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CONTEXTS.

Notes on British Foraminifera. IV. Haplo-
pliragiiiiiim agglutinaiis. D"Orbisny. Sp.
HaplophriigDiium caiiaricnse. D'Orbignv. Sp.
By Eduard Hcrnii-Allen. F.L.S.. F.R.^t.S..

and Arthur Earlaitd 421
On the Study of Double Stars by Amateur

Observers. IV. By G. F. Chambers. F.R.A.S. 426
The Destruction of Weeds by Chemical

Means. II. By Harold C. Long. B.Sc. 430

The Observ.atory on Mount Wilson, where
Mirrors supplant the Telescope Tube.

By Felix J. Koch. 433
Thf. Life History of a New Monad.

By Aubrey H. Drcu: 436
Solar Disturbances During September. 1910.

By Frank C. Dennett 438
Some Mental Illusions of Vision.

By R. T. Leu-is. F.R.M.S. 439
X-Rays for Examining Petrifactions.

By Dr. Alfred Gradenwitz 440
The Shooting Stars of November.

By Vr. F. Denning 440
Curved Photographic Plates.

By F. A. Bellamy, Hon. M.A. (0.vok.I, F.R.A..S. 441

PAGE.

Correspondence ... ... 442

Literary Notices 444

The Face of the Sky for No\embkr.

By W. Shackleton. F.R.A.S., A.R.C.S. 445

Giovanni Schiaparelli. By \V. Alfred Parr. 446

Notes. —

Astronomy. By G. F. Chambers, F.R.A.S. 447

Botany. By Professor F. Cavers. D.Sc, F.L.S. 4^8
Cheniistrv.

By C. .Ainsu-orth Mitchell. B.A. (O.vo/i). F.I.C. 449
Economic Biologw

By Walter E. Collinge. M.Sc. F.L.S.. F.E.S. 450

Geology. By G. W. Tyrrell. A.R.C.S.. F.G.S. 451

Meteorology. By John A. Curtis, F.R.Met.Soc. 452

Microscopy. By A. W. Shcppard. F.R.M.S. 452

Photographv.

By C. E'. Kenneth Mees. D.Sc. iLond.i. F.C.S. 456

Physics. By W. D. Eggar, M.A. 457

Zo61og\-. By Professor J. .Arthur Thomson. .17. .4. 457

Reviews ... ... ... 458

Queries and .Answers 461

Notices 462

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XOVEMISER, I'JIO.

NOTES ON BRITISH FORAMINIFERA.

IV.—HAPLOPHRAGMICM AGGLUTIXAXS D'OKBIGXY, SP.
HAPLOPHRAGMIL M CAXARIEXSH DORBIGXY. SP.

Bv EDWARD HEROX-ALLEN, E.L.S., F.R..M.S., and

ARTHUR EARLAXD.

H.v\'iX(; now described a species representative of
each of the principal groups of the Foraminifera,
viz., the Imperforate or Porcellanous (Massiliiia
secaiis d'Orb. sp.)
and the Perforate
or H\aline {Poly-
stoinella crispd
Linne sp.), uc now
propose to deal with
two species of a
genus representing
the .\renaceous
Foraminifera, i.e.,
the group in which
the animal, instead
of secreting a shell
of carbonate of lime
derived from the
seawater, builds
itself a composite
house of adventiti-
ous fragments of
material obtained
from its environ-
ment, such frag-
ments being ce-
mented together in
a more or less orderh' arrangement
special cements secreted by the animal.

Taken as a whole the Arenaceous Foraminifera
are inhabitants of more or less deep water, some
being known only as deep sea forms. They
are consequent!}- but little known to the student

tioiii a p

whose observations are confined to such material as
can be gathered between tide marks, and although a
few species, such as those now under consideration,

can usually be
found in any ex-
tensive gathering
made on our coasts,
we should perhaps
have omitted them
from our sketches
of the commoner
British Foramini-
fera but for the
extraordinary in-
terest which the
Ljroup possesses
nwing to the mar-
\ellous ingenuity
which is sometimes
displayed b\' the
animals in the con-
struction of their
shells.

The exact zoolo-
gical value of the
Arenaceous group is
somewhat difficult
bv means of to estimate, for although it would be very convenient
for purposes of classification to separate all the
P'oraminifera with agglutinated shells from those
secreting an external shell wall of carbonate of lime,
such a division would be entirely artificial. There
are some species proper to both the Porcellanous and

Figure

Haplopliragiiiiiiin af>gli(tiiutns. d'Orbigny, sp. Specimens from the Mixon

Beacon. Selsey, Sussex, utilising garnet glanconite and coal' dust for the

construction of the shells. X 65.

421

422

KNOWLEDGE.

November, 1910.

the Hyaline groups which habitually mask the
external characteristics of their shells by the
addition of an external coating of sand-grains or
mud. These species are to all external purposes
Arenaceous Foraminifera. but their true position
in the Order is immediately recognisable if a thin
section of the shell is made, as the charac-
teristic shell wall can alwavs be detected under
the external coating. It is not surprising therefore
that among the manv schemes of classification which
have at various times been proposed for the
Foraminifera, there are several in which no essential
\-alue has been attributed to the agglutinated shell,
such species being allotted indifferently to either the
Imperforate or the Perforate group, according to
their external resemblance to recognised types, or the
caprice of the author w here no superficial resemblance
existed. Such schemfs of classification, so far from
solving the (juestion of the zoological value of the
group, appear to increase its difficults", for while there
are some trulv .\renaceous Foraminifera which bear
a close external resemblance to Imperforate species.
and a great man\- more w hich are isomorphous w ith
Perforate types, there are a still greater number
^\■hich ha\-e no particular resemblance to generic
types in either group.

In Bradx's sx'stem of classification, which is more
or less generally accepted as the most convenient in
our present state of knowledge of the Order, the
external investment of the animal is abandoned as
an exclusive basis for a primary division ; that is to
say, such species as possess an internal shell, masked
by an agglutinated test, are allotted to the Imperforate
or Perforate group, according to the nature of the
internal shell. The truly Arenaceous Foraminifera,
that is to say, those in which the shell consists en-
tirely of adventitious material fastened together \\ ith
either a chitinous or ferruginous cement, are sepa-
rated into two distinct families, (i) the Astrorhizidae,
nearly all of which are deep-sea forms, characterised
by large irregular and usualh- monothalamous shells,
sometimes branching or radiate, and segmented b\-
constrictions of the wall, but never truly septate or
symmetrical : and (ii) the Lituolidae in which the
chambers are usually regular. Many of the Lituolidae
are isomorphous with porcellanous and hyaline types.
The species treated in this paper are Lituolids.

The origin of the .Arenaceous Foraminifera is yer\-
uncertain. Neuma^r, Lister and others suppose that
they represent more primitive types than the
Imperforate and Perforate groups. But the
evidence in either direction is ver\- fragmentary
and to our ideas it seems more probable that they
are of later evolution than the shell-secrc-ting forms.
The facts on which we base our belief are as
follows : —

(Ij The power of secreting carbonate of lime is

generalh' present in animal organisms and does not
mark an advance on the selection of foreign material
but rather the contrary.

(2) The geological record does not show that
.Arenaceous Foraminifera preceded the other groups.
So far from this being the case, the earliest
known Foraminifc-ra deposits contain Perforate
types only.

(3) The "selective power" exercised by many of
the .Arenaceous P"oraminifera in the construction of
their shells is. in our opinion, evidence that the
animals possess functions and powers greath' in
advance of their relatives of the shell-secreting
types.

The possession of " selective power " b_\- certain
species has long been known, but the subject appears
to have been avoided by most rhizopodists, probably
owing to the difficulty of explaining a process w hich
seems to require the possession of " intelligence " b\'
organisms w hich, as we know, are merely particles of
nucleated protoplasm possessing no differentiated
organs of an\- kind. We are not ourselves prepared
to furnish an\' explanation of the phenomena, nor do
we expect any explanation to be forthcoming in our
present state of ignorance as to the life-history of
these organisms, but we have in another paper*
attempted a short study of this most suggestive
subject. Space will not p<;rmit of any detailed
reference to the facts which wc have there set forth,
but the student interested in the subject will find in
that paper ample e\-idence that these little organisms
(Protozoa) are endowed with a power of selection
and adaptation of adventitious material, both for
purposes of construction and defence, equal to
an\'thing which exists among the higher forms of
life (Metazoa).

To return to the immediate subject of our paper,
the first species, f/i?^/«/'/n-ir,i,'/;;/;//« iiggliitiiuiiis, ca.nnot
be described as a common British species, for the
records of its occurrence appear to be limited to the
Isle of \\'ight (Millett) and the East Solent (Brady)
and two dredgings in the Irish Sea (Balkwill and
\\'right). We believe, however, from our observa-
tions that this rarit\- is possibly due to the fact that
the cement with which the shell is built up. is when
dried, extremely friable, so that the shells break up
in the process of cleaning the material. It is, more-
over, as we have remarked in the paper already
referred to. a species which, occasionally at an}-
rate, exercises a fantastic taste in the selection of its
building material, selecting grains of marked contrast
in colour for the construction of its shell, in prefer-
ence to the quartz sand among which it lives.

Haplophriii^iiiiimi ii<:;}^lufiihiiis. as w ill be seen from
our Figure 1, commences life with a series of
chambers arranged in a spiral coil ; then departing

'■' Edward Heron-Allen and Arthur Earland " On a new species of TechnitcUa from the North Sea, with some observations
upon selective power as exercised by certain species of .Arenaceous Foraminifera." Journal Ouekett Microscopical

Club, 1900, pp. 403-412. Plates 31-35.

November. 1910.

KNOWLEDGE.

423

Front a pliotoi^rap/i

lliiplopliriii^iinniii

Figure

anaricitsc d'Orbisny. sp. T\pical shalluw water British variety
from Selsev. Sussex. X 85.

■■ perishes " under the in-
fluence of drying by heat,
and that in the subsequent
processes of floating, drying
and sifting, the shell is
disintegrated and disappears.
In .\[)ril and June of this
Near (1910) we made careful
washings of large quantities
of sea-weeds from the rocks
which are exposed at low
tides round the base of
the Mixon Beacon at Selsey
Rill, Sussex. The mud
and sand containing living
h'oramiiiifera thus obtained,
were preserved and cultivated
by us in a series of small
obser\-ation tanks such as we
described in the first jiaper
of this series, and it must be
noted that this material was
never exposed to the elutriat-
ing action of the waves as
thev reach the shore. Among
the first Foraminifera to
emerge from the mud at the
bottom of the tanks were
a large number of exception-
alK' fine specimens of this

from the spiral it adds a
series in a straight line, so
that the entire shell is crosier
shaped. In our small British
specimens this shape is not
ver\- noticeable, but in large
deep water specimens the
elegant crosier shape is \er\
marked. It is a species ol
world-wide distribution, but
very rarely recorded except
from deep water in which it
has been found down tn
a depth of j,125 fathoms.
Its geological record accord-
ing to Brady extends back
to the Carboniferous period,
so that it is one of thi
oldest of the recorded
Arenaceous types.

As we have said above.
Hiiploplinii^iiiitiiu <r,i,',s,'/////;/-
iiits is not a prominent oi'
common object in dried.
floated and sifted shore
gatherings. It seems clearly
established b\- our observa-
tions that the cement which
agglutinates the sand-
fragments of which this
Rhizopod builds its shell

/■/-('/// « plu'l,>ii)n/'h

i>y A. K, Smith.

■IGl'KE O.

HaplDphi-a^iiitiini canancnsc d'Orbigny, sp. Specimens of the large North Sea or
Arctic tvpe K = H. cmsshiiargo Norman. Vice Museum Normanianum, (189i)

p. 17 footnote) X 22.

424

KNOWLEDGE.

November, 1910.

Haplophraf^iiiiinn. They cra\\led up the sides of
the tanks, clini;ing to the glass and to the weed-
grown rocks placed in the tanks, h_\- their pseudo-
podia which extended in all directions from the
aperture. In these early days their appearance was
magnificent. Like the large specimens of Venie-
niliiHT polysfropha which constitute a feature of
the sand and mud of the Mixon Reef, these
Haplophra^niiii appear to be endowed — one says it
with all reservation — with an aesthetic sense.
Unlike, or at any rate to a much more marked
degree than, the specimens of the same species

found among shore gathering

the immediate

neighbourhood, these Haploplinjginia and Veriie-
iiiliiiae deliberatel\- sefect for the construction of their
shells large fragments of finely coloured quart/,
garnets, chips of magnetite and coal, glauconite, and
particularK' of an unidentified gem mineral which
is found in the detritus of the Alveolina lime-stone
rocks which form the Mixon Reef. The result is a
shell built up of shining blocks of black. yellov\-,
crimson, brown and green, of a peculiarly splendid
appearance.

In the course of weeks and months, whilst the
commoner forms continued to flourish and increased
in numbers, most of these beautiful Haplophra^inia
disappeared, though two or three fine specimens still
(September) make their appearance at intervals.
In two of our tanks in which, owing to the
death of larger organisms, the layer of mud
putrified, the Haplopliraiiinia turned black, antl fell
to pieces when fished out of the tank. When the
tanks were cleared out there was no trace of them.
At the end of some months we decided to wash and
examine the layers of clean mud which had lined the
bottoms of three other tanks — it must be borne in
mind that this material had never formed part of any
sea bottom but was washed clean from the fronds of
the .Mga. It was carefully washed on a silk sieve
and dried by very gentle sun-heat with a view to its
being '" floated '" to separate the Foraminifera. Before
this was done, however, \\e examined the dried
material, and \se were astonished to find that on the
sieve which retained the medium siftings the perfect
shells of Haplophragmiiiin agi^liifiiians iormed 20/;'i of
the washed (not floated) material. I'Vom this material
the shells represented in Figure 1 were picked. The
material was then heated, cooled, and floated
in the usual manner and we were provided with
a fresh surprise. name!\-, that in the floatings
Hdplophrai^iniuin iii^i^liitiiums was quite as rare as it
ever is in a shore gathering. We are therefore
justified in assuming that the species may be a
common one in gatherings of living Foraminifera
from .\lgae, and that the shell is constructed with a
peculiarlv perishable cement which conduces to its
disintegration under the action of the waves upon

the shore and the processes of drying and floating.
On this assumption we ma\- infer that the rare
individuals found in shore gatherings are those
which ha\e been washed up alive by the last tide
and have been held together by their contained
sarcode.

In this fragility it entirely differs from our other
species Haplophmgmiitm canariense, which is solidh-
built, smooth and robust, and sur\ives the most heroic
treatment.

[We take this opportunity of recording that the
mud obtained from these tanks contained many fine
and t\pical specimens of Massiliiia secans var.
denticulata Costa in which the final chamber has a
delicate serrate carina. This variety has only been
recorded previously in Britain from the neighbouring
locality of Bognor*. There were also many specimens
of Massilina sccaiis in which the two final chambers
showed deep median constrictions, resembling septal
divisions, somewhat like the specimens for which
Halkyard proposed the varietal name ohlicjiiisfriata,
subsequentlv withdrawn by the same author, and also
of Earland's variety (loc. c7b.) feniiisfriataj

As none of these curious varieties were observed
either in the fresh gatherings which we made at the
Mixon Beacon, or in any of the numerous shore
gatherings made at Selse_\- over a long period and
wide area, we are forced to the conclusion that they
are the result of starved or unfavourable conditions
of life in a confined tank reacting on the shell-
secreting powers of the species in question.]

Our second species Haplopliragmiuin canariense
possesses little in common with H. agghitinans. It
is, as will be seen from our Figure 2, a regularly
nautiloid shell, consisting of several convolutions,
the outermost having from six to nine segments.
The convolutions are embracing, so that the last
whorl entirelv, or almost entirely, includes its prede-
cessors. The lateral surfaces sink towards the
umbilical depression w hich is more or less excavated.
The peripheral edge is rounded and more or less
lobed. The aperture is a thin slit set on the face of
the last segment close to the inner margin, and
sometimes surrounded by a lip. The surface of
shore specimens is usually smooth and neatlv
finished, the wall being built up of fine sand grains
cemented together with a ferruginous secretion
which gives a delicate rust colour to the ^\•hole shell.
The colour, which depends on the cement, is, however,
rather variable, ranging from deep brown to light
grev. and the earlier segments are generally' darker
than the later ones.

The shell-wall in shore specimens is always thin
and nearly smooth, but in deeper water the animal
uses larger sand-grains so that the surface becomes
somewhat rough. In certain localities, notably the

'■'■Earland A. The Foraminifera of the Shore sand at Bognor, Sussex. Joiinutl Oitckctt Micro. C!i(b. 1905, ser. 2, vol. ix..

No. 57, p. 198, pi. xi, fig. 4.

*^Siginoilifia sccaiis var. ubliquist nata. Halkyard, 1889, Trans. Manchester Micr. Soc., p. 61, pi. i, fig. 7. This variety was

subsequently withdrawn by Halfivard in Trans. Manchester Mic. Soc., 1891, p. 20.

XOVKMBKR. 1910.

KNOWLEDGE.

425

North Sea and Arctic Seas, the species often attains
a size which can only be described as huge compared
with the normal t\pe. W'e figure some specimens
dredged in The Gut. North Sea (57" 59' N 0" 57' E)
at a depth of one hundred-and-forty metres whicli
will give some idea of the dimensions attainable
under what is no doubt exceptionally favourable
environment. We also
figure a section through one
of these large individuals
(Figure 4) which it will be
seen is of the microspheric
tvpe, as indeed are all such
specimens which we haw
e.xamined in section. We
should, however, hesitate
n stating that such indi-
viduals represent the
microspheric form of the
species, as their abnormal
size is more probably due
to age and an abundant
food supply, seeing that
other arenaceous t\-pes in
the same attain similarh-
abnormal dimensions.

Haplop)n\i<^niiuiu caii-
ariciise is commonh' distri-
buted on muddv bottoms
all round our coast, and
although not a frequent
constituent in shore gather-
ings, its presence can usually be relied
distribution is otherwise world - wide
recorded range extends from shore
to nearh- 4.000 fathoms. Curioush- enough, for
such a widely distributed species its geological
history is (juite scant\'. According to Brady it
does not extend back be\ond the Pleistocene.

FlCLKl

Haplophi\!^tuu(i)i canarioisc d'Orbigny i-ar. crassi-
iunr}>o. Norman. .\ shell laid open in the median plane
to show arrangement of chambers. The opening between
the chambers is visible close to the inner spiral. The
protoplasmic body in the form of a branching rope is to be
seen traversing some of the later chambers. X 28.

on.
and

Its

its

gatherings

In one of our observation tanks started in .\pril.
1910, we were privileged to witness a phenomenon
which, unfortunately, we were unable to follow up.
.\ fortnight after our observations began we noticed
an indi\idual Haplnplimi^iuiiiiu canaricnse resting
on the front glass of the tank. The whole shell was
surrounded and apparently enveloped in a sphere of

cloud\- protoplasm (not un-
like that observed by Lister
and figured in our last
paper in connection with
Polys/diiiclhi crispal tlie
outer edge and surface of
which was defined by a
dejiosit of mud grains. The
shell was "1 mm. in dia-
meter and the w hole sphere
of protoplasm with the
contained shell was '.i mm.
in diameter. From this
sphere pseudopodia ex-
tended in long straight
filaments which did not
anastomose, and the tv\o
longest filaments extended
in opposite directions from
the sphere to a distance
on each side of twenty to
thirty times the diaiucter
of the sjihere. Beyond
this point the\- fined off
until thev became invisible
under the magnification ( X 65") of the objective.
Next day the w hole phenoiuenon had disappeared,
and we never saw another specimen of the species
though there were many in the mud of the tank
when it was washed and dried in September.
We cannot, therefore, say whether a reproductive
process was in progress or not.

SYNONYMS.

HaplophraiiiniKiii aiiglnthians d'Orbigny. sp.

Spirnlina nggliitiiiaiis d'Orbigny. 1846. For. Foss. \'ienne.
p. 137, pi. vii, iigs. 10-12.

Spiroliiia simplex Reuss. 1855, Sitznngsb. d. K. Ak. W'iss.
W'ien. \oI. xviii. p. 2i2. pi. ii, fig. 30.

Haplophragmiitm rcctiiin Brady, 1876, Monograph Carb.
and Permian Foram.. p. 66. pi. viii, figs. 8, 9.

Haplophyagiiiiuni ciggliitiiians id'Orbignyt Brady. 1884,
Foram. Challenger, p. 301, pi. xx.xii. figs. 19-26.

Haplophraginium agglutinans (d'Orbi.gny) Balkwill and
Wright, 1885, Trans. R. Irish .Acad., xxviii (Science),
p. 330. pi. xiii. figs. 18-20.

Haplophragmiiiiii agglutinans (d'Orbigny) Brady. 1S87-
Synopsis British Foram. Jour. R. Mic. Soc, p. 889.

Haplophragmium agglutinans (d'Orbigny) Goes. 1894,
.■Arctic and Scandinavian Foram.. p. Z2>. pi. v, figs. 140, 141.

Haplophragmium canaricnse d'Orbigny, sp.

X:)nionina canaricnsis. d'Orbigny. 1839. Foram. Canaries.

p. 128. pi. ii. figs. 5i. 34.
Placopsilina canariensis (d'Orbigny) Parker & Jnnes. 1857.

.\nn. and Mag. Nat. Hist., ser. 2, vol. xix. p. 301. pi. x,

figs. 13. 14.
Xonioninajcffrcysii. Williamson. 1858. Recent British Foram..

p. 34. pi. iii. figs. 72. 73.
Litiiola canaricnsis (d'Orbigny/ Brady. 1864, Trans. Linn.

Soc. Lend., vol. xxiv. p. 472.
I.itiiola nantiloidca %ar. canaricnsis (d'Orbigny) (pars)

Parker \- Jones. 1865. Pent-. Trans., vol. civ. p. 406,

pi. XV, fig. 45 a.b.
Haplophragmium canaricnse (d'Orbigny) Brady. 1884.

Foram. Challenger, p. 310, pi. xxxv. figs. 1-5.
Haplophragmium canaricnse (d'Orbigny) Brady, 1887,

Synopsis British Recent Foram. Jonr. R. Micr. Soc, p. 889.
Haplophragmium canaricnse (d'Orbigny) Goes, 1894, Arctic

and Scandinavian Foraminifera, p. 20, pi. v, figs. 92-101.

ON THE STUDY OF DOUBLE STARS BY AMATEUR

OBSERVERS. IV.

Bv G. F. CHAMBERS, F.R.A.S.

VARIABILITY OF DOUBLE .STARS.

On the question of the variabihty ami rolours of
Double Stars, Innes has some remarks which are
worth reproduction. After stating that onl\- in a
few striking cases has he gi\'en any attention to
questions of variability, he suggests that " It is
highly probable that the variation of light so often
recorded is in some sense real." In consequence of
this remark I have generally included in my notes
the question of variabilit\- where any materials were
available for doing so. It must never be forgotten,
however, when one has to deal with or consult
photographic magnitudes, that these are often fainter

than the \'isual : a fact in nearh' all instances arising
in the case of stars which are \'ellow or reddish, these
colours, it is well known, having less actinic power
than white light.

As regards colours, Innes's policv was substantiallv
adopted b\' myself long before I knew that it was his.
He says : " V'ery little attention has been given to
colours. Where, however, they seem generallv agreed
on, they are quoted. The minute differences of shade
recorded by some obser\'ers have been omitted as use-
less if not misleading." I have made some remarks on
the colour question at an earlier point in this paper.

THE SOUTHERN CONSTELLATIONS.

So man\- of the Stars which have come into notice
latel\- thiniigh the labours of Innes being Southern
Heniisi)here Stars, it is necessary to pay some special
attention to the allotment of constellation names to
them in default of his having done so in the xast
number of cases. The question of the boundaries.
and, indeed, of many of the names of those
constellations was long a thorny one, and matters
were not improved by the drastic proposals for the
radical reform of the boundaries of many of the
Southern Constellations put forth by the late Dr.
B. A. Gould in his i'raiioniefria Argeiititia. published
at Buenos Ayres in 1879. It is no wonder that Dr.
Gould's proposals have not met with favour, for
under his schemes the Constellations were cut up
into slices and pieced together in (to put it
mildh') a most inconvenient fashion. liad as
his divisions might have been when recorded on
maps, matters were tenfold worse when one tried by
consulting his Catalogue to find the whereabouts in
it of an\- particular Star whose magnitude one
wished to learn, or to read the " Notes " printed in
another part of the Book. Even w hen a Star was
found in the Catalogue, it was always a matter of
some minutes more to dig up the " Note." Anyone
who ma\' have access to a copy of the Umnoiiwfria
Argentina will readily be able to judge of the time
and labour which would be involved in attempting to
collate an)- Star magnitudes, as usually stated, w ith
the Cordoba magnitudes. The advantage of doing
this has, however, been in great jwrt removed, since

the [Hiblicatiiin of Dr. Gould's results, b\' tlie issue of
the Southern Udrvard I'hotonictry. the value of
which two volumes, in combination with the
Northern volume, it is impossible to o\-er estimate.
I make these remarks on Gould's labours with regret,
because his criticism on the names and boundaries
of certain Constellations and on the lettering of
conspicuous Stars' are \'ery forcible in their wav,
but his endeavours to build a substitute for what he
would pull down ha\e, like many other "reform"
efforts, resulted in confusion worse confounded.

The reader will perhaps now expect some statement
as to how I should treat the matter, which is one by
no means lacking in practical importance, having
regard to the large and increasing number of amateur
astronomers who are compelled to carry on their
labours unprovided with e<iuatoria] mountings, and,
therefore, are dependent on maps tor finding the
objects which the\' wish to observe.

I ma\' state generally that I should for the most
part accept the jirinciples laid down by the late
Mr. E. J. Stone in the preface to his " Catalogue of
12.441 Stars for the epoch of 1880." Without quoting
in detail his statement of those principles, I may
gi\'e in his own words his jirefatory summary of
them, .\fter [irotesting against radical changes
(apparenth' ha\'ing Dr. Gould in his thoughts), he
sa\-s : " I have, therefore, in the present Catalogue,
followed the system introduced by Lacaille, but with
the rectifications of boundaries and modifications
recommended b\' Sir John Herschel. This system

Unuioiii-iif'lnd Ariiciitnia, the 4to \(iliuiic. pp. 4<S-7y,

426

November. 1910.

KNOWLEDGE.

427

i Boiitis.

\tar,'s. 3i, 6*: Distance 2i" (1909).

/8 Scorpii.
Mags. 3, 10, 6: Distances If. 13"

V Scorpii-
Mags. 4 1, 6: Distance 1"

(T Coronae Borealis.
Mags. 6. 61. 12. 11: Distance 5" (1903)

a Scorpii.
Mags. 1, 7: Distance 3"

yjy and ^' Draconis.
Mags. 4i, 5i: Distance 30".

42S

KNOWLEDGE.

November, loio.

1- SaKittaiii.
Nr.igs. 4. 11, IJ, y5. 9}.

e Lyr.ie.
Mags. 5. 61, 5. 5] : Distances 3", 208", 2"

/3' S.iKittarii.
Mags. 3J, 8: Distance 2S".

1 267J and 2074 Sagittae.
Mags. 8. 9], 8, 11: Distances i", 76", 15",

(^ CvKni.
Mags. 3, 5 : Distance 35"

15 Dclnliiiii.
Mags. 7, 7i, T'U 12: Distance 15", 23", k"

^■OVE^tBER. 1910.

KNOWLEDGE.

429

was adopted by Baily in the British Association
Catalogue of <VJJ7 Stars, and in the Catalogue of
9766 Southern Stars formed from Lacaille"s zones,
and it has been generalK- adopted in recent Southern
Catalogues. It has, therefore, the authorit\- of more
than 30 [now 60] years" extensive use in its favour.
It appears to me very doubtful whether all the
changes introduced b\- Herschel and Bail\- were
necessary or, indeed, desirable, but less confusion is
probably now caused bv the adoption of these
changes than by attempts to revert more closely to
Lacaille's original nomenclature."

Stone unfolded the same doctrine in a letter \s hich
he wrote to me under the date of September 8th,
1880. I had consulted him as to the nomenclature
of the Southern constellations, intending to follow in
the new edition of Admiral Smyth's Cycle of
Celestial Objects, as well as I might be able to do.
anv advice which he might give me. Stone said : —
" I have practically followed the B.A.C. in my
nomenclature. Bailv followed Herschel's advice
after Herschel found that no sweeping changes in
Lacaille's svstem would be acceptable."' Stone in
effect said '' Meddle not with him that is given to
change."" and as this conservative idea commended
itself to me I acted upon it. Some years afterwards
Stone, after returning from the Cape of Good Hope,
became Radcliffe Observer at Oxford. In the
Preface to the Radcliffe Catalogue of 6424 Stars
edited bv him, he terselv summed up his treatment
of the subject in the following v.ords: "" In the
division of the sk\- into constellations the nomen-
clature and boundaries adopted by Francis Baily,
with the sanction of Sir John Herschel, have been
generally followed, but no especial importance has
been attached to this part of the work.""

The principles which Sir J. Herschel laid down
are stated bv him under seven heads. As the text of
them is not generallv accessible, though evervbodv
now-a-days is dependent on them (Gould"s organic
changes having been very generallv repudiated), it
will be well to set them out because the\' furnish a
useful clue to the profitable studv of the constella-
tions speciallv affected, including particularlv the
troublesome constellation Argo.

The following is an authoritative statement * of
them : —

■■ ( 1 1 That all the Constellations adopted bv
Lacaille be retained, and his arrangement of the
Stars preserved : subject, how ever, to certain altera-
tions hereafter specified.

'■ (2) That all the Stars having a doubtful location,
such as those which Lacaille (after the manner of
Ptolemv) has considered as afiopfjiwroi (unformed),
be included within the boundaries of either one or
other of the contiguous constellations, so as to
preserve a regularity of outline and nomenclature.

'■ (3) That all the rest of Lacaille's Stars be placed
within the boundaries laid down by him, with the
following exceptions : first, a few Stars which are
located too far from the border of the constellation,
in which they are registered, to admit of an uniform
contour of the lines ; secondly, such Stars as have
been previously observed by Ptolemy or Flamsteed,
and b\- them located in other constellations, or which
interlace, and are confusedly mixed with such
previously observed stars : thirdly, the four Stars that
are placed by Lacaille in the end of the Spear of
Indus, but which are now assumed to form part of
the constellation Pavo, in order to render the contour
of these two constellations less circuitous.

■■ i4i That the letters selected b\' Lacaille be
adopted in preference to those introduced bv Baver
in Argo, Centaurus. .\ra and Lupus. That the
Greek letters (with a few exceptions) be retained
only as far as Stars of the 5th magnitude, inclusive.
That no Roman letters be at present used, except in
the sub-divisions of .\rgo subsequently mentioned.

"(5) That Argo be divided into four separate
constellations, as partly contemplated b\' Lacaille.
retaining his designations as Carina, Puppis and
\'ela ; and substituting the term Malus for Pyxis
Nautica, since it contains four of Ptolem\"s Stars that
are placed by him in the mast of the ship.

" (6) That the original constellation, Argo. on
account of its great magnitude and the sub-divisions
here proposed, be carefulh- revised in respect to
lettering, in the following manner : first, in t)rder to
preserve the present nomenclature of the principal
Stars, all the Stars in Argo (that is. in the general
constellation, regarded as including the sub-divisions
above mentioned), indicated h\ Greek letters by
Lacaille, be retained, with their present lettering,
under the general name, .\rgo ; secondly, all the
remaining Stars to be designated bv that portion of
the ship in which thev occur, such as Carina,
Puppis, \'ela and Malus, and to be indicated b\- the
Roman letters adopted by Lacaille, as far as the 5th
magnitude inclusive. And no two Stars, far distant
from each other in the same sub-division, to be
indicated by the same letter : but in cases of conflict,
the greater magnitude to be preferred : and when
they are equal the preceding Star to be fixed upon.

"(7) That the constellations which Lacaille has
designated b\' two words be e.xpressed bv onlv one of
such words. Thus, it is proposed that the several
constellations indicated by Lacaille as Apparatus
Sculptoris. Mons Mensae, Caelum Scalptorium,
Equulius Pictoris, Piscis \olans, and Antlia
Pneumatica. be called by the respective titles of
Sculptor, Mensa, Caelum, Pictor, Volans and Antlia ;
contractions which have on some occasions been
partially used by Lacaille himself, and are veoi-
convenient in a registry' of Stars.""

' I call this ■" authoritative " because it appears in the Preface to the British Association Catalogue as given by Baily.
apparently on behalf of Herschel ; but it is not expressly stated to be in Herschel's own words, though I infer that the words

are Herschel's.

THE DESTRUCTION OF WEEDS BY CHEMICAL

MEANS. II.

By HAROLD C. LONG, B.Sc.

^Aiifliiir of "Coiiniiiiii W'cciis of tlic Farm am! Garden. ")

Ln the course of his investigations Bollcy obsen-cd : —
(1) That succulent plants and those of slow growth arc
more easily killed than others : (2) That flower })arts
and parts of plants covered with " bloom " or waw
coatings are more or less protected ; (i) That jilants
possessed of hairy surfaces are, as a rule, more easih-
killed th.an those with a smooth surface : (4) That
chemicals act differentl\- upon plants of different
families, even though
the plants he wetted
equalh- readih- — char-
lock and dandelions,
for exami)le.are readih-
attacked bv copper
sulphate solution,
while creeping thistle,
\\ild buckwheat and
clover are slowh-
attacked: and ( 5 )
That most of the
chemicals readily de-
stroy the tissues of
an_\- plant where the
surface is broken.

It was found that
charlock could' be
sprayed with absolute
success ; that king-
head or greater rag-
weed (A III h r o s i a
frificlai could be
sprayed in much the
same way as charlock
and with considerable
success at certain
times, success depend-
ing on the age of the
weed ; that creeping thistle (C/z/c7/\ irrvcnsifi) w as most
effectively sprayed with sodium arsenite (one-and-a-
half to two pounds per fifty-two gallons t)f water).
and common salt (one-half barrel per fift\-two
gallons of water) ; that succulent portions of the stem
and leaves were destroyed when the plants were a foot
high and seeding was prevented : that spraying of
dandelions on lawns and fields with sulphate Of iron
was a marked success ; and that the perennial sow-
thistle (Sonc/nis arveiisisi was practicalh' unaffected
by sprays. (It may be remarked that this weed,
only too common in Britain, is (]uite sniootli and
covered with bloom.)

/■' (>/'/ a /i.'toto^t ,i/>Ji

Figure 10.

Garden Kiglitshadc {Solamiiii iiiiiniiii L.) A pest of arable land

and gardens, and puisonous to an extent which \arics acx'ording

to conditions.

Bolley concluded that the following weeds may be
eradicated or largeh- subdued in grain fields b\- the use
of chemical s\)vayf. : — l'\ilsc Hiix i CcJiiiLiiim scitiva),
worm-seed mustard, tmnblinu; imistard, coiunion
icild imistdrd : clnirldck I, shcf^hcrd''- purse, pepper-
grass, ball mustard, corn aicklt'. chickiceeci. dandelion,
cret'pini> thistle, hiudiceed. plantain, rough pigweed,
king-head, Ked-Riwr weed, ragweed, cocklebur.

The following were
found not to be effec-
tively controlled b\'
chemical spra\s as
now used: — Hare's-ear
mustard, penny cress,
pink cockle, perennial
stnc-th istle. hi nib' s-
quarters. pigeon grass,
uilil oats, chess {Broni us
secalinus) couch gra.'^s,
sweet grass, and icild
harley. (In each case
those weeds named in
italics are of interest
to farmers in Great
Britain).

A large number of
tests with the sulphates
of iron and copper
were carried out some
years ago hv Dr. A. B.
Frank in Germany.*
Thirty-five species of
weeds were involved,
("lover was but little
damaged b\' a 15 per
cent, solution of iron
sulphate (se\'ent\'
gallons per acre, and one hundred and si.\t\' gallons
per acre), or a 5 per cent, solution of copper sulphate,
the clover soon recovering after losing its first
leaves. In addition to charlock, the following
plants were more or less damaged b\- sulphate of
iron : — corn cockle, poppv, sow-thistle, cornfiower,
field thistle, dandelion, groundsel : and the following
were more or less damaged b\' a 5 per cent, solution
of copper sulphate (se^•ent\• gallons per acre) : —
spurrey, groundsel, black bindweed. Though these
plants appear to be rarely destroyed they are pre-
vented from producing flowers and seed.

In experiments conducted in 190o at the Holmes

f'V H. C. l^oiig.

Bckampfung d. Landw. Un];rUu(er dnrch Mefalsalze. — Arh. aiis. tier Biol. Ahtli. til r Iaiiu!. iiiul /-"or/.su'.. I. Hd.. IMOO.

4J0

Novi:mber, 1910.

KNOWLEDGE.

431

when

Chapel College of Agriculture and Horticulture.
"clo\er was untouched
crop was spra\ed with
one hundred gallons of
a 4 per cent, copper sul-
phate solution. In 1899
a 4 per cent, solution
of the sulphate (one
hundred gallons per
acre) completeh' killed
Polyfioiiiini Persicaria.
but c 1 o \- e r was u n -
injured. A 4 per cent,
solution of copper sul-
phate (fifty gallons per
acre) was also used to
destroy charlock in
mangolds. the latter
being uninjured.

Experiments at the
Agricultural Experi-
ment Station of the
Universit\- of Wis-
consin showed ^ that a
20 per cent, solution
of iron sulphate (tifty-
two gallons per acre)
did not injure cereals,
clover seedlings or
lucerne, but cockle-bur,
ragweed, dandelions,
daisies, wild lettuce,
and several common
farm weeds were partl\-
eradicated. Sow-thistles

FiGURl

and creeping thistle

Corn 1-iiitterciip iRiTnuiiculns
arvciisis L.I X 1. Often very
troublesome in corn fields on
.^11 soils, especiiilly on chalU.
Often termed " watch wheels ""
from the flat spiny fruits.

spra\'mg

were not effectively

spra}-ed, and it was

concluded that their eradication b\

is not practical for the average farmer.

In demonstrations conducted throughout
Ontario, the effect of copper sulphate was
observed in relation to twentv-eight weeds, + and
while charlock was the only species readily
destroyed, it was found that the flowers of field
bindweed and white cockle, and the leaves of
creeping thistle, sow-thistle, blue weed i Echiuin
viilgarel. and bull thistle iCiiiciis laiiciohifiis i.
were ver\- sensitive to the spray, and largely
destrox'ed.

At the Yorkshire College, Leeds, experiments
showed ; that clovers were practically uninjured
when sprayed with a 12 per cent, solution of
sulphate of iron, while peas, beans, carrots,
onions, beet, and j^arsnips were but slightl\-
damaged, and this was the case also with swedes,
turnips and mangolds.

Spurre\- iSpcr^iila arvensis) has been found to be
checked hv spraving with a 3 per cent, solution of
sulphate of copper (fortv gallons per acre),
flowering and seeding being checked .
In another trial ' the results were held
to show that a 5 per cent, solution of
copper sulphate (fift\- gallons per acre)
ma\- be relied on to kill spurrey.

.At the Woburn Experimental Farm it
has been shown hv pot trials that the
common poppy [Papavcr Rhocas) is much
injured hv a 2 per cent, solution of
copper sulphate : w hen the solution was
applied to both surfaces of the leaves
these ■■ turned brow n. became shrivelled,
and to a great extent the plant was killed.
for the seeding was almost entirely
prevented, the flower heads withering
up." vj It has also been stated ** that
the common scarlet poppy is ver}- sensitive
to a 13 to 20 per cent, solution of iron
sulphate.

At the Woburn Station also experiment
showed that the wild
onion i AlUtun vincdle)
may be destroyed or at
least largeh' reduced by
spraving with a 5 per
cent, solution of pure
carbolic acid. + +

Dr. Hiltner found
that dodder on clover
m'A\ be destro\ed by
S[)ra\ing with a 15 per
cent, solution of sul-
phate I if iron, so applied
that it hits both the
[jlants and the surface
>oil with some force.
Tile clover was black-
ened at first and
appeared to be ruined,
but sprouted strongly
afterwards. » ^

Sulphate of iron has
been found to destroy
charlock if applied in
the powdered condition
w hen the dew is on the
leaf, three to four cwt.
per acre being necessary.
This is considered by
M. Hitier to be more
easy of application than
in the form of a solution,
and more practical on
small areas.

FlGl'KE 12.

Shepherd's Needle. N'enus' Comb
tScaiitiix Pcctcn-Vcncris L.(X1.
.\n annual corn-field weed some-
times extremely troublesome on
light and chall; soils.

* Bulletin No. 179. 1909. ' .\nn. Report. D.-pt. .\-ric.. Ontario. 1904. Vol. I., p. 39.

; Report cm the Spraying of Charlock and Hunch. 1899. Rept. on l-:xpts.. Midland .Agric. and Dairy Inst.. 1900.

• Uni\ . Coll. of North Wales. Bangor. Bull, ii., 190.S. ? Jour. Roy. .■4.s,'ric. Soc. 1902. p. 360.

** Fr. Maier-Bode. Die licMiupfuiifi der .Acker-Unkrauter. 1908. ' ' Jour. Roy. .Aoric. Soc. 1900, 1901 and 1902.

l^rak. Bhittcr tiir Ptiaiizciibaii mid l\tiaiizcnsclinfz. .\p. 190S. Bull, dcs Scmiccti Soc. \at. d'.Agric. 1909, No. 5.

432

KNOWLEDGE.

November, 1910.

sulphate, arsenate of soda, and
so on. are dealt with.

The foregoing notes show con-
clusively that in one way or
another man\' weeds may be
attacked by means of solutions
of chemical preparations, with
good prospects of preventing

seeding or

of destroying the

plants altogether. It is, however,
still desirable that exhaustive
experiments should be conducted
on a co-operative basis in differ-
ent parts of Great Britain,
for the effects of the various
solutions \'ar\- with the plant
sprayed, the local meteoro-
logical conditions, and the
thoroughness with which the
work is carried out. \\'ith the
results of such experiments
placed clearl\- before them.
British farmers would have
some definite information on
A plot of lawn upon the North Dakota AKi'icnltural College campus infested by which to proceed. We hope
dandelions untreated before blossoming time. Left continuation of Figure 14. tJ-iqt- fl-|p nrenaration of this

article w ill not have been in \-ain.

Figure 13.

(From Bolley's Bulletin, No. 80, see Knoxclccli>e, No. 507, p. 395..

Calcium CNanamidc has also
been found useful for destroying
charlock in corn crops.*

The action of petrol on certain
plants has been observed at
the \\'oburn Experimental Fruit
Farm.^ and it was noted that
the popp\', teasel and wild
strawberr\" were practicalh'
killed.

The efficac}' of carbon bi-
sulphide in killing large troi.Mcal
" weeds " has lately been dis-
cussed b\" E. \'. \\'ilcox in a
press bulletin issued from the
Hawaii Agricultural Experiment
Station, and plants app>ear to be
destro\'ed owing to the freezing
effect.

The results of experiments
at the \'ermont Agricultural
Experiment Station and else-
where are summarised in Farm-
ers' Bulletin, No. 124 of the
U.S. Department of Agriculture
— and salt, carbolic acid, liver-
of- sulphur, kerosene, cop])er

IGURE 14

.■\ plot of lawn upon the North Dakota Agricultural College campus infested by
dandelions of the same strength of growth as those shown in Figure 13. but J
treated with iron sulphate solution thrown by a traction sprayer two weeks before ^
blossoming time. Compare with Figure 13. (From Bolley's Bulletin, No. 80, see
Ktioicledge, No. 507, p. 395). These two photographs show in a striking manner

the effects of spraying.

'■■ Jtiiir. Rd. Agrlc, Dec, l')()7, p. 568; Jan.. 1909, p. 776.

I 10th Annual Report, 1909, p. 20.

THE OBSERVATORY ON MOUNT WILSON, WHERE
MIRRORS SUPPLANT THE TELESCOPE TUBE.

By FELIX J. KOCH.

The reCL'iit appearance and disappearance of
Halle^•'s comet has thrown the star gazers into
the public eve, and among observatories none,
perhaps, has given rise to more comment than
the great Carnegie one t)n Mount \\'ilson. near
Los Angeles, California. This, perhaps, largely
because it is unique

world's ob-

among the
servatories.

To reach Mount \\'ilson
from the end of the near-
est car line means a long
burro ride through the
mountains. There the
one peak of the twins
forming the summit is

given
hotel,

over to a rustic
and surrounding

this, for indi\idual guest
rooms, are a series of
chalets, each a full-fledged
house to be occupied by
the guest.

Entrenched in these
one proceeds through the
forest down into a gulch
and on to the opposite
mountain, where the great
Observatory connected
with the Carnegie Insti-
tute of Washington. D.C.,
is established.

The building, to begin
with, appears like some

1 iie edue ot the Ark.

hug

It is of white

canvas, immense, and in the shape of a barn. It
stands on the very tip of a mountain, surrounded
on all sides b\' open vallev. One surveys lower
forested peaks rising out of this valle_\', and the
flat plain leading off into the distance. The scene
is sufficient!},' magnificent to repav for the journey.

Turning, there lie, basking in the sun, a large
white series of buildings set in perfect line on this
peak.

A professor is at hand to guide you, and he leads
into the main building. This is built up of canvas,
set in eave form on the sides so as to admit plenty
of air. Then outside these canvas eaves there runs
another wall of canvas, such that it can be raised or

lowered, and thus ensure the same temperature
inside the building as out.

One looks at once for telescopes, but in \ain. .\
series of mirrors appears instead, and it is the third
of these, you learn, which does the magnifying
instead of the usual tube telescope. You look

into this mirror and see
enlarged the image of the
star or moon. In order
to get this, plainer still,
a pocket magnif^"ing glass
is brought into pla\-. The
arrangement is a unique
one for an observator\'.

Nor is this all. The
tent in which this third
mirror stands is built
upon a track, so that it
may slide nearer to or
farther from the next
building, in which there
are two other mirrors,
while beyond is a little
shed in the canvas build-
ing, for star work and
for the spectrum instru-
ments.

This telescope, the
guide narrates, is a twent\-
four inch one, made h\-
their own people, and
brought out from the
Yerkes Observatorw On
the end of the building
there is a pier of stone,
by twent\- long, which
a concave mirror of twenty-four inch
aperture h\ si.xtv foot focus. This was made
at the Yerkes Observatory. Any good optician,
however, could make one of these fine circular
mirrors. The concavitv is very great. The mirror,
as a matter of fact is four inches thick, and silvered
on the front surface. It takes about two months for
two men to make such a mirror. This is polished
by jewellers' rouge on pads of chamois skin. The
mirror is burnished every week or ten days to
remove the dust. It is then ke[)t covered over w ith
a galvanized cover.

A second mirror is supported by a number of

perhaps three feet wide
contains

433

434

KNOWLEDGE.

November, 1910.

circular metal (iron) caps. It rests on tweKe
of them, each, in consequence, taking one-tweltth
(if the weight of the mirror, no matter what
i)i)sition it ma\" be in. When the muror is set

that the room-mate of one of their sons up at
Dartmouth is now observer here, and so he shows

them, am
in the ni

\dn. as
;ht tmie.

would

directh- on edge, a band about the outside holds
it in place. It must be thus cNacth' weighted on
account of the tiexures in the glass,
spoil the definition.

The light strikes the first
mirror primarily and from it
is Sent t(i the second, a flat
circular mirror, which is of
t\\ent\-four inch diameter,
and stands on a massive iron
column. This second mirror
is upright, but is racked back
so that it can set the reflection
in an\' direction. Thence the
ra\s are sent from it to the
third mirror, i.e., the concave
one. which does the enlarging,
acting substantially as does
the lens in an ordinar)- tubular
telescope.

It is im|)ossible to reflect
from the first mirror direct tn
the third, as the light cannot be
caught so well, and the station
would ha\e to l)e constanth'
changed. This changing is now
done b\- the second mirror.

I'ive-thirtN- p.m. is supper
time with the astronomers here, and one leaves
them to return to the mountain hotel and his
chalet.

In the evening two Yankees, also on visit, find

their guests, the Obser\ator\-
The moon seen through the
great mirrors is a si.^ht long to
be remembered. The liglit of
the orb falls full through the
two mirr<irs on to the thirtl.
which it fills with its image.
The visitors stand round this
third mirror and then look
at It through a little black
hand niagnif\'ing glass. The
craters and hills and the like
take on new interest and
beauty.

Again, one mar\els at the
site. Here on the long tented
platform, which stands built out
into the canon, \\ith the mag-
nificent forested \'alle\ s in
the moon-light, black in tlie
shadows, but stretching on to
the far lights of Pasadona and
Los .\ngeles. At another place
.1 huge forest fire breaks the
night. Over all a magnificent
clear starry sk\-. with the rising
moon, surrounds this white
K-i'e is sonK'thing inspiring in

this uniipie little mountain star camii.

Next morning. Professor Ellerton. second in

charge here, tells some interesting facts about the

tented huildniL

In the Mirror.

place. Harvard, he states, had an observatory here
fifteen or sixteen years ago. When then the
Carnegie Institute was about to open an obser\'a-
torv, it tested several places hereabouts, trying

November, 1910.

KNOWLEDGE.

435

Mount Lowe and the like, but finding that the
place where the least quivering, due to bad
definition, i.e.. steadiness of the image was here.
The\- also saw that they got out of the way of
dust, which will occasionalK' even come here
as the result of some sand storm, and of
ordinar\- fogs. Fogs, though, will arrive in the
storm\' season.

The site was selected six years ago last June, and
the instruments shipped here.

Since .\pril, 1904, observations have been carried on
more or less continuously. Professor George E.
Hale is director. He came from the Verkes Obser-
\'ator\-. where his chief work was solar ph^'sics.
He is a man about forty-
one or two years old.
a graduate of Boston
Institute of Technolog\-.
Ferdinand Ellerman. next
in charge, has had jiri\ate
tuition, and has been at
the work about eighteen
or nineteen \'ears. His
specialitv is solar work.
Others here of note are
Dr. Adams, Backus, and
the pln'sicist Dr. Gale.
They have their own
camp and offices — even
generate their own elec-
tricity by gasoline engine,
and pum[) up their own
water.

The best time for obser-
vations is considered tn
be half-an-hour after sun-
rise, and for perhaps two
hours later, i.e., as long as
the definition holds good.
This ma\' run through the

\v!n)le da\'. The programme is to make photo-
graphs of the sun with the spectroheliograph. This
is done by forming the image of the sun on a
spectroscope, which is so adapted as to enable one

one would see it in a telescope. The spots, with the
dark nucleus and the granulation in the surface, are
all there. The photographs are almost instantaneous,
being made b\- a high-grade shutter passing before
the "plate in one one-thousandth of a second. One
picture is show n which shows the calcium lines: this
bv letting onl\- these lines through the slit. The
more pronounced waviness in parts is likewise
noted, .\gain one sees that the line which admits
the light of the sun for a given chemical travels
across the plate in such w ise as to get in the whole
surface of the sun. There is now a record of
d fift\- plates with this new

over one hundred
instrument.

.\ Vr

to photograph an nnage of the sun m mono-
chromatic ra\-s of an\- desired wave length. The
light passes through a slit, then through an objective
which renders the rays parallel, then falls on a mirror,
and thence is sent through two great prisms which
form a spectrum. Thence it goes via an objective
and through a second slit which permits one to
select any particular line in the spectrum, and by
this means photographs can be taken which will
show the vapours over the sun's surface, corres-
ponding to calcium. h\-drogen, iron, magnesium and
the like. The photographs are the size of the image,
i.e.. six-and-a-half-inches. The negatives are then
developed and one sees some of these glasses. At
the centre is the round image, like a great fog spot
with a rather crusty, skin-like effect, due to clouds
passing over the surface. Such is a direct photograph
made by a very fast shutter. It shows the sun as

One passes then into the
new laboratory : this is of
solid concrete work, and
w ith instruments all about.
The\- can take a photo-
graph twice a day,
different each time, and
never twice the same,
the sun changing so con-
stantly. Daily a photo-
heliograph is taken:
two or three calcium
plates, and one hydrogen
plate. This is the regular
programme. If the defini-
tion is good, so that they
can compare to advantage,
the\' photograph through
iron and other lines,
and there are special
sittings. The difference
between the calcium
and hydrogen is made
apparent. The results
then are deduced here
and published in scien-
tific publications or monographs.

One has a peep into the professor's home — a series
of little offices and bedrooms off from one hall, and
all built in the mission style. Windows look out
into the tree tops, as at Kila Monasteries in Bul-
garia, and the aisle then terminates in a library
finished in dark hea\-\- woods, with a huge stone
chimnev at one side. Round the walls range the
open shelves of books, with other heav\- splendid
furnishings, and heavy desks on which to write.
One looks right off from the bluff into the great
valle\- here, twenty-six acres below, to the Institu-
tion. As yet thev are not troubled by visitors,
though thev fear the\- w ill have some day to enfence.
The buildings are pe'rmanent, but others are still to
come for the great five-inch reflecting telescope.

Some of the stellar photographs shown here, they
remark, took four nights to expose. The Observatorj-
is connected with the Carnegie Institute and so there
is no fixed sum allotted it. One year they got
S150,000 for maintenance.

THE LIFE HISTORY OF A NEW MONAD.

Bv AUBREY H. DREW.

W'ltli illKsticitioiis from camera lacula ilriiicnina by the Writer.

In December, 1908, whilst examining microscopicalh'
a sample of water from a pond at Keston, Kent, I
first observed the organism of which the life-histor\- is
here given. \\'hilst swimming, this form seemed to be
possessed of but one flagellum. which wasapparentK"
motionless. At first its method of locomotion seemed
obscure, but by accurate examination with high powers
it was seen to possess a second flagellum \er\- much

The central part of the body is generally verv
granular. When stained the organism is seen to
possess a nucleus, which is usuallv situated towards
the side of the body. In swimming, the smaller
flagellum is in constant motion to and fro. the lash-
like extremity of the long flagellum being also usuallv
in vibration. The long flagellum appears to be of use
also for steering purposes, but its main utilit\' is

FiGCRE 1.

Normal f r e e
swimming form.

FiGCKE 2. Fk.lre i.

The organism during feeding.

FiGLRi; 4. Figure 5.

The ingestion of other Monads.

smaller than the other and curved round towards the
bodw This second flagellum was in rapid motion
during swimming. \'ery careful and repeated obser-
vation revealed the fact that the other flagellum was
also used in swimming, as it had a fine whiplash-
like extremitx'. which was in rapid motion. I deter-
mined to work out. if i)OSsible, the life-histi>r\- of the

The

undoubtedh' in feeding, as will be seen later,
normal form, after swimming for a period which ma\-
var\- from minutes to hours, becomes amoeboid and
finally ceases movement. A more or less globular
shape is now taken on, and the whole of the long
flagellum is vibrated with a serpentine kind of motion,
the smaller flagellum being also rapidlv vibrated, the

Figure 6.

Figure 7

Stages in division.

Figure 8. Figure 9.

Conjugation. The sac.

Note. — .\1I the figures are niaiinificd one thousand times.

Figure 10.
The sac dis-
charging yoimg.

monad, and after a year and si-x months steadv w ork
on the form I have been able to accomplish m\-
object.

This Monad is a long oval, or sausage-shaped,
organism, about one three-thousandth part of an inch
in length ; it posesses two flagella, one, the most
conspicuous, being long and curved, somewhat like
an eyelash, and the other being short and bent
somewhat sharply towards the body. The long
flagellum tapers towards the distal end, and becomes
like a whiplash ; the smaller flagellum is of the
same thickness throughout. .\ contractile vacuole is
present, situated about the middle of the organism.

bod\' remaining motionless and apparent!}- adhering
to the slide. B\- means of these flagellar vibrations
currents are set up in the water towards the body of
the monad, and bacteria and other smaller monads
are swept towards the flagellar end of the organism.
On getting near, the long flagellum is often bent o\er
the other organism, which is thus guided to a point
between the two flagella. Here the currents
frequently cause the smaller monad or bacterium
to rotate rapidly for a time, till finally it gets
near the body of the monad. The protoplasm
then seems to flow out and completely engulfs
the smaller organism, and its body is passed

436

November, 1910.

K\0\VL]£DGE.

437

into the interior of the monad and is rapidly
disintegrated. During this process the long flagelkim
is usually vibrated with intense rapiditw Not
only bacteria, water plants, and other monads
are ingested in this manner, but also smaller monads
of the same species, the feeding monad becoming
ver}- large in consequence. In one large specimen
that I had under observation continuouslv for nine
hours, five smaller monads of the same species were
ingested. Three more were captured, but bv intense
flagellar movements they \\ renched themselves free
and escaped. There is no doubt that a kind of
gastric juice of an acid nature is secreted hv this
monad, as I have found that if bacteria are stained
with a saturated solution of blue litmus, and intro-
duced into the water in w hich this monad is living,
on ingesticm they are almost instantl}- turned red.
After feeding in this wa\' for some time, the monad
again becomes amoeboid and finalh" takes on the
normal sausage-shaped form, and active s\\ imming is
recommenced. This period of alternation between
swimming and taking on a globular form, with a repeti-
tion of feeding operations. ma\- continue tor man\-
hours. Finally, however, the organism comes to a stand-
stillandbecomes e.\tremel\amoeboid,the bod\" getting
very granular. Sluggish swimming now occurs, the
body being in intense amoeboid action. Wliile the
organism is in this condition, another normal form
comes into contact with it, and almost instant fusion
occurs, the long flagellum being vibrated with
remarkable rapidity. The organism now speedih-
becomes globular, the long flagellum being cast
off, and the smaller one fusing with the 1kk1\-,
a motionless globular sac is formed, which gradualh-
becomes very granular, the granules showing move-
ment. This sac ma\' remain in an absoluteh"
motionless condition for a period which \aries from
six to ten or more hours. Finalh', however, it
bursts at one end and liberates a number of small
granules about a thirty thousandth part of an inch
in diameter ; these roll away from the sac, and if care-
fully followed soon show signs of growth. In about
two hours they acquire flagella. in what manner I
have not yet been able to determine, though I think
the long one is suddenly shot through the bod}- \\all.
This method of reproduction was alwavs obscure
and was only discovered after months of work on the
form. In the two conjugating individuals there was
this essential difference, viz : that one w as the
ordinary sausage-shaped free swimming form, which
was much smaller than the other amoeboid form :
this latter by long feeding had greath' increased its
size to several times that of the other and was far
more granular. The other method of reproduction
was by fission, and this occurred in the ordinary
form after it had attained a certain average size in the
following manner. After nuclear division, a con-
striction was developed round the body of the
monad which divided it into two : one of the
two nuclei now passed into each half and the
constriction deepened : the smaller flagellum now
gradually appeared in the end most remote from the

other two flagella. From this time the constriction
rapidly increased and the flagella lashed in a manner
which pulled the two halves away from each other.
Finally, they moved away from each other, the thin
connecting strand of protoplasm breaking close to the
body of the monad possessing the two normal
flagella, and this protoplasmic strand formed the long
flagellum of the other form. Periodicallv, the
organism ejects undigested matter, this usually being
at the opposite end to the flagella. A rather
characteristic appearance is thus often given to the
organism, as the effete matter gradually accumulates
round the body and remains there for some tiine, till
finall}- being cast off. The important points with
regard to this organism are I think the following: —
Firstly, that although presumably a certain amount
oi saprophytic nutrition does take place during
active swimming, the organism is unable to obtain
the requisite amount of nutriment bv sapro-
phitic means alone, but is compelled to ingest
other organisms of as complicated a chemical con-
stitution as itself, this method of nutrition being
eminently holozoic. Secondly, the fact that, although
there is no buccal opening, yet food is ingested at
one particular spot, viz : between the roots of the
two flagella, coupled with its method of nutrition,
gives to this monad a higher position in the scale of
organisation than any other known members of the
family: and, third!}-, so far as I. am aware, there is no
other known instance among the Protozoa of what
one ma}- well call a cannibal form.

The anisogamic method of reproduction in thisform
is of considerable interest, inasmuch as the two
conjugating forms differ in several respects. The
larger organism or megazooid having increased its
size greatly b}- continued ingestion of other organisms,
and, apparentl}- in consequence of its increased size,
is far more sluggish in mo\ement, besides being
e.xtremely granular and amoeboid. The microzooid
is the ordinary normal form, and is not amoeboid,
and, in size, is generally from one-half to one-third
the size of the megazooid ; it is far more active in
swin-iming, and, on several occasions, I have noticed
that the nucleus, which is ver}- difficult to observe in
most of the normal forms, was more prominent than
usual. Thus it will be seen that we have here a
method of reproduction resembling a true sexual
process, as both of the two conjugating gametes
differ from one another, not onl}- in size, but also by
the fact that the megazooid had, by continued
feeding on similar forms, laid up a store of
potential energ}- for further reproductive processes ;
whilst the microzooid had arrived at a certain
average size after reproduction b}- fission, and had
not commenced to feed on its own kind in the

manner that the megazooid had done, its

size

apparentl}- precluding its ingesting other organisms,
as large as itself, although bacteria were easily
ingested. The ordinary method of reproduc-
tion by transverse fission, showed little that was
peculiar to this particular monad. On following
one of the discharged granules from the parent sac

438

KNOWLEDGE.

November, 1910.

already described, one found that, as soon as the
form had obtained flagella, and had acquired a size
of about one-third that of the megazooid, the nucleus
became more \'isible than usuah and. if specially
and carefully looked for, a slight constriction was
noticed to be forming round the body, which
gradually deepened in the manner I have already
stated. A rather striking fact in regard to this
monad is that both methods of reproduction are

very slow, the organism not multiph-ing at all
rapidK'. At first I found it extremely difficult to
keep the organisms for any length of time, but since
found that they grew very well in an infusion of
grass to which a small (]uantit\' of the solutions
recommended b\' Dr. \'an Huerck for growing
Diatoms had been added. On account of its cannibal
propensities I have named the organism Moiias
ttarcoplmga.

SOLAR DISTURBANCES DURING SEPTEMBER, 1910.
By FRANIv C. DENNETT.

During September there was quite a revi\al of Solar energy,
yet the days between the 14th and 17th yielded only faculae or
bright spots. The longitude of the central meridian at noon
on September 1st was 103°' 19.

No. 63 of the .August list remained on the disc until
September 11th. and is therefore shown on the present chart.

No. 6ia. — A pore a little north of No. 63. only seen on 8th.

No. 64. — A solitary pore on the 1st, but by the 3rd had
increased toagroup 40,000 miles in length, the western spotlets
being the largest. The 5th found other spotlets enlarged, and
on the 6th there was a great spot 22,000 miles across close to
limb.

No. 65. — Two spots appeared on the 7th, 58,000 miles apart,
in the area of No. 61. The western one, 7,000 miles in
diameter, had its penumbra fringed brightly at the inner edge
on the 8th and 9th. but was reduced to two pores on the 10th.
but only one seen on the 11th and 12th. The eastern spotlet
dwindled to a pair of pores on the 8th, one remaining until the
10th. A group of three tiny dots appeared on the 13th. hut
soon died away. Situated longitude 297°, South latitude 1 2°.

No. 66. — A minute pair ot pores only seen on the 18th.

No. 67, 67a. and 676. — A series of disturbances close
together. On the ISth and 19th only one pore seen amid
faculae, but two on the 20th, 22,000 miles apart. This was
replaced in the afternoon by a new group of eight pores and a
leader 7,000 miles in diameter. The configuration of the
group had changed on the 21st. and next day there was only
one pore with a gray marking near by. On the 23rd there was
another new group 48,000 miles in length, b, which on the 24th
was markedly of an elliptical shape. The western spot had
the form of an arrow head. 12.000 miles in diameter.
Dwindling on the 26th, only two pores were left on the 27th,
and one until the 2Sth, the area being marked after with
faculae.

No. 68. — An active faculic area on the ISth showing three
tiny pores, one remaining until the 19th, but only a dull
marking on the 20th. A pore showed nearer the eciuator on the
21st, whilst on the 22nd two others 20,000 miles apart
appeared within one degree of the equinoctial line. There was

a pair of tiny pores in the same region on the 23rd. when last
observed.

No. 59. — (.)n the 19th. a group of pores and spotlets,
22,000 miles in length, increasing to 40,000 miles by the 21st,
when composed of only two spotlets, only one grayish pore
continuing until the 22nd.

No. 70. — The return of No. 64 on the 20th, still 22,000 miles
in diameter. The bridges and jets on to the umbrae were
interesting. The inner border of the penumbra brightly
fringed from the 21st to the 23rd and on to the 30th. Three
pores appeared west on the 25th. and others east and north on
the 24th, 26th and 27th. Seen until nearly close to limb or
edge on October 3rd.

No. 70a. — .\ double spot east of the spot on the 22nd, seen
single until the 26th, though a pore showed 20,000 miles north
of a on the 24th.

Xo. 71. — On the 23rd. at iirst two pores showed, but later
in day the number increased ; only one continued until the 24th.
On the 26th, there was a little group of pores in front of a
region of faculae, 150,000 miles in length, last seen on the 27th.

No. 71(r. — Two pores a little south of No. 71, 27th to 29th.

No. 72. — What appeared as a single spot seen just on the
disc on the 23rd. proved to be two seen 24th to 28th; then the
western spotlet became shaped like a harpoon head. This,
however, did not last, but a group of four pores, 22,000 miles
long, continued until October 3rd. after which the area was
marked by faculae.

No. 73. — On the 26th, pores had come on disc in a faculic
area — by the 27th it was evidently the forerunner of a large
group. This proved to be 140.000 miles in length, and to be
very deficient in umbra. As is usual in such cases, detail
changed considerably. The largest member was at one time
over 36,000 miles in diameter. The group covers the site of
Nos. 63 and 60, seen until October 9th.

No. 74. — Amongst a bright faculic disturbance close to the
limb, a black spot showed on the 2Sth, not, however, seen since.

The chart is constructed from the combined observations
of Messrs. J. McHarg, A. A. Buss, E. E. Peacock, and
F. C. Dennett.

D.W ol' SEPTEMBER.

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SOME MENTAL ILLUSIONS OE VISION.

K. T. Li:\VIS. l-.K.M.S.

Notwithstanding the popular saying that "seeing is
believing," neither of our faculties is subject to such complete
illusions as our sense of sight, some being optical, others
ocular, whilst again others are purely mental.

To the first kind belong those due to refraction — such for
instance as the mirage, or the apparent displacement of an
object from its true position ; to the second kind may be
referred the phenomena of irradiation, and of subjective
images and colours ; whilst the third includes the impression
which most persons have of the apparent increase
of the San and Moon when rising or setting, and
the similar increase in the apparent size of con-
stellations, or the distance apart of stars when
seen near the horizon, as compared with our
estimate of such at their meridian altitude.

That this last-named illusion is neither optical
nor ocular is shown at once by the fact that
when seen through a telescope no such apparent
increase is found to exist ; indeed, when accur-
ately measured, after making all necessary correc-
tions for height of barometer, temperature, and
refraction in altitude, it is found that the appar-
ent diameter of either body is really greatest when
on the meridian, inasmuch as they are then some
4,000 miles nearer to us than when near the
horizim. though the difference is too small to be
appreciated by the naked eye.

It should be noted, however, that the amount of
the apparent augmentation varies considerably
with individuals — artists for instance depict the
rising moon of a variety of e.xaggerated sizes up
to about 15° diameter, or about thirty times
greater than it should be drawn, and one not
infrequently hears it described as looking " as
large as a dinner plate." whereas a three-penny
bit held at arm"s length is rather larger than is
necessary to hide it completely.

That this almost universal illusion is entirely mental, is not
easy to demonstrate, although it will be readily admitted that if
a false impression of the distance of an object can be created,
the mental estimate of its actual size will be proportionately
altered : in other words, if an object we believe to be near to us
appears of a certain size, and one of the same kind believed
to be at a distance appears also of the same size, we at once
from experience correctly judge that the latter must be the
larger of the two. Hence though the Moon, whether high or
low in the sky, practically subtends the same angle, and
therefore its image on the retina of the eye is in both positions
the same, we naturally from experience imagine it nmst be a
larger body in the latter case, because though so much further
off it appears to be of the same size as the Moon we
see when apparently nearer.

The experiment referred to in the accompanying diagram
affords a convincing illustration of the curious mental eflect
produced by the creation of a false impression of distance.
and is one which may be performed by any persons who
possess sufficient control of the eyes to dissociate the focussing
and the convergence, which, though (|uite separate and
independent actions, are from constant habit usually performed
automatically together. .\-B represents a stereoscopic slide,
which we will suppose to be of the full moon, placed at the normal
distance of 10 inches from the eyes, when the two pictures
are seen clearly in focus. If whilst retaining the focal distance
we alter the convergence so that the axis of the right eye (R)
passes centrally through the picture B, and that of the left

eye (D through the centre of A, as shown by the two firm
lines L-C and K-C, these axes will meet at the point C, which
will be more or less distant from the plane of .A.-B according
to the width apart of the eyes of the observer. The result of
this will be that three images of the pictures A and B will be
seen, of which the central one, consisting of A and B super-
posed, will be seen apparently at C, and of course perfectly
stereoscopic. If then without altering the distance between the
eyes and the slide we look so " cross eyed '" that the axis of K
passes centrally through A. and that of L through B, as indicated
by the two dotted lines, we shall again see three
images, the centre one apparently at D. but in
this case pseudoscopic. It is clear that in both
cases the images of the pictures on the sympa-
thetic portions of the retina will be approximately
the same, but in the former case where the
moon is seen apparently at C, or nmch further
off than it really is, the effect is that of a consider-
ably magnified image, whereas in the latter case
where the picture is seen apparently at D, or much
nearer than it really is, the mental impression
produced (after making due allowance for the
difference between R-A and R-B) is that of a
considerably smaller moon than either of those
seen at A-B, the mental illusion in each case
being due to the fact that a false idea has been
created as to the distances of the objects observed.
.A further experiment may be suggested by
means of the subjective image of any object which
gazed upon long enough to produce a con-
tinued impression upon the eyes. If, for instance,
the filament of an incandescent electric lamp is
steadilv looked at for a few seconds, the impres-
sion produced by it upon the sympathetic por-
tions of the eyes will persist until the vibrations
so excited have run down, and a spectral image
of the filament will meanwhile be seen so long
as the convergence of the eyes is maintained at the same
angle as when the lamp was originally looked at. If this
image is projected upon the distant wall of the room it will
appear of magnified proportions, whereas if thrown upon some
surface nearer to the eye than the exciting cause, it will
apparently be seen of very reduced dimensions, although in
both cases the actual picture formed must be preci-sely
the same.

As yet another, though somewhat difterent class of mental
illusion in the case of vision, I may mention that I have before
me a photograph of the "' Challenger " medal, taken under a
strong oblique light, falling upon it from the top. Knowing
from experience that if the light falls in that direction upon a
raised surface, the shadows would fall as depicted, the mental
impression produced when the top of the photograph is held
towards a source of light is that of a design in strong relief,
although the sense of touch assures me it is flat : but if the
picture is turned round so that the light falls upon it from the
bottom, experience immediately suggests that shadows, as
they then appear, can only be thrown by an intaglio, and the
mental suggestion is that of a sunk pattern, an illusion
which would be complete but for the fact that the inscription
still reads the right way about.

A false estimate of distance, and therefore of size, is very
conuuon to persons in the clear air of high mountainous
regions, who under ordinary circumstances are accustomed
to see landscapes through our own more murky atmosphere,
and the common illusion of meeting suddenly with gigantic

43y

440

KNOWLEDGE.

November, 1910.

figures in the street on a foSK'y night, because they arc much
closer than imagined, will occur to most people.

It .-eenis also quite within the limits of possibility that some
(>t the errors of interpretation as to the meaning of what is
~een under the microscope may be due to mental suggestion.

It will be understood that the extent of such illusions as
have been referred to \aries somewhat according to the

" personal equation " of the observer, and that what has been
described is simply the experience of the writer, who it may be
of some interest to mention, has since he thought out the
matter, almost entirely lost the impression that the Sun and
Moon appear larger when rising or setting than at other times,
though he has been quite unable to divest himself from the
illusion in the case of constellations or stars.

X-R.AV.S FOR EX AMI XI XG PETRI F.ACTIOX.S.

Bv Dk. .\LFRKD GKADENWITZ.

The extremel\' numerous technical and scientific uses ol
X-rays are Unown to be based on the differences in trans-
parence shown by the \'arious tissues in regard to these rays.
The silhouettes produced by
the passage of X-rays there-
fore give an insight into the
internal structure of liuui.iu
and animal organisms, which
would otherwise be for e\er
closed to our eyes.

The latest achievement in
this connection is the use of
these wonderful radiations in
investigating the internal struc-
ture of fossils. In fact, a
French scientist, M. Pierre
Goby, at Grasse. has recently
obtained some excellent X-ray
pictures of petrified starfishes,
of which an example is repro-
duced in Figure 1.

It is well known that those
countries which were formerly
covered by the sea contain in
their soil great quantities of
renmants of the ancient marine
fauna. To these countries
belong the environs of Venice
in Southern France, the fossil
treasures of which have been
lately investigated with especial
care, partly, as has been hinted,
with the aid of X-rays.

In order to understand the possibility of using X-rays in this
connection it should be considered that all the internal
parts of a petrified starfish are filled up b\- a remarkalil\-

l'}\vu a Scitigia^/l

Clypcastcr htti

homogeneous quart/; mass which mainly consists of an
agglomeration of minute transparent grains, bound together
by a glue so loose as to leave small cavities in the interstices.

Though being little trans-
parent to X-rays, this mineral
mass is far less opaque than
carbonate of lime, the sub-
stance of which the shell of
the starfish consists. This
is how the X-ray picture
of the petrifaction, surprising
though this be, absolutely
resembles that "f a li\ ing
starfisli.

.A.ny slight discontinuity in
the \arious portions of the
petrifaction will result in a
difference in the depth of
shades. The five radial grooves,
e.g., are distinctly visible, and
the thinnest portions of the
petrifaction, viz., those at the
edges, are especially clear. The
digesti%e tube which surrounds
the central cavity is seen with
remarkable distinctness, each
of its circumvolutions being
clearly marked.

The naturalist recognises
/■!■ Pi\-rn- c.i/n: '" ^'^'^ X-ray picture a num-
ber of features of much im-
nisfris Agassis. portance from a scientific

point of \' i e w . but which
cannot be discussed in the present article.

From the above is seen that X-ray pictures are likely soon
to prove a powerful aid also in the work of palaeontologists.

THE SHOOTING .ST.AR.S OF NOVEMBER.

The mere mention of the Leonid meteors is sufficient to arouse
a certain amount of enthusiasm amongst meteoric observers.
There are many of us who remember the brilliant display of
November 13th. 1S66. and in many cases it nnist ha\e formed
the chief meteoric spectacle of a lifetime.

There were brilliant and abundant displays of the Andro-
medids or meteors from Bida's comet on November 27th in
1872 and 1885, but these were partially \eiled by clouds at
Bristol, and at certain places nothing could be seen. But
the Leonids formed the most impressive scene everywhere.
They are very rapid, bright streaking meteors, and more
striking objects generally than the star morning meteors of
Bida's comet.

It is true that observers looked in vain for a great displav of
Leonids in 1899 and 1900. Planetary perturbation appears
to have disturbed the orbit and to have been responsible for
the absence of the meteors. They returned, however, in fair
abundance in 1901 and 1903, though the numbers fell far

below those seen in 1799, 1833 and 1866. Will they return
this year ? That is a question now being asked, though every
astronomer knows that the conditions will be unfavourable.
The parent comet of the swarm is now at an enormous
distance from the earth, but has probably left a pretty rich
train of meteors behind it. As a popular spectacle, however,
it cannot be said that the shower is likely to prove
remarkable ; it is more as an astronomical event and one for
strictly scientific observation that we call attention to it. After
11 p.m. on the night following the 14th and 15th a few fine
Leonids ought to be seen wherever the atmosphere is clear
enough for suitable watching. There will be no interference
from moonlight, so that in this respect we shall be favoured.

In our English climate, however, fogs or clouds may quite
eliminate the Stars and Meteors. This has been the experience
on many former occasions ; but with fortunate circumstances
it is hoped that the Leonids will be patiently looked for and
successfully witnessed. w_ p- DENNING.

CURVED PHOTOGRAPHIC PLATES.

Bv F. A. BELLA^fY. Hon. M.A. COxon.). F.R.A.S.

A SHORT note on this subject may be of interest.
From the earhest days in photographic astronomy
one of the difficulties to be met and overcome was

Two exposures were made on the same plate, the left hand one with the
plate curved, the other with it flat.

the curvature of the field, or the rapid falling off in
the definition or good focus in the images of the
stars away from the centre of the photographic plate.
It is obviously of the greatest importance,
for accuracy and utility, for uniformh-
good quality definition to be obtained over
as large an area on the plate as possible.

To an astronomer the reduction of the
aperture of the photographic lens is not
permissible, or, at least, usually yer\'
inadvisable for stellar \vork, as the
maximum aperture is required in order
to reduce the time of exposure as much
as possible.

Though curved plates have i
been suggested and used with
overcome the want of good focus be}ond
a very limited area, they have never
found favour with astronomers, for various
reasons, among these being the difficult\'
of making them uniformly suit the area
of good focus simultaneously at the
centre and edges, the great cost of
making satisfactory plates (uniformh-
coating them), greater risk of breakage,
difficulty of measurement, storage, and so on.
When the first Conference in connection with
the Astrographic Survey was held in Paris, in 18S7,

one of the subjects proposed and discussed was
the use of curved plates for the Survey : the plan
was rejected as not feasible. In twent\-three years
knowledge has advanced, and the utilization
of methods and appliances — common in
other branches of science — has greatly
increased ; so that what was impossible or
inconvenient years ago is now rendered
more convenient and available for use.

The suggestion to use curved plates
has been brought up again. This time,
from a personal acquaintance with the
\\orker and his excellent work, we may
say that there is a much greater chance
of the method being tried under every
condition that promises success, which,
we hope, will ultimately be achieved b\-
Dr. J. H. Metcalf.

The lens he is using is a Petzval

Doublet, and the focal length is seven

times the aperture and gives a scale of

picture of 90" to 1""". WJth this lens he

has found by re-focussing for various

parts of the plate that all parts of a

10-in.x8-in. plate, equal to an area of 5

degrees square, can be brought into good

focus and excellent star images obtained. As the

lens can do so much by merelv altering the focus

gradually bet\\een the centre and edges, the extreme

n the past
a view to

Figure 2. The Edge of the Plate.
Here there were two exposures as in Figure 1.

amount to be allowed for in changing the focus for
these two positions is only three one-hundredths of
an inch (0"8""") ; it seems quite possible to bend a

441

442

KNOWLEDGE.

November, 1910.

plate tcmporarih- by tliat amount witlKuit fracture.

\'arious methods \\ere tried to protliiee the
required amount of hendin;; artificially : of these
the most successful, as one might expect, is that
produced by atmospheric pressure on the outer
and film side surface of the plate, caused hv
exhaustion of the air in a closed chamber at the
back of the plate.

From a trial made with the 16-inch Metcalf
Telescope in 1910, June 29th, ocular e\'idence can be
obtained hv the examination of the two sets of star
images shown on the accompanying illustrations. The
region is that surrounding R.A. 19''' 0'" and + 5° and
is enlarged nine times from the origin plate, so that
10" equal 1""". In obtaining these two exposures
the first and left hand image was taken with the
plate temporarily curved and the second image shows
the same star with the plate flat : each exposure was
of ten minutes duration. In Figure 1 the centre of
the plate is substantially in the same focus, the flat
plate image being slighth' the better one of the two.
When the outer parts of the same plate are compared
a marked improvement becomes obvious with the
curved plate images, the bright stars showing less
diffusion and naturalh- smaller images, there being
less scattering of light : and the faint stars — the
stars" light being more compact and in focus — are

distincth' improved ; almost invisible and diffused
images become quite \-isible and better formed.

Further plates have since been taken with that
instrument to test the effect on the determination of
magnitude and position. From an examination of
sixty-one stars, fainter than the 10th magnitude, it
was found that the flat plate lost 0"17 magnitude at
1 '5 from the centre : in the curved plate the brightness
increased by 0'06 magnitude : no s\'stematic error
was detected.

The effect on the actual positions of the stars has
not yet been determined : this requires careful and
accurate measurement of a number of plates,
preferably of the same area.

For the convenience of use, storage, and measure-
ment, it w ill be a distinct gain to be able to have the
plates flat rather than have to deal with plates with
a permanent curvature. When the temporarily
curved plates are measured there are obvious
advantages in having them flat in the measuring
instrument.

The plate reproduced here is from the Harvard
Circular, No. 161.

Knowing Dr. Metcalfs skill in practical photo-
graphic astronom\- and his power to overcome
difficulties, we miw expect still better results from
his instruments.

CORRESPONDENCE.

.SPECTROSCOPIC DOLiBLE STARS.

To tlie luiitiirs of" Kxowi.EnGE."

Sirs, — Sir Robert Ball's work, " In the Hi-li Heavens," has
a chapter entitled " The New .Astronomy," in which the anthor
discnsses, with all his admirable clearness of exposition, the
modern methods of determining the motions and masses of
Double Stars by means of the Spectroscope. In illnstiation
of this subject he takes the well-known star Mizar, the
principal component of which was discovered by Professor
Pickering to be a Spectroscopic Double, " a discovery," says
Sir Robert Ball, " which will take its place in the history of
astronomy as the inauguration of a new process in the .study
of things sidereal."

It will be needless to give the readers of " Knowledge " a
detailed account of the method by which the examination of
the spectrum of a Double Star is held to atloril iis infonnation
as to the velocity, period of revolution, nuitnal distance, and
masses of its components. Sir Robert l!all iNplains the
whole process in his charmingly lucid manner, and the
argument would be absolutely convincing were it not for one
most important assumption which seems to be scarceh-
justified. This is that the earth's line of sight lies in the plane
of revolution of the Double Star, or, in other words, that we are
observing the orbit of the Double Star "edgeways."

The whole reasoning is based on the velocities of the
components as revealed by the spectroscope. But the spectro-
scope can only reveal to us velocities in thr line nf sight, .and

as the orbits of Double Stars ma\- lii- in .ill possible planes, it
is surely an unwarrantable assumption that the velocities
deduced from the spectrum are the true velocities of the
components. If, for instance, the earth's line of sight
happened to be inclined at an angle of sixty degrees to the
plane of the Double Star's orbit the velocities of the
components, as deduced from the spectrum, would be only
half their real velocities, and the whole argument as to the
masses and distances of the components would be \itiated.

There seems to be one, and only one, condition under which
the spectrum may be depended on to give us the true velocities
of the components of a Double, and that is the condition that
the Double is at the same time a Variable. For if we may
assume that v.iriabilitx- is due to periodic eclipse of each
component by the other, it follows that in the case of a
variable star oiu' line of sight lies in or near the plane of its
orbit of revolution.

But no stich condition is nicnlioned in any discussion of the
subject which has come under my notice, and my object in
writing this is to inquire whether any of your astronomical
correspondents can explain what I in the absence of the
condition just stated) seems to me an insuperable difficulty in
the theorj' of Spectroscopic Doubles.

Yours faithfulK'.

A. E. MADDOCK.

Banparawela,
Ceyi.on.

November, 1910.

KNOWLEDGE.

443

This is due to several causes.
2nt!. the method of illuminating;

1-

PODUKA SCALES.
To the Editors of " Knowledge."

Sirs, — From the ver\able article upon the Podura Scale by
Mr. T. L. Smith in your
September issue, arises
Phoenix-like that very old
standing enigma to micro-
scopists,'"What is its actual
structure and wherein lie
the difficulties of observa-
tion, seeing that the object
is coniparati\ely large ? '"

When we consider the
instruments in use upon
this scale as far back as
1827. the year about which
it loomed forth as a "test,"
and the very much ini-
pro\ed optical appliances
of the present day. it would
seem that its accurate
delineation has not ad-
vanced in progressive ratio.
1st, the method of mounting:
3rd. the extreme fineness of
the scales usually selected;
4th, the necessity for
correct adjustment in tube
length for cover thick-
ness ; and 5th, the scarcity
of fresh scales.

With regard to the
mounting, as the refrac-
tive index of the scale
itself is high. To at least,
to momit it in Balsam
is to practically obliterate
it, while Realgar or
other high refractive

mountants do not appear to have been used with success,
so that we are left with the only alternative in contrast
between the normal of air and the scale
itself ; here, then, we make no advance upon
the ver\- earliest methods. True, we augment
ver>- much our view by placing the scale flat
upon the under side of cover glass, leaving a
small margin for air between it and the slip,
but therein lies the difficulty. As the object
is not perfectly even, it is almost impossible
to obtain optical contact aU over, so that
where the scale leaves the coverglass ever
so slightl_\' we get a distorted appearance, and
some of the views thus obtained account in
no small degree for conclusions as to new
structure being obser\ ed.

As to the manner of illuminating, it is usual
nowadays to holdfast to the so-called "Critical
Method," which means practically placing the
scale in the midst of your illuminant and
viewing both focussed in the same plane, at
the same time having them centred axially.
When this is done with the Podura there is
insufficient contrast to bring out several of the
finer phases of detail. It is much the same as
if one placed a piece of plain glass in the
midst of a lamp flame and were asked to
observe its une%en surfaces, or to direct your
telescope boldly towards the full moon and
expect to trace its finest details. There are
many microscopists of the present day who
do not find in the practice of this '' Critical
Method," that which theor>- would have them
believe as ipso facto.

I suggest therefore the use of oblique light
in this instance, and the photographs here reproduced have
been taken more or less in this wav.

Figure 1,

FiGf

Podura

-Again, the exceptionally fine scales generally experimented
with. I belie\e those usually procurable are taken from near
the head of the insect, but it is possible to obtain others much

more decidedly marked
along the side and dorsal
portions. It has also been
suggested that one might
rear a few Podurae using
some innocuous aniline
stain along with their food,
such as Medical Methylene
Blue, with a view to obtain-
ing— possibly — through an
absorption of colour, a
scale showing greater
contrast. To this, how-
ever, I can only say my
own effVjrts have been
entirely abortive.

I have found that small
well-defined scales gave
me the best results, whilst
some of the larger variety were so exceedingly fine in their
longitudinal as well as transverse markings as to appear mere

shadows of themselves,

Fourthly.it is ver\essen-
tial to haveawell-corrected
objective, both chromati-
cally and spherically, and
to carefully adjust the tube
length for thickness of
cover in use,

.And lastly, the dearth
of fresh scales, A veiy-
eminent microscopist wrote
recentlythat Podura scales
were " scarcer than dia-
;. _. monds," and it would seem

there is much truth in that
remark at the present time; yet we are told the insects abound
plentifuUv, that some species are quite common about the
houses and .gardens, in damp cellars or vaults,
or again to be found among the dr\' refuse and
corners of outhouses, potting sheds, and the like.
If some expert entomologist would come to
the rescue and place a number of fresh scales
upon the market worthy of careful obser\a-
tion, he would not only relieve a much felt
want, but at the same time give a much needed
impetus to the improvement of condensers and
their proper usage for high-angled apochromats ;
both as regards their aplanatism and the
aperture suitable with particular objects,

A word or two with regard to the photographs.
In Figures 1 and 2, it will be seen that apart
from the usual exclamation marks, there are
long sinuous lines from root to tip, while in
Figure 3 can be readily observed similar lines
transversely.

If the exclamation marks be simply wedge
shaped pouches with an oily secretion within,
these longitudinal lines appear to run over the
outer edges of the wedge and again to dip under
beneath the preceding one, interlacing with
the transverse lines and forming an elastic
but strengthening structure to the whole scale.
It is noteworthy that either side has always
presented the same appearance to me. so much
so that I am unable to recognize any top or
bottom as distinct from one another. The piu"-
pose of these markings can only be conjecturalat
present ; it may be they are the edges of a flat-
tened cellular structure.thoughthiscan hardly ac-
count for the transverse ones.or simply a finenet-
work of tubes for the purpose ofconveving some form of nutrition,

F, J, W, PLASKITT,

■144

KNOWLEDGE.

November, 1910.

THE ASTROGKAPHIC SURVEY.
To the Editors of '" Knowi.ei.ige."

Sirs, — A sentence on p. J99, referring to this work, is
liable to misinterpretation. A share of one thousand one
hundred and eighty plates, equal to more than one-twentieth,
in this International Survey was undertal;en at the University
Observatory at O.xford. The worl< was commenced and
the first plates were talcen in 1892, and it was then under-
stood that twenty-five years would be required to complete
it. All tlie plates were talcen, completely measured, reductions
made, and the measures of about four hundred thousand star
places were copied for printing by 1904, February 17th; this
would have been accomplished from one to two years earlier but
for interruptions and loss of time due to a new dome being
built, during which no progress could be made with the
telescopic work ; to the planet Eros work ; and to a struggle of
some months with bad emulsion on the plates. Looking up
the Greenwich Observatory reports, I find that in l')0(),
February, their share of the survey, one thousand one hundred
and forty-nine plates, was still unaccomplished : at the present
moment none of the other sixteen observatories, with one or
two exceptions, are near the end of their shares; in some
cases the measurement of the plates has barely commenced,
and all the negatives required are not yet taken. The
University Observatory at Oxford liad thus comiileted its share
of the Catalogue two years or umii' befnre that at the Royal
Obser\'atory.

These remarks refer to the main portion of the schenie .lud
by far the most important. As to the supplementary portion,
repeating the work by exposures of forty minutes on separate
plates for the purpose of reproduction only as star-maps, it
became apparent soon after the commencement of the work
in 1S92 that it would be a waste of time, energy and money to
carry out this portion. The reasons for the decision not
to do the Chart portion at Oxford were the supercession, or
doubtful need, of the 1887 and 1889 programmes relating to
the Chart scheme, by the advent of the doublet form of photo-
graphic lenses of large dimensions (such as the Bruce lens at
the Areguipa Observatory, with which it is easy to photograph
about five-and-a-half plate areas on each 17X14 plate and
with less exposure to obtain the same limit of magnitude), so
that the whole of the Oxford area could be covered by less

than two hundred plates instead of one thousand one hundred
and eighty plates and with much less risk of having to reject
plates by reason of cloud interference ; another reason was the
impossibility of obtaining the /. 10,000 required to reproduce
and distribute tlie maps on the same luxuriant scale as those
published by aid of the French Government, and the inadvisa-
bility of spending such a sum ; and a third reason, which
I see is referred to by your correspondent on page 409,
may be considered as a strong point — the enlarged reproduc-
tion of the long-exposure chart plates. Had the prints
been kept to the same si^e or scale as the catalogue
plates, it would have been a very simple process to have
utilised the numerous measuring instruments already avail-
able for the measurement of positions if required ; that
this can be done with a considerable degree of accuracy
was pointed out in the Mo/if /i/j' A'of/ct's by Professor Turner
more than twelve years ago. Thus has the Oxford area for
long exposed plates been "in the field" since 1895 ; it is only
this portion of the survey which the Greenwich Observatory
has appropriated : that the short exposure plates are also to
be taken at this near epoch appears to me to be indicative of
waste and annoyance.

Notwithstanding all eftbrts to obtain the money, the printing
could not be commenced until 1906, so that no progress could
be made in this direction during the progress of the other
stages of the work. Since that date the amount printed has
been such that six volumes have been published and distributed,
and the seventh — the last of the catalogue — is almost
completed, the whole giving accurate measures of more than
four hundred and fifty thousand star positions contained,
besides other information, on two thousand three hundred
quarto pages. No assistance for the main share — the cata-
logue— has been given by the Royal Observatory to Oxford
as the words on page 399 would seem, to one unacquainted
with details of the scheme, to imply.

It should be added that Prof. E. C. Pickering's suggestion
in 1886 to use a large double lens for the Chart portion was
rejected by the Astrographic Congress at Paris — probably no
one except himself then realized its great advantage for such
work as charting the stars; by the generosity of Miss Bruce
he was able to accjuire such a telescope of 24-in aperture
in 1893.

F. A. BELLAMY.

L I T V. R A R \' NOTICES.

THh: CHARACTIIRISTICS OF FAMOUS Ml':\.— In a
work shortly to be published by Messrs. Rebnian — "' Makers
of Man": A Study of Human Initiative, by Charles J.
Whitby, M.I). — the problem of indi\'iduality is investigated by
means of an analytical study of forty world famous men.
The book is not a series of biographies — the lives are treated
collectively with a \iew to the attainment of general results.

LICHEN EXCHANGE CLUB.— The annual report shows
that this club is doing a considerable amount of useful work,
in the way of distributing specimens, on the part of eighteen
out of the twenty-nine members. The report quotes the
sx'stematic arrangement of the class of lichens which is used
in the recent memoir of the United States Herbarium. The
Secretary and Treasurer, Mr. A. R. Horwood, of Leicester
Corporation Museum, appeals for information with regard to
species which are likely to become exterminated.

THE BACILLUS OF LONG LIFE.— Messrs. T. C. and
E. C. Jack announce that they will pviblish in November,
under the above title, a manual of the soured milk industry, by
Loudon M. Douglas, F.R.S.E.

HOUSE FLIES AND PUBLIC HEALTH.— A valuable
leaflet has been issued on the dangers resulting from house
flies and the preventive methods to be employed. Copies may
be obtained free on forwarding a stamped addressed envelope
to Walter E. Collinge, 59, Newhall Street, Birmingh.im.

THE MICR(.)LOGIST. — The second part of a new
magazine called Tlie Micrologist has reached us. It is
published quarterly by Messrs. Flatters, Milborne and
McKechnie, Ltd,, at a price of eighteenpence. The paper
contains useful hints to the microscopist, and there is a very
good collotype plate of starch grains, Volvox, Hydra, and of
Polyzoa.

THE ISIKLIOGRAI'HY OF AERONAUTICS.—
Aeronautics has for years past been universally indebted to
the Smithsonian Institute of America for its research work in
this new science, and for the clear and concise manner in
which it has always published the results of its labours.

To-day, in The Bibliography of Aeronautics, we have
another work from the same source, compiled with similar
care, and « onderful completeness.

In this book we have a complete index to every article of
the least \ alue in any language which has been published, and
to find any such article we have merely to look under the
author's name, when the title of the paper or manuscript in
which it appears will be given.

As a test the writer looked up certain small articles, and in
every case found the proper references as above.

Everything is indexed under "Authors' Names"; may we
some day hope to see the sister volume, in which the articles
will be indexed under " Subject Matter" ?

THE FACE OF THE SKY FOR \0\-EMBER,

\V. SH.\CKLETOX, F.R..^.S.. .\.R.C.S.

The Scn. — On the 1st the Stin rises at 6.54 and set* at 4.33 :
on the 30th he rises at 7.43 and sets at 3.54. Sunspots and
faculae may usually be seen on the disc, but of late spots have
been small, although faculae have been fairly conspicuous.
The equation of time is a maximum on the 3rd, the Sun being
16°" 20^ in advance of the clock, thus making the afternoons
short and the mornings long. The positions of the Sun's axis,
centre of the disc, and heliographic longitude of the centre are
given in the following table : —

Date.

Axis inclined
from N. point.

Centre

N. of Sun'.s

Equator.

Heliographic
Longitude of
Centre of Disc. |

Nov. 2 ...

24° 3i'E

4° .1'

5° ,,'

,. 7 -

,. 12 ...

.. I? ...

23° 32'E

22° 23'E

21° I'E

3° 39'
? 3°'

299° It,'

233° 20'
167" 25'

,, 22 ...
,. 27 ...

Dec. 2 ...

Itf 29'E
17° 46'E

15° 53'E
■3° 5^'H

0° 38'
0" 0'

101° 31'

35° 37'
329° 43'
263° 50'

There is a partial eclipse of the Sun on November 2nd,
invisible in this country, but visible in Japan. Xorthern Pacific
and Alaska.

The Moon : —

1 Date.

Phase.s.

H.

M. 1

Nov. 2 ...

•

New Moon

I

56 a.m.

.. 10 ..

H

Eirst Quarler

5

29 a.m.

.. I-

0

Full Moon

0

25 a.m.

,. 23

■^

La.'^t Quarter ...

6

13 p.n..

\\v. I ..

•

New Moon

9

II p.m.

N-uv. 3 .

Apogee

6

12 p.m.

,. 17 ■

Perigee

14

48 a.m.

„ 30 •

-Apogee..

'

0 p m. 1

Eclipse of the Moon. — There will be a total eclipse of
the Moon on the 16th. visible in this country.

The details and times are as follows : —

First Contact with the Penum-
bra, Nov. 16th, q*" 46" p.m.

First Contact with the Shadow .
Nov. 16th, 10" 44" p.m.

Beginning of Totalitv, Nii\.
16th. 11'' 55"" p.m."

End of Totalitv. Nov. 17th.
12'' 47°' a.m'.

Last Contact with the Shadow .
Nov, 17th. l"" 5S" a.m.

Last Contact with the Penum-
bra, Nov. 17th. 2" 56°" a.m.

The Magnitude of the Eclipse =
1'131 (Moon's Diameter
= 1).

Diagram .-.howing lirst and last con-
tacts in tlic total Eclipse of the Moon,
Novcniljer i6th.

During totality observation should be made of the colours
of the moon's surface, and also of the varied luminosity of
different regions. The general appearance is that of a copper
coloured disc, but during the progress of the Eclipse changes
of tint may be discerned.

OCCULT.4TIONS. — The following are the principal occulta-
tions visible from Greenwich : —

Date

.Star's

Name.

5

Di.--

Reappearance.

Mean
Time.

.Angle
from N.
point.

.Mean
Time.

-4ngle_
from X.
point.

E. 1

Nov.

I I

_1 ,

' .Aqu.trn

50

p.m.

5 \

52'

l-.m.

6.:S

248°

II

~~ .Aquaiii

44

6.46

10°

7.36

2S6'

IJ

14 Cell

5-4

9-3'

344°

9-55

303°

14

^ Piscium
1'^ Ta.ni

50

9 43

--0

3/

10.51

234-

17

4-2

S.37

33

9. 28

282°

■7

V Tauri

5-4

917

s--

9-49

307--- 1

"'

iS

uS Tauri

5'4

7-23

115"

8.4

215"

The first cont.act with the shadow is at 94° from the North
point towards East and the last contact at 227\ as shown
below.

The PL-ANETS. — Mercury (Nov. 1st. K.A. \i^ 58*"; Dec.
S. 10° 50'. Dec. 1st. R.A. \1^ 11'": Dec. S. 24=52') is an
evening star in Scorpio at the end of the month, setting at
4.12 p.m. on the 27th. and is thus very unfa\()nrably placed
for observation.

The planet is in Superior Conjimction with the Snn on
the 12th.

Venus (Nov. 1st. R.A. 14" 1'": Dec. S. IT 5'. Dec. 1st.
R.A. 16" 32'"; Dec. S. 21" 48') is in Superior Conjunction
with the Sun on 26th. and hence is invisible throughout the
whole month, being In close proximity to the Sun.

Mars (Nov. 1st, R.A. 13" 40"": Dec. S. 9" 44'. Dec. Est,
R.A. 14" 58"": Dec. S. 16° 35') is situated in Virgo and rises
at 5.40 a.m. on the 15th. thus for all practical purposes the
planet is unobservable.

Jupiter (Nov. 1st, K,A. 13" 45™; Dec. S. 9 42'. Dec. 1st,
R.A. 14" 9"": Dec. S. 11° 52') is observable for a very short
time before sunrise towards the end of the month. The
planet rises at 4.45 a.m. on the 25th.

.Saturn (Nov. 1st. R.A. 2" 6"'; Dec. N. 9° 50'. Dec. 1st,
1" 58'": Dec. N. 9 11') is very favourably placed for
observation, being due South on the 1st at 11.24 p.m., and on
the 30th at 9.22 p.m. The telescopic view is splendid, as the
rings and belts are readily seen even when seeing is com-
paratively poor. In addition to the ring, the belts on the
disc and also some of the numerous satellites may be observed.
.A telescope of three inches aperture is sufficient to show the
four larger satellites, namely. Titan, Japetus, Rhea, and
Tethys. Titan is generally to be looked for at a considerable
distance from Saturn, not only to the sides, but also
apparently above and below the planet.

The di\ ision in the ring may be seen in a good telescope of
two inches aperture ; whilst the daik ring requires an aperture
of four inches, with good atmospheric conditions.

445

44fi

KNOWLEDGE.

November, 1910.

During the past month the seeing has been very fine, and
Saturn has been the admiration of man\' astronomers. se\eral
of whom say it has never been seen to such advantage.
Professor Barnard has discovered several new features of the
ring, and on Mount Wilson magnifying powers of six hundred
and more have been brought to bear on the planet, and still
retain excellent definition.

The apparent diameters of the outer major and minor axes
of the ring system are respective!},- 46" and 13". and we are
looking on the Southern surface at an angle of 16°. so that the
ring appears open. The diameter of the ball is 18". The
ring is visible with a power of about 50. and the belts « ith .i
power of (SO. The moon appears near the planet on the 15th.

Uranus (Nov. 15th. K.A. 1')" Jfi'" ; Dec. S. 22° 7') is
unfavourably placed for observation on account of his low
altitude. The planet is situated in Sagittarius, in a p.ut of
the sky devoid of good reference stars, though the 4tli magni-
tude star /; Sagittarii is about 2 to the South.

The planet sets at 8 p.m. on the 15th.

Neptune (Nov. 15th, R.A. 7'' 2,2'" : Dec. N. 21" 6') rises
about 7.55 p.m., and crosses the meridian at J. 55 a.m. on the
15th. The planet is situated about four degrees SouthT-'ast
of the star S Gcminoruni.

Meteors. — The principal meteor showers during the month
are the Leonids and .Andromedids : —

Radianl.

Dale.

K.A.

Dec.

h. 111.

N.

V. 14-ifa .

10 0

+ 22°

Swift, stieak*;.

[Gjeal LcVi 2 d show ev).

\'erv slow, trains.

, 17-23 ..

I 40

+43°

(Greai Andiomedid shower:.

1

Algol will be at luinimuin on the Jnd at y.3S p.m.. 5th at
6.27 p.m.. 25th at S.'i p.m.. and 2,sth at 4.5.S p.m. The period
is 2'' 20'' 49'" from which other miniuia ma\' be deduced.

Telescopic ( )hji-;cts : —

Double St.\rs. — v Cassiopeiae O'' 43'", N. 57° 17'. m.ags.
3t. 7i ; separation 6".2. Binary star.

\ Arietis l'' 52". N. 25° 6', mags. 4. S ; separation 37".
Components white and blue; easy with power 20.

V Persei 2'' 44"'. N. 55° 2«'. mags. 4. S: separation 2,S".
The brighter component is orange, the other blue. There are
also se\eral other fainter stars verv near.

( ; 1 0 Y A N \ I .S CI I I A 1' A R !{ L L I

(Born March, 1S35. Died Jlr^. I'ikil
Bv W . .\L1"RED PARK.

Though Astronomy has had to mourn of late the death of
many a faithful worker, the name of Gio\anni Schiaparelli
amongst them brings home the fact that in him has passed
away not only the greatest astronomer of Italy, but one of the
greatest astronomers of our times. Great as an observer, he
was equally great as a philosophic interpreter of what he saw,
for throughout his long life the attainment of scientific truth
was ever his highest ideal. E\en at a time when his name
became closely associated with one of the most extraordinary
telescopic discoveries ever made, he carefully abstained from
offering speculative explanations, or entering upon controversies
in connection with the novel facts he was the first to present
to the scientific world, for with the discovery in 1877 of the
now famous Martian "Canals," Schiaparelli certainly opened
a new era in observational astronomy. To the popular mind
this is perhaps his best known achievement, and by a curious
irony of fate the non-committal name of canali, or " channels,"
which, with his characteristic scientific reserve, he gave to
these interesting phenomena, was at once seized upon by an
imaginative public to supply the ruddy planet with a complete
set of waterways, dug by a longsuffering and famine-stricken
populace. The brand-new nomenclature, drawn from ancient
classical geography, with which Schiaparelli baptized the
Martian markings, was perhaps the only unpopular item in
this memorable discovery.

.A discovery of far greater scientific import was Schiaparelli's
announcement of the close connection existing between comets
and meteors, a profoundly philosophic piece of work which
secured for its author the " Lalande " Prize, and which vastlv
extended our knowledge of the constitution of the universe.
Scarcely less important has been his work on double-stars,
and the rotation-period of Mercury and Venus, while his
learned excursions into the domain of ancient astronomical
history proved his classical and literary erudition to be on an
e(|ual footing with his purely scientific attainments.

Schiaparelli's student-years were passed at the University
of Turin, where he graduated as a civil engineer, but he soon
obtained the means to dedicate himself entirely to the .study of
astronomy. Through the influence of a friend some years
were accordiiiglj- spent at the obscr\atories of Heilin and

Pulkowa. where he studied under Enckeand W. Struve I'espec-
tively, and on returning to Italy the young student found
himself, at the early age of twenty-five, elected to the post of
second astronomer at the celebrated obser\atory of the Brera,
at Milan : on the death of the director of which, (jarlini, in 1862,
only two years afterwards, he succeeded to the directorship.
This famous institution had been founded as early as 1764 by
Boscovich, and was in a somewhat neglected state when
Schiaparelli took over the leadership. His own indefatigable
actixity, however, both in the astronomical as well as
geodetical departments, and the new nineteen inch Merz
refractor, for the installation of which in 1886 the Italian
Government voted the sum of two hundred and fifty thousand
lire, soon restored to the Observatory its former illustrious
name — a name still ably upheld by Schiaparelli's successor,
Giovanni Celoria.

Since his resignation on account of failing eyesight, some
ten years ago, Schiaparelli, though honorary member of over
forty European learned societies, had chosen to lead a com"
paratively retired life. Nevertheless, despite his dislike of
publicity, he was ever ready to come forward in the cause of
scientific truth, and almost his last utterance was contained in
a newspaper article which appeared only a few months ago, in
the Corrierc del I a Sera, calmly setting forth the ascertained
facts in connection with Halley's Comet, by way of protest
a.gainst the absurdly fantastic and sensational accounts with
which the Italian press was deluged at the time of the comet's
near approach to our earth. Throughout a busy life he found
time to carry on a voluminous correspondence with most of
the great intellects of his time, and it is interesting in this
respect to note that Herbert Spencer frequently had occasion
thus to consult him on the various mathematical details
occurring throughout the Synthetic Philosophy.

Personal!},'. Schiaparelli added to a grave and dignified
bearing extreme courtesy of manner, and the writer of this
sketch retains the pleasantest remembrance of an interview
enjoyed several years ago, when passing through Milan, and
the exquisite kindness with which the great Italian astronomer
conducted him, though an entire stranger, over the Brera
( )bser\atorv.

NOTES.

ASTRONOMY.

By G. F. Chambers. J. P., F.R..A.S.

AN .ASTRONOMICAL PILGRIM.AGE.— ruder the above
title Tlic Times has published an interesting narrative of a
trip by some unnamed correspondent to the Mount Wilson
Observatory in California. -At a Conference of .Astronomers
there, papers were read on various subjects, one of which
concerned a possible Trans- Neptunian Planet. Respect-
ing this we make the following e.xtract ; — '" .Another
paper worthy of mention dealt with a possibilit\' onl\-. but a
possibility so majestic that its realisation would startle the
world. Since the discovery of the outermost planet Neptune,
there have been several attempts to infer the existence of
another planet further out still. Such attempts have been
based on one or other of two indications, one cometary,
the other planetarj'. From the fact that several comets
are related to the same direction of approach to us, it has
been thought that there may be an unknown body in that
direction. The planetary indications are based on the distur-
bance of other planets, similar to that of Uranus by Neptune,
which led to the discovery of the latter. No success has
hitherto attended any search based on either kind of evidence.
But now Professor W. H. Pickering thinks that he has a com-
bination of both clues: he infers that there is a planet of great
size, and at the same time of such great distance from the sun
as to be very faint and difficult to find, which would not only
account for several comets, but also for a peculiar disturbance
of Neptune, observed, but not hitherto e.xplained. The start-
ling novelty of his suggestion lies in the direction in which
this planet must be looked for. He thinks it is in a direction
nearly perpendicular to the ecliptic 1 Now all the other
planets and most of their satellites revolve in orbits nearly
coinciding with the ecliptic ; and no one has hitherto regarded
a planetary orbit almost at right angles to this general plane
as even a possibility. But Professor \V. H. Pickering has
already upset one preconception with regard to the solar
system. He found a ninth satellite of Saturn which was
going round the wrong way — in the direction opposite to that
of the other eight of Saturn, the known five of Jupiter, the
two of Mars, and the Earth's one Moon. Since then his
example has stimulated the discovery of three more satellites
of Jupiter, one of which also goes the wrong way round ; and
it has been shown that the apparent anomaly can be explained
by tidal action."

THF: (iERM.AN .ASTRONOMICAL SOCIETY.— This
Society, which has done such excellent work in the publication
of many meridian Star Catalogues, held its twenty-third
ordinary assembly, or meeting, at Breslau this year.

Unlike the Astronomical Society in this country, the German
Society does not hold regular monthly meetings at a fixed place,
but about once in two years, for three or four davs, at a place
selected by vote from time to time. Its constitution does not
apparently limit the place of meeting to Germany. As it
affords a good opportunity for its distant members to meet,
discuss suitable subjects, see other observatories, and make
friends, it would be a pleasant thing if an invitation could be
offered for the Society to meet one year in this country, when
many of us who do not travel abroad could make friends with
our fellow- workers.

The meeting opened on September 13th, at the suitable
hour of 10.15 a.m.. in the Music Hall of the University, when
a hearty welcome was given by several high officials of the
University and State.

The Secretary, Professor von Seeliger, gave a report upon
the work achieved during the last two years, and, before doing
this, expressed regret that the meeting clashed with the Solar
Physics Conference at Pasadena, where Backlund, Lehmann-
Filhes and Duner were. He said that in 1909, January, the
number of members was three hundred and eightv-three :

eighteen members were lost by death and removal, and as
thirty-four members had been elected, and four names were
then proposed, the total was four hundred and three ; the most
prominent losses by death were the veterans, Newcomb, Galle.
and Schiaparelli.

The Lindemann Prise was awarded to Cowell and Crommelin
for their work on Halley's Comet, and two ordinary prizes to
Krause and Hnatek for their researches upon the Comets
of 1846 vii and 1(S52 iv : the former essay has been printed by
the Society and forms No. xxiii of the series.

The parts of the Vierfeljalirssclirift have appeared
regularly and. at last, the second part of the first series of the
Astrononi ische GescUschaft Zone-Catalognes, for zone + 70
to + 75°, has been published. The observatory to which this
zone was allotted having failed to do the work, the lacuna was
filled in by the Berlin Observatory a few years ago, this being
the third portion of the Society's scheme of 1868 that has
been accomplished at Berlin : that scheme has thus taken
forty-two years to complete. It is now proposed to re-observe
these northern zones ! Cui bono ?

Of the second or southern series, which was only com-
menced a few years ago, all the catalogues are published
except those tor Harvard (No. 3) and .Algiers (No. 51. The
manuscript is being prepared for the former, and it is expected
that the .Algiers zone may be completely observed in 191 Land
the whole of the second series, it is hoped, will be published
N\ithin two years.

The meeting agreed to 1.000 marks being spent in the
preparation of the Variable Star Catalogue and to 10.000
marks for printing the work. We heartily commend the
appropriation of this and similar Societies funds to such good
works, instead of the accumulation of funds derived from
profits on annual income, without any iiKirr definite object
than mere hoarding.

The delay of the publication to July, 1910, of that very
valuable annual handbook to astronomical work for 1909
the Asfrononiischcn Jalircsbcricht was due to the non-arrival
of the foreign contributions. We nmch regret that Herr
Berberich was compelled, by the state of his health, to
withdraw from the enterprise. The committee of the Society
have made great eft'orts to ensure the continuance of
this very useful annual, which is of importance, and has
become indispensable to astronomical writers in all parts of
the world, and it is very gratifying to learn that their efforts
have been crowned with success and that the preparation and
publication will in the future be carried on at the
Recheninstitut in Berlin ; Dr. Naumann, the Ministerial
Director, promising to procure the necessary means. With
this annual available there is no need for the more expensive
and less efficient similar annual as conducted by the Royal
Society.

Dr. Kobold read a report upon recent Comets and Cometary
Work : and Dr. Bruns read the treasurer's report.

Upon the proposals before the meeting, the Chairman was
of opinion that the next meeting should be in 1913, as that
year would be the fiftieth year of the Society's existence. .An
invitation had been received from Backlund to meet in 1912 or
1913 at Pulkowa. Battermann gave an invitation for the
Society to meet at Ktinigsberg in 1913, as that year was also
the hundredth anniversary of the foundation of that
Observatory ; also Schorr invited the Society to meet at
Hamburg in 1913. -At the third meeting this was discussed;
the year and place were left for future decision by the members
and committee.

The members were invited to visit the seismological station
at Krietern near Breslau.

Dr. Bruns. after lunch, introduced a discussion upon the
" going " of pocket watches, and the compensation for the
barometric influence ; and Dr. Prey brought forward a point
concerning the correction of an astrographic lens.

F.
I To be conti)iiicclJ

447

448

KNOWLEDGE.

November, 1910.

BOTANY.

Bj' Professor F. Ca\'ers, D.Sc. F.L.S.

AMMONIUM SALTS AND PLANT NUTRITION.—
.According to Prianischnikow (Ber. dcidsch. bot. Gcs., 1909),
the partial substitution of sodium nitrate by ammonium
sulphate in cultures increases the power of the plant to gain
phosphoric acid from raw phosphates. In the absence of
annnonium sulphate the plants (grasses were used in the
experiments) show phosphoric acid starvation, while total
substitution greatly reduces the harvest, and the best results
are obtained by replacing about one-half of the sodium nitrate
by ammonium sulphate. These effects are attributed to the
liberated sulphuric acid ; in partial substitution, the acid was
strong enough to aid in dissolving the raw phosphate, while in
total substitution it was so strong as to injure the plants
seriously. The consumption of phosphate was favoured, and
injury by ammonium sulphate pre%'ented, by adding carbonate
of lime. With barley, peas, and buckwheat, the author claims
that mixtures of sodium nitrate and ammonium sulphate are
better sources of nitrogen than either one alone, because the
former is physiologically basic and the latter physiologically
acid ; fhi' two together keep the culture mcdiiun neutral.

THE HYDROGEN BAG TERI A. — Winogradski's
researches established the existence of non-chlorophyllous
plants that make their organic food by energy obtained from
the oxidation of various simple inorganic substances. Lebedeft
{Bcr. (h'litsch. bot. Ges., 19101 has made an extensive study
of the hydrogen bacteria, which oxidise hydrogen as the source
of energy for the assimilation of carbon dioxide. These
bacteria, it appears, are capable of using organic food as well,
and they are therefore distinguished from the nitrite, nitrate
and sulphur bacteria. The fixing of any given volume of
carbon dioxide requires the oxidation of from five to fifteen
volumes of hydrogen. The oxygen required for the process is
best obtained from .atmospheric oxygen, but in absence of it,
nitrates can be decomposed as the source of oxygen. 1 he
oxidation of hydrogen still continues in the presence of organic
food, l)ut no carbon dioxide is fixed in that case.

SOME RECENT WORK ON SELAGINIXLA.— A very
small xerophytic species of SclagiiicUa — -S. prcissiaiia — has
been described by Bruchmann [Flora. 19101. In this curious
little plant, which grows in West Australia, Victoria, and
Tasmania, the cotyledons are larger than the foliage-leaves ;
the first branching of the young plant gives off an erect shoot
a little over an inch high, the other branch becoming the
creeping rhizome, which then gives off erect branches right
and left. The stem is protostelic ; in the young stem
(hypocotyl) there is a single exarch protoxylem, hence the
structure is very simple. The roots have no root-hairs, but
are infested by an endophytic fungus; the hyphae wcmc
observed penetrating the epidermis from the soil.

Miss Mitchell (.4)(/;. Bot.. 19101 has recorded \'arious
observations on the cone of Selagiiiclla. The axis may
renew its ordinary vegetative growth beyond the sporangia ; a
second cone may be produced on such an axis, the two cones,
or fertile regions, being separated by a sterile region ; the
cone may undergo branching. The distribution of sporangia
is variable, and in different species we may get ( 1 ) one large
basal megasporangium, (2) several basal megasporangia.
succeeded by niicrosporangia. 13) cones with numerous
microsporangia only. (4) cones with numerous megasporangia
only. (51 an indeterminate arrangement. Then, there are
species with one, two, or three megaspores in each megaspor-
angium, instead of the usual four ; also, two rare cases in
which there are eight (S. iiivolvens), and twelve (S. vogelii)
megaspores.

Our knowledge of SclaiJiiiclla. familiar to students and
teachers as a botanical " type," has been greatly extended
during the last few years, especially by the remarkable
observations of Lyon, who showed that in some species the
megaspore germinates, producing the prothallus and
archegonia, in situ in the sporangium, which opens and lets in
the antliero^oids, so that we get practically a seed formed.

Lyon showed also that in some species the embryo is formed
directly from the fertilised egg cell, without the development
of a suspensor.

ACTION OF MANGANESE ON PLANTS.— One of the
very few definite examples, so far discovered, of localised
action produced by absorption of a specific chemical element
by a plant, has recently been noted by Molisch iSitz. kiiis.
Ak. Wiss., Vienna). It was found that the introduction of
manganese salts into water containing submerged aquatics —
Elodea. VaUisiteria. Water Milfoil, Water Crowfoot —
produced, after exposure to light for a few days, a deposit of
brown substance in the walls of the epidermis cells, which
soon increased so much as to mask the green colour of the
leaves.

SOME RECENT W( )KK ON FOSSIL GVMNOSPERMS.
— Bit bv bit, our knowledge of the lower seed-plants is
increasing, and the gaps between already known forms are
being gradually filled up.

Scott and Maslen (Ann. Hot., 1910) have described a new
genus (Mesoxylon) of Cordaitales, from the Lower Coal-
Measures of Lancashire. This genus is intermediate between
Cordiates and Poro.xylon, resembling the former in general
anatoms' — especially in the large pith — and the latter in
having centripetal xylem. The wood is dense, with narrow
ravs and small tracheids. It is regarded as completely
bridging the gap, so far as anatomy is concerned, between the
Poroxyleae and the Cordaiteae.

Nathorst (Handl. K. Sv. Vet. AI;.. 1910) has described
the reproductive structures of several Bennettitales. He found
both microsporangia (with spores) and seeds in three species
of Williain.'ionia. from the Jurassic of Whitby and Scar-
borough. In a new genus, Wielandiella. a remarkable
vegetati\e structure is described — the stem, which is very
slender, branches freely in an apparently dichotomous manner ;
in the cones, which occur in the forkings, there are remains of
both pollen and seeds, k third genus, Cycadocephalus. has
pollen-grains with remarkably close resemblance to fern spores.
Nathorst also describes two cones from the Rhaetic of Sweden,
in which the seeds apparently had an aril like that of the Yew.
In Palissya, the ovuliferous cone scales bear two rows of
seeds : while Stachyta.xus has Yew-hke foliage, and attached
to the ends of the twigs are loose cones with distant scales,
each of w-hich bears two ovules.

Gothien iHandl. K. Sv. Vet. Ak.). describes \arious t\pes
of fossil wood from the Jurassic of King Karl's Land. In
Cedroxylon transiens. the wood shows the fitting character-
istic of Araucarineae. together with the ray structure of
Abietineae.

Of greater general interest are the remarkable results
obtained by Hollick and Jeffrey [Mem. 'New York Bot.
Garden. 1909), from a study of the plant remains in Cretaceous
clays of Staten Island. The Conifers include three genera of
Abietineae [Pinns, Prepinus, Pityoxylon), of which the
species of Pinns are more archaic than any living species,
while Prepinus is still more primitive. The most important
result, however, is the discovery of no less than sixteen genera
of Araucarineae, of which nine are new. These Araucarians
include tvpes which had previously been referred to other
families of Coniferae (Taxodineae, Cupressineae, and so on).
from the general appearance of their leafy twigs. The authors
believe that the Araucarians of to-day have come from
.•\bietineous ancestors, through a group represented by those
Cretaceous Conifers which connect .Araucarineae with
.Abietineae. Thev also bring forward e\idence for the great
age of the pine-like Abietineae, and urge that the Conifers
have, Uke the Horsetails and Clubmosses, undergone extensive
reduction, those now living representing the degenerate
survivors of a once great race.

That the Araucarians are very sharply distinguished from
all the other Conifers is further emphasized by the results
obtained by various workers on living types. It would seem,
in fact, that great modifications will have to be made in the
views that have generally been accepted as to the inter-
relationships of the Conifer group, which apparently forms a

November. 1910.

KNOWLEDGE.

449

puzzling maze of cross-affinities. The conflicting lines of
resemblance among Conifers probably point to a more ancient
lineage for all the families than has hitherto been realised.

TRYPANOSOME-LIKE P.4R.A.SITES IX PL.\XTS.—
It has recently been discovered that parasitic flagellates,
resembling the trypanosomes which occur so widely in animals,
and which cause malaria and other diseases in man, are found
also in plants. The presence of a trypanosome-like parasite
in plants was first made known by Lafont (Coinptes rendus,
1909-1910), who found these organisms in the milky juice
(latex) of a spurge (Euphorbia) from Mauritius. The
discovery has been confirmed by Donovan iLancct, 1909) in
the same species of spurge, growing in Madras, and in his
second paper Lafont gives a full account of the organism,
which he has now found in three species of EiipJtorbia. The
infected plants show marked signs of malnutrition, and finally
drop their leaves and die. Lafont found that injection of the
parasites into the blood of small animals produced no infection,
though some of the animals died " from unknown causes."
The further development of this remarkable addition to our
knowledge of plant diseases will be awaited with great interest.

THE WOODL.AXDS OE EXGLAND.— An ecological
memoir of great interest has recently appeared in the Xeic-
Pliytologist under this title. It represents the first satisfactory
attempt to give a bird's-eye view of English Woodlands as a
whole, and is based on a paper read by Tansley at the Dublin
meeting of the British Association in 1908. The authors
(Tansley. Moss, and Rankin), after discussing the general
characters of British Woodlands, the relations of climate and
soil, and so on. proceed to the classification of the Woodlands,
of which they recognise three main series : —

I. The Alder-Willow Series. This is a lowland type
occurring on very wet soils, and is characteristic of low-lying
alluvial districts, as along the banks of the slow streams of the
New Eorest, the remoter valleys and lowland peat-moors of
the North of England, and in the fens of Norfolk. The woods
of this series at present existing probably represent merely
fragments of a once e.\tensi\'e development, by now greatly
reduced in consequence of drainage and culti\ation. At least
two plant associations occur in it, e.g.. the Carrs of Xorfolk.
fed by alkaline and calcareous waters, harbour several woody
species characteristic of chalky and limestone soils, such as
Rhaiiiiiiis catharticiis and Vibitnitiin Laiitatin. while in
the Alder- Willow thickets occurring on soils fed with neutral or
acidic waters, calcicole species are absent. From this lowland
type two great systems occur, the distribution of which follows,
in the main, two chief classes of soil, siliceous and calcareous.

II. Oak and Birch Series. The woods in this series occur
on all the "siliceous" (/.c, non-calcareousi soils, ranging from
the stiffest clays to sand and gra\el, and deri\ed from rocks of
various ages. Within this series three associations occur, but
more or less merging into one another. 1.4) An Oakwood
Association, by far the most widely distributed of
British W'oodlands. The dominant tree is Uiierciis robitr
(^O. pcdnnculata\. Owing to the great variety of soils on
which the oak is dominant, the associated trees and especially
the ground vegetation, show a wide range, and two groups of
associations are distinguished — (a) Damp Oakicoods on clays
and loams of the London Clay, the Gault. the Weald Clay,
and so on. in the south of England : these are connected by
every gradation with (6 1 the Dry Oakic-oods.ioimdon coarsely-
grained, siliceous, shallow soils of the Palaeozoic and igneous
rocks of the west and north of England. In these woods
Q. sessiliflora is usually dominant, but with a varying
.admixture of O. robtir. iB) The Oakbirch-hcath association
is a type characterised by the presence in the ground vegeta-
tion of bilberry, hair grass and ling. Such woods cover wide
areas in Kent, Surrey, Sussex, and locally as far north as
Cheshire and Xottingham. This wood is probably a stage in
the degeneration of oak forest to heath land, similar to that
described by Graebner in the great heaths of the north-west
German plain. In the hilly districts of the north of England,
the woods on non-calcareous soils are dominated by O.
sessiliflora, but this tree becomes rare above 1.000 feet, and
owing to cUmatic influences tends to be replaced by (C) The

Birchicood Association, in which the woods are floristically
\-ery similar to the Oakwoods, but the ecological differences
appear in the rearrangement of the dominant members of the
two associations. Judging from the remains of Scots Pine
in the peat of the Pennines, this tree was doubtless a
constituent, but probably not an abundant one, of the
primitive Pennine birch forests.

III. The Beech and Ash Series is sharply marked oft" from
the two preceding series. These woods are found on
calcareous soils (such as marl, chalk, limestone) where the
lime content of the soil is high. Here three associations are
distinguished — (A) an Ash-BeccJiwood Association ; (B) an
AsliK-ood .Association ; IC) a. Beecli\i.ood Association. (A)
and (B) are the characteristic w-oodland types on all highly
calcareous soils, e.xcept those of the south-east of England,
where the beech is dominant on the chalk. The area of
natural and semi-natural beechwoods appears to have a
western extension on the Inferior Oolite of the Cotswold, but
for the most part it does not extend north-westwards of the
chalk escarpment.

For each association in these series, lists are given of the
subordinate woody species, as well as the characteristic species
of the ground vegetation.

The foregoing summary of this most useful memoir is based
upon that given in the Naturalist by Ur. Woodhead, well
known for his own valuable work in Ecolog\'. Readers
interested in the subject should obtain the memoir itself,
which has been separately issued as a " Nexv Pliytologist
Reprint " and can be purchased at a shilUng (by post. Is. Id.)
from the Editor, " A'cxc Pliytologist." Botany School, Cam-
bridge, or from Dr. W. G. Smith. Agricultural College, George
Square, Edinburgh.

CHEMISTRY.

By C. .\iNS\voRTH Mitchell. H..\. (O.xon)., F.I.C.

METALLIC RADIUM.— Until recently radium has only
been known in the form of salts, such as the chloride or
bromide, but Madame Curie and M. A. Debierne ha\-e at
length succeeded in separating a small quantity of the
elementary substance, and give an account of its properties in
the Coiiiptes Rcndtis (Vol. cli. 523).

A licjuid amalgam of radium was first prepared by electro-
lysing a solution of radium chloride by means of a cathode of
metallic mercury and an anode of an alloy of platinum and
iridium. This amalgam was rapidK- dried and placed in an
iron boat, which was heated in a quartz tube containing an
atmosphere of hydrogen, the pressure of which was maintained
at a point abo\e the pressure of mercury \apour at the
temperatures of the experiment. After the bulk of the mercury
had distilled the temperature was gradually increased, until at
about 700° C. the remainder of the mercury was expelled, and
the volatilisation point of the radium was reached. The residue
left in the iron boat was a bright white metal, which melted at
700" C. and at higher temperatures volatiUsed and attacked the
quartz tube.

The radium thus obtained rapidly blackened on exposure to
air, a nitride apparently being formed. It also decomposed
water, being itself for the most part dissoKed in the process.
Like its salts it was radio-active.

AN ANCIENT GLASS MIRROR.— The current issue of
the Monatshcft.Clicni.Wol xxxi.p. 781 ) contains a description
by Messrs. Wafert and Milkauz of an old Roman mirror that
was discovered in the ancient burial ground at Laibach, and
is believed to date back to the second or third century .\.D.
It was a slightly convex glass plate fitted into an indented
and ornamented leaden ring, and from its appearance under
the microscope and the results of chemical examination, the
mirror had probably been formed by attaching lead foil to the
back of the thin glass by means of some balsam. In the
course of centuries the balsam had become resinified and had
combined with the lead to form a resinate. The bulk of the
lead of the foil had been converted into red lead (Pb.i04),
whereas the lead of the frame and on the back was largely in
the form of basic lead carbonate.

430

KNOWLEDGE.

November, 1910.

CLOTH FROM BAN.\N.\ FIBRE.— .\ specimen of Cloth
made from banana fibre, recently exhibited at the fair at
Chunking, has been sent by the British Consnl of that place
to the Board of Trade.

It is prepared in China by unrollinsi the stall<s of the
banana when about a year old. and steaming them over boilint;
water until qnite soft. The green outer skin may now easily
be stripped off by passing the stalks through a machine
provided with two blunt scrapers, the residue then containing
the fibres. The material is ne.xt wrapped in a cloth and
hammered so as to separate the fibres and expel the moisture,
and the fibres are then pulled apart and spun into threads for
"Caving. The method of separation is thus very similar to
that used in the preparation of ramie fibres.

So far only a few lengths of cloth have been woven, and the
price is therefore high (/.I 3s. fid. for a roll 15 feet long by
3 feet broad), but with increased demand the price will fall
and the material will probably be extensively used in the
manufacture of clothes for summer wear.

The ultimate fibres, the microscopical form of which is here
shown, are about fifteen inches
in length and \ery strong.
It will be noticed that the
twisted form of the bottom
fibre in the photo-micrograph

recalls the characteristic twist ^^^^^^^^^^■■^■^L
of the cotton fibre, from
which, however, it may be
distinguished by not having
the twists along its whole
length. The jointed structure
is similar to that of the linen
fibre, which it also resembles
in its general chemical
characteristics and behaviour
towards difi"erent reagents.

A specimen of the pali
yellow cloth, for which the
writer is indebted to the Com-
mercial Intelligence Branch
of the Board of Trade, was

exceedingly tough and apparently very durable. It contained
10'5 per cent, of moisture, and yielded, on ignition, F? per
cent, of mineral matter (ash), the latter figure being very
similar to that given by linen, which usualK- contains about
F5 per cent, of mineral matter.

CHEMISTRY AT THE BRITISH ASSOCIATION.—
The reports of various Committees to Section B (Chemistry)
at the recent meeting of the British .Association at Sheffield
included those on the " Study of Hydro-aromatic Substances."
on " Electro-.Analysis." on " Dynamic Isomerism." and on
■'The Transformation of Nitro-amines. etc." all of which
are interesting only to the chemist.

A report on " Gaseous Combustion," by Dr. Rone. gi\ es an
extremely interesting summary of the chemical researches upon
the nature of gaseous combustion during the last 30 years.

Of the papers read before the Section mention may be made
of that on "The Influence of Chemical Composition and
Thermal Treatment on the Properties of Steel," by Professor
McWilliam, and that on "The Crystalline Structure of Iron
at High Temperatures," by Dr. Rosenhain, who shows that
between the ordinary temperature and 1000° C, iron exists in
three distinct modifications, possessing very different physical
properties. There was also a contribution by Dr. Copeman
on " Ferro-silicon," the dangers attending the transport of
which have already been described in these columns.

The paper by Dr. Howe on " .-Mlotropy or Transmutation "
is a plea for regarding the (juestion of transmutation of the
elements from a different point of view than the usual one.
The allotropism of the two forms of carbon, diamond and
lampblack, which may be transmuted into each other, is
conunonly explained on the ground that they are the same
element because the> \irld the same products of decomposition.

FiGL KL

In place of the statement that "the elements cannot be
transnuited into each other." it is suggested that it would be
more philosophical to say. " Hitherto no elements have been
transmuted into each other except those which transmute so
readily that the derivatives of only one of them ha\e been
recognised." Such a point of view would render the transmu-
tation of an element, say copper, into another, say, lithium,
not so inherently improbable as to demand exceptionally
conclusive evidence.

FXONOMIC BIOLOGY.

By Walter E. Coi.linge, M.Sc, F.L.S., F.E.S.

THE CLASSIFICATION OF BACTERIA.— In the
investigation of plant diseases due to bacteria, great difficulty
is frequently presented to the investigator in identifying the
species under observation. This diificulty of arriving at a
conception of species has been experienced in other branches
of biological science, and has led to the recognition of groups

of related species, such groups
being treated as units until
such time as the progress of
knowledge would allow them
to be broken up into their
component species.

The early work with bac-
teria was \ery largely con-
fined to pathogenic forms,
and pathogenicity was relied
upon to define the limits of
the species, but as the study
extended to non-pathogenic
forms, reliance was placed on
various other physiological
reactions, singly or in com-
bination, although, unfortu-
nately, there has been little
agreement amongst workers
as to the relative value of the
different reactions recorded.
Recognizing the importance of a uniform and concise
metliod of recording such reactions the Society of American
Bacteriologists adopted an official classification card for this
purpose. An important part of this card was the " group
number." in which the results of ten different reactions were
expressed numerically.

CONSTANCY OF CHARACTERS.— As the usefulness
of the group number becomes recognized there is a growing
desire to extend its range until it shall classify cultures as
closely in accord with the idea of species as possible. It
therefore becomes imperatively necessary to know both the
constancy of these reactions and the extent to which the
group number can be followed in classification without
separating various strains of the same species.

In this connection an excellent piece of work has recently
been published by Mr. H. A. Harding (Tech. Bull. No.
13, N.Y. .\gric. Exp. Station), who has selected an organism
{Psciidoiuonas caiiipcstris) the limits of which are clearly
defined ; he has also studied a large number of strains under as
wide a variation in conditions as could be reasonably expected
to occur in ordinary laboratory work. The study has
extended o\-er a year and a half, using media prepared by
difterent workers, and in some cases the observations were
made by three different workers separately. In short, the
effort was made to find the maximum variation which could
be expected where obser\ations were made in accordance with
the official directions, or with the deviation therefrom which
could be reasonably expected in practice.

CONCLUSIONS. — The results obtained are set forth in
great detail, and show that the card system offers a basis for
classification which for convenience of application and in

111.

November, 1910.

KNOWLEDGE.

451

certainty of result surpasses anything which has preceded it.
It furnishes a form for recording and organizing a mass of
observations, and intelligently appUed it is calculated to bring
order out of chaos, and be a potent factor in raising
bacteriology to the dignity of a science.

Tested on forty-four strains of Pscudoinoiias caiiipcsfris
it gave constant results without breaking the species into
smaller groups. The author concludes that the qualitative
variations and apparently discordant reactions which have
commonly been attributed to bacteria are probably due
largely to faults either in observation or in technique,
Onantitative variations are constantly met, but these are
undoubtedly largely due to lack of knowledge concerning the
proper re\'ivifying process to be applied before determining the
culture characteristics.

FUNGOID PAR.\SITES OF SC.\LE INSECTS.—
In the current number of the W'cst Indian Bulletin. Mr.
F. W. South gives a valuable account of work accomplished
on the infection of various scale insects with fungi. In the
Lesser Antilles four species of fungoid parasites occur on scale
insects, all of which may be artificially spread either by the
spore-spraying method, or the tying-in method. Experiments
showed that the fungi were most effective in the islands of
Dominica and Montserrat upon the scale insects attacking the
limes, but they are of general importance in all the islands.
The factors affecting the usefulness of these fungi are tempera-
ture, wind, and moisture ; of these the two last are the most
important locally. Mr. South concludes that the natural
means of controlling scale insects is that most suited to the
circumstances in the West Indies, both owing to the general
conditions and to the much smaller expense involved.

GEOLOGY.

By G. \V. Tyrrell, A,K.C.S., F.G.S.

DEFORMATION OF MINERALS AND ROCKS
UNDER P R E S S U R E. — In the July issueof "Knowledge"
occurred a note in which the work of Profs. F. D, .Adams and
E. G. Coker on the eftects of differential pressure on marble
was described. Prof. Adams has extended the investigation
to other rocks and various rock-forming minerals. His results
are given in the latest number of the Journal of Geology.
The method of compression used was that invented by Prof,
Kick. The specimen is placed inside a stout open copper
tube, and the space between the two filled with paraffin wax,
alum, or some other material susceptible of deformation under
pressure. The ends of the tube are covered with brass plates,
and the whole then squeezed in a powerful press. The first
effect of the pressure is to force the copper tube into the
plates at each end and thus to form a very strong box, from
which nothing can escape except by the rupture of the tube,
A series of minerals in a scale of increasing hardness was
tested. Selenite, rock-salt, calcite, and fluorite (with hardness
under five in Moh's scale), showed distinct plastic deformation
with some development of twinning and cleavage. The
minerals with hardness greater than fi\'e showed no marked
change of shape, but in some cases evidence of internal move-
ment was obtained. Thus a perfect basal twinning was
developed in diopside. No plastic flow was obtained in hard
minerals such as quartz and garnet. These were broken
down and powdered under the pressure. A \'ery curious
phenomenon was observed in fluorspar, green crystals becoming
violet-coloured under pressure. The softer rocks experimented
on. such as Carrara marble, were readil_\- deformed, the shapes
assumed varj-ing with the character of the embedding material.
Dolomite was found to be more resistant, and movement
within the rock took place chiefly through the development
of cataclastic structure. The harder rocks, such as granite,
simply crumbled under the pressure. Much higher pressures
would be required in order to induce a flow-structure in such
hard rocks.

SUBMARINE GEOLOGY,— In a recently-issued memoir
of the Geological Survey of Ireland, Profs. G. A. J. Cole and

T. C. Crook discuss the rock-specimens dredged from the
floor of the .-Vtlantic off the coast of Ireland in relation to their
bearing on submarine geology. Specimens were obtained from
the Porcupine Bank, and from off the coasts of Galway,' Mayo,
Donegal, Kerry, and Rathlin Island. Oft' the north-west coast
little but submerged masses of rocks common in the west of
Ireland wtre obtained. The Porcupine Bank, however, was
found to be composed of an olivine gabbro, which is believed
to be allied to the Cainozoic gabbros of Carlingford and the
Inner Hebrides, It is therefore suggested that the Porcupine
Bank may represent the site of a Tertiary volcanic vent.
Another interesting point is that Eocene limestones occur in
the dredgings from the coast of Kerry, as well as abundant
relics of Cretaceous strata. These observations are held to
indicate a westward extension of the types of strata known in
the Paris basin, and are in accord with the results of
F, H, Worth, who obtained similar rocks from the English
Channel.

GLACIAL PROTECTION .—An interesting paper by
Professor E. J. Garwood on " Features of Alpine Scenery due
to Glacial Protection," appears in the September number of
the Geographical Journal. The protective action of ice is
considered in relation to certain plateaux, aretes, cirques,
hanging valleys, and \alley steps in the Alps, It is not denied
that moving ice erodes an Alpine district. The problem is
whether it is more or less powerful than the ordinary agents of
erosion. The author considers that some characteristic Alpine
features might be explained on the assumption that ice, on the
whole, erodes less rapidly than other denuding agents, and
that, under certain conditions, it may act relatively as a
protection to the rocks beneath. Similar views have been
vigorously advocated in the past, and have been restated by
Dr. T. G. Bonney in his recent Presidential .Address to the
British Association. Professor Garwood's paper is illustrated
by many beautiful photographs of Alpine scenery.

THE CANADIAN SHIELD.— In his Presidential Address

to the Geological Section of the British Association, Professor
.\. P. Coleman dealt with the history of one of the corner-
stones of the earth — the Canadian Shield. This .great mass
of ancient gneiss and schist is for the most part destitute of
overlying formations save the products of Pleistocene glaciation.
There is here, therefore, as in the North of Scotland, the
meeting of geological extremes, between which is the most
tremendous discordance in geological history. The great
masses of gneiss are not, as some have thought, relics of the
original crust of the earth. They are definitely known to be
intrusive in a still more ancient formation, the Keewatin, in
which is found quartzite, arkose. slate, and phyllite, besides
metamorphosed representatives of these rocks and great
masses of igneous material. All the ordinary types of sediment
accumulated in the Keewatin sea apparently under much the
same conditions as they do now in modern seas. Thus the
ordinary processes of denudation were operating on broad
land areas ; rocks like granite or gneiss were weathering into
sand and mud. long before the Archaean mountains came into
existence. The pre- Keewatin land and sea-bottom have
disappeared, and have probably been fused and trans-
formed into the Laurentian gneiss. Such considerations
as these compel one to think of the inunense duration
of Pre-Cambrian time, and contrast its vistas with the
comparatively short period represented by the fossiliferous
formations.

.Another interesting point is that the Lower Huronian,
which rests unconformably on a floor of Keewatin and
Laurentian, has a basal conglomerate which is almost
certainly an ancient till. It is the oldest known boulder clay,
and upon its denuded surface in many places rests the
youngest boulder clay. Professor Coleman remarks " It is
not a little impressive to see modern till resting on the
Huronian tillite and including fragments of it as boulders. It
is possible to break out from the modern glaciated surface
stones whose underside received their polish and striae in the
Lower Huronian. while their upper surface has been smoothed
and scratched bv Pleistocene ice-movements,"

452

KNOWLEDGE.

November, 1910.

METEOROLOGY.

By John A. Cirtis. F.R.Met.Soc.

Thk weather of the week ended September 17th was fair and
dry, thou,sjh there was a thunderstorm in London on the 14th,
with heavy rain in many places. Temperature was below the
average, and ranged from 69' at Stonyhurst to 30° at West
Linton. On the .grass readings as low as 28° were reported.

Rainfall was more than twice the average in England, E.,
but was light in all other parts. At many stations in the
West the week was rainless. In spite of the low rainfall
sunshine was also deficient, e.xcept in Scotland and in
Ireland N. Douglas reported the largest ag.gregate. 50'S
hours (56%). and Birmingham the least 1'? hours (2%).
Glas.gow had more sunshine I37'6 hours. 42"., I than Guernsev
I23'3 hours. 26%).

The teniperatiu'c of the sea round the coast \aried from
61° at Newquay, and about 60" on the Southern Coasts, to 52°
off the East of Scotland.

The week ended September 24th. was fair and dry xery
generally, but cool. Temperature was below the average in
all Districts. The highest readings were 71° at Scarborough,
and 70" at Raunds, on the 24th, but at no other station was
70° reached. In Ireland the highest reported was 65° at
.Armagh and at Killarnex'. Rainf.iU was \ery light, and the
South of England uas practically rainless. Sunshine was
more abundant than in the preceding week, but it was still
defective in Scotland, N. and in Ireland. .At Strathpeft'er. the
total was only 1 TO hours (13%), and at Gordon Castle 11*3
hours. On the other hand many stations in the South reported
r.J hours and upwards, Tottenham as much as 56"9 hours
(66'':j). The temperature of the sea water ranged from 61° at
Newquay and at Margate to 52° on the East Coast of Scotland.
Frost on the ground was reported at many stations, and at
Llangannnarch Wells, while the minimum in the screen was
27". the reading on the grass fell to 19°.

The weather during the week ended October 1st w-as less
settled than that of tlie preceding fortnight. Rain fell on
several days in the N.W. and W., and thunderstorms were
experienced on the 1st in many parts. Temperature, how-
ever, was markedly higher, being above the average in all
districts. The highest readings w-ere 76° at Raunds on the 2tSth,
and 75° at Tottenham. The lowest mininuun was 34° at Markree
Castle. Sligo, on the 30th. Atonlyafew stations didtheminimum
on the grass fall below freezing point, the lowest being 27° at
Cockle Park. Morpeth. Rainfall was less than the average in
all districts, except Ireland. S., where both rainfall and rainy
days were more than usual. .At some stations in the South
no rain was reported, and at others the fall was only one-tenth
of the a\"erage.

Sunshine exceeded the average in some parts, but was less
than tlie average in Ireland, Scotland, England, S.W,, and
English Channel. Cromer reported the highest aggregate,
46'0 hours (55%), while Falmouth had only 16'4 hours (20%).
Glasgow reported lO'l hours (12%^).

The week ended October Sth opened with hea\y rain in the
Western and N.W. districts, and some more moderate falls
with thunderstorms elsewhere, but was afterwards fine and
warm. Temperature was above the average in all districts,
by as nntch as 6' in Scotland, E. The highest reading was
74° at Cromer on the 2nd. with 73° at Hillington and Raunds.
In Jersey the highest reported was 66°. and in Scilly only 63°.
The lowest reading obserxed was il° at West Linton on the
7th, the next lowest being 37° at Newton Rigg, near Penrith.
On the grass the lowest reading reported was 29°. Rainfall was
below the average in all districts, especially so in the East and
.South of England. .At Yarmouth, Felixstowe and Clacton no rain
fell, and at a large number of places there was rain on only
one day. Sunshine was in excess generally. The highest
aggregate was 46'2 hou-s (5S%) at Guernsey, the lowest 6 6
hours (8%) at Castlebpy, Birmingham reported 15'5 hours
(.19%), while Glasgow had 230 hours (29%). The temperature

of the sea water varied from 61' at Margate and Seafield to
51" on the N.E. of Scotland. .Aurora was observed in
Aberdeen on October 6th and Sth.

During a kite ascent at Pyrton Hill on (October 4th, a
remarkable current of dry air was observed. On the ground
the humidity was 90% (saturation = 100). at 300 feet no
change was observed, but at 1,600 feet the humidity had
increased to 95%. At 3,300 feet, however, the percentage
was only- 40%, at which it remained till the kite reached its
greatest height. 4.400 feet.

Pyrton Hill at the time was on the Northern side of a large
anti-cyclone, which had its centre over the Bay of Biscay.
On the ground the wind was from W. by N., but as the kite rose
the direction veered to N.W., and the force increased to
10m. per second. A few clouds were met with at about
2,300 feet, and from 2,500 feet the temperatiu-e increased with
height instead of falling.

LECTURES ON MlCTi:) >ROLOGV.— Announcement is
made by the University of London that Dr. W. N. Shaw,
F.R.S., Reader in Meteorology and Director of the
Meteorological Office, will deliv er two lectures on '" Modern
Meteorology, Dynamical and Statistical." at the new-
Meteorological Office in the Exhibition Road. South
Kensington, on Mondays, November 21st and 28th, 1910,
at 5 p.m. I No tickets required).

.MICROSCOPY.

By A. W. SHErPAKD, F.R.M.S.,
icitli the assistance (if the foUoicing luicroscopists : —

Ariiilk C. IUnkiki I) .\rthlk Kari am'.

lAMts Bi RTON. Richard T. Ekwis, F. R.M.b.

The Rev. E. W. Bowkui., M.A. Chas F. Rolsselet, F.R.M.S.

Charles H. Cafkyn. D. |. ScotKhfEiD, FZ.S., F.R..M S.

C. 1). Scar, F.K.J).S.

AN INTERESTING LARVA (Sitniiliiiiii reptaiis).—
During a recent holiday, camping out on the banks of the
river Teme, near Tenbury, Worcestershire. I was much
interested in these larvae, which are common in that river,
or. at all events, in that locality.

The larvae are only found in the most rapidly running
water on various water weeds — in this instance R. aqitatilis.
No mere words can give an idea of the vast numbers in which
they were found ; one could pull out a length of weed which, as
weed, was usually invisible on account of the wriggling
niass of larvae attached to it. Had one so desired, a bucket
could have been filled solid with them without difficulty.

The larva itself is a curious little animal, when full grown
about 11-12 mm. long, of a greenish black colour, and,
although not so transparent as the bulk of aquatic larvae,
still permits its internal economy to be easily made out. Its
nervous system, in particular, is very distinct.

From the nature of its environment of rapidly rushing
water, it is provided with most efficient devices for retaining
hold of its support, in the form of two suckers, one on the
thorax, the other at the extremity of the last segment of the
abdomen. These suckers are each furnished with many rows
of sharp claws, or hooks, to add to their efficiency.

The larva appears to hang on to its support as a rule by
the abdominal sucker, using the other to crawl about the weed
in the same manner as a geometer larva. It normally holds
on with its body as near to a right angle to the weed as it can
get, waving the body to and fro in all directions in search of
food. Should it be accidentally dislodged, it has another
safeguard in its capacity for spinning a thread, and along
which it slowly crawls back to safety. The salivary glands
which furnish this thread are of enormous size, and form the
most prominent anatomical feature of the insect.

The head is furnished with a powerful biting mouth of the
usual type, and, in addition, is provided with two pairs of very

NO\EMBER, 1910.

KNOWLEDGE.

beautiful aud extraordinary ciliated appendages, xvith which
It continually sweeps" the water in search of food

Professor Miall. in his admirable Natural History of
Aquatic Insects, deals verv fnllv with this larva but

4.i3

4th. and when I left on August l-'th, practically all had pupated.
The Hies were due to appear d.irins the last week in August
and these I unfortunately missed.

The Fly in this country is harmless, but others of the genus

FiGfRE 1.

The larva of Siiiiuliuiu rcptaus.

curiously enough, only refers to the most prominent, or
external, pair ot sweepers. A smaller pair, within the larger
IS however, easily visible with a low power of the microscope.
These appendages the larva keeps constantly in motion, and
all food withm their range is instantlv swept into the capacious
mouth.

The larva pupates within a conical silken cocoon, which it
hrmly attaches to the weed with a glutinous secretion of both
silk and cement supplied by the saUvary glands. The cocoon
is very transparent, and enables one to readily make out
details of the imago within. The pupa is prox-ided with
dehcate tubular gills, visible in the photograph, for breathin-
purposes. "

Unfortunately, my stay in the countrv was too short to
make complete observations; when I first examined the weed
(July 24th) I found larvae only, a few pupae were found August

Fic.ruE 2.
The pupa of Siiuuliuni rcptans.

^f^^l^^>/^

Figure 3.
The head of the lar\ a showing mouth aud thoracic claw.

m the United States (8. molcstuiii) and the \alley of the
Danube (S. columhaczcnsc) form a terrible scourge, in bad
years driving cattle mad by the hundred. The insides of the
ears and nostrils are the favourite points of attack— to such an
extent indeed, that these organs are packed almost solid in
bad cases. Fortunately, the family is a small one, containing
but one genus and about sixty known species.

The larvae I failed to keep in aquaria, as might be
expected from their normal habitat, all dying in a few' hours.
They might possibly be reared in aquaria violentlv aerated by
mechanical means. In a round tank a steadv, well-aerated
flow of water could easily be assured, that would give a good
imitation of their natural surroundings.

The final metamorphosis of the Fly is most interesting,
but this I missed, as above mentioned. The perfect insect
leaves the cocoon in a bubble of air, floating in safety

454

KX(1\VLEDGE.

November. 1910.

to the surface of the water, forming, in all probability.
Nature's most ingenious device for the escape of an insect
from surroundings that have become unsuitable. Professor
Miall gives a spirited description of this act in his book, which
is well worth reading by those who \\ ish to pursue the subject

f'"'''^^''- .\KTHl-K C. BAXFIELD.

BATRACHOSPERML'M ATRCM (L~)ill\v.) H.ARV.—
At a recent meeting of the OueUett Microscopical Club,
Mr. Higginson exhibited a
mounted specimen of the
abo\e. It was found grow-
in,< on the brick-work of a
weir at Colnbrook. in May.
This species is not nearly
so familiar as the common
B. iiioiiilifonuc. Roth., in fact
many would scarceU- recognise
it at first sight as belonging to
the same genus. The branches
which are the salient feature
in B. iiionilifornie are here
reduced to the smallest dimen-
sions, as shown in the illustra-
tion. Figure 1, which is from a
photograph by Mr. Banfield
of a mounted specimen. Dr.
Cooke describes it (British
Freshwater Algae, p. 292) as
" vaguely and much branched,
whorls abbreviated, distant ;
interstitial branchlets very
short, one or two celled."
Ouoting Hassall. he says:
'■ The articulations, or inter-
nodes, may be compared to
reversed cones, the superior
part or whorls being formed
of a few short, simple subu-
Late filaments, which are not
beaded. That portion of each
articulation which is below
the whorl is transparent, and
beautifully exhibits the tubular
and jointed structure of the
layers which invest the prim-
ary cells in all the species of
the genus Batracliosperiniiiir,
from many of these tubes short
branches are gi\en off which
have almost the appearance
of scales."

At a later date Mr. Higginson
had the good fortune to find on
the shell of a pond snail another
specimen which appears to
agree exactly with the variety named by Dr. Cooke, Dillcini.
In describing it, he says: " F'ilaments Aery thin, lower nodes
remote, the interstices beset very densely with prominent cells,
upper nodes crowded, branchlets very short, consisting of three
to four cellules, extreme apical nodes confluent." In a note, he
says: "This is usually considered as a variety of B. va^iiin. but
it seems more closely allied to B. atriini, if that be really a
distinct species." In this latter specimen the features Dr.
Cooke describes are very distinct ; what he speaks of as
"prominent cells" ax^e very numerous, and in several cases
show short branches, but they cannot be mistaken for the
actual branches Iwhich occur at the nodes! and are obviousK-
only proliferations of the cortical cells which envelope the
internodes. There are several cystocarps on this example.
The colour of the lixing plants was much masked by the
presence of numerous diatoms and other epiphytes, as is so
commonly the case with this genus ; in the mounted specimens
it is a clear pale green, but that is largely due to the mounting
medium. In the figure the irregular projecting thre;ids are
epiphytes, chiefly diatoms, mostly Syncilnr. i jj

Figure 1.
Bat rachuti[>criii II III at ruin

A M1:TH()D in MICRO-TECHNIQUE.— In the
Zcitschrift fi'ir wissciiscliaftliclic Mikniakopic. Bd. XXVH,
Heft. 2 (Aug. 1910) there are some notes on microscopical
technique by J. T. Wilson, F.R.S.-, Professor of .\natomy in
the University of Sydney, in which he gives the following
details of a convenient and simple expedient for suspending
blocks of tissue in fluid, and more especially for passing them
through successive series of fluids. He uses short segments of
glass tubing from ISmm. to iOnnn. in diameter, one end of which

is closed by means of fine net
tied round it ; the tissue is
placed in the tube, which is
then closed at the other end
by a perforated cork of suffici-
ent size to float the whole in
the fluid. Such a floating
vessel can be transferred from
one fluid to another with the
utmost readiness, and with-
out, in any way. handling the
tissue. Similar arrangements
have been described before,
but this has the merit of very
great simplicity and cheapness.
If the gauze bottom of the
tube, prepared as above de-
scribed, be dipped in a 10 per
cent, solution of gelatine and
allowed to set. it can then be
formalinised and preserved
indefinitely either in very weak
formalin or in alcohol. Such
a tube may be utiHsed as a
floating dift'erentiator. Thus, a
piece of tissue may be placed
in it in a small quantity of
one fluid, and after inserting
the perforated cork it may be
floated in a vessel containing
another fluid, thus securing a
ver)- gradual diffusion of one
fluid into the other through the
gelatine membrane.

MICROSCOPICAL APPA-
R.\TUS. — The first section, of
more than twenty pages, in Mr.
C. Baker's new classified list
of second-hand instruments is
devoted to microscopes and
accessories of all kinds, and
of verj- special interest is
the sepai'ate list of apparatus
that belonged to the late Dr.
Dallinger. It contains many
interesting items, among which
IS a water immersion objective of one-fiftieth of an inch focus,
by Powell & Lealaud. — We have before us also the first
catalogue of second-hand apparatus issued by Messrs. Angus
and Company. .As said in the preface, the possibility of acquiring
apparatus at a cheap rate may be a real boon to those who
wish to try experiments at the least possible cost. — We^ ad\ise
our readers to get a copy of the little booklet entitled, " Some
Hints on the use of the Shding Microtome for the Paraffin
Method," which has been issued by Mr. E. Leitz. and which
contains some very useful information.

SECTION OF KIDNEY. — We are able, by the courtesy
of the Bausch & Lomb Optical Coy., of Rochester, U.S.A.,
to publish a reproduction in half-tone of a photograph of a
cross section of an entire infant's kidney, under a magnifi-
cation of 7 diam. This beautiful photograph was taken by the
Bausch & Lomb-Zeiss Micro-Tessar 72 nnn. ; a special
condenser was used. The slide was stained with Eosin and
Haemoto.xylin. The reproduction illustrates, in a measure
onlv, the excellence of the original jihutograph.

By the courtesy of

The cross section of an entire Infant's Kidnev. X 7.

J cssrs. l-'aic^Lit e-^ ,

455

456

KNOWLEDGE.

November. 1910.

AN ALMOST FORGOTTEN BINOCULAR DEVICE.
— .'Vs many readers of " Knowlkdge " still use that most
excellent but discredited instrument, the stereoscopic bin-
ocular, it may be worth while to bring to their remembrance a
simple yet almost fortjotten de%'ice. now more than a ijuarter
of a century old, which certainly improves the image.

If one of the eye pieces is removed and the back of the
object glass is examined, when a full cone is used, it will
appear as in Figure 1. Generally the iris below the substage
condenser is somewhat closed, and the appearance seen is
like Figure 2. If now. instead of closing the iris, a stop of the
form Figure 3, be inserted underneath the substage condenser,
the back of the object glass will appear like Figure 4 in each
tube, and a much improved picture of the object will be
obtained.

o

Some little care is required in making this double hole in
the stop of a proper si^e. The best procedure is to experiment
with stops cut out of cardboard, and when the right effect is
obtained to have it copied in brass. Of course it will be
necessary to have a special stop for each objective, and to
remember that it can only be used with the substage condenser
for which it was made — this, however, is a minor difficulty
which can be readily oxercome.

Some years ago I made expei'iments by placing at the back
of the object glass a stop having two circular apertures, as in
Figure 3, but with larger holes ; since then experience has
shown that nothing much is gained by doing this ; the improve-
ment seems to depend entirely- upon the stop ;it the back of
the substage condenser.

Great care must be taken with the illumination, so that it
appears the same in both holes when viewed at the b.ick of
the object glass, the eye pieces being removed for that
purpose.

In general, the best illumination for transparent objects,
when a stereoscopic binocular is used, is obtained by focussing
the image of the flat of the flame upon the plane of the object,
of course without a bull's eye.

Edward M. Nelson, F.R.M.S.

For the purpose of producing duplex illumination for the
binocular instrument Kiddell made use of two mirrors, and
Stephenson a duplex stop with cylindrical lenses. It was
in 1892 that Mr. Nelson first suggested the use of the
above described stop in conjunction with the achromatic
condenser. — [A. W. S.J

VAMPYRHLLA LATERITIA Li: IDV.—While engaged
in an exploration of the Sikkim Himalayas my friend. Dr.
Kellas, made his camp for several daj's near a small lake
called the Green Lake, at an altitude of nearly sixteen
thousand feet. From this lake he very kindly obtained for
me a small quantity of mud. As the " mud " consisted of a
coarse glacial detritus, one could hardly imagine less promising
material for examination. However, on placing some of this
mud in a large specimen-tube and allowing it to remain for a
few days. I was agreeably surprised to find I had a small
collection of the living micro-fauna from this Himalayan lake.
As the material was quite free from putrefactive bacteria, the
organisms remained alive for some weeks. Besides several
infusorians there were two bdelloid rotifers, which Mr. Da\ id
Pryce kindly named for me i they were Ph iliuhiia aciiticoni is
Murray and CaUidina clcf^ans Milne, both, as I understand,
recorded from Scotland. But my first and only acquaintance
with the Rhizopod named at the head of this paragraph, was
from this material. It is recorded by Cash, from Cheshire,
and by Professor West, from North Wales, but it certainly
seems of interest to find it high up in the Himalav'as.

fn the first tube I examined I found several actinophrvs-like

organisms, the protoplasm of which was coloured a bright
orange. This was recognised as \'ainpyrcUa lateritia from
the description and figures in Cash's British Rhizopods (Ray
Society's Publications). It appears to have been first
described by Cienkowski in 1863. under the name
VampyrcUa spirogyrac, but Professor Leidy has shown
reason for considering that Fresenius had described it under
the name Aiiiochn lateritia in 1856. hence this specific name
takes priority over spirogyrac. Professor Leidy. in Tlic Fresh-
water Rhizopods of A^ortli America, in 1879, describes the
'granular protoplasm as pervaded with colouring matter of
different shades of orange. The periphery of the body is
hyaline, and it is surrounded by pseudopodial rays giving it
an actinophrys-like form." The pseudopodia are further
described as being " of two kinds, the ordinary delicate,
straight rays and pin like rays ending in a minute round head."
.■\s the specimens had travelled from India in an encysted
condition, my observations were carried out under adverse
circumstances — since they never really attained a state of
active metabolism. The pin-head appearance of certain of
the pseudopodia seemed to be the effect of refractive granules
passing outwards along the threads of protoplasm. It is very
possible the small lake from which the specimens came was
so named from some filamentous alga w hich coloured it green.
This also would be the food of V. lateritia which feeds on
the chlorophyll of such algae as spirogyrae. I was, of course,
unable to observe its method of feeding, but there seems to be
some divergence of opinion as to how it is effected. The
earlier observers describe the Vampyi"ella as perforating the
cell vv.ill of Spirogyra, and thus extracting the chlorophyll.
M. Penard adds that in addition to perforation of the cell wall
there is a suction action on the part of the Vampyrella. Mr.
Cash in the above mentioned book describes and figures a
method which differs from that of the other observers. He
says the Vampyrella anchors itself by means of its pseudopodia
to the terminal cell of a thread of Spirogyra and actually
bends this cell luitil it separates from the thread, when it is
able to extract the chlorophyll : it proceeds in this way until
there are a number of empty separated cells.

PHOTOeiR.APHY.

By C. E. Khxxeth Mehs. D.Sc. (Lond.). F.C.S.

PHOTOGRAPHY BY INVISIBLE RAYS.— Professor
R. W. Wood, of The Johns Hopkins University, gave the
Thirteenth Traill Taylor Memorial Lecture before the Royal
Photographic Society on September 27th. He discussed the
methods which he has adopted for photography by the infra-
red and ultra-violet rays, and the results obtained.

Photography by the infra-red requires only plates having
sensitiveness in that region and a screen removing .almost all
the visible spectrum, and permitting only rays of wavelength
superior to 7,000 A.U. to pass. These long infra-red, or
rather deep red, rays are very little scattered in their
passage through the atmosphere, and are almost wholly absent
from the light reflected from blue sky, so that by their use blue
skies appear very dark, entirely black near the zenith and
lightening towards the horizon. Even the lightest clouds
become very bright compared with the sky, so that the method
seems well adapted for the study of faint cloud forms in
meteorology. Vegetation, on the other hand, has but little
absorption in this region of the spectrum and reflects the
light plentifuUv, so that trees appear snow-white against the
black skv.

The photographs in the ultra-violet were taken by means of
a quartz lens silvered until it was opaque to ordinary light.
Such a silver film transmits light between the wavelengths
3,000 and 3,200 A.U.. by which light the photographs were
produced.

These ravs are scattered so powerfully by the atmosphere
that the air always appears to be full of haze; the general
appearance of landscapes in clear bright sunshine being

November. 1910.

KNOWLEDGE.

457

similar to that presented to the eye when the sun shines
through a Ught haze. Owing to this effect, shadows, which by
infra-red light appear solidly black, are. in ultra-\'iolet light,
almost entirely absent, the diffused light from the skv prevent-
ing the formation of clear shadows.

The reflecting power of natural substances for ultra-violet
light is, of course, very different from that which they possess
for visual light.

Silver has only about the same reflecting power as glass,
and would appear like anthracite coal, while Chinese white
absorbs the rays more powerfully than printer's ink. White
garden flowers also absorb the ultra-violet light strongly.

Photographing the surface of the moon. Professor Wood
found a large deposit near Aristarchus which appears quite
black by the ultra-violet light, though it is not distinguishable
by \isual light.

The method seems to hold out some promise for the
in\'estigation of the petrolog\- of our satellite.

METHODS OF IMPROVIXG UNS.ATISF.ACTORV
TECHNICAL RESULT S.— While some scientific
photographs leave nothing to be desired, the technical cjuality
of others is so poor that they pro\e less satisfactory for
purposes of demonstration than their author might desire.
Apart from actual bad work, there are two chief causes
tending to produce inferior results ; —

(1.) Sufficient exposure cannot be given, or is very
difficult to gi\e ; e.g., in photographing objects in
motion.

(2.) The contrast in the subject is insufficient.
The results obtained in both these cases are susceptible of
improvement by after treatment, and I have found that the
following methods ai'e satisfactory : —

(1.) If the negative is so badly under-exposed that after
development to the limit only a ghost is obtained, ordinary
methods of intensification are not of nmch use. After thorough
washing, the plate should be completely bleached by leaving
in a solution of mercuric chloride until the whole deposit has
become quite white to the back. The negative is now washed
and dried, care being taken that it does not come into contact
with developer, hypo, or ammonia solution. After dr\-ing. the
back of the glass is covered with a black varnish, or with
' Photopake,' or Indian Ink. The photograph will now appear
as a good positive, which can be put in front of a camera
and copied.

(2.) If the contrast in the subject is insufficient much may
be done in the case of coloured subjects by using colour filters
with appropriate plates to increase the contrast, but some-
times this is useless. A case in point was supplied by the
photography of the A and B lines in the solar spectrum with
considerable dispersion and a high sun. The resulting nega-
tive, while admirable for purposes of measurement, gave quite
insuflicient contrast for printing, even when intensified. I
therefore made a contact positive upon a slow lantern plate,
and developed the positive with a physical developer, con-
sisting of an acid solution of metol to which a small quantity
of silver nitrate had been added. By this means the blackness
of the deposit can be increased to any desired extent. A
contact negative was then made from the positive, in the same
manner, and from this excellent prints were easily obtained.

A PHOTOGRAPHIC PROCESS BV FERMENTATION.
— Dr. Leo Jacobsohn, in a paper in PJiotographische
Rundschau, describes some experiments which he has made
on the peptonic fermentation of gelatine by the gastric juice,
or by solutions of pepsin. Gelatine coated upon glass plates,
and containing bichromate, was exposed to light and then
subjected to the action of pepsin solutions, with the result
that theunexposedgelatine was dissolved, while that which had
been exposed to light proved incapable of digestion.

Gelatine which was hardened by the usual hardening agents,
such as alum or formaline, proved as subject to attack by
pepsin as unhardened gelatine.

Dr. Jacobsohn has employed pepsin for " developing " pig-

mented gelatine prints, instead of hot water, but it would seem
doubtful if there is any real use for the process.

Further investigations upon the same lines, however, might
prove useful as a means of enquiring into the structure of
gelatine, and the alterations produced in its molecular structure
by \arious reagents.

PHYSICS.

By W. D. EgGar, M.A.

RADIU.M STANDARDS AND NOMENCLATURE.— In
Nature of October 6th. Professor Rutherford gives an
interesting summary of the discussions which took place at
Brussels in September, at the International Congress of
Radiologj' and Electricity. -At the opening meeting he himself
read a report on the desirability of establishing an international
radium standard. He had compared by the X-ray method
several European standards and had found differences in
some cases amounting to twenty per cent. It is possible to
measure with considerable accuracy such magnitudes as the
heating effect, the rate of production of helium, and the rate
of emission of a and j8 particles. But the value of such
determinations depends on the accuracy of the radium standard
used in expressing the results. A powerful Conmiittee of
representative workers was appointed to report on the best
method of fixing an international standard. This committee
reconuuended. and the congress adopted their recommendation,
that Madame Curie, herself a member of the Committee, should
prepare a radium standard containing about twenty milli-
grammes of radium. This standard will cost about ,^,500, and
will become the property of the International Committee. It
will probably be kept suitably at Paris.

It has been suggested that the name Curie should be used
to express the quantity or mass of radium emanation in
equilibrium with one gramme of pure radium. The amount
in equilibrium with one milligramme of radium would then be
called one millicurie. The (juestion of names of radioactive
products was discussed informally at the Congress. The
present system seems to be fairly satisfactory, and capable of
extension. For instance, if radium C is found to consist of
se\eral constituents, these might be called Ci Ca, etc. But the
giving of fancy names by individual workers is regarded as
undesirable.

A NEW OPTICAL GRATING.— Prof. R. W. Wood,
whose reputation as an experimenter extends far beyond the
United States, delivered the " Thomas Young Oration " to the
Optical Society on September 29th. In this he described a
new form of grating, occupying a position intermediate between
the ordinary diffraction grating and the echelon. It is ruled
on gold deposited on copper, using a crystal of carborundum,
which possesses an advantage over diamond in having straight
sides meeting at an angle of 120'. The gold is compressed so
as to form ridges and hollows with highly polished and almost
perfectly flat sides. The spacing is coarse. These gratings
are specially suitable for heat waves, and are much more
efficient than prisms of rock-salt. Prof. Wood has given the
name echelette to this form of grating.

ZOOLOGY.

By Professor J. .\rthur Thomson, M.A.

BARNACLES AND SNAKES.— One of the most curious
of zoological pictures, mediaeval at first glance, is that given
by Dr. Willey (in Spolia Zeylaiiica. May 1910), of a sea-snake,
Hydrus platurus. bearing a bunch of barnacles on the end of
its tail. The barnacles are of two kinds iLepas anserifera
and Coiicltodernia liuiiteri) and form a dense group. The
attachment of barnacles to the skin of sea-snakes has long
been known, but the case figured is \ery quaint. The
specimen was brought alive to the Colombo Museum. Dr.
Willey writes : " The barnacles are not ectoparasites, as they

458

KNOWLEDGE.

XOXEMBLK, 1910.

do not feed upon the sUin of the snnke. nor do they assist the
snake in any way ; on the contrary, their presence nuist have
seriously impeded the movements of the snake. Moreover,
they thrive equally well when attached to floating bottles and
drifting spars. So far as the snake is concerned they are
simply an incubus which cannot be shaken off. and the snake
is merely their facultative vehicle. These barnacles are
sedentary animals destitute of proper powers of locomotion,
although capable of securing their own nourishment, but they
have acquired a planozoic or passi\-ely vagrant habit, and they
must be kept on the move." Dr. Willey recalls the associa-
tion (described by .-Vlcockl between certain Hydroid polyps
iSfylactis iiiiiioi) and a small rock perch. Miiioiis incniiis.
He also notes that the barnacle Lcpas aiiscrifcra is
frequently accompanied by two Annelid worms of the family
.•\mphinomidae.

LUNGLESS XEWT.— There is a newt {Triton or
Eiiprocfiis iiiDiifitiiKs) in Corsica which li\es under stones
in the dry beds of streams and dispenses with lungs. A
number of similar cases are known and there are two opinions
as to their respiration. Wilder's view is that the respiration
is essentiall}- cutaneous ; Camerano's view is that the bucco-
pharyngeal cavity, which may be very rich in blood-vessels, is
the main respiratory area. Obser\ations and experiments
have led Lapicque and Petetin to the conclusion that in the
Corsican newt the skin plays the essential role in the gaseous
exchange, and that the bucco-pharyngeal cavity, liighly
vascular as its walls are, and in spite of persistent pumping
movements, has only a secondary role, and is insufficient by
itself to keep the animal alive.

.AN .\D.\PT.\TION TO LIFE .AT HIGH .ALTITLDES.—
It is a familiar fact that living at a high altitude puts a strain
on the heart, which has more work to do. In this connection
it is interesting to notice Strohl's recent comparison of
ptarmigan from high altitudes and willow grouse from the
plains. He found that in ptarmigan, even in the young bird,
the right ventricle of the heart is very distinctly stronger
than in the willow grouse, — a specific adaiitation to the
difference of habitat.

.\l).\rT.\TIOXS HEFOKK HIRTH.— In an interesting
account of a large saw-fish 'Prist is ciispidiitus i, which was

fifteen and a half feet long, Mr. T. Southwell notes that
twenty-three embryos were present in the oviducts. As each
of these was about fourteen inches long, including a toothed
rostrum of five inches, one naturally becomes curious as to
the relation of the weapon to the wall of the oviduct. Mr.
Southwell points out that, while the dentition on the rostrum
was quite apparent, it was "entirely covered by a transparent
cartilaginous tissue, which of necessity must disappear later."
This reminds one of similar adaptations before birth, such as
the finger-stool cushions which Dr. Agar has described over
the claws of some unborn Reptiles and Birds.

MVRMECOPHILOUS PUPA.— H. Viehmeyer got from
Manila a number of Lepidopterous chrysalids. which were
discovered in the heart of the well known hanging earthen
nest of the ant Campoiiotns qiiadriscctus. When the nest
was broken the furious ants grouped themselves around the
chrysalids (which lay in special cells) as if to protect them.
.An examination of the chrysalids showed that the anxiety of
the ants was far from disinterested, so to speak. At the end
of the abdomen there is a chitinous crater into which opens a
secretory gland, apparently making a sort of honey-dew.
" \\'e have here undoubtedly the peculiar spectacle of a lepi-
dopterous pupa acting as a food purveyor to ants." . . . "It
would be very interesting to search further for the reciprocal
relationship of the symbionts on the spot, chieHy to fiiid out if
the butterflies, when emerging, are not possibly in need of
assistance from the ants, as well as to \erify the secretion l>y
actual observation."

HORX-FEICDING L A R\' A E.— August Busck has
published two fine photographs of the horns (two feet long) of
a water-antelope iCohus sp.) much infested by the larvae of a
microlepidopteron. Tinea fastclla. which had burrowed in
the horn and formed numerous projecting tubes. The
specimen was picked up on the ground in British East .Africa
by the Smithsonian .African Expedition, under the direction of
Col. Theodore Roosevelt. The dark brown tubes, which occur
in thick bunches, are about a ([uarter of an inch in diameter and
half an inch to two and a half inches in length. They are made of
silk plus earth and chewed horn. They are " closed at their
outer end like the fingers of a glove and are connected at their
basal end with round holes leading into galleries in the horn,
where the larvae found their nourishment."

KI-: VI i:\v.s.

GEOGRAPHY.

.4 First Book of Pliysictil Ccoi^rapliy. — B\- W. M.\cli;a\
Caki;v. 4'-in. J^ 7-in. Pp. viii + 150. 57 figures.

(Macmillan \ Cn.. Ltd. Price 1 0 net.)

This little book is intended to pro\ ide a basis for general
geographv. by explaining the principles relating to land forms,
climate, vegetation, and so on, which control its physical
conditions. The requirements of such examinations as the
Oxford and Cambridge Locals, Londim University Junior
School, and the College of Preceptors have been specially
kept in view. Each chapter is headed by a few suggestions
as to practical exercises for pupils to work at before reading
the text. Following each chapter comes a series of questions
culled from the examinations of the above bodies. The first
five chapters are devoted to the morphological aspects of the
earth. Meteorology occupies the next eight chapters — a pro-
portion of space justified by the author on the ground that
observations on the weather are easily carried out, and form a
valuable training in the methods of science. Remaining
chapters deal with the sea, the structure and movements of
the earth, and the distribution of mankind. In general, the
book seems quite adequate to its purpose. The style is simple
and clear, the facts as a rule unimpeachable. We do not

believe, however, that the tor-scenery of Devon and Cornwall
is due to sand-erosion (p. 10). The book can be recom-
mended to teachers who ha\e to train pupils for the above
examinations.

GEOLOGY.

Principles of CJuinica! Gcoloiiy. — By J. \'. lu.siDN, D.Sc,
F.G.S. 5i-in. A Si-in. 2^2 pages. 42 figures.

iW'hittaker ,.^ Co. 5 - net.)

-Apart from its own peculiar contributions, such as
stratigraphy, geology calls in the aid of many sciences in
unraselling the history of the earth. Geology has therefore
many boundaries with sister sciences. One of these boundaries
is dealt with in the book under review. Dr. Elsden undertakes
to indicate the main points of contact between recent chemical
and phvsical researches and the various problems of geological
chemistry. The title of the book connotes more, perhaps, than
its p.ages contain. Dr. Elsden deals almost exclusively with
the principle of equilibrium in relation to the formation of
minerals from solution, and especially to the conditions
obtaining in igneous magmas. Under the heading of
" Chemical Geology," we are accustomed to put a much wider

November, 1910.

KNOWLEDGE.

459

range of phenomena, such as is covered by Clarke's recent
" Data of Geochemistry." This does not detract, however,
from the real usefulness of the book. Much work has been
done recently in elucidation of the physico-chemical con-
ditions obtaining in rock-magmas and other mineral solutions;
and this adds physical chemistry to the number of sciences
with which the unfortunate petrographer is expected to be
acquainted. He will find all that he wants in Dr. Elsden's
book. Herein are treated the subjects of viscosity, diffusion,
vapour-pressure and surface-tension, as factors of equilibrium,
in their relation to mineralogical and petrological, or as the
author prefers to say, geological phenomena. Other subjects
dealt with are polymorphism, eutectics and solid solutions,
each with their appropriate petrological application. The
book is not intended to be a complete exposition of the
subject, and is therefore not written for the beginner, but for
the mature student. A certain knowledge both of physical
chemistry and of petrology and mineralogy is assumed. Its
chief value is to the student of petrogenetics who needs a
concise manual dealing with physico-chemical theory in
relation to petrology. The book has a somewhat wider range
than is covered by the chapters on this subject in the recent
books of Harker and Iddings. Not the least valuable part of
Dr. Elsden's book is the wealth of references to foreign
literature. Both author and subject indexes are provided.

Tlic Rucks of Huiisfaiitoii ami its Xcighboiirliooil. — By

J. 1~. Jacksox. 5-in. X To-in. 56 pages. Illustrated, i plates

and map.

(Premier Press, Ltd. Price 1'- net, interleaved, cloth ; 6d. net,
paper wrappers.)

This little book is remarkable, if only for the fact that it is
the production of a boy of fifteen. "B.L.," who contributes
Forewords and Afterwords, tells us something of the author's
history and makes an appeal. He says " The author has read
little but geology ; he talks geology, thinks geology. Given a
chance he might make the name of Hunstanton as famous in
the annals of the science as now is Cromarty. But the lad
needs help if he is to do much. He needs books, a petrological
microscope, access to Jermyn Street or South Kensington, and
freedom from the necessity to earn his living as a house-
painter or attendant on beach chairs." This appeal is well
worth sustaining, for the book is an excellent guide, and shews
far less immaturity than the age of the author would lead one
to expect. It is a work of great promise, and. given the chance.
Mr. Jackson will do well in the future. The book is di%ided
into chapters dealing with the various strata, beginning with
recent deposits and ending with the Carr Stone (Lower
Greensand). the oldest rock in the district. Naturally the
famous cliffs and the Red Chalk receive dtJtailed attention.
All exposures are indicated, and lists of fossils given. The
latter are illustrated in several plates. The work thus forms
a very efficient guide to the geology of Hunstanton, and should
be in the hands of every geologist visiting this interesting
district, for his own sake, as well as for the sake of helping a
lad who has thus early shown great aptitude for the science.

Uitii'crsity of California Piihlicatioiis, Bulletin of the

Department of Geology. Vol. 5. No. 29, pp. 41 1-437 : No. 30,

pp. 439-448. 7-in. X 10-in. Illustrated.

(Prices 15c. and 10c. respectively.)

No. 29, by Louise Kellogg, describes the rodent fauna of the
Late Tertiary beds at 'Virgin Valley and Thousand Creek,
Nevada. One new genus and eight new species are figured
from this rich collecting ground.

No. 30. The Wading Birds from the (Quaternary .\sphalt
Beds of Kancho La Brea, California, are described by L. H.
Miller. New species of Ciconia and Grus have been found,
together with Jabiru myctcria (Lichtenstein), Grus
canadensis (Linn.), and Ardea lierodias (Linn.). The fossil
forms of these seem to be smaller than their living relatives in
the Western Hemisphere.

MEDICINE.

Diseases of the Skin. — By Erxest Gatcher, translated

and edited by C. F. Marshall, M.Sc, M.D., F.R.C.S.

6-in. X 9-in. 460 pages.

(John Murray. 15 - net.)

This book is in the main a translation by Dr. C. F. Marshall
of the volume on Diseases of the Skin, written by Professor
Gaucher in collaboration with other authorities in the Nonvcaii
Traite de Medecine. It gives a very clear account of the
subject, and is thoroughly up to date. The illustrations,
reproduced from photographs of the actual diseases and fron>
those of wax models in the St. Louis Hospital Museum, are
also for the most part excellent.

To the ordinary reader it is probable that the section
dealing with the treatment by radium and X-rays will probably
appear most interesting. We have heard so much recently of
the marvellous curative eff'ects of these agents on cancer of
the skin and other org.ms that the opinion of one of the
foremost of French authorities on skin diseases, practising
where the radium treatment has been tried more thoroughly
than anywhere else, cannot fail to claim attention. This is
what Professor Gaucher says ; " It is necessary to deal with
radiotherapy at some length because it is the treatment in
vogue, but it does not appear to me to be notably superior to
the older methods of treatment for cutaneous epithelioma "
(cancer). The radium treatment is a new treatment, and
there is a tendency to expect too much from it. The above
quotation from Professor Gaucher's recent work may therefore
be usefully remembered by those interested in this subject.

Lessons on Elementary Hygiene and Sanitation, with

special reference to the tropics. — By W. T. Prout, C.M.G.,

M.B., CM. iFdin.l 5i-in. X 8|-in. 159 pages.

(Messrs. J. ^; .^. Churchill. Price 2 6 net.)

The subject-matter of this volume takes the form of fourteen
lessons which are written in lecture style, and would appear
to have been originally delivered at Freetown, Sierra Leone,
for examples from this town are constantly recurring in the
text. Everything of \alue. usually to be found in a book of
this description, is here included — in particular there is an
excellent account of bacteria and the diseases which they
cause. But the special feature of the book is the clear
description which it contains of the special diseases of the
tropics. Thus two lessons are devoted to Malaria, and besides
this, sleeping sickness, yellow fever, and many other tropical
diseases are fully dealt with. The lessons are exceedingly
clearly worded and should be understood by ever.vone. and
the suggestions for preventive treatment are above all things
practical. There nnist be a very considerable need for a book
of this kind, and the present volume exactly meets it.

MINING.

First StepsiiiCoa! Milling.— ByA\,EX.FORBES. M.IxsT.M.E.
5-in.x7'-in. Pp. viii 4- 320. Illustrated.

(Blackie \- Sons, Ltd. Price 2,6.)

This book is for the use of pit-lads, from twelve to sixteen
years of age, in supplementary and continuation classes, and is
intended to give them instruction in the subject of their
calling and the rules framed for their safety. After an intro-
ductory section, the first eight chapters are devoted to geology,
especially such as is necessary to understand the formation
and occurrence of coal. In general this is well done, but there
is one serious misstatement which calls for correction in any
future edition. In the table of formations (p. 91), the
Archaean or Pre-Cambrian is made a mere sub-division of the
Palaeozoic. The same error occurs in the text. The stratified
rocks are divided into Palaeozoic. Mesozoic, and Cainozoic ;
but the student is not made aware that the Archaean base on

460

KNOWLEDGE.

November, 1910.

which the Palaeozoic. Mesozoic and Cainozoic rest, probably
represents a longer period of time than these three groups put
toijether. If it were intended to restrict the reference to the
fossiliferous rocks, then Pre-Cambrian or Archaean might
have been omitted from the stratigraphical table altogether.
Figure 56 is intended to give an idea of the appearance of a
granite, but actuallv it represents a granite-porphyry, a rock
of somewhat different aspect. The remainder of the book is
occupied with the technique of coal-mining. The methods of
proving, reaching and working the coal, the use of explosives,
the means of ventilating and lighting the shaft and workings,
the raising and preparation of coal for the market, are
expounded in simple language and with the aid of numerous
diagrams. Four chapters on elementary chemistry and physics
are intercalated in this part, which concludes with a chapter
on such miscellaneous subjects as electricity, surveying,
accidents, rescue appliances, ankylostomiasis, and baths. The
whole of this technical description, in which the author is on
his own ground, is excellently done. The style is clear and
direct, well suited to the type of boy for which the book is
intended. Further points for commendation are the freedom
from misprints, and an adequate index. No better book could
be taken up in the supplementary and continuation classes in
which pit-lads receive some training in the principles under-
lying their work, and we agree with the remark in the preface
that such instruction tends to reduce the deplorable number
of fatal and serious non-fatal accidents in the mines.

The Bearing of Recent Theories on flie Xattire of the

Earth's Interior upon the Question of Deep Mining. — Bv

Professor E. H. L. Schwarz, A.R.C.Sc, F.G.S. Soiitli

African Journal of Science. .April, 1910. pp. 234-241.

(South .\frican Association for the Advancement of Science.)

This paper is really a condensation of the author's daring
speculations on the nature of the interior of the earth which
were more extensively developed in his Causal Geology. He
is a whole-hearted supporter of Professor T. C. ChamberUn's
Planetismal Hypothesis. The earth's crust is believed to be
self-heating by means of various chemical reactions, radium,
and frictional heat, and is supposed to rest on a solid nucleus
which is probably near the temperature of outer space. On
this theory the temperature gradient in the crust will increase
downwards until a certain limit is reached, and beyond that
there will be a decrease. The author finds confirmation
for this idea in the low temperature gradients of South .Africa,
an ancient denuded region (the stalk end of Jean's pear-
shaped globe), which has not been covered by the sea
for an immense period, and therefore represents as deep a
part of the crust as can be got anywhere on the earth.
In view of the abov-e theory, the old objection to deep-
level mining on the score of temperature is disposed
of — in South Africa, at any rate. Whilst we do not endorse
many of the ideas contained in this paper, it is interesting to
find the problems of the earth's interior and origin so fully
and freshly discussed in South .\frica.

PHYSICAL CHFNHSTKV.

The Relation between Chemical Constitution and some

Physical Properties. — By Samuel Smiles, D.Sc.

pp. xiv. 4- 5S3. Crown 8vo. 7?-in. X 4i-in.

(Longmans. 14 -.)

This book forms one of a series edited by Sir William
Ramsay, of which ten \-olumes have already appeared, while
four more are announced as in preparation. The immense
development of the Physical side of Chemistr)- in recent years
is remarkable, and Dr. Smiles' book is itself a miiie of
information about the work done in certain directions, which
it would be difficult to obtain from the orignnal sources for any
chemist who did not know exactly where to look. As the
author points out in his preface, the relations between con-
stitution and optical rotation, electric conductivity and heat of

combustion are dealt with in other volumes of the series.
Crystalline form has been omitted as requiring a \olume to
itself. But the student who wishes a statement of the present
state of knowledge on the relation of chemical constitution
to capillarity, viscosity, specific heat, volume, fusibility, boiling
point, refractive and dispersive power, absorption, fluorescence,
magnetic rotation, and electric absorption, will find in this
book abundant information, with many references to the
original sources. The author is careful to state that he has
written from the standpoint of the organic chemist.

.4 Te.xt-hool; of Physical Chemistry Theory and

Practice. — By Arthur W. Ewell, Ph.D. pp. ix. 4- 370.

Si-in. X 5i-in.

Ij. and A. Churchill. 9 6 net.)

This book is written for .American students who have been
through the College course of elementary physics, chemistry,
and m,atheniatics. It will serve as a laboratory manual, and a
book of reference. The ground covered is very wide, and the
te.xt is intended to be supplemented by lectures ; but the
business-like brevity and conciseness of the statements and
explanations show the hand of an experienced teacher, and we
can imagine the book proving extremely useful to an English
student who wishes to revise old work, at the same time that
he is continuing his laboratory practice. The range of the
book may be gathered from the statements that it contains
sixty-three tables, that the subject matter ranges from the use
of the balance to radioactivity, and that sixty experiments and
twenty-nine collections of problems are included.

Physical Chemistry : its bearing on Biology and Medicine.

—By James C. Philip, M.A., Ph.D.. D.Sc. pp. vii. 4-312.

7.J-in. X 45-in.

(Edward .\rnold. 7 6 net.)

This book is intended for students of biology and medicine
who wish to obtain a grasp of the fundamental principles
underlying the application of the methods and ideas of physical
chemistry to physiological and biological problems. It has
grown out of a course of lectures delivered to such students
in the University of London, and appears admirably adapted
for its purpose. Naturally stress is laid on such parts of the
subject as osmosis, permeability of membranes, colloidal
solutions, etc., which have a special bearing on the problems
in question, and the treatment is, as far as possible, non-
mathematical. The style is clear and easy.

PHYSICS.

Wonders of Physical Science. — By E. E. Fourxier. B.Sc.
7-in.X4n^-in. Pp. viii. 4- 201. 77 Illustrations.

(Macniillan & Co. Price 1,6.)

This is one of a projected Series of Readable Books in
Natural Knowledge. To quote from the publishers' note " An
intimate knowledge of the simplest fact in Nature can be
obtained only by personal observation or experiment . . .
but broad views of scientific thought and progress are secured
best from books in which the methods and results of investiga-
tion are stated in language which is simple without being
childish." In this little volume, which is intended to promote
interest in physical science, there are seventeen chapters, each
of which contains a bright and brief history of some
important discovery. The chapters on Archimedes, Dr.
Gilbert, the .\n Pump and the Electric Telegraph strike us as
particularly fresh, and indeed the whole book is admirably
suited to its purpose. In the chapter on Arabian Days we
find no reference to the Arabic numerals which have made
physical calculations possible ; and perhaps more might have
been made of Faraday's life and example in the chapter which
is headed by his name. The final chapter on Airships and
Flying Machines is somewhat unnecessary in a book of this
kind.

November, 1910.

KNOWLEDGE.

461

ZOOLOGY.

Threads in the Web of Life. — By Margaret R. Thomson

and J. Arthur Thomson'. 4T-in. x 7-iii. 198 pages.

72 figures.

(Macmillan & Co. Price Is. 6d.)

" Threads in the Web of Life " belongs to the same series
as the book last noticed, and, like it. is intended to promote an
interest in science in a way quite different from laboratory
guides, text books, or works of reference. Our readers ha\e
been long familiar with the fascinating way in which Professor
Thomson is able to put his facts before us, and in the
production of the little volume imder consideration he has

successfully collaborated. The book is very skilfully planned
to suit its special purpose. It begins with an account of
man as a hunter, which must appeal most strongly to the
interest of the reader, and proceeds through the consideration
of domesticated animals which are well known and of value to
man, to the flesh-eating forms with which he has had to
struggle, and those that destroy his crops. The balance of
nature, which it is so important not to upset, comes in for
attention, and as an instance of the scientific spirit which
leads men to devote their lives to the advancement of natural
knowledge, Pasteur and his work, are considered. This
" readable book in natural knowledge " is one from which e\ery
nature student should obtain inspiration and new interests.

QUERIES AND ANSWERS.

Readers arc invifc{,

I to send in Questions and to ans-u'cr the Queries which are printed on this page.

13. THE FINDING OF TIME AT NIGHT.— F.R.A.S.
asks whether he may repeat Question 2. which is as follows : —
Without instruments, books, or knowledge of the compass
bearings, how can time be found appro.ximately at night ? The
substance of it is asked of boy scouts who desire to obtain the
Star Badge of Astronomy ; as it seems a question which
would be more suitable for University examinations and is
unfair to boy scouts it would be interesting to learn what
answers our readers would give.

14. SIGHT AND HEARING.— Which is the quickest,
sight or hearing ?

F. P. H.

15. E.\RTH TIDES. — Has any account appeared other
than that of Mr. Hardcastle in the September number of
" Knowledge " of Dr. Becker's work ? I am anxious to
follow up the subject and should be grateful for any
information.

T. E. HODGKIN.

16. ST.\R ATLAS. — The enquirer would be glad to know
if any amateur astronomer could refer him to a simple and
reasonably priced Star Atlas giving particulars of the R.A. and
Dec. of the principal objects of interest in the constellations
visible in the northern hemisphere. Owing to short sight and the
usual unsatisfactory atmosphere, the writer finds some difficulty
in picking up the various objects from "" Serviss's Pleasures of
the Telescope." The difficulty would be almost entirely
overcome if the book referred to gave declinations only, as
with an equatorial with a declination circle it is a fairly
simple matter to find an object, knowing the constellation in
which it should be. The ideal atlas for the amateur having a
telescope with or without divided circles should satisfy the
following main requirements : —

1. Portability for use outdoors and fairh- large print.

2. Whole page map of each constellation with small portion
of the surrounding constellations, the map being as near as
possible to the descriptive matter.

3. Each constellation to be shown and described in the
rotational order in which it becomes visible.

4. The R.A. and Dec. and short pithy descriptions of each
sufficiently important object of interest.

Reflector.

17. METEOK AT HONOR OAK.— On September 19th.
at exactly 11 p.m.. at Honor Oak Park, a magnificent Meteor
of a yellowish tint travelled in direct line from N.E. to S.W.
leaving a fairly developed tract along the entire line. Radiated
almost directly under Cassiopeia, took four seconds from
appearance to disappearance. .-Vny other information would be
interesting. Brilliance, double that of Jupiter at his best.

W. B.

IS. STARS BY DAYLIGHT.— On page 63 of Sir John
Herschel's " Treatise on Astronomv " he states that stars are

\isible by daylight from the bottom of a deep narrow pit. such
as a well or shaft of a mine.

Professor Maunder in "' Astronomy without a Telescope,"
page 240. mentions this assertion of Sir John's, and suggests
that a first-hand scientific testimony of an observer is still to
seek ; by scientific testimony meaning the day, hour and
minute when the star is seen, the latitude of the place, the
depth of shaft and the breadth of its mouth. Professor
Maunder says, " There must be not a few . . . who could
report " I have seen such a star at such a time,' or ' I have
watched for such a star at the time of its transit across the
zenith on so many occasions . . . and could see nothing '."

19. THE PLANET NEPTUNE. — Would any of our
friends who are fond of the study of Astronomx- and follow
the orbital motion of the Planets kindh' inform me if the
calculations with regard to the orbit of Neptune agree with
those made shortly after the discovery of the Planet in 1846.
The distance given in the various books on .Astronomy is so
much at variance with the "formula of Bode" that it does
not seem to follow the order of the other Planets. The distance
of Jupiter to Saturn is almost double; again, the distance of
Saturn to Uranus is almost double, but that of Uranus to
Neptune does not bear anything like the same proportions.

W. C. Dixon.

20. THE DISTANCE OF THE EARTH FROM THE
SUN. — Would some reader inform me if a reward has ever
been offered for the discovery of a more accurate means of
determining the distance of the Earth from the Sun than by
the obser\ation of the transit of Venus, or by means of the
minor Planets? Professor Newcomb, says : — ".•^s we before
observed we cannot ascertain the distance of the Earth from
the Sun within a few hundreds of thousands of miles."
Sir R. Ball, says : — '" These circumstances make it difficult to
determine the distance of the Sun from observations of the
transit of Venus with the accuracy which modern science
requires. It seems therefore likely that the final determination
of the Sun's distance will be obtained in quite a different
manner." Sir R. Ball, also says : — " The transit of Venus can-
not be described as a very striking or beautiful spectacle. It is
not nearly so fine a sight as a great comet or a shower of
shooting stars. Why is it then that it is regarded as of so
much scientific importance? It is because the phenomenon
helps us to sohe one of the greatest problems which has e\er
engaged the mind of man. By the transit of Venus we may
determine the scale on which our solar system is constructed."
When it was considered desirable to ascertain a correct mode
of ascertaining the longitude at sea a large reward was offered ;
surely the distance from the Sun, on which all the other data
are based, is a matter of great interest to the scientific world
and should be worthv of a like reward.

W. C. Dixon.

462

KNOWLEDGE.

NO\EMBER, 1910.

REPLIES.

7. SCIENTIFIC IDEAS OF TO-DAV.— There are
probably many readers who will sympathise with the ditficulty
e.\perienced by your correspondent " Perplexed." The truth
at the present time is that hardly anything is known for
certain about the formations of the radiating systems
associated with the atoms and molecules of a body reflecting
light.

The complexity of optical phenomena calls for the detailed
investigation of special cases before it is possible to do more
than generalise. The problems of radiation are now in the
process of solution, and such notable advances as the discovery
of the Zeeman effect are gradually throwing some light on the
question of the forms of orbital or other motion performed by
the radiating electrons ; but there is a very great deal to be
done before any definite statement of what occurs in special
cases can be made with safety — until then only the most
comprehensive generalisations are possible.

The formation of mental pictures of the processes in\ olved
in the radiation and reflection of light is a great help to under-
standing them, but, in the present state of our knowledge, such
pictures must not be too definite and rigid ; there must be
ample room for modification. I am sure that the author of
Scientific Ideas of To-Day. will agree with me that we
cannot yet form any adequate idea of the motions performed
by the electric charges in a body which is reflecting light.
The book in question, being a popular treatise, contains some
forceful, and. I think, skilful descriptions and analogies. The
temptation in writing such a work is probably towards too
definite a form of statement, but where emphasis and
simplicity of illustration are essential in order to make the
subject as clear as possible to readers who have no special
scientific training, it is hard to see how this can be altogether
avoided. Personally, I would congratulate the author on his
generally successful attempt to accomplish an admittedly
difficult task.

To turn to the special difficult^' mentioned by your
correspondent, I will point out that in the case of solids we
have to deal with more or less complex molecular aggregates.
The effect of increased temperature in many cases is to
modify and partialK- break down such groupings into simpler
forms. The selective reflection of incident waves of any
particular frequency seems to depend on what may be termed
the " laxity " of the electron system in the reflecting body.

Stated somewhat crudely, the question becomes one of the

natural period of oscillation of the electric charges within the
complicated molecular groupings as related to the periods of
the mixed incident radiation. If, now, we break down or
otherwise modify these molecular aggregations, the " tuning "
of the whole system is altered, and the freedom of excursion
of the receptive electrons is affected either on the side of
increased or decreased frequency. We do not know in such
cases the distribution and subsequent redistribution of the
restraining forces which come into play in controlling the
movements of the electrons, and the acquisition of such
knowledge is one of the problems for future science to
endeavour to solve. In the case under consideration — the
double iodide of mercury and silver — I would put the matter
thus: — Increase of temperature to about 110° F. results in
partial dissociation of the molecular groupings which were
characteristic of this compound at normal temperatures. As
a result, a different electron system or arrangement is instru-
mental in the selective reflection of light, in this case the
period being longer.

I \euture to think that we can form a more definite concep-
tion of the probable interior structure of an atom as made
evident by the phenomena of radio-activity, than we can of
that particular radiating portion of it which is responsible for
the emission of light-waves, or of the complex groupings of the
electrons bound up in molecular aggregates on which selective
absorption and reflection depend. The electro-magnetic
theory tells us this: — That light (and similar radiation) is due
to electro-magnetic disturbances, periodic in space and time,
propagated in the ether of space, and that these waves
are originated by the oscillation of electric charges about a
mean position, or position of equilibrium within the radiating
body. From such a broad generalisation, science is proceed-
ing to the investigation of special cases. A host of facts have
to be embraced in any future theory of optics which claims an
approach to completeness, but the work already done is a
splendid testimony to the zeal and skill with which the subject
is being investigated, and to the success with which the
enquiry has so far been attended.

Chari.es N\'. Kaffetv. F.R.A.S.

10. \VAT1:K and ITS own level,— Things are said
to be on the same level when they are equally distant from the
centre of attraction of the earth. The radius of the earth
is so large that such things appear to lie in a plane instead of
on a curved surface, and hence a small surface of water appears
to be flat, and the curvature is only seen on a large extent of
surface, such as the ocean.

A. T.

NOTICES.

A PICTORIAL BAROGRAPH CHART.— Mr. John
Browning has published a new form of chart for the barograph.
It is printed in colours, and pictures of clouds have been
introduced with such pleasing effect that a greater interest
will, no doubt, be taken in barometrical records if made with
its llelp.

BRUSSELS EXHIBITION AWARDS.— Among the
scientific instrument makers who have received awards at the
Brussels International Exhibition we notice that Messrs.
Adam Hilger, Ltd., obtained a grand prix for spectroscopes
and spectroscopic apparatus, and Mr. J. H. Steward a grand
prix and gold medal for surveying and militai-y instruments.

THE CAMBRIDGE POCKET DIARY.- We have received
a useful little diary from the Cambridge University Press,
which covers the period of the academical year, nameh- from
September 20th, 1910, to the end of December. 1911. On
one side of the page information useful to members of the
University is given, and the price in roan, limp, with gilt edges,
is one shiUing. A larger diary is also published, each sheet
of which, measuring ten inches by eight inches, contains
seven days, and the price is one. shilling net.

NATURE-STUDY LANTERN SLIDES.— We are pleased
to notice the series of slides made by Mr. Holmes, of Rochester,
of which he has submitted a number to us. They illustrate
trees and their life-history, mammals and birds' nests and
many British plants. The slides are really excellently turned
out and the only criticism that we may offer is that the parts
of plants, at any rate, are too large, and remind one of crowded
plates rather than nature photographs. We would suggest
that the effect would be better, and greater justice done to the
photographs if a little more margin were left.

LEWIS'S CIRCUL.ATING SCIENTIFIC LIBRARY.—
We have received from Mr. H. K. Lewis, 136, Gower Street,
W.C., a copy of the list of new books and new editions added
to the library during July, August, and September, and find, as
usual, that it includes every book of any importance published
during that period. We ha\e previously called the attention
of readers of " Knowledge " to the great utility of this library,
providing access, as it does, to all books on scientific subjects
for a comparatively nominal subscription. The list also affords
a \aluable means of selecting scientific books for purchase, as
it gives full particulars of each one, together with the published
price and postage. It is sent post free on application.

November, 1910.

KNOWLi:n(^,i:

AITCHISON & Co.

Opticians to H.M. Government.
The only makers in the world who have
succeeded in making
Prism Binoculars magni-
fying 25 diameters.

PRICE £12 10 O

with best solid leather case.
W'itii central focussing motion £1 extra.

Every Glass Tested at the
BRITISH GOVERNMENT
LABORATORY AT KEW,
and Certificate of Power, Defi-
nition, &c., signed by Dr.
R. T. Glazebrook, F.R.S.,
the director, is given with the
Glass to Purchaser.

The Night and Day Marine Wide Aperture Prism Glasses.

X 9 MAGNIFICATION £6 10 0 x 16 MAGNIFICATION £8 10 0

X 12 MAGNIFICATION £7 10 0 x 20 MAGNIFICATION £10 10 0

X 25 MAGNIFICATION £12 10 0

With ijenl:al iV.t u--i;i.; m >ll n £1 exlr.i.

Prices include Best Solid Leather ^silng Case, postage an packing to .'my

part of the World.

/'?-/<(■ Lisf o^ Ptisi't a)td other Binontttus l^o'^f F'it\

AITCHISON & Co.

Opticians to H.M. S: L.S.A. floifs..

428, STRAND, and Branches, LONDON. J

bSIb

TRADE MARK

Lewis's Circulating!

Medical and

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tjvering the subjects .f Astronomy, Bio!og:y, Botany, Chemistry,

Electricity, Engineering.Geography. Geology. Microscopy, Mining,

Philosophy . Physics, Physiology, Sociology, Technology. Travels,

Zoology. iScc. in aJuition to Every Branch of Medical Science.

A'eu'

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Works aad Sew Editions are added to tiie Library
immediately on publication.

Subscription. Town or Country, from 21s.

The Library Reading Room i- j -n daily for the use of .Siih>ci ibti,-..

I London: H. K. LEWIS, 136, Gower Street, W.C.

^^ BOOKS IN ALL DEPARTMENTS OF LITERATURE.

mm^mm^

THOTOMICROGRAPHY'

Containing a discussion of ihe considerations L^overn-

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November, 1910.

CIVIL SERVICE COMMISSION.

FORTHCOMING EXAMINATION.

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BOOKS!

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A Malicgaiiy Case- fur ali<i\c. cuTisisLmg i]|
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for u<^e. Price 52/6.

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Fresh Watcrand Marine Slides.— /'tj/i'ctjn, Hydi-ozoa.

extended as in li'e. beautiful mounts of Medusa ,
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Ohjectives. -A large number in slock from 3-in. to
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Accessories.— Eyepieces, Polariscopes, Sclenite
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Half ,. ., „ O 4 O

I lisi .Hinls for Series of Insertions and Rales for Special

I'nsitions, when \'acant. nn apjilicalion to
Thf Ai)\ ertishmi- n r M,\n\,.ek,

KNOWLEDGE OFFICE,

42, BLOOMSBURV SQUARE. LOSDON, W.C.

November, 1910.

KNOWLEDGE,

Watsons Microscopes.

British made at Barnet, Herts, witli 5 years' guarantee.

The long evenings will soon be with us and a really attractive

and intelligent hobby or means of recreation is wanted by manv.

Have you ever tried a WATSONS' MICROSCOPE?

Vou have scientific tastes and inclinations or you would not
read h'iiow/eiii;e. A Microscope is an ideal means of developing
such. The wealth of information it reveals, the new world it
discloses, the never ending subjects which can l)e examined,
together with the comfortable use of it at the fireside render it
unequalled for home use.

Watsons make more than 20 different Models

At varying prices. They are noted for their permanent working-
quality, and convenience of design.

It is important that a Microscope Stand is selected to which
additions can he made as required.

Watsons' "F " Edinburgh
Student's Microscope

forms an admira.ble base for future
additions. It is a stand of the highest
class that always gives pleasure and
satisfaction.

It is of convenient size, has very rigid
tripod foot, Watsons' Standard Lever
Fine Adjustment; Diagonal Rackwork
for Coarse Adjustment. Large stage,
covered Ebonite.

PRICE.

Stand only

Mahogany Case

STAND ''F" completely
fitted with Eyepiece, i"
and i/6" Parachromatic Ob-
jectives, in Mahogany Case

£5
I

8 7 6

"F' Kd. Student's Microscope,

WriH COMFOLND SlbsTACE.

Compound Substage and Mechanical
Stage can be added at any time.

Full particulars of Watsons* Microscopes are ^iven in their 168 page

Catalogue of Microscopes (2K). which with their booklet. " The choice

of a Microscope." will be sent free on request.

ASTRONOMICAL TELESCOPES.

All interested in A'^tronomy should send fijr Watsons' Catalogue
(6K) which gives information about their instruments and the
celebrated Watson-Conrady Objectives, post free on request.

Watsons' Instruments may be purchased by progressive payments.

SECOND-HAND
ASTRONOMICAL TELESCOPES.

A list of Second-hand Telescopes is Issued monthly. A copy will be
sent on application.

6 inch Equatorial by Giubli. with Clockwork
on Iron Column. Electric Illumination to
Verniers, Telescope for Vernier from Eve
End; original cost, £290. In fine condition

4 inch Equatorial by Cooie &• Sons, on stout
Tripod Stand, with Struts, ij inch Finder,
4 Astronomical and Solar and Pancratic Eye-
pieces, Clamps and Slow Motions ; complete
with Packing Cases. Cost £77 10s. Od. Price

24 inch Reflector Telescope by Grubb, Equa-
torial Stand, Electrically controlled Clock.
Fitted with 6 inch Finder Telescope. Cost
£650 Price

SJ inch Reflector Telescope, with 2 Finders,
Equatorial Mounting and Iron Stand. The
Mirror has recently been re-worked and the
performance is guaranteed. A bargain

£185 0 0

£50 0 0

£375 0 0

£35 0 0

For full particulars of the ahoz'e, also of nianv others^with sundry accessories
a7id fittings^ afpiy to

W. WATSON & SONS, V

(Established 1S37),

313, HIGH HOLBORN, LONDON, W.C.

Works: BARNET, HERTS.
Branch: 16, FORREST ROAD, EDINBURGH.

npnnis- /2- Easy Row, BIRMINGHAM.

uepois. ^jg^ Swanston Street, MELBOURNE, AUSTRALIA.

DENT'S CLOCKS

WATCHES AND CHRONOMETERS

FOR SCIENTIFIC USH.

Sidereal or Mean Time Clocks for
Observatories, £21 and upwards.

THREE GRAND PRIZES
AND ONE GOLD MEDAL

FRANCO-BRITISH EXHIBITION.

The only Grand Prize awarded
to a British Firm for Watches,
Clocks and Chronometers.

The only Grand Prize awarded
for Astronomical Regulators,
Chronog:raphs, and Ship's
Compasses.

TRADE MARK.

61, STRAND, and 4, ROYAL EXCHANGE, LONDON.

Telephone No. 61 City.

V( lU CAN OUT.VIN A

SATISFACTORY TYPEWRITER

For £5.

All Makes — over 200 Machines to Select from.

Call or Write . . .

THE WHOLESALE TYPEWRITER Co., Ltd.,

22, GRAY'S INN ROAD, W.C. (Eleven Doors from HoIborn\
COPYING AND DUPLICATING AT SPECIAL PRICES.

BEST
COCOA

SCHWEITZERS

Kocootina

EARTH.

GUARANTEED ABSOLUTELY PURE SOLUBLE COCOA ONLY

<!:^:S>-::^:------piET'7;'''-''H'-^^

,. ?S a fie i^RINTeO from iy%> ;:;,,

LASCELLESM

MAYBURY STUD/OS, /^M

WILLISDEN CREEN, N.W.

V; TE.LEPHONE No 45, HARLESDEN.

iS\ 4? sff

KNOWLEDGE.

November, 1910.

I ISENTHAL & Co.

I Remember our Specialities:

I Resistances.
■ Volt- & Ammeters.
I High Tension Condensers.
I Electric Heaters.
1 Apparatus for

Wave Telegraphy.

WE MANUFACTURE AT OUR
OWN WORKSHOPS.

(Dept. 2),

85, MORTIMER STREET, W.

Cofiiractors to the Admiralt\\ War^
India^ and Colomal Offices^ ^c.

FLATTERS &GARNETT, Ltd

32, Dover Street,

(Close to the University and Museum),

Telephone: 7845 Centr.ll. IVIanCrieSter , SiEi

Telegr.iins: "Slides," M .inchester.

DEPARTMENTAL \ Any sent post free; please state which is
CATALOaUES. I required.

"A" Microscope Slides-over 40,000 in stock.

"B" Microscopes and Accessories.

Mounting Requisites.

Dissecting Instruments,

Scientific Glassware, &c.

"C" Collecting Apparatus.

Glass Top Boxes,

Pocket Lenses, &c.

"D" Zoological. Botanical & Geological

Models, Specimens, Diagrams.

"E" Lantern Slides— over 25,000 in stock.

F" Optical Lanterns and Accessories.

•P" Photographic Work.

Developing, Printing, Enlarging, &c.

[/\c'ac^y shortly.

FLATTERS & GARNETT, Ltd.

Note abofe o?ily Address.

No connection with any otlter Firm.

I A GIFT OF LASTING INTEREST. |

The " DUPLEX BAROGRAPH

with our new Opal glass dial altachnient, showing present reading of tlie
Barometer in addition to the record on the chart. Very be<t quality, in
solid oak, walnut, or niahoganv case, with bevelled ed^e plate glasses and

chart drawer.

Ink,

Price complete, with a year's supply of Charts
and Instructions.

£6 2

CARRIAGE PAID AND SAFE DELIVERY GUARANTEED IN U.K.

Sole Manufacturers:

PASTORELLl & RAPKIN, Ltd.,

ESTAB.

1730.

ACTUAL MAKERS of all kinds of Meteorological Instruments.

CONTKACTONS TO H . M . GovT.

46, HATTON GARDEN, LONDON, E.C.

Telegrnms : " Raplcin, London." Telephone: 1981 Holborn.

" Illustrated List of Standard Instruments Post Free,

iPV" Special Illustrated List of Barog;raphs and Thermoj;raphs (covering
various patterns, from £3 lOs.) post free.

RED

DELICIOUS COFFEE.

WHITE

&

BLUE

For Breakfast & after Dinner.

In making, use less quantity, it being mucti stronger
than ordinary Coffee.

SECONDHAND

MICROSCOPES AND APPARATUS.

Secondhand ••Discovery" Microscope by Swift, double
nosepiece, 2 eyepieces, ^ and ^ objectives, in case, £5 10s.
Second-hand ^V Oil Immersion by Gowlland, £2 2s.
,, Abbe Condenser and iris diaphragm. £1 Is.

,, Centring Achromatic Condenser and iris diaphragm

in case by Zeiss, £2 10s.
,, Air Pump with bell cover on mahogany base, 18s. 6d.

Pine case of 12 drawers to hold 6 dozen objects, 2s. 6d.
A comprehensive selection of Microscopic Obiects, including Geolof^ical,
Botanical, Anatomical, Minerals, Diatoms, Insect parts, &c., at 6d. each.
The Largest Stock In London of Secondhand Microscopes and
Objectives by all the leading makers, comprising Outfits suitable
for Histology, Bacteriology, Botany, and all branches of Science.

Cataioques /ost free on applicatio}!.

MILLIKIN & LAWLEY, iS^NolSI'^''^

w.c.

Telephone— City J 706.

Printed for the Proprietors (Knowledge Publishing Company, Limited), by John I\.ing, Ealing and Uxbridge. - November, 1910.