360 
NATURE 
probably to the Biela-Gambart comet than to Krakatoa. The 
longitude (246°) of the ascending nucleus nearly coincided with 
that of the earth on June 1, when the afterglows again began to 
acquire great intensity. 
August 3.—M. Bouley, President, in the chair.—The death of 
M. Henri Milne-Edwards, who died on July 29, was announced 
by the President, who remarked that a great loss was sustained 
by the Academy in the person of the illustrious Member of the 
Section for Anatomy and Zoology, one of the greatest savazets 
who had shed lustre on French science.—Discourses pronounced 
at the obsequies of M. Milne-Edwards, by M. A. De Quatre- 
fages, in the name of the Academy of Sciences, by M. Fremy, 
Director of the Museum of Natural History, by M. de Lacaze- 
Duthiers, in the name of the Paris Faculty of Sciences. —On the 
oxalic acid present in vegetation ; methods of analysis, by MM. 
Berthelot and André.—Researches on the effects of direct electric 
excitation on the glands, by M. Vulpian.—Frictionless reflection, 
ona plane, of the elastic displacements in a body of any form 
and contexture, by M. X. Kretz.—Letter addressed to the Per- 
petual Secretary on the subject of vaccination against cholera, 
by Dr. J. Ferran. In reference to this letter M. Vulpian ex- 
pressed his regret on the part of the Commission that the writer 
had misunderstood the meaning of the note inserted in the last 
issue of the Comptes Rendus. What was-asked was not Dr. 
Ferran’s statistics now promised, but the official returns of the 
Spanish authorities. In a question of this sort, affecting as it 
did all humanity, it was hoped that the Spanish Government 
would consider it a point of honour to give forthwith all possible 
information regarding the value of Dr. Ferran’s method of pre- 
ventive vaccination.—Note on an asymptotic law in the theory 
of numbers, by M. Stieltjes.—On the ‘‘herpolhodie” in the 
case of any surface of the second degree, by M. de Sparre.— 
On the employment of alternative electric currents for the 
measurements of the resistance of fluids, by MM. Bouty and 
Foussereau.—Note on the formation of the crystallised hydrate 
of zinc, by M. J. Ville-—On the hexabromide of benzine, 
by M. J. Meunier.—Heat of formation of the picrates. From 
the tables accompanying the paper the author shows that the 
anhydrous picrates of magnesium and copper are formed with an 
insignificant loss of energy in the components, while the picrate 
of zinc even absorbs a little heat. Hence the latter will yield 
more useful results than the former under the influence of the 
same oxydant.—Note on the essence of citron, by MM. G. Bou- 
chardat and J. Lafont.—On the form of the larva of Dorocidaris 
papillata, by M. Henri Prouho.—On the digestive tubes, the 
corpus Bojani, reproductive organs, and eggs of Fissurella (F. 
gibba and F. reticulata), by M. L. Boutan.—On the hydro- 
carbonated reserves of mushrooms, by M. Léo Errera. The 
author’s researches show an unexpected parallelism, from the 
standpoint of physiological chemistry, between the germination 
of mushrooms and that of the higher order of plants.—On the 
comparative evolution of sexuality in the individual and the 
species, by M. F. Laulanié.—Influence of sunshine on the 
vitality of various species of Micrococcus, by M. E. Duclaux.— 
Comparative studies of leprosy ; its pathological anatomy, by 
M. Henri Leloir.—Researches on poisoning by sulphuretted 
hydrogen, by MM. P. Brouardel and Paul Loye.—Note on a 
Cetacean (Hyperoodon rostratus) stranded at Rosendael, near 
Dunkirk, on July 24, by MM. Pouchet and Beauregard.— 
Remarks on some electric lights constructed by M. G. Trouvé 
for the purposes of naturalists, chemists, microscopists, &c. (one 
illustration), by M. de Lacaze-Duthiers. 
BERLIN 
Physical Society, June 26.—Dr. Konig produced a new 
apparatus for the measurement of the modulus of elasticity, 
which was constructed according to the suggestions of Herr 
von Helmholtz, and was utilised in the Institute for measure- 
ments of elasticity. The modulus of elasticity was determined 
by loading in the middle a bar of the substance to be examined, 
resting both ends on firm supports. The flexion whieh set in 
was measured by means of the cathetometer, and, its value being 
introduced into the formula of the elasticity theory, furnished the 
modulus of elasticity. A source of error in these measurements 
arose from the circumstance that the bar resting on edges 
was in part pressed in and sank, asa whole. This depression 
was the greater as the loading was greater, and it added to 
the magnitude of the flexion. To avoid this disturbance in 
the account Prof. Kirchhoff, in 1859, placed horizontal mirrors 
on the two ends of the bar, and, by means of telescope and scale, 
observed at each side the change in situation of each mirror, a 
change which occurred in consequence of the flexion under the 
loading in the middle, and which produced on both sides an oppo- 
site displacement of the scale. The sinking of the bar on account 
of the pressure on the edges, and even a slanting position on the 
part of the whole bar exercised no influence in these measure- 
ments. The apparatus suggested by Prof. von Helmholtz 
developed this principle still further. It had two perpendicular 
mirrors with the reflecting surface directed inwards at the two 
ends of the bar ; on one side stood a scale, on the other a tele- 
scope. The image of the scale fell on the opposite mirror, then 
on the second mirror, and thence into the telescope. If now 
the bar were loaded so that flexion occurred, then the image 
in the telescope became displaced to the extent corresponding 
with the angular changes of the two mirrors. By glancing 
therefore into the telescope the whole amount of flexion might 
be very rapidly and conveniently measured and the loading 
altered at pleasure; the commencement of the elastic after- 
effect might likewise be directly observed with great facility. In 
the Institute a series of measurements with this apparatus had 
been executed by two experimenters, measurements which 
yielded values agreeing with a fair dezree of precision. In the 
case of cylindrical bars differences presented themselves accord- 
ing as the bar was examined in one direction or in the direction 
perpendicular thereto. In the case of rolled brass the difference 
amounted to as high as from 2 to 24 per cent. ; in the case of 
cast brass the difference was inappreciable. Bars of cast iron 
likewise showed differences of only } per mill. Dr. Konig fol- 
lowed this up with a proposal to measure Poisson’s constants— 
that is, the relation of the longitudinal increase to the decrease of 
the transverse section. The measurement should be carried out 
as in the experiments of Prof. Kirchhoff, only, instead of the hori- 
zontal mirrors and two telescopes, two parallel mirrors inclined 
at an angle of 45° should be used at the two ends of the bar with 
one telescope, thus enabling the moduli of elasticity and of 
torsion to be measured, the relation of which furnished Poisson’s 
constants. 
CONTENTS Pace 
Dr. Lauder Brunton’s ‘Sf tae ly Prof. 
Arthur Gamgee, F.R.S. .. . + 3) 7s hie tae mee 
Elementary, Practical’Physics . 2°. 2 2) eee 339 
Our Book Shelf :— 
Watt's ‘‘ History of a Lump of Gold from the Mine 
to‘the Mint? 23... 2 7 <5. ent - 340 
Baker’s ‘‘ Magnetism and Electricity ” MOR oh OF) 9 52 
Sée’s ‘‘Bacillary Phthisis of the Lungs” .... . 341 
Williams’s ‘‘ Mineral Resources of the United States” 341 
Letters to the Editor :— 
Pitcher Plants. —W. Watson. . . Pe 
Colourless Chlorophyll.—C. Timiriazeff . ol 3) vf eee 
July Meteors.—W. F. Denning ........ 342 
The August Meteors.—H. B. Jupp . . 342 
A Possible Windfall for Science. —Dr. Hyde Clarke 343 
Electrical Phenomenon in Mid-Lothian.—Dr. Robert 
Tucasi\. 4.945. 5045) cw Ae 343 
On a Radiant Energy Recorder. —Prof. J. Ww. Clark 343 
Our Ancestors.s—Ne 0. 2.) 5 Ser o|! rgera eres 
The Institution of Mechanical Engineers ot eee 343 
A Voltaic Cell with a Solid Electrolyte. By Shelford 
Bidwell)... : ie a os = ee oe. 345 
Formosan Ethnology .....:..... 3 te Cae 
The Aurora, IT. (2?/strated)) .. <1) eae ee 
The British Association ..... 5 dea never sh 
Notes2) 2. 4e ssp, ese os ee 5, oa ie ae 
Our Astronomical Column :— 
Occultations of Vesta. . ....% © « . « 355 
Anthelm’s Nova of 1670 5° 705 <2. 2) ie) ee 
The Cincinnati Observatory... . . MMC 
Tempel’s Comet;-1867 T-ta> o)2-r08n ie One 356 
Astronomical Phenomena for the Week 1886, 
August 16-22... OE SEE HARD oo Soe INA 
Geopraphical Notes”. 2 2 = cis. acs aoe 356 
Measurement of Evaporation. By George Haslam. 
(flustrated) 5 jc eee eae afer") (wl laue ANE 
University and Educational Intelligence . . 2. 0 357 
Sciéntific/Serialsinu-i) ne) cee Relea © +. SSS 
Societies/and/Academiies)-9 7-9-1 -19-) ae > oe GD 
[August 13, 1885 
4 
