124 Scientific Intelligence. 
chlorate of copper, he found that in general the —— character 
of the compound results from that of its elements. He has madea 
number of experiments on the laws of equilibrium of domnesitie bod- 
ies in the magnetic field, and on the reciprocal action of diamagnetic 
bodies; the methods of observing used being simple and ingenious, 
chiefly by observing the change of form or the curve of the common 
surface of one fluid when floating on another. He passed over many 
other topics with brief notice ; and concluded with calling Prof. Fara- 
day’s attention to what he believes to be the most important fact of these 
researches, and _— relates to an experimental theory of diamagnetic 
phenomena. abstain from publishing a full abstract, as the au- 
be Peo aig himself to arrange these eget before publication. 
Ona Monies Binocular Camera; by A. Cuavper, (Proc. Brit. 
Pat Ath., No. 1299.)—The author "eehibited a Double Camera for 
taking the two ayabes ic daguerreotypes of groups or individuals,— 
and by which four double pictures could be successively taken with suc 
rapidity as to be exact representations of the same circumstances. It 
would be impossible to make all the mechanical arrangements of this 
instrument intelligible without drawings. The author also exhibited an 
instrument, which called a rice eee by which he coul 
accurately measure the angles, by which could be determined the 
place of the group or figure to be taken, and the position in every 
one of their ssa of the double camera and its slides. 
13. On on’s Theoretic Anticipation of a erystallic Action ; 
by Dr. Tudtntiss (Proc. Brit. Assoc., Ath., No. 1299.)—In an article in 
the Phil. Mag. for March, 1851, Prof. W. Thomeon had drawn attention 
to the fact that Poisson had theoretically anticipated the discovery of mag- 
no-crystallic action by Pliicker ; and, in the Jatest number of the “ Annu- 
al Report of Liebig and Kopp,” Dr. Tyndall’s oe are refer 
red to as especially corroborating the above view s he prized 
the support and coincidence of Prof. Thomson on a ceaagie subject, 
he must decline subscribing to his views in the present instance ; and 
he ise he would prove that the theory of Po oisson was unsuited to 
explain the phenomena of magno-crystallic act By means of @ 
powerful electro-magnet, Dr. Tyndall had been iiehine to prove each 
of his meena by actual experiment. Poisson suppose a! 
body to be an assemblage of magnetic molecules, and in the case 
certain crystalline bodies, he imagined that these molecules 
an ellipsoidal shape. Supposing such a body to be magnetized in @ 
certain direction, and all these ellipsoids to lie with their longer axes! $i 
the same direction, the attraction of such a body parallel to these long’ 
er axes be different from its attraction in a transverse direction. 
" differential action, such as that here indicated, was certainly esiab- 
lished by the experiments of Prof. Faraday and Dr. Tyndall ; but its 
cause is not to be referred to the shape of the molecules, as as supposed 
by Poisson. A crystal of calcareous spar was hung in the magoe™ 
field, and its action exhibited,—its optic axis set equatorial. A mode 
A cry: tal of carbonate of iron was ge ey —its axis 
.. oe S to yon a magnetic model of the stom did the same. Dr 
ay 
