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fal analysis of the contents is prefixed to the memoir. Dr. glasses could be affected in this way. On passing a spirit lamp N. Cole (pp. 378-388) discusses the simple groups from behind a strip of mirror, a dark band could be caused to pass r 201 to order 500, and arrives at the conclusion that “the along the screen illuminated by light reflected from the mirror. ible orders of simple groups of compound order between 201 By writing on lead foil and pressing the foil against a glass 500 are reduced to 360 and 432." The volume closes with mirror by a heater, the writing was caused to appear on the te (p. 389) by M. M. D'Ocagne, correcting a slight mistake screen. Prof. Thompson had also found that Japanese mirrors memoir by him in the 1888 volume, entitled “Sur certaines which are not "magic” when imported, could be made so by bes," and the title page and index.

bending them mechanically so as to make them more convex. In conclusion, he showed a large mirror 15" X II", the reflec

tion from which showed the prominent parts of the pattern on SOCIETIES AND ACADEMIES.

its back with the exception of two conspicuous knobs; these LONDON.

knobs gave no indication of their existence. Prof. Ayrton said

the simple mechanical production of the magic property oyal Society, February 2.-"On a Meteoric Stone found

described by Prof. Thompson led him to think that some lakariwa, near Invercargill, New Zealand.” By G. H.

experiments on “seeing by electricity" by the aid of selenium Jlrich, Professor of Mining and Mineralogy in the Uni

cells which Prof. Perry and himself made some years ago, might ty of Dunedin, N.Z. Communicated by Prof. J. W. Judd,

lead to some result if repeated with thinner reflectors. Speak

ing of the effect of scratching the back of a Japanese mirror, he e specimen described in this memoir was found in the year

| pointed out that if metal be removed by pressure a bright in a bed of clay, which was cut through in making a rail.

image was seen, whilst if removed chemically a dark image it Invercargill, near the southern end of the Middle Island resulted. Since the original paper on the subject was ew Zealand. Originally, this meteorite appears to have written he had been led to modify his views as to the about the size of a man's fist, and to have weighed four or effect of amalgamation, for some time ago he showed the ounds, but it was broken up, and only a few small fragments

society how brass bars were bent if one edge be amalgamated, been preserved. The stone evidently consisted originally

thus proving that enormous forces were developed. He now intimate admixture of metallic matter (nickel-iron) and of

regarded amalgamation as an important part of the manufacture. material, but much of the metallic portion has undergone | Mr. Trotter inquired if it had been proved that there was no tion. Microscopic examination of tħin sections shows that

difference in the metal in the thick and thin parts? One would ony portion, which is beautifully chondritic in structure,

expect the thin parts to be harder and polished away less. ins olivine, enstatite, a glass, and probably also magnetite ;

After some remarks by Mr. J. W. Kearton and Major Rawson, hrough these stony materials the nickel-iron and troilite

Prof. Thompson said the magic effects produced by heating stributed. The specific gravity of portions of the stone

the back of a glass mirror remained for a short time after the vund to vary between 3'31 and 354, owing to the unequal

heater was removed. The question of whether differences in ution of the metallic particles. A partial chemical ex.

hardness of the thick and thin parts of a mirror were of tion of this meteorite was made by the author and Mr.

consequence in the production of the magic property had been Allen, but the complete analysis has been undertaken by

py tested by using sheets of brass thickened by pieces soldered to Fletcher, F.R.S., of the British Museum. The analysis,

s, the back as mirrors, and found to be unimportant. Prof. when finished will be communicated to this Society, has

Ayrton also described an experiment pointing to the same con. o far as to show that the percentage mineral composition clusion.-Mr. W. F. Stanley read a paper on the functions of Makariwa meteorite may be expressed approximately by the retina-Oj The Perception of colour. Referring to lowing numbers : nickel-iron 1, oxides of nickel and iron

Young's three-nerve theory of colour-sensation, the author said vilite 6, enstatite 39, olivine 44.

Prof. Rutherford had pointed out that there was no necessity to ysical Society, January 27.—Walter Baily, Vice-Presi assume that different perves conveyed different colour-sensan the chair.- Prof. S. P. Thompson, F.R.S., made a tions, for as a telephone wire would transmit almost an infinite inication on Japanese magic mirrors, and exhibited | variety of sound vibrations, so the nerves of the retina were pus specimens showing the magic properties. Referring probably equally capable of conveying all kinds of light vibra

theory of the subject, he said the one now generally tions. Prof. Rutherford had further pointed out that the image d was that proved by Profs. Ayrton and Perry in 1878, of a star could not possibly cover three nerve-terminals at once, owed that the patterns seen on the screen were due to and therefore could not be seen as white if Young's theory was ices in curvature of the surface. The experiments he now correct. The author then described Helmholtz's experiments t forward fully confirmed their views. Brewster had with a small hole in a screen illuminated by spectrum colours. ined that the effects were due to differences of texture in For red illumination the greatest distance at which the hole faces causing differences in absorption or polarisation, but could be seen sharply defined was 8 feet, and for violet 1} feet.

that the character of the reflected image depended on When the hole was covered with purple glass, or with red and vergency or divergency of the light, and on the position violet glasses superposed, and a bright light placed behind, the icreen, showed this view to be untenable. Another proof eye, when accommodated for red light, saw a red spot with a differing curvature theory was then given by covering a violet halo round it, and when focussed for violet light, saw a le mirror with a card having a small hole in it. On violet spot with circle of red. These experiments the author

the card about, the disc of light reflected from the ex thinks show that the chromatic sense in distinct vision under ortion varied in size, showing that the curvatures of por critical conditions (i.e. where a single nerve or a small group of

the surfaces were not the same. The same fact was nerves is concerned) depends on the colours being brought to by a small spherometer, and also by reflecting the light foci at different distances behind the crystalline lens. He also through a coarse grating from the mirror, the lines being infers that the same focal position in the eye cannot convey distorted. To put the matter to a test demanded by simultaneously the compound impression of widely separated !r, he had a cast' taken from a mirror by his assistant, colours. Helmholtz's observations are further examined in the usseau ; this had been metallised, silvered, and polished, paper, and a series of zoetrope and colour disc experiments dev gave unmistakable evidence of the pattern reflected scribed which tend to show that the eye cannot follow rapid

original. The true explanation of how the inequalities changes of colour. Changes from red to violet could be followed ture were brought about during manufacture had also much more quickly than from violet to red. The red imven by Profs. Ayrton and Perry, but there were some pressions were, however, more permanent. The observed is of detail on which difference of opinion might exist. effects were found to depend on the intensity of the light, and

Prof. Govi had noticed that warming a mirror altered its also on the distance of the eye from the coloured surface. ties. A thick mirror which gave no pattern whilst cold Summing up his observations, the author infers that by systems ed one on being heated, was shown to the meeting. of accommodation of the eye, the colours of the spectrum are rompson also showed that a glass mirror having a pattern brought to focus on special parts or points of the he back developed magic properties when the mirror rods or cones of the retina, such focal points being t. When made convex the reflected pattern was dark equivalent, by equal depths or distances from the crystalline lens, ht ground, and when made concave, light on a dark | to a focal plane formed across the whole series of nerve-terminals.

Warming ordinary mirror-glass by a heater whose sur- That all the rays of light from an object, or part of an object, s cut to a pattern gave similar effects. Very thick of very small area and of any spectrum colour, will converge to

BE

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a point upon a nerve terminal, and that this terminal will be a function of the letters a, di, ag...... ; bong bóng.......
most excited by the light. At the end of the paper Dr. Stanley corresponding to the marks a, b, ...... &c. of the simple
Hall's views of nerve structure are examined. Captain Abney contained in the compound form represented by the grande
thought the results of the zoetrope experiments were what one latter factor being an invariant of the quantics
would have expected when pigmentary colours were used. To
be conclusive, such experiments must be conducted with pure

{ao, Q1, Ang .........62)(x, y):
spectrum colours. The statement about the size of star

(bo, bi, boy . . . . . . ...bs)(x, y)s

&c., &c.
images being less than that of a nerve terminal would pro-
bably need revision. Speaking of colour vision, he said the

where a is the valence of the simple forms of mark a, sbiad modern view was to regard light as producing chemical action

here supposed to be all of the same valence, and similarly a in the retina, which action gave rise to the sensation of colour.

case of B, y, &c. On the author's theory he could not see how colour-blindness

In this second part a method of algebraically represe could be explained. 'Mr. Trotter said he understood Helm invariants is considered, which is directly derivable for holtz to have proved that nerves could distinguish quantity, but

method of the first part, and was suggested by the grads; I not the quality of a stimulus. Since the speed at which stimuli

differs essentially from the earlier method in that it is a travelled to the brain was about 30 metres a second, the wave dent of the use of polar elements. It shows, morcover, thri length of a light vibration, if transmitted in this way, would be graphs may be regarded as absolutely equivalent to the very small. Taking Lord Kelvin's estimate of the minimum ants they represent, in lieu of being equivalent to those me size of molecules of matter, it followed that there must be many

ants multiplied by a number of polar elements. This wa wave lengths in the length of a single molecule. This, he method deals in the first instance with “primary" intus thought, hardly seemed possible. Mr. Lovibond pointed out i.e, invariants of two or more quantics linear in the cei that the observations referred to by the author could be equally / of each. If these quantics are well explained on the supposition that six colour sensations existed. The confusion of colours he had mentioned arose from

(ao, aj, Ag, ... ... ...Q2)(, y)

(oor 61, 62, .........bs)(x, yje lack of light. Mr. Stanley replied to some of the points raised

&c., &c.,
by Captain Abney. In proposing a vote of thanks to Mr.

and we take
Stanley, the chairman said it had been shown that light could
be resolved into three sensations, but it was not known how this

d+ &c. ad infinitas
resolution occurred. Prof. S. P. Thompson said the gist of Mr.
Stanley's paper seemed to be that lights of different colours

b=1 +62 +63 were concentrated at points situated at different depths in the

+&c. ad infinitus.

?db9db, 3 db, retina, the violet falling on the part nearest the crystalline lens,

&c., &c. and the red furthest away. Another view of the action was that the different sensations might be due to the vibrations of we may express any primary invariant by an expression, 311 longer wave length having to travel greater distances along the sum of two or more expressions, consisting of the proce nerve terminals before they were completely absorbed.

differences of the operators a, b, ..... operating upon the

of the corresponding leading terms, aa, bar &c. Thes
Mathematical Society, January 12.-Mr. A. B. Kempe,
F.R.S., President, in the chair.—The President (Prof. Elliott,

(a - b) a,b,=12bo - 2016, taglio
F.R.S., Vice-President, in the chair) read a paper on the appli- is an invariant of the two quantics
cation of Clifford's graphs to ordinary binary quantics (second

amx?+ 2a xy +agja,
part). In the first part it was pointed out that by some small

bazo + 2b, xy +,y,
modifications and a recognition of the fact that the covariants
of f(x, y) are invariants of the two quantics f(X, Y) and linear in the coefficients of each ; and
(Xy-Yx), the theory of graphs, which had been left in an un (a -b)a – cha bocagboto - asbo 1 - 2096263 +24,6,1"
finished state by the late Prof. Clifford, furnished a complete

a buco -2,2-1
method of graphically representing the invariants (and therefore
the covariants) of binary quantics. The method as modified

| is a similar invariant of the three quantics
depends essentially on the fact that any invariant, when multi-

sa, r8 + 3a1x*y + 38.9x2 + avis plied by a suitable number of polar elements U, U',V,V', &c.,

bor + 2b, xy + baja
can be expressed as a “pure compound form" (or sum of two

Portay.
or more such forms), the product of a number of “simple
forms." Each of the latter has a “mark,” viz. one of the

These two invariants are graphically represented by
letters a, b, c,...... and has also a certain valence, 0, 1, 2, 3, &c.
and these being given it is fully defined, e.g., the simple form of
mark a and valence 3 is graphically

respectively, where the relation between the algebraisi graphical expressions is obvious, viz. to every letter algebraical representation there corresponds a nucleus

the mark p, and to every factor (4-9) in the algebraical having three radiating bonds, and is algebraically

tation there corresponds a bond connecting the nudes a, UVW+a, (U'VW+UV'W + UVW') + a, (UV'W'

pand 9. + U'VW' + U'V'W)+ ag U'V'W',

We can pass to invariants of higher degrees in the sky

of the various quantics by substituting like coefficients for
the pairs of polar elements U,U'; V,V'; and W W', corres. | Thus, if we make bo=do, b,=, bo=dy, the prima
ponding to the three bonds of the graphical representation. A
pure compound form is graphically represented by a number of

agbo - 2a76, tagli
simple forms having their bonds connected so that there are no becomes the invariant of degree 2
free ends. If in the algebraical expression of a compound form

2(2012-07)
two simple forms both contain the pair of polar elements U,U', ) of the single quantic
there will be a bond connecting their graphical representations ;

Louita + 2a2xy + av.
if the two simple forms both contain two pairs of such elements,
viz. U,U' and V,V', there will be two bonds connecting their This invariant will be graphically represented by
graphical representations and so on ; if they contain no common the mark a for the mark in the graph representing
pair their graphical representations will have bond connecting sponding primary invariant.
them. A pair of polar elements will appear in two simple If we proceed to deal in the same way with the same
forms only, so that each bond in the graphical representation of

azboco - agbori - 20,0.60 + 2a, 6161 + cena - **) a compound form corresponds to a distinct pair of polar ele. ments. If the algebraical expression corresponding to a graph

| we get, as the invariant represented by substituting fix be multiplied out, it will be found to consist of two distinct

| b and c the mark a, the expression of the third degree factors, viz. :-(1) the product of all the polar elements, and (2)

aza,a - 3494jam + 2a;

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and

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This is not an invariant of a single quantic, but of the is no sensible difference. These two classes include all that

have much physical importance. The remainirig types can be Ayrs + 39,74y + zagry2 + azpis

classified as :--Class III. Extensional vibrations. -The motion Ora + 2a +y + a,12,

may be purely radial or partly radial and partly tangential. In apr + ay'.

the second case there will be an integral number of wave: bears, however, a definite relation to the first of these

lengths, and when this number is n we have the formula for the e quantics, viz. : it is a seminvariant of that quantic, being

frequency act the source of its cubic-covariant J. The paper points

p2 = (1 + 112, ! that all seminvariants are thus invariants of two or more atics, and can therefore be represented by graphs; the Putting n = zero we find the frequency of the purely radial rence between a graph representing an invariant of a vibrations. The pitch of any mode of extensional vibration of atic and one representing a seminvariant of the same quantic the ring is of the same order of magnitude as the pitch of the isting merely in this, that the simple forms, i.e. the small corresponding longitudinal vibration of a bar of length equal to es or nuclei of the graphs in the former case are all of the half the circumference, the formula for the latter being in fact

“valence," i.e. have the same number of bonds, while in derived by writing n' for I + n2. Class IV. Torsional vibralatter, though of like marks, they differ in valence. The tions.—The motion consists of an angular displacement of the ification of seminvariants, according to the valences of the sections about the elastic central-line accompanied by a relale forms composing them, or, in other words, according to tively very small displacement of the points on this line perOrders of the quantics of the systems of which they are re- pendicular to the plane of the ring. When there are n wavetively invariants, obviously throws considerable light upon lengths to the circumference the frequency is given by the structure,

formula he paper also deals with the breaking up of graphs into ler ones; and gives a theorem upon the subject which leads

p2 = (1 + 0 + 122) a,

PO me interesting results. It points out, moreover, how the

in which w is the rigidity of the material. There is one symhs representing the sources of covariants can be instan

metrical mode for which n is zero, and since 2u (1 + 0) = E, pusly derived from those representing the covariants them

the frequency of this mode is Ñ 2 of that of the radial vibra1 the evaluation of a certain surface-integral and its applica.

tions. The pitch of the torsional vibrations is comparable with

that for a straight rod of length equal to half the circumference, to the expansion of the potential of ellipsoids in series, Dr.

the formula for the latter being in fact derived by writing no in son. the vibrations of an elastic circular ring, by Mr. A. E. H.

place of 1 tot 11. Formulæ equivalent to those given in

connection with Classes II. and IV. have been obtained by Mr. --The ring is supposed to be of small circular section of

Basset (Proc. Dec. 1891), but he has not interpreted his results. is (, and the elastic central-line a circle of radius a. There jur ways of displacing the ring. A point on the central-line

Entomological Society, February 8.-Mr. Henry John move along the radius of the circle which is its primitive

Elwes, president, in the chair.-- The President announced that or perpendicular to the plane of this circle, or along the

he had nominated Mr. F. DuCane Godman, F.R.S., Mr. 'nt to this circle ; and the circular sections may be dis

Frederic Merrifield, and Mr. George H. Verrall as Viced by rotation about the central-line. The modes of vibra.

Presidents during the Session 1893-1894.-Mr. S. Stevens exfall into four classes, of which two are physically import

hibited a specimen of Chærocampa celerio, in very fine condi. -Class I. Flexural vibrations in plane of ring.–These

tion, captured at light, in Hastings, on September 26 last, by investigated by Hoppe in 1871 (Crelle, bd. lxxiii.). The

Mr. Johnson.—Mr. A. J. Chitty exhibited specimens of Gib. in of a point on the elastic central line is compounded of a

bium scotias and Pentarthrum huttoni, taken by Mr. Rye in a icement in and out along the radius and a displacement along

cellar in Shoe Lane. He stated that the Gibbium scotias lived ingent to the circle, so proportioned that the central-line

in a mixture of beer and sawdust in the cellar, and that when ins unstretched, and the nodes of the former displace.

this was cleaned out the beetles disappeared. The Pentarthrum are the antinodes of the latter. There must be at least

huttoni lived in wood in the cellar. -Mr. McLachlan exhibited vave-lengths to the circumference, and the frequency (P/2)

a large Noctuid moth, which had been placed in his hands by mode in which there are n wave-lengths to the circumfer

Mr. R. H. Scott, F.R.S., of the Meteorological Office. It is given by the equation

was stated to have been taken at sea in the South Atlantic, in

about lat. 28° S., long. 26° W. Colonel Swinhoe and the Lin" (n2 - 1)2 E c?

President made some remarks on the species, and on the migrana + 1 Po at

tion of many species of Lepidoptera.-Mr. W. F. H. Blandford ich E is the Young's modulus, and po the density of the

exhibited larvæ and pupæ of Rhynchophorus palmarum, L., ial. Except for the numerical coefficient this is precisely

the Gru-gru Worm of the West Indian Islands, which is eaten ir to the formula for the lateral vibrations of a straight bar

as a delicacy by the Negroes and by the French Creoles of same material and section and of length ta (for which the

Martinique. He stated that the existence of post-thoracic stig. mental tone has the same wave-lengths). The sequence

mata in the larva of a species of Rhynchophorus had been nponent tones when n is very great is ultimately identical

mentioned by Candèze, but denied by Leconte and Horn. that of the tones of a free-free bar of length ma, but the

They were certainly present in the larva of R. palmarum, but nce for the low tones is quite different to that for a bar.

were very minute. ---Mr. G. T. Porritt exhibited two varieties of II. Flexural vibrations perpendicular to the plane of the

Arctia lubricipeda from York ; an olive-banded specimen of - It is found to be impossible to make the ring vibrate

Bombyx quercus from Huddersfield ; and a small melanic so that each particle of the elastic central-line moves per

specimen of Melanippe hastata from Wharncliffe Wood, Yorkcular to the plane of the ring, unless at the same time the

shire.—Mr. H. Goss exhibited species of Lepidoptera, Coleopns turn about the central-line through a certain angle.

tera, and Neuroptera, sent to him by Major G. H. Leathem, lexure perpendicular to the plane of the ring is always

who had collected them, last June and July, whilst on a shootpanied by torsion. As in Class I. there must be at least two

ing expedition in Kashmi territory, Bengal. Some of the lengths to the circumference, and the frequency of the

specimens were taken by Major Leathem at an elevation of in which there are n wave-lengths to the circumference is

from 10,000 to 11,000 feet, but the majority were stated to have by the equation

been collected in the Krishnye Valley, which drains the glaciers

on the western slopes of the Nun Kun range. Mr. Elwes reA2 = 1 n' (n2 - 1)? E ? Ito + no po a*

marked that some of the butterflies were of great interest.

Mr. G. F. Hampson exhibited a curious form of Parnassius, ir is the Poisson's ratio for the material and the other taken by Sir Henry Jenkyns, K.C.B., on June 29 last, in the ints have the same meaning as before. (For most hard Gasternthal, Kandersteg.-Mr. J. M. Adye exhibited a long o is about 1.) Since n must be at least 2 the sequence of series of remarkable varieties of Boarmia repandata, taken last is very nearly the same as in the vibrations of Class I., July in the New Forest.--Mr. C. O. Waterhouse exhibited a le pitch is slightly lower, the ratio of the frequencies for photograph of the middle of the eye of a male Tabanus, showravest tones being J

N
2

ing square and other forms of facets, multiplied twenty-five
, which is very little less
20'

times. -Mr. R. Trimen, F.R.S., communicated a paper entitled I comma. For the higher tones, as we should expect, there | "On some new, or imperfectly known, species of South African Butterflies," and the species described in this paper were ex gr. (350° 10 450°). (5) Pure tin 1000 gr. ; pure nickel 10: hibited.-Mr. T. D. A. Cockerell communicated a paper gr. (350° to 450°). These give a slightly yellowish titt, bars entitled “Two new species of Pulvinaria from Jamaica." — very durable. (6) Pure tin 900 gr. ; copper 100 gr. ; bisturb : Mr. Martin lacoby communicated a paper entitled “Descrip. 3 gr. This is specially suitable for soldering aluminium brocktions of some new genera and new species of Halticidæ."

Action of acetic acid and formic acid upon terebenthine, bir Linnean Society, February 2.- Prof. Stewart, President,

Bouchardat and Oliviers.-On the mode of eliminata in the chair.-On behalf of Mr. Thomas Scott, the Secretary

carbonic oxide, by M. L. de Saint-Martin. Experiment the read a report on the entomostraca from the Gulf of Guinea,

that animals partly intoxicated by carbonic oxide, when pie collected by Mr. John Rattray.-Mr. H. Bernard gave an

in conditions under which natural elimination is imposis account of two new species of Rhax.- An important paper by

destroy slowly but regularly a certain quantity of the posts Mr. Arthur Lister, on the division of nuclei in the mycetozoa,

gas, this destruction being the more active the less the icon gave rise to an interesting discussion, in which Dr. D. H.

tion. It is probably converted into carbon dioxide. The Scott, Prof. Howes, and others took part.- This was followed

effect is entirely dependent upon the time during whida by a paper on the structural differentiation of the protozoan

organism is exposed to the gas, and a very small quantity cps body as studied in microscopic sections, by Mr. J. E. Moore.

fatal on prolonged exposure. -Influence of pilocarpine and this The meeting adjourned to February 16.

zine on the production of sugar in milk, by M. Comeria – the seat of the colouring matter in the green oyster,

Joannes Chatin.-On pseudo-fertilisation in the Uradi, PARIS.

MM. P. A, Dangeard and Sapin-Troufily.-On the substans Academy of Sciences, February 6. — M. de Lacaze formed by the nucleole in Spirogyra setiformis, and the for Duthiers in the chair.-On the variations in the intensity of i force which it exerts upon them at the moment of the bo terrestrial gravitation, by M. d'Abbadie. Observations begun of the cellular pucleus, by M. Ch. Decagny.-On a procesi in 1837 at Olinda (Brazil), on the variations in the direction of measuring the double refraction of crystalline plates, gravitational force also made its constancy doubtful. Experi. Georges Friedel. --A horizontal section of the French also ments on falling bodies revealed irregularities similar to those M. W. Kilian. --On the arrangement of the cretaceous best described (last number) by M. Mascart. The closed barometer the interior of the Aquitaine basin, and their relations so ter employed by the latter may be termed a brithometer.-On the formations, by M. Emmanuel Fallot. preparation of carbon under high pressure, by M. Henri Moissan (see article). - On the reproduction of the diamond, by M. C. Friedel. Remarks by M. Berthelot (see article).- On the

CONTENTS. pathogeny of diabetes ; part played by the expenditure and the

Qualitative Chemical Analysis. By Chapman Jope : production of glycose in the deviations of the glycemic function,

Popular Lectures on Physical Subjects. By Di by MM, A. Chauveau and Kaufmann. The same inferiority of

James L. Howard .. venous with respect to arterial blood, as regards the amount of British Jurassic Gasteropoda. By H. Woods. 7 sugar contained in it, occurs in all the deviations of the glycemic

Our Book Shelf:function produced by a lesion of the central nervous system.

“ The Year-Book of the Imperial Institute of time This inferiority is equally pronounced in the hyperglycemia re

United Kingdom, the Colonies, and lodia" .. sulting from the extirpation of the pancreas.-On the progress of

Barber : “Beneath Helvellyn's Shade" ..... * the art of surveying with the aid of photography, in Europe and

Letters to the Editor :America, by M. A. Lausedat. Since 1888 a zone of twenty miles

Dr. Joule's Thermometers.-Prof. Arthur Schuster, on each side of the Canadian Pacific Railway, in the neighbour

F.R.S. .....:::: hood of the Canadian National Park, has been surveyed with Dust Photographs and Breath Figures.-W. B. the aid of photography under the direction of Messrs. Deville, Drewry, and McArthur, at an average rate of 1040 square km.

Fossil Plants as Tests of Climate.-J. Startis per annum for four men under great climatic disadvantages. The

Gardner .....::::: cost of the undertaking amounts to three dollars per square km. An Optical Phenomenon.-Joseph John Murphy --Determination of the amount of carbonic oxide which can be Foraminifer or Sponge ?—R. Hanitsch , contained in confined air, by means of a bird employed as Unusual Origin of Arteries in the Rabbit.-Philip physiological reagent, by M. N. Gréhant.-On the properties of

J. White ..... faculæ ; reply to a note by Mr. G. Hale, by M. H. Deslandres.

Holmes's Comet.-W. F. Denning - The probability of coincidence between solar and terrestrial

Helmholtz on Hering's Theory of Colour. phenomena, by M. G. E. Hale.-Note on an explicit expression

Prof. J. D. Everett, F.R.S. ... of the algebraic integral of a hyperelliptic system of the most

Automatic Mercurial Air-Pumps. By Dr. August general form, by M. F. de Salvert.-On a generalisation of Ber

Raps. (With Diagram.). ..... trand's curves, by M.Alphonse Dumoulin.-On the surfaces which Crystallised Carbon . . admit a system of lines of spherical curvature and which have

Lines of Structure in the Winnebago County the same spherical representation for their lines of curvature,

Meteorites and in other Meteorites. By Pred by M. Blutel.-On semicircular interference fringes, by M. G.

H. A. Newton ... Meslin. Rectilinear interference fringes are sections of hyper

The Late Thomas Davies, F.G.S. By L. Fletebe boloids by planes parallel to their axis, the light being propa. F.R.S. gated in a direction at right angles to that axis. If the light Notes .......... .......... proceeds along the axis, a screen perpendicular to it will cut

Our Astronomical Column: circular sections, and the fringes will have the form of a The Total Solar Eclipse of April 15-16, 1893. . ] circumference of which a greater or smaller arc will be seen

Remarkable Comets : .... accordingly as the two pencils overlap more or less. In Comet Holmes (1892, III.). .. practice these circular fringes were obtained by separating two

Comet Brooks (November 19, 1892). . of Bellet's half lenses and placing them one before the other in

Relative Positions of Stars in Cluster x Persei . front of a very small hole illuminated by sunlight, such that the

L'Astronomie . axis of the pencil passes through the optical centre of the two

Jupiter's Fifth Satellite .......... . lenses. Under these conditions two pencils are formed from

Geographical Notes ............ . the same source of light, which may be made to show circular Twenty Years in Zambesia ...... fringes by moving the lenses slightly in a direction perpendicular

The Distribution of Power by Electricity froc a to their optical axes. -Study of the fluorides of chromium, by

Central Generating Station. By A, Siemens M. C. Poulenc.-On a new soldering process for aluminium Magnetical and Meteorological Observations made and various other metals, by M. J. Novel. For aluminium at the Government Observatory, Bombay, Isa the following solders are recommended : (1) Pure tin, fuses at

with an Appendix. .............! 250°. (2) Pure tin 1000 gr. ; lead 50 gr. (280° to 300°). (3) Bacteria and Beer ... Pure tin rooo gr. ; pu.e zinc 50 gr. (2809 .0 320°). These

Ucive.sity anu Educational Intelligence ... solders do not stain or attack aluminium. A nickel soldering

Scientific Serials .............. bit is preferable. (4) Pure tin 1000 gr. ; red copper 10 to 15

Societies and Academies ...........

Croft .....

if climate.-). Stare

Just Published. PHILOSOPHICAL TRANSACTIONS

1892, SERIES A. With 16 Plates, Price £2 15.

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