— 
¥uly 8, 1886] 
NATORE 
233 
the bars have been magnetised without being first subjected to 
reat variations of temperature and kept free from telluric action 
by being held in a vertical position. 
SOCIETIES AND ACADEMIES 
LONDON 
Royal Microscopical Society, June 9—Rey. Dr. Dal- 
inger, F.R.S., President, in the chair.—Mr. G. F. Dowdeswell 
described a preparation of the microbe of rabies in the spinal 
cord of a rabid dog, which he exhibited X 400. — Prof. 
. Jeffrey Bell exhibited a specimen (received from Prof. 
McIntosh) of a very young starfish, in a stage so early 
as to show clearly the knob-like portions of the larval 
ergan. Prof. McIntosh has been giving some of his know- 
ledge and skill to fishing observations, which had been ren- 
dered possible by the facilities afforded by an enlightened 
ishery Board in Scotland.—Mr. F. R. Cheshire exhibited a 
device for the better examination of Bacteria in culture tubes, 
the cylindrical form of the tube so distorting the appearance of 
the contents that it was almost impossible to make any observa- 
tions upon them under the microscope. The first plan adopted 
was that of placing the tube in a trough of water and then 
Tooking at it through the front of the trough. This was found 
‘to diminish the aberration very much, but it did not get rid of it 
_ altogether, and was, therefore, only available under very low 
powers. Water having a refractive index of about 1°333 and 
alcohol of about 1°374, by adding water to alcohol a mixture 
having a refractive index of anything between the two could be 
obtained according to the proportions used. Gelatine has a 
tefractive index rather higher than that of water, and the inter- 
position of a cylinder of glass added something to this. The 
trough which he employed had a front of rather thin glass, the 
hottom being sloped in such a way as to cause a tube placed in 
the trough to lie always near to the front. The tube to be exa- 
mined was placed in the trough with some water, and then alcohol 
was added until the proper density was arrived at, and by this 
means it was quite possible to use a 3-inch objective effectively. 
—Prof. Bell, at the request of the President, gave an account of 
What he regarded as the most extraordinary biological fact 
brought to light during the last twenty-five years—that of a third 
“eye at the top of the head of certain lizards. —Mr. Crisp called 
attention to a new lamp for the microscope which had been sent 
‘for exhibition by Mr. Curtis, and which was so cheap and 
Tes that it seemed likely to become the lamp of the future. 
it was founded on the lamp originally devised by Mr. Nelson.— 
Mr. A. Brachet’s communication suggesting the use of a hyper- 
“bolic lens for the field-lens of the eye-piece was read. Mr. 
' Brachet claimed that thereby the diaphragms in the eye-piece 
/ and objective could be dispensed with, and the image much im- 
_preved.—Dr. Crookshank read a paper on photo-micrography, 
which was illustrated by the exhibition of a large number of 
| prints, negatives, &c. Mr. Glaisher, President of the Photo- 
graphic Society, said he had examined Dr. Crookshank’s 
exhibits, and thought they were certainly very beautiful produc- 
‘tions. He had for many years taken a great interest in the sub- 
“ject of photography, and had looked to it with hopes which had 
been more nearly fulfilled than ever before by the specimens 
before them. He had heard the paper with great pleasure, and 
could only express his admiration of it, believing as he did that 
itheld out great promise for the future.—Mr. F, Enock exhi- 
hited sketches of some of his slides, the various parts being 
‘numbered and named and accompanied by a short explanation. 
Ttis intended to issue sketches of all the mouth organs of British 
bees and other interesting insects. 
‘Mineralogical Society, June 22.—Mr. L. Fletcher, Presi- 
‘dent, in the chair.—Mr. Andrew Taylor was elected a Member. 
—The following papers were read :—C. O. Trechmaine, Ph.D., 
on barytes from Addiewell, West Calder, N.B.—Prof. E. Kinch, 
on plattnerite.—F. H. Butler, M.A., on dufrénite.—R. H. 
Solly, on anglesite from Portugal ; and on apatite from Cornwall. 
—Mr. R. Simpson (visitor) exhibited a very large rolled crystal 
topaz from Tasmania.—Several interesting specimens were re- 
exhibited by the President, Mr. Rudler, and others. 
: 
PARIS 
ies ; 
| Academy of Sciences, June 28.—M. Jurien de la Graviére, 
President, in the chair.—On the theory of minima surfaces, by 
; 
Fs 
M. G. Darboux. The results hitherto arrived at in the study 
of minima surfaces lead naturally to the inquiry here instituted 
regarding the determination of all minima algebraic surfaces 
contained in a given algebraic curve, or, more generally, to 
determine all the minima algebraic surfaces inscribed in a given 
algebraic curve.—On the subject of certain circumstances pre- 
sented by the movement of the hydro-extractor, by M. de 
Jonquiéres. The author deals with the normal case (omitted 
by Poinsot), in which the movement of precession is compli- 
cated and rendered irregular by movements of nutation.—On a 
process by means of which the oscillations of an absolutely free 
pendulum may be mechanically counted, by M. M. Deprez. The 
principle is described of an apparatus not yet constructed, which 
is intended to record the number of vibrations without exer- 
cising any mechanical influence on the pendulum. Without 
this condition the results would be worthless, as the vibrations, 
instead of being effected under the influence of gravitation alone, 
would be affected by the action of a force of unknown magni- 
tude. The problem is solved by the aid of optics, light being 
the only agent which exercises no mechanical action on the bodies 
exposed to its influence.—On the persistence of voluntary move- 
ments in bony fishes after removal of the cerebral lobes, by M. 
Vulpian. The author’s experiments with carp fully confirm 
Steiner’s recent conclusions regarding the persistence of the 
voluntary movements in fishes thus operated upon. They also 
show that the faculty of sight is unaffected by the operation, as 
already proved by the author in 1864.—On the normal metro- 
nome, by M. Saint-Saens. Owing to the defective character of 
this instrument, it is found to be of little practical service 
to musicians. Hence the Academy is urged to supply a 
normal metronome mathematically regulated which, before 
being issued to the public, should be tested and stamped like 
all diapasons, weights, and measures. The matter was referred 
by the President to the Section for Mechanics and Physics. —On 
the extension of a theorem of Clebsch relating to curves of the 
fourth degree, by Prof. Sylvester.—A fresh series of experiments 
on the automatic action of the regulating apparatus constructed 
at the Aubois sluice, by M. A. de Caligny.—On the fluorescence 
formerly attributed to yttria, by M. Lecoq de Boisbaudran. 
By recognising the complex character of yttria and announcing 
the existence of new elements characterised by fluorescent bands 
at first attributed to yttria (NATURE, June 17, pp. 160-62), the 
author considers that Mr. Crookes has implicitly adopted the 
opinion always held by him regarding the true character of these 
bands. But from the fresh experiments here described it is 
pointed out that further interesting studies will have to be made 
in order thoroughly to elucidate the subject.—Remarks accom- 
panying the presentation of a work entitled ‘‘ Cosmogonic Hypo- 
theses: an Inquiry into the Modern Scientific Theories on the 
Origin of Worlds, with a Translation of Kant’s ‘ Theory of the 
Heavens,’” by M. Wolf. In writing this work the author's 
object has been to show that the theory of Laplace, completed 
by the labours of M. Roche and other savaze/s, still answers best 
to the conditions required of a cosmogonic hypothesis. He 
claims to have met all the objections urged against it, and 
especially that of M. Faye regarding the pretended necessity of 
a retrograde rotation of the planets.—Report on M. Poincaré’s 
memoir entitled ‘‘Influence of the Moon and Sun on the 
Northern Trade- Winds,” by the Commissioners, MM. d’Abbadie 
and Mascart. With certain reservations this memoir is re- 
commended to the favourable consideration of the Academy. 
It shows that there is some truth in the popular opinion respect- 
ing the influence of the moon on the weather, but that this 
influence should be referred not to the new, but to the waning 
phases of the moon, while account should also be taken of the 
antagonistic influence of the sun.—Action of an electric current 
on anhydrous hydrofluoric acid, by M. H. Moissan.—On the 
flow of gases in the case of a permanent 7¢g?me, by M. Hugoniot. 
It is shown that M. Hirn’s experiments in no way contradict 
either the kinetic theory or the laws of hydrodynamics, and, so 
far from refuting, actually confirm the well-known formula of 
Weisbach or Zeuner.—On the condensation of vapours, by M. 
P. Duhem.—On the coefficient of self-induction in the Gramme 
machine (three illustrations), by M. Ledeboer.—On the spectra 
of didymium and samarium, by M. Eug. Demarcay. Some 
fresh results are described, which the author has obtained from 
the study of the photographed absorption-spectra ef various pro- 
ducts of the fractionation of didymium and samarium.—On a 
new double iodide of copper and ammonia, by M. A. Saglier. 
The process is explained by which the author has obtained this 
