than those of Burnett, Hutchinson, and * Some further reference to the writings alluded to in the text, will be found in an article by the author of the present paper, in the Edinburgh Review of Dr. Buckland’s § Reliquie Diluviane ? Edin. Rev., October 1823, yol. xxxix. p. 196. + Catcott, ‘A Treatise on the Deluge.’ S8vo, London, 1761. t Townsend, * Vindication of Moses,’ &c, 1813. 446 Dr. Fitton’s Notes on the History of English Geology. other writers, who treat professedly of events beyond the limits of human observation*. Having thus sketched the progress of facts and opinions, to the period when Mr. Smith began his researches on the stra- tification of England, we shall next inquire respecting the method of expressing the results of geological observation by means of maps. 0 We have seen that Lister, though he did not ‘carry into execution his own * project for a Map of Soiles,’ entertained a very philosophic expectation of the: benefit that might re- sult from it:—‘ If the limits of each: soil,’ he says, ‘ appear- ‘ed upon a map, something more might be comprehended ‘ from the whole, and from every part, than I can possibly ‘ foresee; but I leave this to the industry of future timest+.’ We now know how amply the advantages to science, fore- seen by the author of this project, have been realized. A:still more refined, and, as it then may have appeared, more re- mote anticipation of the future progress of geological in- quiry, occurs at the close of FonTENELLE’s observations on a paper of De Reaumur, giving an account of a remarkable accumulation of fossil shells in Touraine :-—* M. de Reaumur ‘imagine comment le Golfe de Touraine tenoit a locéan, et ‘ quel étoit le courant qui y charioit les coquilles; mais ‘ce ‘n’est quune simple conjecture, formée pour tenir lieu du ‘ yéritable fait inconnu, qui sera toujour quelque chose d’ap- ‘ prochant. Pour parler surement sur cette matiére, 2 fuu-+ ‘ droit avoir des especes de Cartes Géographiques dressées selon ‘ toutes les miniéres de coquillages enfouis en terre. Quelle ‘ quantité d’observations ne faudroit il pas, et quel temps, pour ‘les avoir! Qui scait cependant, si les sciences n’iront pas un ‘ jour gusque-la, du moins en partie t ?’ MIS8 It is now little more than a century since this passage was written: yet, if geology advances during the next hundred years as it has done during the last fifty, is it not highly pro- bable that the prophetic anticipation of Fontenelle will have been fulfilled ? * The title of Burnett’s eloquent and celebrated work, ‘ Theoria Sacra,’ is as follows: ‘The Theory cf the Earth, containing an account of the ‘ original of the earth, and of all the great changes which it hath already “undergone, or is to undergo, till the consummation of all things.’ 3rd edition : London, 1697. + Lister, Phil. Trans, yol. xiv. p. 739, &c. { Histoire de Academie Royale des Sciences, 1720, p. 5; and Mémoires, p. 400.—The report here referred to is ascribed to Fontenelle on the authority of Faujas. fuvres de Valissy, Ato, p. li. Dr. Fitton’s Notes on the History of English Geology. 447 About fifty years after Lister’s project for a geological map, a work was published, under the title of * A new Philosophico- ‘ chorographical Chart of East Kent, invented and delineated ‘by CurisvopHer Packe, M.D.,’ which is one of the most valuable contributions to the physical geography of England that has appeared. It was preceded by a letter to the Royal Society, and accompanied by a Tract of greater length*, ex- plaining the purpose of the work; which, from the author’s frequent employment of anatomical terms, seems to have been suggested by his professional studies. The map it- self represents, on a scale of rather more than an inch and half to a mile, a circle of about two and thirty miles round Canterbury: the principal object being, as the title of the Tract imports, to represent the course and connexions of the valleys, all of which are described with great minuteness of detail,—their ramifications being compared to those of the veins in the human body. As the greater number of these valleys are at present without streamlets, it is inferred that they were formed not by existing causes, but by the retiring waters of the Deluge; and that the surface since that event has undergone no change. There is no allusion to stratifica- tion either in the map or the memoir; but the natural fea- tures of the country are very correctly distinguished, and divisions pointed out, which correspond with those of the pre- sent day:—the first including the chalk district; the second, under the name of ‘stone hills,’ the ridge of the lower green- sand ;—between which and the chalk range, the vale occupied by the gault is also clearly indicated:—and the ‘clay-hills,’ constituting a third division, occupy the valley of the Weald. Nothing can be better than the general plan upon which the author proceeded ; more perfect execution only, having been wanting to render his map complete: and he seems himself to have had a just sense both of the importance of his under- taking, and of the true mode of accomplishing it.—‘ For this,’ he says, ‘is no dream or devise, the offspring of a sportive ‘or enthusiastical imagination, conceived and produced for * The title is * ATKOTPA®IA, sive Convallium Descriptio; in which “are briefly, but fully, expounded the Origine, Cause, and Insertion, Ex- “tent, Elevation, and Congruity, of all the Valleys and Hills, Brooks and “Rivers ; as anExplanation of a new Philosophico-chorographical Chart of * East Kent. Canterbury, 1743.’ This Tract, which everywhere shows the patriotism of the author, and his:enthusiasm about his subject, contains some yery amusing passages. He’ rejects indignantly the title of ‘Map’ for his performance; ‘there * being,’ he asserts,‘ as manifest a difference between this chart and a map, “as there is between the frame of any building, and the same finished into * acomplete house, adorned with all its furniture.’ 448 Dr. Fitton’s Notes on the History of English Geology. © want of something else to do, at my leisure in my study,—but ‘it is a real scheme, taken upon the spot with patience and ‘ diligence, by frequent or rather continual observations, in ‘ the course of my journeys of business through almost every ‘the minutest parcel of the country: digested at home with ‘much consideration, and composed with as much accuracy, ‘ as the obseryer was capable of.’—P. 98. Buacue’s map of the Northern Hemisphere, published in 1756*, with his other productions, relate more properly to physical geography, than to geology; and were founded upon an hypothesis which assumed the existence of a frame-work, or skeleton, of the earth, consisting of chains of mountains,— which were supposed to traverse not only the continents, but the seas and oceans, throughout the face of the globe. ‘The islands were considered only as the more prominent points of these chains; and in order to connect the islands of the greater oceans with the continents, the author was obliged to form by interpolation, or to imagine, submarine chains, of many thousand miles in length. GvueETTarp appears to have been the first author, in France, who formed the project of a mineralogical map. is plan was that of representing upon ordinary maps, by means of detached characters, the several mineral substances found at each point observed: but his general views were very loose and hypo- thetical; nor was there a sufficient stock of facts, at that time, to support them. The Mineralogical Atlas and Description of France, by Monnver}+, was undertaken and conducted in continuance of Guettard’s, and expressly upon his principles; though, for some reasons which are not stated, he himself withdrew trom the direction of the work. It was an elaborate undertaking ; and the value certainly is not proportioned to the labour and expense bestowed upon it: though, if the observations were correct, the collection would still furnish useful materials to those who examine the country with sounder general views. The great defect appears to be, that the authors of the work do not seem to have been impressed with, or to have acted upon, the stratigraphic principles, so well explained by Michell * Philippe Buache,—Essai de Geographie Physique, ou Pon propose des vues generales, sur Vespece de charpente du globe, composée de chaines des montaines, qui traversent les mers comme les terres.—Mem. de |’Acad. 1752, pp. 399, 416.—Buache was bern in 1700, and died in 1773. + Atlas et Description Minéralogique de la France, entrepris par ordre du Roi ; par MM. Guettard et Monnet. Publiés par M., Monnet, d’apreés “4 nouveaux Voyages—Ire Partie ;—Paris: folio, 1780; pp. 212, with 31 aps. t Dr. Fitton’s Notes on the History of English Geology. 449 twenty years before its publication; and this is the more ex- traordinary, as vertical sections, detailing the order of the beds, accompany the maps. Some of the copies, which we have seen,—in which the characters expressing the predominant mineral substances are coloured,—approach so near to the expressive power of the modern geological maps of stratified countries, that one is surprised that the authors did not, by advancing this step, give that connexion to their results, which is the: essence of geology. It is not a little remarkable that Dre Saussure, who pub- lished some years after the appearance of Monnet’s atlas, and must have been acquainted with that work, as well as with the maps of the German school*, does not appear to have attempted any geological map of the tracts he has described. Had he made that trial, it is probable that he would have an- ticipated some of the important results which have since been afforded by the maps and sections of the Alps, by Ebel and Escher +. We have not yet seen the maps referred to by the late M. Desmarest, as intended to be annexed to the Lncyclo- pédie Méthodique; but this writer judiciously insists on the benefit arising even from attempts to express in maps the re- sults of geological investigation ; and on the advantage of com- bining with them vertical sections of the tracts represented. Some of the geological maps in colours, of the older Ger- man mineralogists, are valuable; but the best plan,—which Mr. Jameson has informed us, was devised, or much improved, by Wernert{,—is that of representing the several formations in distinct but sober hues, and marking the superior rock by a narrow band of deeper colour along the line of its contact with the subjacent one; and this is nearly the method which is em- ployed by English geologists at present. Of the county surveys, published by the Board of Agricul- ture in 1794, five only have maps which indicate the compo- sition of the surface; and of these, that of Devonshire alone has any pretension to geological distinction,—enumerating dun- stone and limestone in its list of ‘ Soz/.’—The remaining four, Lancashire, Lincolnshire, Sussex, and Wiltshire, represent by colours the superficial soz/s, in the agricultural sense of the term ;—the first two distinguishing also the coal tracts, But * The four volumes (4th edition) of De Saussure’s Voyages dans les Alpes, are dated respectively,—I. 1779; I. 1786; III. and IV. 1796. ah Uber der Bau der Erde in dem Alpen Gebirge. I. Tom. 8vo. Ziirich, 1808. t Transactions of the Wernerian Society, vol. i. p. 149. Third Series. Vol. 1. No. 6. Dec. 1832. 3M 450 Reviews, and Notices respecting New Books. there is not in any of these maps any intimation of stratigra- phical structure, nor are any sections connected with them. We are not, indeed, aware that any maps which can be called geological, had appeared in this country before that of Mr. Smith; unless two of the Plates which accompany the Historical Atlas of England, by ANpREws, published in 1797*, are entitled to that name. These, however, though very de- fective in execution, and on a very small scale are at least, well intended: one, exhibiting the basins, valleys and courses of the great rivers; another being entitled, ‘A map of the sum- ‘ mits of the chain of mountains and great ridges of hills of * Albion, as it is supposed they appeared when the water was ‘descended after the Deluge.’ This last plate is a sort of skeleton of England, after the manner of Buache, whose sy- stem the author seems to have imbibed; it points out the great ridge of “yellow limestone” (perhaps the oolite), and the chalk ranges,—from Sidmouth to the sea in Norfolk, and eastward through Surrey, Kent, and Sussex. Toa person acquainted with the geology of England, such a sketch presents some interesting views but nothing respecting stratification, nor the internal structure of the country, is either indicated in the maps, or mentioned by the author in his treatise. [To be continued. ] LXXXI. Notices respecting New Books. Dr. Pzarson’s Introduction to Practical Astronomy. 4to. 2 vols. {Continued from p. 375] pil first volume of this laborious publication consists of a com- plete series of astronomical Tables, arranged in the most conve- nient form for giving the corrections. In the completion of this ‘ar- rangement, the author has evidently spared no trouble or expense ; and he has availed himself of the adviceand labours of other computers. In arranging the series of general Tables of Precession, Aberration, Lunar and Solar Nutation, where much care is requisite, we ‘are glad that his own labours were assisted by the mathematical talents of the late Cape Astronomer, Mr. Fallows, who was remarkable for his great skill and precision in such arrangements, and to whom the author has expressed a sense of great obligation. With such helps, and by his own indefatigable industry, our author has pro- duced a collection of Tables, which are among the most extensive and valuable that have ever appeared. * “ Histoireal Atlas of England, physical, political, astronomical, &c. from the Deluge to the present time ; by John Andrews, Geographer,” &c. Lon- don, fclio, 1797; printed for the author. This work does not appear to have been completed. The maps-are only 13 inches in length by 10 in width. Dr. Pearson’s Introduction to Practical Astronomy. 451 “This volume is dedicated to the Astronomical Society of London, of which Dr. Pearson was for ten years the treasurer ; and he has taken this opportunity of showing his high sense of the honour con- ferred upon him, by dedicating to its members in general this collec- tion of ‘Tables, so well calculated to promote the objects for which the Society was instituted. « Some opinion may be formed of the extent of the author’s la- bours, when it is stated, that, of the 457 pages constituting this volume, 325 contain new Tables, or explanatory matter; 46 are filled with Tables that have been enlarged, or otherwise improved ; and 86 only comprise Tables that have been copied in their original state.” The first set of Tables contains the corrections to be applied to the apparent place of a star, in order to obtain its place clear from the effects of refraction. The first four Tables are computed from the formula of Bradley; and as the explanation given of their use is quite clear, we need say no more about them. The Tables of Refraction next in order are those published in 1806 by the French Board of Longitude: these, as our author informs us, are founded on the profound investigations of La Place. But whether the most elaborate formula deduced by this eminent geometrician is more to be depended on than that given by Bradley, may perhaps be questioned. The arrangement given by our author is that adopted at Greenwich. The next set of Tables for this purpose are those computed by Stephen Groom- bridge, Esq., who conducted a long series of observations for this purpose, with one of the most perfect meridian instruments that was ever constructed. We allude to the beautiful transit circle made by Troughton, and which is fully described by our author in his second volume.—The Tables next in orde rare Piazzi's: these were constructed without any reference to theory, and were deduced from observations made out of the meridian. Among those who have laboured in this interesting department of science, the late Dublin astronomer, Dr. Brinkley, must not be passed over. Our author has introduced the Tables computed by this acute philosopher, and they deserve notice, inasmuch as the for- mula on which they depend is original, and displays the greatest ingenuity. We refer our readers to the original papers in the Irish Transactions, as they are most peculiarly interesting and instruc- tive. We also refer to the account and explanation of these Tables given by our author.—The late Dr. Young, whose penetration was so remarkable that few things passed under his observation without undergoing some improvement, also investigated a formula for re- fraction. Our author informs us that the Tables computed from this formula are said to agree more exactly with the latest observa- tions than any others. The Tables following are constructed by the indefatigable Bes- sel. Our author’s account of them is as follows: ‘ He has investi- gated the subject of Refraction, and, retaining the characters of La Place, has deduced the following formula, on which he calcu- 3M2 452 Reviews, and Notices respecting New Books. lated a set of Tables that comprehend quantities even too minute to be generally serviceable in practical astronomy.” The addition of Bessel’s Tables, as also of Carlini’s, with the Ta- bles computed from the elaborate formula of Mr. Ivory ; also of Littrow’s and Zach’s modifications of Bessel’s ‘Tables,—seems to have been an after-thought on the part of our author : yet in doing this he has adhered to his original determination of sparing no trouble in making his collection as complete as possible. We come next to another set of the most important Tables. These are the Tables from I. to XIV. inclusive, originally pro- posed by Baron Zach, and reduced to their present shape by the late Mr. Fallows. They are arranged in two sets, the first contain- ing the corrections in right ascension, and the rest the corrections in north polar distance for precession, aberration, lunar nutation, and solar nutation. Table XV. contains the proportional parts of the annual preces- sion, so as to give the correcticn for any given day of the year.— Tables XVI. and XVII. are for the purpose of giving the sun’s longitude correctly at the moment of the culmination of any known star; for as the aberration and solar nutation are both functions of the sun's longitude, neither will be obtained correctly unless this longitude be accurately known at the instant of observation. Table XVI. gives this; and Table XVII. gives it also with still greater accuracy. But this last Table also answers another purpose, viz. that of adapting the sun’s longitude, calculated for one observatory, to the meridian of any other. The labour bestowed on Table XVIII. must have been very con- siderable. We will refer to the author’s own account of this Table, given in page 322, and so leave it with our scientific readers to appreciate its merits. We need only observe, that although to an “expert mathematician” there would be no difficulty in com- puting these numbers, yet having them computed for him, saves him a great deal of trouble; and therefore it is not only to those ‘who are not skilled in trigonometrical calculations” that this Ta- ble is useful, but to every practical astronomer. This Table con- sists of 45 pages ; and we will readily take our author’s word for it, that they “have been calculated at the expense of considerable la- bour.” The next Tables in the collection are the universal Tables of Delambre, which, from the facility with which they can be applied to single observations, our author has thought proper to introduce. After these follow a few small Tables, called Dzfferential Tables, the object of which is to give by inspection the changes which take place in the aberration and junar nutation, when a small alteration, such as one degree, is given to the place of a star in right ascension or declination ; and also two other Tables, the former tor correcting the diurnal aberration, and the latter for determining the aberration of light in the case of a comet or planet. The next series of Tables is of a different kind, inasmuch as the corrections to be taken from them do not result from physical Dr. Pearson's Introduction to Practical Astronomy. 453 causes. The first of this series is for the purpose of reducing ob- servations made out of the plane of the meridian, to what they would have been had they been made in that plane. This method of observing is particularly useful with the altitude and azimuth circle. There are two Tables given for this purpose: one by De- jambre, and another somewhat more simple by the late Dr. Young. For an account of the Tables entitled “ Terrestrial Graduation,” we refer to the detail given by our author. The Tables for converting space into time, and the contrary, will be found very useful on many occasions. Also the new Tables for converting solar into sidereal time and the converse, with one for obtaining the proportional parts of the clock’s daily rate, will be found equally useful. We now come to aset of Tables of the corrections to be applied to any one of the forty-eight stars for which they are calculated. The object of these Tables is to obtain the mean place, the amount of the several corrections, and the true apparent place of any one of these forty-eight stars, for any day of the year for many years to come. This set of Tables is followed by another containing the compa- rative mean places of the same forty-eight principal stars, as re- cently determined by the most eminent astronomers for the epoch 1800. The Table in page 147 is useful as containing the changes which take place in the arguments, with which the above Tables are en- tered, depending on the value of the subsidiary angle used in their computation. By means of this Table the corrections for the forty- eight principal stars may be adapted to any year for a long period before or after the year 1830. The Table next in order is that of Bessel for determining by an abridged method the apparent right ascensions of Dr. Maskelyne’s thirty-six stars. We now arrive at another class of Tables, viz. Solar Tables, of which there are twenty-five, contained from page 153 to 180 inclu- sive. Table I. contains the mean longitudes of the sun and of his perigee for one hundred and fifty years, commencing with the year 1750. Table II. is supplementary to Table I., and contains the quantity to be added to the mean longitude of the sun, and of his perigee, to obtain the mean longitude for any day in the above- mentioned period. Of Tables II]. and IV., the first is for the pur- pose of obtaining a near approximate value of the sun’s ¢rue lon- gitude, as the argument with which some of the preceding Tables are entered; and the last for obtaining an approximation to the sun’s mean right ascension, for the purpose of comparing solar with sidereal time. ‘Table V. affords the means of obtaining the suns right ascension when his longitude is given. Table VI. con- cists of the sun’s declination, corresponding to every 10’ of his longi- tude, with an equation for a small variation in the obliquity. The use of Table VIL., containing proportional parts of the sun’s daily variation in longitude, is obvious. Table VIIL., entitled “ Reduction 454 Reviews, and Notices respecting New Books. of the Ecliptic to the Equator,” is only a modification of Table V., the difference between the sun’s longitude and right ascension being given in space. Table X., entitled ‘*Reduction to either Solstice,’’ furnishes the means of obtaining the sun’s declination at the solstice, (i. e. the apparent obliquity of the ecliptic,) from observations of his right ascension and declination when near the solstice. We refer our readers to this, and Table XX., with our author’s explanation of both, and also to his explanation of the discrepancy existing between the winter and the summer reductions to the solstice, according to the Greenwich observations. Tables XI.and XI{. contain minute equations of the equinox and obliquity depending on the small oscillations of the earth from the mean plane of her orbit, produced by the combined dis- turbances of the Moon, Venus, andJupiter. The ‘lables XII1. to XIX. are all useful, and for their application we refer to the explanation given in the work.—W hen the time ofapparent noonis determined by meansof equal altitudes of the sun, asmall equationis found requisite on account of the change in the sun’s declination in the interval of the observations. The Tables XXI., XXII. by Delambre, and XXIII., XXIV. by Zach, contain the corrections to be applied to obtain the true time of the passage of the sun’s centre over the meridian. These Tables are essential when a sextant or any equal altitude instrument is made use of, but are superseded by the use of the transit instrument. Table XXV. being the last of the Solar Tables, contains the sun’s parallax in altitude: and the method of taking this from the Table, when the horizontal parallax is given, is obvious. The Tables next in order are the Lunar Tables. There are fifteen of these contained in pages 181 to 203 inclusive. ‘Table I. contains the epochs of the mean longitude of the moon’s ascending node, for 120 years, beginning with the year 1800; and Table II. contains the proportional parts of the annual regression to be applied to the mean longitude of any epoch, to obtain the mean Jongitude for any day of the corresponding year. Table III. gives the moon’s semidiameter for every second of her equatorial horizontal parallax. Table IV. contains the differences of the moon’s horizontal parallax in the sphere and spheroid computed for two different compressions. | For the use of Table V., and also that of Table VI., containing the angles between the normal and the radius, in different parallels, we refer to our author. Table VIII. gives the moon’s parallax in altitude, and is very conveniently arranged. Table [X. gives the time of the moon’s semidjameter passing the meridian, and is of use in deter- mining the moment of the passage of the moon’s centre over the meridian : the example given by our author fully explains its use. Table X. is also for the same purpose. The changes which take place in the moon’s right ascension, de- clination, &c. being far from uniform, we cannot interpolate by means of parts taken proportional to the time elapsed, since she was in any given position: we must, therefore, in order to obtain a tolerable approximation, make use of the second differences. ‘Table XI. is constructed for this purpose. Tables XII. and XIII. are both of considerable use for the practical purposes for which they are con- Dr. Pearson’s Introduction to Practical Astronomy. 455 structed. Tables XIV. and XV., giving the aspects, are of but little use ; they are, as our author observes, “more calculated to gratify curiosity than to answer any useful purpose.” The next set of Tables are termed Zodaical Tables, so called by the author because they are applicable to those phenomena which occur in the zodiac, such as eclipses, occultations, &c. On this account some Tables which, strictly speaking, ought to have appeared among the Lunar Tables, find their place here ; such as the Tables from XIII.to XX V. inclusive, relating to the moon’sparallax inlongitude and latitude, in right ascension and declination. These Zodiacal Tables extend from page 203 to page 261. The first is the converse of the Solar Table V. or VIII., and is given for the purpose of obtaining the sun’s longitude from his right ascension. ‘Tables II. and III]. are very laborious Tables, originally constructed by Dr. Maskelyne, but here enlarged and improved by our author. Tables IV.and V. contain corrections to be applied to the quantities determined by the pre. ceding Tables, for a small variation in the obliquity. As one of the principal uses of these Zodiacal Tables is to furnish the elements of computation in the determination of the longitude from an occulta- tion of the fixed stars, it is of importance to know what stars may be occulted by the moon. ‘Table VI. is introduced for this purpose, as copied from the Jahrbuch of 1780; but an enlarged one, in the order of right ascension, is subsequently givenin the Appendix (p.515—528), As the longitude and altitude of the nonagesimal, or the highest point of the ecliptic above the horizon, are requisite elements in the determination of the moon’s parallax in longitude and latitude,a Table for facilitating these laborious computations by furnishing the above elements must be of great use. For this purpose Table VII. has been constructed. The angle of position is also another useful element on many occasions: the two Tables VIII. and IX. have been added by our author for facilitating its computation for zodiacal stars. This angle, with the latitude and longitude, enters into the formule for aberration, and is moreover an element in the computation of eclipses, parallaxes, occultations, &c. Tables XI.and XII. are only modifi- cations of the Solar Tables VI. and V.. Table XIII., with its appen- dix, is of more importance, as it furnishes us with an important ele- ment in the computation of occultations of the fixed stars by the moon. In the explanatory part of the work we find a few additional Tables given; the first is fot the correction of parallax in the spheroid, computed from a formula given by Dr. Young. Following this are six small Tables, the first of which gives the longitudes and latitudes of Dr. Maskelyne’s thirty-five stars, and the rest relate to the correc- tions of the mean longitudes and latitudes. After two Tables expressing the lengths of circular arcs in terms of radius, there follows in the proper order a collection of Planetary Tables. ‘The first six of these are for determining the parallaxes of the planets. The seventh affords the means of converting the geocentric longitude of a planet into right ascension. Then follow five more 456 Reviews, and Notices respecting New Books. Tables, lettered from A to E; the first is a Table of Zach's, giving:the horizontal parallax of each of the ten planets, and also their apparent diameters: the remaining four relate to the aberrations of the{planets in latitude and longitude depending on the eccentricity of their re- spective orbits. We apprehend that all the Tables of the planets are very kit: ras being in a state of perfection; and we are glad to find that the Plumian Professor of the University of Cambridge, who fills the im- portant and distinguished office of principal astronomer in the mag- nificent observatory recently erected there, has expressed his deter- mination of paying attention to this much neglected department of astronomy. Without making any further comments of our own’on this subject, we will quote the very pertinent and just remarks made by the Plumian Professor, Mr. Airy, in his Preface to the first volume of the Cambridge Observations: ‘‘The part of astronomy which appeared to me to have been most neglected, at least in the observa- tions of this country, is the observation of the planets. And the deficiency in this respect is most deplorable. In the published ob- servations of our national establishment, there is not a sufficient number of observations of the planets to assist, in any material degree, in improving their theory. And any one who wished to revise the planetary Tables would now find himself nearly destitute of the ne- cessary data upon which to found his investigations. As soon, there- fore, as the Cambridge Observatory was placed under my direction, I determined to make the observation of the planets the leading object of my labours. And I was further led to do this by the:con- sideration that my own personal exertions would probably be: suffi- cient to accomplish the greatest part of this undertaking; but that, unassisted as I was, I could not hope to complete any pian ofa more extensive nature.” We most cordially wish this learned gen- tleman success to his labours in this much neglected field of science, the intricacies of which he, on account of his very great talents, is so peculiarly qualified to unravel. Our author’s next Table, headed Velocity of Light, is serio plain in its construction and use. Then come seven Tables relating to the mean places of the pole star; and we refer our readers to the work for their use and explanation. The next two Tables are of: considerable use in adjusting the meridian position of the transit instrument. The first is a catalogue of circumpolar stars, to be observed both at their upper and lower culminations. Dr. Pearson has given another Table for the same purpose, to which we also refer, containing a collection of stars of nearly the same right ascension, but having declinations of opposite denominations. After these come a few Tables, for different purposes, with which the volume in its original form closes. Among these additional Tables we find Schu- macher’s catalogue and constants for 500 stars, and also the second series of Tables by the late Cape Astronomer. With these Tables the work in its original form concludes.—Since its publication, however, the author has made a large addition to it Royal Astronomical Society. 459 as an Appendix. The reasons which induced him to make this addi- tion will be best understood by consulting the remarks at the begin- ning of this Appendix. _ The author has also given a set of Tables for computing some very minute corrections depending on twice the longitude of the moon's ascending node (2. Q). He also gives some account of Mr. Baily’s Tables, computed for, and published by, the Astronomical Society of London. Besides several other useful Tables, the author has added a ca- talogue of 520 zodiacal stars liable to occultation, containing the auxiliary constants for gaining the various corrections. This is ac- companied by another table referring the same stars to the catalogue of the Astronomical Society. To these is added an arrangement of the above zodiacal stars in.a table consisting of fourteen pages, before alluded to, in which the stars that may at a given time be seen occulted in England, are distinguished from those seen in any other country, giving also the place of the moon’s node when the occulta~ tions may be expected. A Guide to the Carpenter's Rule. By Bexsamix Bevan, Civil En- gineer, London, 1832; }2mo. pp. 23. Weare informed in the preface to this pamphlet, that “ the Author's mode of explaining the operations to be pertormed on the Slide-rule has been some years before the public” in his larger treatise on this instrument, and that it ‘is allowed to be superior to any other hitherto published.” The present treatise is confined to those opera- tions which can readily be performed with the common Carpenter's ‘Rule, divested of the more extended furmule contained in the larger one. For Schools, the author presumes, it “ will be found useful in teaching instrumental arithmetic, and qualifying the student for the active pursuits of life.” It consists of an Introduction, explaining the notation employed on the Rule, and of general formule, with examples, in the following arithmetical. processes and branches of mensuration; viz: Multiplication, Division, Proportion, Inverse Proportion, Squares and Roots, Cubes and Roots, Mensuration of Superficies, Solid Measure, Brickwork, and Gauging. These formule and examples are all perspicuously and accurately stated ; and at p. 18, under the head “‘ To estimate the comparative Strength of Seant- lings used in Buildings,” we find a very useful little table of the numbers expressing the tomparative strength of various scantlings as used in different buildings. LXXXII. Proceedings of Learned Societies. ROYAL ASTRONOMICAL SOCIETY. £ hoere following is a list of such papers read before, and communica- tions made to, this Society, during the session of 183]—32, as have not already been noticed in our reports of its proceedings. Third Series. Vol. 1. No 6. Dec. 1852. 3N 458 Royal Astronomical Society. Jan.13, 1832.—The following communications were read :— : I. The conclusion of Sir J. Herschel’s paper on the Orbits of Binary. tars. If. Account of the Occultation of 119 and 120 Tauri by the Moon, on ae 18, 1831. By Sir James South. In a Letter to Mr. Baily. I[[. Observations of Occultations of Stars by the Moon, made at Bedford, by Captain Smyth, between the months of January and December 1831. IV. Observations of Occultations and of Stars observed with the Moon, at the Cambridge Observatory, during the year 1831. By. Professor Airy. V. Stars observed with the Moon at Greenwich, in December 1831. From the Astronomer Royal. Mr. Baily announced from the Chair, that he had received a com- munication from Professor Schumacher, stating that His Majesty the King of Denmark had founded a gold medal, to be given to the first discoverer of a comet, not of known revolution, nor visible to the naked eye ; subject to certain conditions, which have been recorded in the Phil. Mag. and Annals, N.S. vol. xi. p. 155, (The proceedings of Feb. 10 will be found at p. 234, and those of March 9, at p. 390, of the present volume.) April 13.—The following communications were read, &c. I. Comparisons of the Right Ascension of Polaris, as obtained by observation, with that given in Bessel’s catalogue for 1831; and observations of \ Urse@ Minoris and 51 (Hevelius) Cephei, made with a 5-feet transit at Blackheath. By Mr. Wrottesley. II. Mr. Sheepshanks gave an account of the mural circle, with the methods of using it hitherto followed, and a description of the state and defects of the circle at the Cape Observatory. Ill. A List of Stars observed with the Moon, at the Royal Obser- vatory, Greenwich, March 1832. 1V. Transits of the Moon, with Moon-culminating Stars, obseryed at Cambridge in the month of May 1832. Mr. Baily stated, in reference to Dr. Robinson’s paper “‘On,the dependence of a clock’s rate on the height of the barometer,” read in June 1831, of which an abstract was given in Phil. Mag. and Annals, N.S. vol. x. p. 445, that he had recently swung the mercurial pen- dulum in a vacuum apparatus, and found that a variation of one inch in the pressure of the atmosphere produced a difference of 0:42 se- conds a day in the rate of the pendulum; which is more than double the quantity deduced by Dr. Robinson, from the observed alteration of rate, when compared with the height of the barometer. May 11.—The following communications were read :— {. On the transit of Mercury, which took place on the 5th instant: consisting of, 1. observations made by the Astronomer Royal and Mr, Simms, at the Royal Observatory; 2. by Mr. Riddle at Greenwich Hospital ; 3. at the Observatory, Exchequer-street, Dublin ; and 4. by Mr. Simms, in Fleet-street, Il, .Observations of the Occultation of Saturn on the 8th instant: Royal Astronomical Society. 459 i}. at Greenwich Hospital, by Mr. Riddle; 2. at Islington, by Mr. Simms ; 3. at Bedford, by Captain Smyth; 4. at Lapley, near Brewood, Staffordshire, by the Rev. M. Ward. IIT. Observations of the Occultation of 119 and 120 Tauri, March 9, 1832, at Islington. By Mr. Simms. IV. Correction of the Formule for determining the Longitude from an observed Occultation, with Suggestions for simplifying the appli- cation of these and other Formule to the case of corresponding Ob- servations. By Mr. Riddle. V. Observations of Eclipses of Jupiter’s Satellites and Occultations between the years 1827 and 1832, and Measures of Double Stars taken in 183] and 1832. Also Observations of the Comet of Ophiu- chus in Jan. 1831. By the Rev. W. R. Dawes. Communicated by Sir J. F. W. Herschel. VI. A New Method of reducing the apparent Distance of the Moon from a Star to the true. By Baron Zach. VIL. A Method of finding the rate of variation of the Moon’s mo- tion at any instant. By Lieut. Raper. VIII. On the Determination of the Solar Parallax from Observa- tions of the transit of Venus, June 3rd, 1769. A posthumous work of Don Joseph Joachim de Ferrar; followed by a Summary by Don Joseph Sanchez Cerquero. Communicated by Sir James South. IX. An Ephemeris of Encke’s Comet for the Southern Hemisphere. By Professor Encke. Communicated by Lieut. W. S. Stratford. X. A List of Stars observed with the Moon, at the Royal Obser- vatory, Greenwich, in the month of April, 1832. X1. Observations of the Moon and Moon-culminating Stars made at Cambridge Observatory, in the month of April 1832; Long. 23° 54 E., Lat. 52° 12' 50". June 8.—The following communications were read :— I. On the transit of Mercury, of the 5th of May 1832. By the Rev. J. Fisher. Communicated by Captain Beaufort. II. Observations of the Occultation of Saturn of May 8, 1832: 1. by W. Lawson, and another at Hereford; 2. by Mr. Holehouse at Islington; and 3. by Mr. Snow. Ill. Observations of the Solstices from December 1829 to De- cember 1831; and Observations of Moon-culminating Stars during the year 1831; made at the Hon. East India Company's Observatory at St. Helena. By Lieut. Johnson. Communicated by Captain Beaufort. IV. On the Calculation of the Geographical Longitude and Lati- tude of a place whose geodesic distance from the Meridian and Perpendicular of another place is given, the Earth being considered as a Spheroid. By Baron Zach. V. Mean Right Ascension of Fifty-five unknown Stars, observed in 1831, with a transit instrument, of twenty inches focus, and a sidereal chronometer beating half-seconds ; also Occultations observed in the month of March 1832. By Mr. Snow. VI. Fifth Catalogue of Double Stars observed at Slough, in the years 1830 and 1831, with the twenty-feet reflector, and reduced to the epoch 1830-0. By Sir J. W. F. Herschel, K.G.H. SN 2 460 Soological Society. VII. Observed Occultation of Aldebaran. By Mr. Rothwell. Com- municated by Mr. Tulley. sais VIII. Ephemeris of Encke’s Comet for the Southern Hemisphere. ‘From Professor Encke. IX. Stars observed with the Moon, at the Royal Observatory, Green- wich, in May 1832. X. After the reading of the preceding communications, Mr. Sheep- shanks made some remarks upon the mode of adjusting the transit instrument, and proceeded to describe minutely the various corrections requisite for obtaining correct results, illustrating his statement from various transit instruments furnished for the occasion by Messrs. Troughton and Simms. ZOOLOGICAL SOCIETY. Proceedings of the Committee of Science and Correspondence. May 8.—A preparation was exhibited of the generative organs ‘of a hybrid male bird, bred by the Society, and produced between a Muscovy Drake and a common Duck; and Mr. Yarrell described the external and internal appearances of the individual from which ‘the preparation was obtained, and which, he stated, strongly re- sembled, externally, the true Muscovy, while internally the viscera were as decidedly indicative of the common Duck. The skeletons of Capromys Fournieri, Desm., and Dasyprocta Acouchy, F. Cuy., having been placed on the table, Mr. Owen en- tered into a series of remarks explanatory of their peculiarities, which he pointed out with reference to the skeletons of other Ro- dentia exhibited for the purpose of comparison: the substance of Mr. Owen’s remarks, together with a table presented by him of the admeasurements of the skeleton in both the above animals, have been printed in the “Proceedings” of the Committee. The exhibition of the collection of Shells formed by Mr. Cuming on the western coast of South America and in the South Pacific Ocean, was resumed ; and of these, the following new species were characterized by Mr. Broderip and Mr. G. B. Sowerby : viz. by the latter naturalist, Cu1Ton dipunctatus, exiguus, (the smallest species Mr. Sowerby has seen, length ;3,ths, breadth ;th of an inch,) ca- tenulatus,graniferus, stramineus,and Pusio; MARGINELLAcurta; and by Mr. Broderip, Buttxus Vexillum, pustulosus, Pupiformis, Pana- mensis, albicans, affinis, modestus, scutulatus, turritus, pubchellus, ero- sus, derelictus, varians, Tigris, Proteus, (four well marked varieties of this species, forming a series of which the terms pass into each other by a gradual transition,) mutabilis, and versicolor. May 22.—Mr. Yarrell exhibited skeletons and stuffed specimens of the oared Shrew, Sorex remifer, Geott., which he had recently ascertained to be an inhabitant of Britain, and a species of Arvicola, also British, and apparently new to science: he characterized the latter as Arv: riparia, also modifying the characters of Arv. agrestis, on account of the near relation to it of the new animal, pointing out on the specimens exhibited the external and the osteological differ- Roological Society. 461 ences between these species, stating certain differences in their internal anatomy, and noticing those of their habits. »» An extract was read from the ‘ Analyse des Travaux de la Société @ Histoire Naturelle de l' Ile Maurice, pendant la 2de Année’ it was communicated to the Committee by its author, M, Julien Desjardins, Corr. Memb. Z. S., the Secretary of the Suciety whose labours are enumerated in it. Among the novelties which have occupied that Society during the season of 1830-1831 have been some observations by M. J. Desjardins on the Zoology of the Mauritius as compared with that of the Isle of Bourbon, from which has resulted the curious fact, that notwithstanding that these islands are situated in such close proximity to each other, are of the same formation, and present a most remarkable analogy in their soil, their animals are not univer- sally the same, some species being met with in one which never occur in the other. In some remarks on the bones of the Dodo, (consisting of a ster- num, a cranium, and four bones of the extremities, ) which were sent by M. Desjardins to Paris, and which excited so much attention during the past summer from M. Cuvier and M. de Blainville, oc- casion is taken to correct some errors which have crept into the published statements respecting them. They were discovered, in 1786, in a cavern on the island of Rodriguez. Mr. Gray exhibited living specimens of the common Lizard, La- ceria agilis, Linn., for the purpose of pointing out the marks of dis- ‘tinction between the sexes. The male is generally larger than the female, and more distinctly coloured ; the under side of his body and base of his tail are very bright orange, while in the female these parts are pale yellowish green; his ante-anal scale is short and transverse, that of the female being much longer and hexagonal; and the under side of the base of his tail is flat, with a slight longitudinal middle depression just behind the vent, this part of the tail being in the fe- male rounded and convex. In April and May the male may also be known by the base of the tail being dilated on the sides, just behind the thigh, a dilatation probably caused by the size of the penes, which ave retracted into these parts. Mr. Gray further explained various particulars of the habits of this species, observed by him in individuals which he had kept in a Jiving state ; and added, that in the only instance in which he had observed the coitus, one alone of the penes was inserted, June 12,—The exhibition was resumed of the new species of Shells collected by Mr. Cuming on the western coast of South America and among the islands of the South Pacific Ocean. The whole of the new species, thirty-nine in number, of the Genus CoLuMBELLA contained in the collection, were illustrated by Mr. G.B.Sowerby. They areas follows: CoLUMBELLA pulcherrima, Har - piformis, bicanalifera, spurca, Buccinoides, coronata, lyrata, uncinata, elegans, unifasciata, gibberula, turrita, fulva, rugosa, fluctuata, re- curva, lanceolata, maculosa, hemastoma, varia, scalarina, pyrostoma (This species somewhat resembles Col. mendicaria. Mr. Sowerby, is 462 Roological Society. doubtful as to the propriety of admitting it among the Columbelle; although wherever Col.mendicariais placed this species must of course follow. Perhaps it might not be inconvenient to separate these from Columbella, and to combine them with their cognate species from among Lamarck’s Purpure, Ricinule and. Murices, and thus bring together a number of shells which would form a very natural genus.) Maura (somewhat related to the last, though partaking rather less completely of the characters of Columbella), lzvida (intimately related to the last two, forming a part of the same division of the genus), nigro-punctata, obtusa, fuscata, costellata, guiiata, varians, angularis, castanea, sulcosa, major, procera (remarkable for its gigantic size, length 2,3,, breadth 4%, inches), pygmea, unicolor, versicolor, and dorsuta. The characters of these species, together with those of all Mr. Cuming’s shells exhibited at various meetings of the Committee, will be found in its ‘« Proceedings.” June 26.—Specimens preserved in spirit were exhibited of two species of Mus collected by Lieut, Col. Sykes in Dukhun, both of which were apparently new to science. ‘One of them is that referred to in Col. Sykes’s ‘ Catalogue of the Mammalia noticed in Dukhun.’ (Phil. Mag. and Annals, N.S., vol. x, p. 308.) It was characterized by Mr. Bennett as Mus oleraceus, ‘The extreme Jength of the tail, which measures 42 inches, as compared with that of the body, which, including the head, measures only 23 inches, and the comparative length of the hinder tarsus, furnish characters sufficient to distinguish this Indian field Mouse from all its congeners. The second species belongs to that section of the genus Mus in which spines are inter- mixed with the fur, It was designated Mus platythrix. Several imperfect skins of Mammalia, recently obtained by Mr. Gould from Algoa Bay, were exhibited ; and Mr. Bennett remarked, that notwithstanding their deficiency in the most important particu- lars, they were yet of sufficient interest to claim the attention of the Committee, on account of the extreme rarity of two of the species to which they belonged, and of the probability that a third was alto- gether unknown to science. One of them, the skin of a Monkey deficient as to head and hands, was, Mr. Bennett stated, evidently referable to the Colobus polyco- mus, Illig.; the long milk-white tail, strongly contrasting with the bright deep black fur of the body, being fully sufficient to charac- terize it. On the upper part of the skin, above the shoulders, some nearly white hairs were intermingled with the black ones. The only discrepancy observable between the specimen and the description of the species given by Pennant, was in the great length of the hairs of the body, the greater number of them being four or five inches long : this, it was remarked, might be dependent on age or locality.‘ Another skin, equally imperfect with the preceding, was that of the Colobus ferrugineus, Llig., with the state of which, described by M. Kuhl under the name of Col. Temminckii, the specimen agreed in every respect except in the absence of any yellow tinge in the rufous fur, covering the under surface of the body. at The third skin was still more imperfect than the others, having Zoological Society. 463 attached to it no portion of the neck, extremities, or tail, and con- sisting only of that of the body. Its length is 2 feet, its width 14. The dorsal portion is of a bright rufous fawn, which is continued on the shoulders and on the buttocks, but from which the red nearly disappears on the under surface, that being pale fawn. | Across the whole of the back, commencing between the shoulders and passing backwards, a series of broad transverse glossy black stripes are seen, which run down the sides, becoming narrower towards the belly. These stripes are twelve in number, and are preceded and succeeded by a few similar, closer set, and fainter stripes, of a deeper rufous than the ground. The broadest of the dark stripes are on the loins, where they are fully an inch in width: their direction in passing down the sides is rather backwards. The commencement of a dark streak is also seen on the skin leading to the outside of the thighs. The quality of the fur is rather rigid, and the hairs are adpressed, resembling in these particulars the covering of the Zebras. It may: not improbably belong to some species of Antelope, with which Eu- ropeans are yet unacquainted, but for which travellers to the country from whence the specimen was obtained may be induced to inquire, on being made aware of the existence of so beautiful an animal in that locality. The dark cross markings which ornament the fur are so uncommon among the Mammalia, that they alone will probably furnish a sufficient character to distinguish the quadruped in ques- tion from any other species inhabiting the interior of Africa, in the neighbourhood of Algoa Bay. Several specimens were also exhibited of imperfect skins of Cer- copithecus Diana, obtained from the same locality. Specimens were exhibited of two species of Hedgehog from the Himalayan Mountains, which had recently been added to the So- ciety’s collection. Both of them belonged to that extra-European form of the genus Erinaceus, which is distinguished by the posses- sion of long ears. The first was characterized by Mr. Bennett as Erinaceus Spatangus. The small size of this species (the total Jength of which is only 34 inches), its elongated form, the regular disposition of its spines, the more rounded form of its ears, and the comparative length of its ‘hinder foot, distinguish it from the other species exhibited, which Mr. Gray was disposed to consider as the Er. collaris figured in the ‘Illustrations of Indian Zoology,’ but which Mr. Bennett rather regarded as a new species, it being desti> tute of a white collar» and differing in other particulars from the figure referred to. Mr. Bennett accordingly characterized it as the Erinaceus Grayi. The exhibition was resumed of the new species of Shells collected by Mr. Cuming on the western coast of South America and in the islands of the South Pacific Ocean. ‘Those exhibited on the pre- sent occasion were accompanied by descriptions from the pen of Mr. Broderip. They were as follows: Butrnus rubellus, and Nuz ; PARTULA rosea, auriculata, and varia; PLANORBIS Perwvianus ; shel ip muricala; PECTUNCULUS maculatus, ovatus, and inter- medius, 464 Soologicul Society. At the request ofthe Chairman Mr. Spooner read his notes,of the: post-mortem examination of the Dromedary, Camelus Dromedarius, Linn., which lately died at the Society's Gardens. The liver, kidneys, Jungs, and heart, were greatly diseased. eiekS July 12.—At the request of the Chairman, Mr. Arthur Strickland, of Boynton near Burlington, Yorkshire, exhibited a specimen, from his collection, of a Puffin, shot in the middle of August 1828, ina very stormy day, at the mouth of the Tees, which was apparently, referable to the Puffinus fuliginosus (Procellaria ( Nectris) fuliginosus, Kuhl). The Proc. fuliginosa of Solander’s MS., though similar in size and colour, is entirely different, and at once distinguishable by haying the bill short and powerful, and the nostrils in a raised tube, like the true Procellaria. The Proc. fuliginosa, Lath., is also alto- gether distinct, being the Thalassidroma Leachii, Vigors: and the only description in the ‘General History of Birds’ which at all re- sembles the present species, is that of the Proc. grisea, a species distinct from that described under the same name by Linnzus.. In its distinct and very little raised nostrils, the bird in question agrees with the Shearwater Petrel, Puffinus Anglorum, Ray : it has no back toe, but in lieu thereof a strong claw; and its tail is rounded. After characterizing this bird as 'Puffinus fuliginosus, Mr. Strickland concluded, by remarking, that although a single and perbaps purely: accidental instance of a species appearing in this country may not fully entitle it to be ranked as a British bird, yet that the circum- stance is worthy of being noticed, as it is only by carefully recording such instances as do occur, that we can decide what is entitled to that appellation, and be thereby enabled to perfect our local catalogues. ‘At the request of the Chairman, Mr. Gould exhibited numerous. specimens of two Birds hitherto confounded under the name of Mota- cilla flava. In a communication which accompanied his exhibition, Mr. Gould explained the differences between the species, and entered at some length into their history. One of them, the yellow Wagtail of England, was described by Ray under the name of Mot. flava: its head is of a fine olive colour, and the stripe above and below the eye is of abright yellow. ‘The other, the Mot. flava of Linnzus, has the head of a lead colour approaching to blue, and the stripe above and below the eye of a clear white. The latter bird does not appear to have been ever met with in England: it is the one described by con- tinental authors under the Linnzan name; while British writers have as constantly described under that name the bird to which it was originally given by Ray, and which regularly visits their own country. For Ray’s bird, Mr. Gould suggested that the name of Mot. flava, under which it was described by our illustrious countryman, ought, according to the established rules of nomenclature, to be retained: To that of Linnzeus, M. Temminck, and other continental authors, he proposed to apply the name of Mot. neglecta. Mr. Owen referred to his Notes (published in the First Part of the ‘Proceedings,’ pp. 141 and 154, Phil. Mag. and Annals, N.S. vol. xi. p: 65and 137) on the anatomy of individuals of two subgenera of the Linnzean genus Dasypus ; one of which, the Das. 6-cinctus, Linn., Linnean Society. 465 had not, he believed, been previously dissected. He stated, that two other individuals of that species, one an adult female, the other a young one of the same sex, having subsequently come under his. examination, he was enabled to confirm some of the peculiarities observed in the dissection of the young male specimen, and parti- cularly the existence of the double cecum, and the additional lobe of the lungs. He was also enabled to add to that account a de- scription of the genital and mammary organs. !n the absence of distinction between the uterus and vagina, in both species and in the mode of communication of what may be considered a single elon- gated uterine tube with the genito-urinary canal, may be observed the first traces of that approximation to the oviparous type of the genital organs which peculiarly characterizes the Marsupial Edentata. Mr. Owen subsequently adverted to several external peculiarities _ which he had observed in the 6-lLanded Armadillo, and which, he remarked, were of some insterest, as connected with the burrowing habits of the animal. On the second toe from the inside there is a soft large cushion, evidently a modification of the organ of touch : at the hinder part of the fore-foot there is also a warty prominence, from which many hairs grow. There is a loose portion of integu- ment below each eye, supported upon a prominence of the zygoma, hirsute, and resembling an inferior eyebrow; by means of which, and the coronal plate of armour above, the eye is well defended during the act of burrowing. LINNZZEAN SOCIETY. Nov. 6.—Read an extract from aletter, addressed to Robert Brown, Esq., V.P.L.S. &c., by John B. Batka, apothecary and druggist, at Prague, containing remarks on Vateria indica and some other plants. The Eleocarpus copalliferus of Retzius, which Koenig and Vahl have referred to Vateria indica of Linnzus, M. Batka considers quite different. This plant was supposed to yield the copal ; but M, Batka has examined specimens of its resin, as also of the resin of the true Vateria indica, which he finds different from each other, and also from copal, which is now ascertained to be the produce of Hymenea verrucosa. The author expresses the difficulties he has met with in tracing the synonyma of Laurus Cinnamomum and Laur.Cassia, which after a careful examination he is inclined to consider identical ; the plant which is found commonly cultivated in collections for L. Cassia, being L. Malabathrum, distinguished by its large, glossy, coriaceous leaves, thinner inflorescence, divided calyx, and smaller fruit. The differences observable in the specimens of these plants he at- tributes to the influence of soil and climate, The L. javanensis, which yields the bark brought from Java under the denomination of Cassia lignea vera, the author also regards as only a variety of L. Cinnamomum. — The Chinese Cassia lignea bark, and the Cassia buds of commerce, M. Batka regards as the produce of an unknown species of the genus, distinct from the Laurus dulcis of Roxburgh, and perhaps identical with a species in Mr, Lambert's herbarium from Cavanilles, marked L. manillensts. Third Series. Vol. 1. No. 6. Dec. 1832. 30 466 Intelligence and Miscellaneous Articles. The Guinea grains and Madagascar cardamoms M. Batka con- siders as the productions of two different plants, the former of Al. pinia Granum Paradisi of Afzelius, and the latter of Alpinia mada- gascariensis ; both different from the Alpinia melegneta of Roscoe. LXXXIII. Intelligence and Miscellaneous Articles. ON CERTAIN POINTS, HITHERTO UNEXPLAINED, IN THE NATU- RAL HISTORY OF THE PAPUANS, OR ASIATIC NEGROS. ve Hepes following sketch of the history of the Asiatic Negros, a race of people, who, of late years, have attracted much attention from naturalists and historians, was drawn up in the year 18928, for the purpose of being annexed to a biographical Memoir of the late la- mented Sir Thomas Stamford Raflles, which had been commenced, in the preceding year, in the third volume of the Zoological Journal. That Memoir having been subsequently discontinued, the subjoin- ed article has hitherto remained, unpublished, in the portfolio of the writer. It is now made public in the Philosophical Magazine and Journal of Science, as contributing, in some degree, to fill up a chasm in our knowledge of a very remarkable and interesting va- riety of the human species; and as offering a view of their ancient location in India and subsequent distribution over the regions south of that country, which, so far as the author’s reading has extended, has never before been distinctly promulged, and certainly not in that generality which a careful investigation of the subject appeared to authorize him in giving to it. f It may be proper to mention, that since the completion of the inquiry, the results of which are summarily given in the following sketch, the attention of the author has been almost entirely with- drawn from subjects of this kind: he is not aware, therefore, whether the conclusions at which he had then arrived, have been in any de- gree either impugned or confirmed by subsequent discoveries; his own knowledge of the subject, at the present time, remaining just what it was when the sketch was originally drawn up. The remarks on the existence of a woolly-haired race in south- eastern Asia, which are promised in a note appended to a passage in Sir S. Raffles’s Discourse on the Sanda Isles, &c,, quoted in the Memoir before alluded to (Zool. Journ, vol. iii, p, 47), but the publication of which, in fulfilment of that promise, was prevented by the discontinuance of the Memoir, it may be well to add, are com- prised in the sketch now given. Oct. 4, 1832. When the late Sir T. Stamford (then Mr.) Raffles returned to Europe, after having resigned the government of Java, in 1816, he was accompanied by a young Papuan, or native of New Guinea, whom, in the preceding year, he had rescued from slavery on the island of Bali. On his arrival in England, much curiosity was ex- cited by the young Asiatic, who was the first individual of the Intelligence and Miscellaneous Articles. 467 woolly-haired race of Eastern Asia that had ever been seen in this country. He was examined by the late Sir Everard Home, who drew up some remarks on his physical conformation, as compared with that of the African Negro race, which were published by Sir Stamford Raffles in the Appendix to his History of Java (edit. 1817, vol. ii. App. p. ccxxxv.), illustrated with an engraving of the Pa- puan, from a portrait by Phillips. At the period of the discourse on the Stnda Isles and on Japan, which he delivered before the Batavian Society of Arts and Sci- ences, in 1815, Sir Stamford appears to have been of opinion, that this woolly-haired race of modern Asia had been originally derived from the African continent, and that their existence throughout the Indian Archipelago, indicated, that extensive intercourse had taken place, in ancient times, between the Asiatic islands and Ethiopia. But the researches into the physical and political history of the varied population of the Indian Archipelago, into which he was Jed, subsequently, by the preparation for the press of the History of Java, which he published in 1817, appear to have shaken his belief on this point. For, in that work (uz sup.), after noticing the opi- nion of their origin which he had formerly adopted, as just stated, and also the opposite notion of their being the aboriginal inhabi- tants of the countries through which they are now scattered, he merely says, ‘I shall content myself with observing, that they appear at the present day to form the bulk of the population of Papua or New Guinea*.” Since the publication of the History of Java, the scattered infor- mation which was previously extant respecting the people of the various Archipelagos in the Indian and Pacific oceans, has been collected together and combined ; chiefly by those naturalists whose attention has been more especially devoted to the physical history of the human species: by this means, considerable light has been thrown upon the interesting subject now before us. * Subsequently to the preparation of the above article for the press, the writer has observed another statement of Sir Stamford Raffles’s views re- specting the origin of the Papuan race, which it would be unfair to omit while discussing the fluctuation of his opinions on this subject. It is con- tained in a letter from Sir Stamford to Mr. Wilberforce, dated September 1819 (Memoir of the Life and Public Services of Sir T. S. Raffles, by his Widow, p. 410), and is as follows: “I am far from concurring in the opi- nion regarding the aborigines of these islands, and rather consider the Catties [the term Caffres is used by Sir Stamford, throughout his corre- spondence, in reference to inhabitants of the Indian Archipelago, as sy- nonymous with that of Papuans, as above defined] we now find in them to have been brought by traders in remote periods as slaves—as sueh they are generally considered and treated whenever entrapped.” When taken in conjunction with Sir Stamford’s former opinions, as cited above, this merely shows that his mind continued in a state of indecision on the subject, but inclining to a belief in the alleged African origin of the Papuans: being, however, nothing more than an opinion, it leaves the subsequent represen- tations in the text untouched. Nothing farther occurs on the subject in the Memoir here quoted. 302 468 Intelligence-and Miscellaneous Articles. From a carefal exatnination of the knowledge respecting the Asiatic Negros which has thus been obtained, and more’ particularly from their characters and history, as detailed in the works of Pro= fessor Blumenbach, Mr. Lawrence, Dr. Prichard, and M. Virey, and compared with the results of some of M. Julius Klaproth’s profound researches into the ancient history of Asia, the present writer has been led to deduce the following view, of the original location and condition in India, and of the eventual dispersion, throughout the regions to the south and south-east of the eastern part of the Asiatic continent, of this singular race of mankind. The actual inhabitants of Papua, or New Guinea, may be. con- sidered as constituting the type, at the present day, of the Papuan or Asiatic Negro race, properly so called. This race may be defined as the black savages with woolly hair, who are to be met with, trom the interior of Malacca and Siam, and the islands in the gulf of Bengal, on the north, to Van Diemen’s Land on the south. The facts and statements relating to the Papuan race, which ‘are furnished by the authorities mentioned above, taken collectively, and mutually explained, and corrected or modified py each other, appear to lead to the following conclusions: First, that the Papuans have not been derived from the population of Africa, even if they should ever prove to be descended, as Negros, from the same ori- ginal stock: Secondly, that (in conjunction perhaps, as: will pre- sently be noticed, with the black savages having straight hair, who are at present nearly co-extensive with them) they were the Adore: gines, or at least the most aneient people of whoin any traces ean now be discovered, of both the great Peninsulas of India,—that is, of Hindiistan and Malacca, and probably also of the seat of the present Birman empire, Siam and Cochin China. And further, that the bulk of this race migrated, either voluntarily or compulsorily, from the Peninsulas, to the islands of the Indian Archipelagos whence again they extended, in process of time, through New Guinea (which at present constitutes as it were their Metropolis) to the Australian regions. These Negros of Asia appear to have been driven from the Pe- ninsulas as well as the great islands of India, or compelled to inhabit the interior fastnesses only of those countries, partly by the in- creasing ascendancy, and partly by the actual prowess, of some of the Caucasian and Mongolian races, who, whether or not they professed the Hinda or Baddhaic faith, at the time when they subdued India and the * Farther East,” were unquestionably, as settled in those countries, the lineal though remote ancestors of the present Hindis and worshipers of Biddha. The latter races of people, as is well known,—-to a great extent on the continent of India, and almost wholly in the islands,—were afterwards subjugated, and, in some of the islands, annihilated, as a distinct people, by the Mohammedans, Such also, it is probable, was the course of things with the black savages having straight hair, who exist nearly co-extensively with the Papuans, and by whom Australia itself is peopled; so that the Aborigines of India would appear to have consisted of these two Intelhgence and Miscellaneous Articles. 469 black races, of mankind... The wide extent upon the globe of a people having the same physical peculiarities, is indicated, in a re- markable manner, by the fact, that the characters described by Sir Everard, Home, as existing in the Papuan of New Guinea brought to England by, Sir Stamford Rafiles, are identical with those assign- ed tothe inhabitants of Van Diemen’s Land, so far distant-to the south of New Guinea, by M. Peron and other naturalists. » This view of the subject, if, followed. out into particulars, would probably remove many of the difficulties and contradictions in which the history of the biack people of India and the southern Archipe- lagos, is at present involved. . There is one circumstance, however, in the natural history of these people, and that one. of equal. diffi- culty and interest, which, it must be acknowledged, would ‘still remain unexplained: viz. The strong resemblance, as well mental as physical, which the lowest of the Papuan race, in. intelligence, and in the scale of humanity in general (the natives of Van. Die- men’s Land, for example), bear to the. Hottentots of Southern Africa ;.notwithstanding, that, as. stated above, the entire history of the Papuan race is inimical to the supposition of its being derived from Africa ;—notwithstanding the facts (forming part of that bi- story) that although the extreme aberrant varieties of this group of mankind, and of that formed by the African Negro race (applying to the natural history of man some of the terms introduced into phi- losophic zoology by Mr. W.S. Macleay) are thus similar in, charac- ter,—the intermediate varieties, as well as the normal or sub-typical Papuans of New Guinea and Negros of equatorial Africa, are ma- nifestly distinct in character, being (as inhabitants of those countries, at least,) descended from different stocks. But this circumstance, ap- parently so anomalous, may be explained, probably, by the consi- deration, that, in these two sets of people, forming the zero points, as it were, of their respective races, we behold the human species, though derived from different stocks, and thus deviating from the type by different routes, in parallel extreme states of degradation, —equally distant, that is, from the type of the species, or the sum- mit of the scale of human perfection. The principal facts from which the foregoing deductions have been made, will be found in the following works: Lawrence's Lee- tures on Physiology, &c. First Edit. p 568, &c.; Prichard’s Re- searches into the Physical History of Mankind, vol. i.; Virey, Hist. Nat. du Genre Humajn, 1824, tom. i. p, 499. tom. ii. p. 16; and Julius Klaproth’s Essay on the Authority of the Asiatic Historians, as translated in the Asiat. Journ, vol. xvi. p. 216, et seq. Lk. W. B. QUESTIONS AS TO THE CONTINUATION: OF METALLIFEROUS VEINS FROM PRIMARY INTO SECONDARY FORMATIONS. BY A CORRESPONDENT. To the Editors of the Phil, Mag. and Journ. of Science. Gentlemen, In Cornwall, the same veins, without interruption, traverse both 470 Intelligence and Miscellaneous Articles. the granite and slates ; their contents, however, varying in the dif- ferent rocks. Being myself confined by circumstances to a district of primary rocks, | beg permission, through the pages of your Journal, to inquire whether any of your geological readers have ever traced the same vein from a primary into a secondary rock? If so, what were the attendant phenomena? Were the contents identical in both formations? Or do the veins which traverse each of these dif- ferent formations, respectively terminate when falling in contact with rocks of the other series ? In the present imperfect state of our knowledge of the phenomena of metalliferous veins, any information connected with the subject of this inquiry cannot fail to be highly interesting ; and it strikes me, that the intelligent agents of the lead mines in North Wales might supply some valuable matter. I remain, &c. Tavistock, September 19th, 1832. W. J. H. NOTICE OF A NEW OXY-HYDROGEN BLOWPIPE APPARATUS. BY J. O. N. RUTTER. I have caused to be constructed by Messrs. W.and S. Jones, 30, Holborn, an apparatus which is more simple, and at the same time more effective than either Clarke’s or Gurney’s blowpipe ; and it possesses the additional advantage of being perfectly safe. The most timid may use this instrument without the slightest danger of explosion. With ordinary precautions such an occurrence is abso- lutely impossible. In Clarke’s and Gurney’s blowpipes it is well known that the gases are mixed in their due proportions previously to changing the re- spective reservoirs. In this consists their principal cause of inse- curity,—to obviate which I condense the gases in separate vessels, and they are not mixed until in a state of combustion. Excepting that the vessels I employ are larger than ordinary, I may describe my apparatus as consisting of two of Clarke’s blow- pipes, fixed parallel to each other on a mahogany slab, the jets being inclined so as to form an angle of about 5°, and separated by a partition ,*,th of an inch thick. The orifices of the jets are con- siderably larger than those commonly used. The dimensions of the vessels are as follows:—That for hydro- gen (marked Hyp.), 1Oinches long by 5 wide, and 4 deep ; that for oxygen (marked Oxy.), of half the capacity of the former, viz. 10inches long, 24 wide, and 4 deep. It is important that the copper vessels be made very strong: this is the greatest difficulty I have had to contend with. With a 9-inch syringe I can condense from 800 to 1000 cubic inches of hydrogen gas into the largest vessel, and about half that quantity of oxygen into the vessel appropriated for it. That there can be no necessity for safety-valves, safety-tubes, wire-gauze, water, or oil, or mercurial chambers, must be apparent to every one whom the present communication may concern: these are consequently dispensed with. ‘The tubes which conduct the gas from the respective vessels have each two stop-cocks to Intelligence and Miscellaneous Articles. 471 regulate the escape. A very little practice enables the operator to determine the quantity so as to produce the maximum of heat. The usual experiments as performed by the apparatus I have thus, I fear, imperfectly described, are, if 1 may be allowed the use of the expression, dfinitely more splendid and more impressive than can be effected by any other means with which I am ac- quainted. The lime experiment, especially, is inconceivably bril- liant, exhibiting a disc of pure white light 14 inch in diameter. With a piece of clock-spring I have filled an area of 3 feet dia- meter with the most beautiful coruscations, The advantage of this apparatus is that of sufficient capacity that one or two charges will be sufficient for a course of illustrative experiments in a lecture-room, ‘There is not the slightest dan- ger of explosion. It is more powerful and more striking in its effects than any other instrument. I shall have great pleasure in furnishing any further details that may be required.—Might not vessels of sufficient strength and cas pacity be constructed in which a store of gas could be kept at the most important light-houses, to be used in thick weather, in further- ance of Lieut. Drummond’s plan? Dr. Faraday has informed me that about the time that Clarke's blowpipe was invented, an instrument somewhat similar to mine was shown him, and was, he believes, described in the Phil, Mag. But that instrument consisted of one vessel only, divided by a diaphragm. Hence there was no‘security against an explosive mix- ture forming in either of the chambers through a defect in the metal. Lymington, Hants, Sept. 10, 1832. NOVICE OF A MARINE DEPOSIT IN THE CLIFFS NEAR FAL-. MOUTH. BY R. W. FOX, Many persons are no doubt aware, that in some parts of the cliffs between Falmouth and Helford harbours, there exists an horizontal bed of rolled quartz pebbles, gravel and sand, similar in every respect to the materials which prevail on the contiguous sea-shore. Hence it cannot be questioned that the origin of both is the same; and L think it may also be assumed, from the above-mentioned materials being in many parts arranged in separate layers in the bed, that the sea must have frequently risen to its level. The thickness of the bed varies from one to three feet and upwards, and it is situated generally about nine to twelve feet above the level of the highest spring tides. 1 have not yet extended my observations on this bed beyond about four miles of coast, but within these limits it seems almost everywhere to exist when the cliffs are not composed of solid rock. This bed does not appear to penetrate far into the cliff, if we may judge from the few parts where it has been broken away or cut through. In one place I have observed it about eight feet, and in another twenty, within the face of the cliff. The rocks on this coast are of clay-slate, having a very considerable underlie, mostly towards the $,E.; but, the bed in question is found only in those parts of the cliff which are composed of earth, stones, and de- 472 Intelligence and Miscellaneous Articles. tached rocks, and which rest upon the bed, and are also under it in many places. It seems, in fact, that these substances have fallen upon the bed, and covered it over after its formation by the sea; and in time the mass has become so consolidated, as often to present nearly a perpendicular surface to the sea, of from thirty to fifty or sixty feet in height. ‘ : - In some parts of the cliff, particularly within the parishes of Budock and Mawnan, the pebbles and gravel have been formed into a con- glomerate, apparently, by the oxides of iron and manganese. The bed may have been produced by a succession of extraordinarily high tides, resulting from some long operating or more temporary cause, at a very remote period. However this may have been, the fact is curious, and seems to be at variance with the notion, that the sea has made considerable encroachments on the coasts of Cornwall. If it should be surmised that the Jand itself might have been ele- vated, it may be remarked, that such an hypothesis is not in accor- dance with the horizontal position of the bed for so considerable a distance, notwithstanding that the cliffs are in many places intersected by valleys. —_——- INQUIRIES RESPECTING THE DIMENSIONS AND VALUE OF THE LOCAL MEASURES IN COMMON USE At COVENT GARDEN MARKET. BY B. BEVAN, ESQ. To the Editors of the Phil. Mag. and Journal of Science. Sometime Jast year, I inquired through the medium of the Gar- dener’s Magazine, (as the most probable channel for the information sought,) the dimensions of the local measures in common use at Co- vent Garden market; at present no one has thought proper to favour the public, through that channel, with a specification of those mea- sures, which are generally unknown to country gardeners, and on that account the relative prices of fruit and vegetables in the coun- try are also unknown. The Sieve, being a measure frequently used, its diameter and depth should be specified. The Half-sieve also,—for although it is so denominated, it may not perhaps usually contain half the quantity of a sieve. The Punnet should also be defined, by specifying its dimensions, or by naming its proportion to some known measures. The Pottle, is a measure already known; but probably there may be some variation in the local pottle of Covent Garden and the Im- perial pottle. There are some other articles sold by the Bunch, which to a coun- tryman is an undefined quantity. If any person would take the trouble to ascertain the weight of these bunches, and favour the public, through the medium of your Magazine, with the informa- tion, it would be acceptable to many in the country. The trouble of ascertaining the dimensions of the measures above described, will be very little. The gallon and pottle measures, perhaps, may be not quite con- formable to the general Act, in the proportion of their diameters to their depths. ' Yours, &e. B. Bevan. Intelligence and Miscellaneous Articles. 4.73 AN EPHEMERIS OF THE STARS PROPER TO BE OBSERVED WITH MARS, AT THE PRESENT OPPOSITION OF THAT PLANET. {Concluded from page 407.] Apparent Place. Semidiameter. | pyor, 1832. Stars. Par. Declin. North.| In time.| In are. ° Dec. 7|65 Arietis 20 2 i Mars! 20 0601 | 8,46 F! Tauri > 19 1 65 Arietis 20 Mars? 20 F* Tauri ; 19 9'65 Arietis 20 Mars! 20 F! Tauri : 19 \65 Arietis le 20 Mars! 5 | F! Tauri (38) Arietis 65 — 596 | 8,39 — wow CSwWww OWW 8,32 — 8,25 12 (38) Arietis 65 Mars! 13,(38) Arietis ! 65 (38) Arietis | Mars! 65 Arietis (38) Arietis Mars! 65 Arietis (38) Arietis Mars! 65 Arietis 17\(38) Arietis Mars? 65 Arietis 18|(38) Arietis Mars! 65 Arietis 19|(38) Arietis ars! 65 Arietis 14 48,29 |20 12 19,8 Third Series. Vol. 1. No. 6. Dec. 1832. “¢P A7 4 Intelligence and Miscellaneous Articles. Apparent Place. Semidiameter. 1832. Stars. |Mag. i eA ee aor. Right Ascens. | Declin. North.| In time. | In are. ‘ | bh jms ° UP Oi Dec. 20 (38) Arietis| 8 |3 11 15,78}19 54 0,7 2 ” " Mars? S) 12 2.56/19 54 20,9|0:531 | 7,49 | 13,40 65 Arietis 6 14 48,29 |20 12 19,8 21 (38) Arietis| 8 |8 11 15,78|19 54 0,7 \Mars! N 11 49,87 |19 54 33,6| -526 | 7,41 | 13,26 65 Arietis 6 14 48,29 |20 12 19,8 22 (38) Arietis| 8 |3 11 15,78|19 54 0,7 |Mars! ; S 1] 40,61 }19 54 56,4} -520 | 7,33 | 13,12 165 Arietis 6 14 48,28 |20 12 19,8 28 (38) Arietis| 8 |3 11 15,77/19 54 0,7 |Mars" N 1] 34,72)19 55 29,2) -515 | 7,25 | 12,99 65 Arietis 6 14 48,28 |20 12 19,8 24 (38) Arietis| 8 (3 11 15,77|19 54 0,7 |Mars! ) 11°32,18 |19 56 11,9} -510 | 7,18 | 12,85 65 Arietis 6 14 48,27 |20 12 19,8 2538) Arietis| 8 (8 11 15,76)19 54 0,7 Mars! N 11 32,95|19 57 4,7| -505 | 7-10 | 12,71 65 Arietis 6 14 48,27 |20 12 19,8 LUNAR OCCULTATIONS FOR DECEMBER. Occultations of Planets and fixed Stars by the Moon, in December 1832. Computed for Greenwich, by THomas Henperson, Esq.; and circulated by the Astronomical Society. x Immersions. Emersions. sg Stars’ = ¥ 3 | Angle from ¢ |Angle from 1832.| Names. | &, Bz oe 23 |_ | q |Sidereal PE PR Sis |ss lag |eal 2 | ome) oe | eal 3 sa ie ea A Klos Be 3 [28| 8 h mh m| 4 him) | hee, Dec. 6 63 Tauri* | 6 | 490| 7 37|14 33) 24] 61] 7 50 |14 46} 0} 38 7|104mTauri| 5 | 592123 3) 5 57] 79] 39 |23 52 | 6 46} 313/272 8|15 Gemin. | 6 | 799| 7 1614 5] 52] 71 | 8 12/15 0/308|337 10) 3 Cancri*...| 4°5 |1066)12 2519 5/357] 37 |12 39 | 19 19/331| 11 17| 2! Libre ---| 6 |1688)10 716 20/100} 64 {11 0117 13/210/178 18| » Libra. ...| 4°5 |1787\10 016 9| 82| 43 10 58 |17 7|234/199 27|74i Aquar. 6 |2732| 2 39) 8 14)111)144 | 3 45t| 9 19 297 | 334 * These occultations doubtful—perhaps appulses only. + Emersion in horizon. 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Of |LE0-08 1 290 ‘ouy Boy WYSG “LE aoqopQ—wopucy | wy Cee a ef: WE XUN| MHA XUA gy te} ct | eA | cern | xe ‘2881 & R B Ea kK 5 uojsog! ‘a0uvzuag ‘uopuo'T ‘uoyy ‘5 Hi aay jo sktqd PAVUSy “Uley *PULAL *LOJOUIOUAIE,T, “s9jaWOIegT INDEX to VOL. TI. —=>— A CACIA,experimentson thestrength of, 17. Airy (Prof.) on a new analyser, and its use in experiments of polariza- tion, 75; on the phenomena of Newton’s rings formed between sub- stances of different refractive powers, 400, Alloys, fusing points of, 264. Ammonia and formic acid formed from hydrocyanic acid and cyanurets, 83. Amniotic acid,on the true source of, &e., 319. Analyser, a new, and its use in expe- riments of polarization, 75, Anchors, Pering’s improvements in, 74. Andrews (T.) on the blood of cholera patients, 295. Antrim, geology of the county of, 228. Arachnida, on a new species of, 190. Asia, on the negroes of, 466. Astronomical Society, grant of a Royal charter to the, 234. Astronomy, researches in physical, 69; Dr. Pearson’s Introduction to Prac- tical Astronomy, 370, 450. Atomic weights, on some, 109. Babbage (Mr.) on the economy of ma- chinery and manufactures, 208. Baily’s (Mr.) paper on the pendulum, 379. Barlow's (P., jun.) experiments on Acacia, 17 ; experiments on timber, remarks on, 116. Barometer, periodical oscillation of, 388; on a water-, 387. Basalt, of the Titterstone Clee hill, 231. Botto (Prof.) on the chemical action of magneto-electric currents, 441. Beaumont’s (M. de) theory of the pa- rallelism of contemporaneous lines of elevation, remarks on, 118. Bevan (B.) on the cohesion of ce- ments, 53; on the strength of tim- ber, 116; on the difference of level between the sea and river Thames, 187; on the dimensions and value of the measures used in Covent Garden Market, 472. Biela’s comet, 401. Birds, on the diving of aquatic, 23. Blackwall (J.) on the diving of aquatic birds, 23 ; observations on the house- spider, 95; on a new species of Arachnida, 190. Blood of cholera patients, researches on the, 295. Blowpipe, a new oxy-hydrogen, 470. Boddington (B.) on the effects of a stroke of lightning, 191. Bones of the rhinoceros and hyena in the Cefn caves, discovery of, 232. Boroughs, on a formula for the relative importance of, 26. Boulder-stone, on a large one in Ar- gyleshire, 232. Braconnot (M.) on isomeric modifica- tion of tartaric acid, 83. Brewster (Sir D.) on M. Rudberg’s memoir on crystals, 146; on a new species of coloured fringes in object- glasses, 15; on the effect of com- pression and dilatation on the retina, 89; on his formula for mean tem- perature, 135; on the undulation in the retina excited by luminous points and lines, 169; notes on Prof. Kup- ffer’s observations on the tempera- ture of Nicolaieff and Sevastopol, 135,,260: remarks on Prof. Rud- bery’s paper on crystals, 410; on the action of heat on glauberite, 417; observations on the isothermal lines, 431 ; on a Chinese mirror, 438. Brown (Mr.) on the impregnation of the Orchidee and Asclepiadea, 70; on the structure, &c. of Cephalotus, 314. 4 Buenos Ayres, on the discovery of three skeletons of the Megatherium in the province of, 233. Burning cliffs, on the south-east coast of Newcastle in Australia, 92. Caffein, composition of, 165. Carbonate of lime, formation of, under the influence of sugar, 84. Carlisle’s (Sir A.) letter, with the reports on the health of the workmen cleans- ing the Westminster sewers, 354. Caustic potash, preparation of, 244. Caves of Cefn in Denbighshire, on the, 232. Cements, on the cohesion of, 53. Cephalotus, on the structure and affini- ties of, 314. Challis (Rev. J.) on the resistance to the motion of small spherical bodies in elastic mediums, 40, INDEX. Cheltenham, mineral waters of, 223. Chemistry, on a perfect system of sym- bols in, 181. China, a curious mirror brought from, 438. Chlorine, extemporaneous solution of, 85. Cholera, on the health of the workmen cleansing the sewers during, 354. Cholera patients, chemical researches on the blood of, 295. Chrome, preparation of metallic, 86. Coal, on the lower series of, in York- shire, 349. Cohesion of cements, on the, 53. Comet, Biela’s, 401. Comets, Encke’s and Gambart’s, 287. Conybeare (liev. W. D.) on M. De Beaumont’s theory of the parallelism of contemporaneous lines of eleva- tion, 118. Cotteswold hills, on the geology of, 921. Crystal, on an apparent change of po- sition in a drawing of a, 337. Crystals, refraction of the coloured rays in, 1, 136; on the effects of tempe- yature on the double refraction of, 410. Cumberland, on the geological forma- tion of the mountains of, 229. Daniell (J. F.) on a new register- pyrometer, 197, 261. Daniell ( Prof.) on the water-barometer in the hall of the Royal Society, 387. Davy (Dr.) on the torpedo, 67. Decomposition, chemical, effected by the magneto-electric current, 161. Denbighshire, on the Cefn caves in, 232. Denmark, King of, his encouragement of science, 16. Disinfecting properties of supporters of combustion, 386. Diving of aquatic birds, on the, 23. Drinkwater (Mr.) on the telescope, 9. ' Ear, on the anatomy and physiology Eee Earth, on the electro- and thermo- magnetism of the, 310, f East India Company’s present of their herbarium tothe Linnzan Society, 71. Edmonds’s (R., jun.) notice of the me- teor seen June 29th, 306. Elastic mediums, on the motion of small spherical bodies in, 40. Elasticity of cast iron, 74. Electric spark from a natural magnet, on an, 49. Electricity, on experimental researches in, 61; of the torpedo, 67. Electro-motive battery, on a new, 48. 477 Encke’s comet, observations of, 287, Eupion and paraffin, on, 402. Expansion of solids, new register- pyrometer for measuring, 197, 261. ‘Eye, effect of compression and dilata- tion on the retina of the, 89; ona new membrane of the,.113; experi- ments on the effect of light on the retina, 255. Fairholme (G.) on the spider’s power to escape from an isolated situation, 424, Fallows (Rev. F.), memoir of the late, 234. Faraday (Mr.) on Signor Negro’s mag- neto-electric experiments, 45; on experimental researches in electri- city, 61. Fielding (G, H.) on a new membrane of the eye, 113. Fitton’s (Dr.) notes on the history of English geology, 147, 268, 442. Flint-glass, on the reflection at the second surface of, at incidences of total reflection, 57. Forbes (J. D.) on an electric spark from a natural magnet, 49. Foster (Capt.), account of the late, 238. Fox (R. W.) on the magnetic needle, and the electro-magnetism of the earth, 310; on the igneous hypo- thesis of geologists, 338 ; on a ma- rine deposit in the cliffs near Fal- mouth, 471. Fusion of metals, 202. Fuss’s (M. G.) magnetical and me- teorological observations at Pekin, 130. Gambart’s comet, observations of, 287. Geology of the south-east line of coast of Newcastle in Australia, 92. Geology, English, notes on the history of, 147, 268, 442. Geology, on the igneous hypothesis in, 338. Glauberite, on the action of heat on, 417. Gray (Mr.) on the genus Paradorurus, 397. Great Britain, on the population of, 213. Gums, analysis of, 244. Hall (Dr. M.) on the laws of mutual relation of respiration and irritability, 72, Harriot (Thos,), on some old MSS. of, 378. Haworth (A, H.) on the Narcissinee, 275. Heat produced by friction and percus- sion, 164; evolved by friction and 478 percussion, 247; action of on glau- berite, 417. Hemming’s (Mr.) safety-tube for the combustion of oxygen and hydrogen, 2. Henwood (W. J.) on the variations in springs, 287. Herschel (Sir J.) on the action of light in determining the precipitation of muriate of platinum by lime-water, 58; on subterranean sounds, 221. Horizon-sector, on the measurement of the instrumental error of the, 98. House-spider, observations on the, 95. Hydrocyanic acid and cyanurets, con- version of into ammonia and formic acid, 83. Hydrogen and oxygen, safety-tube for the combustion of, 82. Insects, several new British forms among the parasitic hymenopterous, 127. f Tron, separation of the oxides of, 86. Tron beams, on the strength and best form of, 207. Tron, cast, on the elastic power of, 74, the temperature of melting, 262; Tsothermal lines, on 431. Jloulouk, mean temperature of, 427. Kupffer (Prof.) on some recent mag- netical discoveries, 129; on the mean _ temperature of Nicolaieff, 132; on the mean temperature of Sevastopol, 259; Dr. Brewster’s observations on, 260; on the mean temperature of Sitka in America, 427. Lava, on the curvilinear structure of, 228. Lead and bismuth, separation of the oxides of, $26. Lenses, on giving figures to, 55. Light, action of in determining the precipitation of muriate of platinum by lime-water, 58; effect of on the retina, 251; on experiments relative to the interference of, 433. Lightning, on the effects of a stroke of, 191. Lime, carbonate of, formation of, 84. Lime-water, precipitation of muriate of platinum by, determined by the action of light, 58- Linnzan Society, present of the East India Company’s herbarium to the, 71. Lisbon and Oporto, on the geology of, 227. Lithotrity, Baron Heurteloup’s im- provements in, 75. Lloyd’s (Capt.) levelling from the sea tothe Thames at London Bridge, 187. conic-sectional INDEX. London, historical account of, 364. London clay, on the, 233. Longitude deduced from the moon’s right ascension, on the, 60. Lubbeck’s (Mr.) researches in phy- sical astronomy, 69, 381, 389. Luetke’s (Capt.) account of experi- ments with an invariable pendulum, 420. Lunar occultations for July, 87; Au- gust, 167; September, 247; Octo- ber, 327; November, 405; December, 473. Magnet, on an electric spark from a, 49, 63. Magnetism, action of on electro-dyna- mic spirals, 45. Magnetical discoveries, notice of some recent, 129. Magnetic-needle, irregularities in its vibrations produced by warmth, $10. Magnetic polarity, on the distribution of, 31. Magneto-electricity, Mr. Prideaux on, 309. Magneto-electric current, effect of in chemical decomposition, 161; on the chemical action of, 441. M‘Intyre’s (Dr.) remarks on the for- mula for boroughs, reply to, 26. Mammalia, carnivorous, experiments on feeding, 395. Manufactures and machinery, Mr. Babbage on, 208. Maps, on geological, 446. Mars, ephemeris of stars to be observed with at the ensuing opposition of that planet, $23, 406, 474. Measures used in Covent Garden Market, dimensions of, 472. Megatherium, discovery in Buenos Ayres of three skeletons of the, 233. Mercury, transit of, observed at Ge- neva, 246; transit on May 5th, $22. Metalliferous deposits, on the relative position with regard to the unstrati- fied rocks, 225. Metalliferous veins, questions on, 469. Metals, fusing points of, 202, Meteor, seen June 29th, Mr. Ed- monds’s notice of, 306; Mr. Pri- deaux’s, 307. Meteorological table, by Mr. Thompson, Mr. Giddy, and Mr. Veall: for May, 88; June, 168; July, 248; August, 228; September, 408; October, 475. Michell on stratification, 268. Mines, variation of the quantity of water in, 288. Mirror, account of a curious Chinese, 438. Mollusca, on marine testaceous 384. INDEX. Mont Blane, on the varying colours of, at sunset, 335. Monticelli (Sig.) on the structure of lava, 228. Morphia, new process for obtaining, $27. Murchison (R. I.) on the structure of the Cotteswold and Cleveland hills, 221. Narcissinez, Haworth on the, 275. Necker (Prof.) on some remarkable optical phenomena seen in Switzer- land, &c., 329; on therrelative position of mnetallic deposits and unstratified rocks, 225. Negro’s (Sig. Dal.) magneto-electric experiments, 45. E Negros, Asiatic, natural history of the, 466. Newcastle (in Australia), geology of, the south-east coast of, 92. Newton’s rings, on the phenomena of, 400. Nicolaieff, on the mean temperature of, 132, Nixon (J.) on the measurement of the instrumental error of his horizon- sector, 98; ona repeating circle, 340. Object-glasses, on a new species of coloured fringes in, 19. Occultations, lunar, for July, 87; Au- gust, 167; September, 247; October, 327; November, 405; December, 473. Optical phenomena, some remarkable, seen in Switzerland, 329. Optics: on the undulations excited in the retina by luminous points and lines, 169; on a new photometer by comparison, 174; on the action of the brain on vision, 249. Ornithorhyncus paradorus, on the mam- mary glands of the, 384. Oxford, meeting of the British Associa- tion at, 77. Papuans, on the natural history of the, 466. Paraffin and eupion, on, 402. Patents, list of new, 167; on the law of, 212. Pearson’s (Dr.) Introduction to Prac- tical Astronomy, 370, 450. Pekin, magnetical and meteorological observations at, 130. Pendulum, Mr. Baily on the, $79; in- veriable experiments with, 420. Peroxide of iron, separation of from protoxide of manganese, 85; from protoxides of iron, 86; from oxides of cobalt and nickel, 86. Phillips (J.) on the lower coal series of Yorkshire, 349. 479 Photometry, by comparison, on a new instrument for, 174. Platinum, muriate of, action of light in determining its precipitation by lime-water, 58. «“ P, M.” on chemical decomposition effected by the magneto-electric cur- rent, 161. Polarity, magnetic in metallic bodies, Sie Pons (J. L.), notice of the death of, 239. Population of Great Britain, compa- rative account of the, 213, 361. Potash, preparation of chlorate of, 164; preparation of caustic, 244. Potter (R. jun.) on giving conic sec- tional figures to lenses, &c., 55; on the reflection at the second surface of flint-glass at incidences of total reflection, 57; on a new photometer by comparison, 174. Powell (Rev. B.) on experiments re- lative tothe interference of light, 433. Prideaux (J.) on the meteor seen June 29th, &c. 307. Pulo Pinang, on the geology of, 224. Pyrometer, on a new register-, 197,261. Refraction, of the rays in crystals, on the, 1, 136. Respiration and irritability, mutual re- lation of, 73. Retina, on the effect of compression and dilatation on the, 89; on the undulations excited in the, by lumi- nous points and lines, 169; experi- ments on the effect of light on, 251. Reviews of books:—Dr. Goring and Mr. Pritchard’s ‘* Microscopic Cabi- net,” 163; Edmonds’s “ Life-tables,”” 204; E. Hodgkinson ‘‘on Suspen- sion Bridges and Iron Beams,” 207 ; Mr. Babbage ‘on the Economy of Machinery and Manufactures,” 208 ; “‘ Comparative Account,—Popula- tion of Great Britain,’ 218, 361; Dr. Pearson’s “ Introduction to Practical Astronomy,” 370, 450; Todd ‘on the Anatomy and Physiology of the Organ of Hearing,”’ 375; Bevan’s «‘ Guide to the Carpenter’s Rule,” 457. Rocks, unstratified, relative position of metallic deposits with regard to, 225. Rudberg (Prof.) on refraction of the rays of crystals, 1, 136; on the varia- tions produced by temperature in the double refraction of crystals, 410, Safety-tube for combustion of hydro- gen and oxygen, 82. Saturn, occultation of, observed at Ge- neva, 327. 480 Sedgwick (Prof.) on the rocks of the Cumbrian mountains, 229. Sevastopol, on the mean temperature of, 259. , Sewers, on the health of the workmen employed in cleansing, 354. Sharpe CB.) on the geology of Lisbon and Oporto, 227. Sitka, mean temperature of, 427, Smith (Mr. T.) on certain phenomena of vision traced to functional actions of the brain, 249. Societies, learned :— Royal Society, 60, 378; Linnean Society, 70, 465; Royal Institution of Great Britain, 72; Cambridge Philosophical So- ciety, 75, 400; British Association, 77; Geological Society, 220; Royal Astronomical Society, 234, 390, 457; Zoological Society, 392, 460. Solids, linear expansion of, by heat, 266. Somerville’s (Mrs.) mechanism of the heavens, 242. Sphinx ligustri, on the neryous system of the, 382. Spiders, their power to escape from an isolated situation, 424. Springs, variations in the quantity of water of, 287. Steam, new facts on the production of, 378. Steel, effect of rust in improving, 472. Sturgeon (W.) on the distribution of magnetic polarity in metallic bodies, $1. Subterranean sounds, on the cause of, 221. Suspension-bridges, Hodgkinson on, 207, INDEX. Tartaric acid, isomeric modification of, 83. Telescope, on the invention of, 9 ;. the interior of the eye reflected on the eye-glass of the, 318, Temperature, mean, of Nicolaieff, 132; of Sevastapol, 259; of Sitka, 427; of Jloulouk, 429. Thames, difference of its level and the - sea, 187. ‘ Timber, on the strength of, 116. Tod (D.) on the anatomy and physio- logy of the ear, $75. Torpedo, electricity of the, 67. Turner (Dr. E.) on some atomic weights, 109. Venus, on the rotation of, $91, Vesuvius, on the lava of, 228. Vision, on certain phenomena of, 249. Volcano in the Mediterranean, notice of, 60. Warrington (R.) on chemical symbols, 181. t Wax, experiments on bees’ and vege- table, 166. Werner’s merits as a geologist, 274. Westwood (J. O.) on several new British forms amongst the parasitic hymenopterous insects, 127. Whewell’s (Prof.) paper on chemical symbols, remarks on, 181. Wilton (Rev. C. P. N.) on the geo- logy of the south-east line of coast of Newcastle in Australia, 92. York, city of, specification of trades in, 218. Yorkshire, on the lower coal series of, 349. LONDON: PRINTED BY RICHARD TAYLOR, RED LION COURT, FLEET STREET. 1832. ao Pals Ls in| f fa Mee. ¢ ‘ny ie : ge % y a . ee 4 t, ’ be erent” 4 . ae é Pe Mor “y : . H . a Eyer eas oe on A = ‘ +, . ray y Ye « rt ig A. mK iy ar” th Is ‘ sy ry x . ay ; ' r Ae t ‘ ; i ss at ‘ , u : b/ ‘ , : ‘ bs * . “St i) iy nd ‘ ’ . , ‘ y 4 ne /t ’ . be ‘ - ‘ = 4 i , ¥ ~ 5. ‘ y 4 4 ; ' . 5 ¥ ’ [ ‘ 4 yo as ae Ab