PHYSICS AND NATURAL HISTORY OF GENEVA. 275 
processes the phenomena of coloration in extremely thin surfaces of the liquid. 
The dark part presents not more than ;93555 of a millimetre, whence we may 
conclude, says M. Wartmann, that the radius of the sensible activity of molecu- 
Jar attraction is below 55,555 of a millimetre. 
M. de la Rive submitted to inspection a minimum thermometer of Casella, 
an ingenious instrument, in which, instead of a movable index, there is a lateral 
reservoir adroitly constructed, into which the mercury flows when it rises. M. 
P. Plantamour described to us the injector of Giffart, designed as a substitute 
for the supply pump in steam-engines. M. Eugene de Morsier exhibited a 
erust taken from boilers of those engines, which is impenetrable by water, 
and thus gives rise to accidents. 
Our regretted colleague, M. Ritter, of whom I propose presently to speak, 
had presented to the Society a curious memoir* on the gamut of the mathema- 
ticians compared with that of the musicians. M. Alexander Prevostt subse- 
quently analyzed this memoir, and, after deducing from it certain consequences, 
proceeded to compare them with the opinions and practice of musicians. Both 
memoirs having been published, we merely indicate them to the savants who 
interest themselves in questions of this nature. 
Professor Plantamour and M. Hirsch, director of the observatory of Nenché- 
tel, have commenced a series of observations to determine the relative position 
of Geneva and Neuchatel, by availing themselves of the electric telegraph. 
The highly improved instruments would have yielded satisfactory results had 
not causes arising out of the state of the sky and of the telegraphic lines inter- 
rupted the proceedings. ‘The observation from Neuchatel to Geneva gave a 
ditference of longitude amounting to 3/ 12'.22; but when the observers would 
have changed their stations, in erder to eliminate the personal equation, the sky, 
had become overcast, and a derangement of the line prevented a prosecution: 
of the work. The meteorological observations of the Great St. Bernard, com~ 
pared with those of Geneva, have long been a subject of investigation, but sue~ 
cessive improvements in the systems and processes of observation had rendered. 
desirable a comparison after the lapse of the last twenty years. This has been. 
undertaken by M. Plantamour in a first memoir relative to St. Bernard, pub-- 
lished in the Bibliotheque Universelle, January, 1862, under the title of Notes: 
on the periodical variations of temperature and atmospheric pressure at the 
Great St. Bernard. 
A memoir by M. Ch. Martins, on the increase of temperature during the night, 
above the surface of the earth to a certain height, has given occasion to M.. 
Marcet, who had been previously occupied with this subject, to make new ex- 
periments. They have confirmed certain differences which he had remarked 
between his own facts and those observed by M. Martins at Montpellier. A. 
new series of observations was undertaken by M. Marcet with the view of 
determining whether the decrease of temperature exists above an aqueous sur~ 
face of great extent. He ascertained that the phenomenon does not occur above: 
water, and that it is even scarcely sensible in the immediate neighborhood of. 
a large liquid surface, so that in effect there is, at the moment of the setting 
of the sun, a difference of from 2° to 3° between the temperature at a certain 
height above the land and above the water. The memoir of M. Marcet was. 
published in the Bibliotheque Universelle, November, 1861. 
M. Soret has visited the glacier of Shafloch, which M. Thury had examined 
the yeer before, and remarked the aureola structure previously noticed. He 
observed, moreover, that the entire surface of the ice was covered with small 
striz nearly parallel in each aurecola, but not having the same direction in the 
different fragments. ‘These small striz, which were also observed by M. Soret 
* Memoires de Ul’ Institut Genevois, in quarto, vol. vii. 
t Biblioth. Univ. Archives des Sc. Phys. et Nat., April, 1862. 
