Fresruary 4, 1897 | 
NATURE 
335 
Kelvin, on osmotic pressure against an ideal semi-permeable 
membrane, and ona differential method for measuring differences 
of density and of vapour pressure of solutions, -were also read 
(see pp. 272-3). 
DUBLIN. 
Royal Dublin Society, December 16, 1896.—Mr. Thomas 
Preston in the chair.—The following papers were presented :— 
The geographical distribution of dragon-flies, by Mr. G. H. 
Carpenter.—A suggestion as to the origin of the canals of Mars, 
by Dr. J. Joly, F.R.S. The formation of the principal curved 
lines and double ‘‘ canals” observed by Prof. Schiaparelli and 
Mr. Lowell is referred by the author to the disturbances of the 
crust of the planet produced by the gravitational attraction of 
small satellites in past times rotating close to the surface. It is 
shown that a satellite so small even as Phobos, if rotating some 
50 or 60 miles above the surface, would produce very appreciable 
stresses in the surface crust of the planet. Integrating the 
horizontal component of the gravitational pull outwards from 
beneath the satellite, a ring of maximum stress defined as the 
base of a cone having the satellite at its summit andasemi-angle 
of 71°, is obtained. If the satellite is moving relatively to the 
surface of the planet, tangents to this circle in the direction of 
motion define parallel lines of probable rupture. There is also 
probable development of a central line of weakness vertically 
beneath the satellite’s line of motion. These disturbances 
probably gave rise to mountain ranges—possibly of small 
altitude—which constitute the ‘‘double canals’ and lines 
observed on the surface. Mountain ranges more readily ex- 
plain the seasonal changes in visibility than any other hypothesis 
as to their nature. Satellites rotating so close to the surface 
will probably exist only for a score of years, or thereabouts, 
between such limits of distance as 70 to 50 miles, when, sinking 
deeper into the planet’s atmosphere, their energy will be 
rapidly absorbed, and they will fall in ; assuming as most pro- 
bable that the day is longer than the month, or that the 
satellite’s motion is retrograde. The intersection of the radius 
vector of the satellite with the surface of the planet will describe 
certain curves, the span of which upon the equator will depend 
upon the rates of relative angular velocity of planet and satellite. 
Given the span and rise, the curvature is completely defined. 
The curves upon Mr. Lowell’s map, and those given by Prof. 
Schiaparelli, are apparently in close agreement with the theoretical 
curves. They are not great circles. It is shown that nodal 
points will give rise to centres of radiating lines. “The location 
of Mars’ orbit so close to the ring of asteroids—some of which 
are known to come within his mean distance from the sun—is 
considered to render @ frzorz probable the assumption that Mars 
has throughout the past at intervals picked up satellites which, 
after describing a spiral path round him, ultimately fell in. 
Phobos is—according to lunar theory—probably in the way to do 
so at some future time. It is shown that a small solid satellite, 
even if composed of no stronger material than basalt, will be 
amply stable under the unbalanced gravitational and centrifugal 
forces to which it will be subject when close to Mars’ surface.— 
An account of some experiments to determine the exact position 
from which the-X-rays emanate in a focus tube was given by the 
Right Rev. Monsignor Molloy. 
Paris, 
Academy of Sciences, January 25.—M. A. Chatin in the 
chair.—The President presented to M. Faye the medal struck 
on the occasion of the fiftieth anniversary of his nomination to 
the Academy, and gave a review of his contributions to 
Astronomy.—Verbal report on the contents of a sealed letter, 
opened at the request of the heirs of the late M. B, Heire ; and 
relating to several questions in surgery, by M. le Dr. Guyon.— 
Note on a screwbrake, with yertical action on the rail, by M. 
G. Camps.—On two errata in the ‘‘(Eures de Gauss,” by M. 
Schering.—Photography of an extraordinary protuberance, by 
M. H. Deslandres. An account of a solar protuberance photo- 
graphed at the Observatory of Paris on May 31, 1894, which 
attained the enormous height of 10/23” of arc, or one-third of 
the solar diameter.—On the first integrals of dynamics and 
~ on the problem of x bodies, by M. P. Painlevé.—On the 
expansion of nickel steel, by M. C. E. Guillaume. By 
comparison with a platino-iridium bar, the expansion of 
"which had been carefully studied, the expansion of nickel 
steels was found to be anomalous, in the sense that instead of 
NO. 1423, VOL. 55] 
following approximately the law of mixtures, the expansion was 
even higher than bronze. To further elucidate this point, the 
expansions of a-series of nineteen bars were determined, in which 
the proportions of nickel varied from o to 100 per cent.. The 
coefficient of expansion reaches a maximum at about 24 per cent. 
of nickel, and rapidly falls until a minimum is reached at 36 per 
cent. of nickel, after which it slowly increases until the original 
value is obtained. —Fluorescence of vitrified materials, under the 
action of the Rontgen rays, by M. Radignet. By the use of screens 
of glass (especially the glass from the manufactory of Saint- 
Gobain, called crysta/), enamel, or porcelain instead of the 
usual ones of cardboard covered with fluorescent crystals, the 
images obtained are less brilliant, but more sharply defined.— 
On an absolute electrometer designed to measure small differences 
of potential, by MM. A. Perot and C. Fabry (see p. 327).—An 
optical apparatus by which objects cast or engraved can be seen in 
relief and in their normal position, by M. Ernest Moussard.— 
On the determination of the ratio of the two specific heats of 
acetylene, by MM. G. Maneuvrier and J. Fournier. The 
method of Clement and Desormes was used, the flask employed 
holding fifty litres. It was found that the acetylene obtained 
by the action of water upon calcium carbide was by no means 
pure, only 94 per cent. of it being absorbed by ammoniacal 
cuprous chloride. The system of purification adopted reduced 
this to less than 0°5 per cent., and the gas thus obtained was 
found to have lost its allicaceous odour, held up to the present 
to be one of its characteristic properties, although still possess- 
ing a strong penetrating odour. The value found for & was 
= 
1'273.—The physical, physiological, and therapeutic effects of 
rapidly alternating currents, by M. Boisseau de Rocher.—Action 
of carbon monoxide and dioxide upon aluminium, by MM. 
Guntz and Masson. Ata high temperature, in the presence of 
a little iodide or chloride of aluminuim, aluminium is readily 
burned in a current of either CO or CO,. With the former the 
reaction is 
6Al + 3CO = Al,O; + C3Al, 
the aluminium carbide giving practically pure methane on boil- 
ing with water. Carbon dioxide gives the same product.—On 
the phosphides of chromium and of manganese, by M. A. 
Granger. By theaction of phosphorus vapour upon the chlorides 
of chromium and manganese, the phosphides CrP and Mn3P, 
were obtained.—Spectra of the metalloids in their fused salts, 
silicon, by M. A. de Gramont.—Influence of temperature upon 
the rotatory power, by M. P. A. Guye and Miss E. Aston.— 
On two isomeric triethylene-diphenylhydrazines, by M. H. 
Causse. —On a superior homologue of urea, by M. Oechsner de 
Coninck. Thesubstance has the composition CyH,,N.O, and 
was obtained from the urine of a person suffering from alcoholism. 
—New researches on the embryonic nervous system of the 
Crustacea, by H. Nicholas de Zograf.—On the histology and 
microscopical anatomy of the encephalon in fishes, by M. Catois. 
The results obtained by the use of methylene-blue as a staining 
reagent are entirely confirmatory of the researches of R. Cajal. 
—On the biology of Dendroctonus micans (Ratz), by MM. A. 
Menegaux and J. Cochon.—On the pseudo-larval pairing of 
some Sarcoptide, parasitic in the domestic pigeon, by M. Ss. 
Jourdain. The species studied were Prerolichus falciger, 
Dermoleichus asternalis, and Pterophagus strictus (Mégnin).— 
Phenomena of autotomy observed in the goubs‘of Wonandroptera 
inuncans and Raphiderus scabrosus, by M. Edmond Bordage. 
—On the gases given off in water by metallic carbides, by M. 
E. Maumene. 
SYDNEY. 
Royal Society of New South Wales, September 2, 
1896.—Mr. J. H. Maiden, President, in the chair. —Papers 
read :—Note on recent determinations of the viscosity of water 
by the efflux method, by G. H. Knibbs—Current Papers, No. 2, 
by H. C. Russell, F.R.S. E eeu 
October 7.—On the occurrence of precious stones in New 
South Wales, with a description of the deposits im which they 
are found, by Rev. J. Milne Curran. The Society’s bronze 
medal and money prize of 257. were awarded to the writer of 
this paper—On the constituents of the sap of the “‘ silky oak 
Grevillea robusta, R.Br., by Henry G. Smith. te 
November 4.—On sill structure and occurrence of fossils im 
eruptive rocks in New South Wales, by Prof, T. W. E. David. 
