430 Miscellaneous Intelligence. 
vision, with the preservation of the contractility of the iris. 
There are two means of destroying vision, without departing 
from the cerebral mass; one, the removal of the cerebral lobes, 
which causes the loss of sensation in the eyes; another, the re- 
moyal of the tubercula quadrigemina which occasions the loss 
of motion. Finally, the cerebral lobes being removed, the ani- 
mal cannot commence any motion; but if a motion be begun, 
it continues. It does not walk spontaneously, but it walks if 
pushed. It is no longer volition which determines its move- 
ments ; but an external irritation may supply its absence, and 
determine them like volition. 
Art. XVII.—MISCELLANEOUS INTELLIGENCE. 
MEcHANICAL SCIENCE. 
1. Addition to a Memoir on the Theory of Elastic Fluids, by 
M. de Laplace.—This theory is founded on the principle, that 
each molecule of a body is submitted to the actions of 
three forces: 1. The attraction of the surrounding molecules. 
2. The attraction of the caloric of the same molecules. 3. The 
repulsion of its caloric by the caloric of these molecules. The 
two first forces tend to make the particles approach each other; 
and the third tends to separate them. The three states solid, fluid, 
gaseous, depend on the respective predominance of these forces. 
In the solid state the first force is greatest: the influence of the 
figure of the molecules is very considerable, and they are united 
in the direction of their greatest attraction. Increase of caloric 
diminishes this influence, by dilating the body; and, when this 
increase becomes such that this influence is very little or no- 
thing, the second force predominates, and the body takes the 
liquid state. The internal molecules are then moveable among 
themselves, but their attraction by the caloric of the surrounding 
molecules retains the whole in the same space, with the excep- 
tion of the molecules at the surface, which the caloric raises in 
the form of vapours, until the pressure of these vapours arrests 
the effect. Finally, when by an increase of caloric the third 
force overcomes the two others, all the molecules of the liquid, 
at the interior as well as at the surface, separate from each 
other, and the liquid assumes rapidly a considerable volume, and 
would be dissipated in vapours, if not strongly retained by the 
surface of the vase or tube containing it. It is to this state of 
very compressed gas that M. Cagnard-Latour has reduced 
ether, alcohol and water, in the curious experiments lately com- 
municated to the Academy of Sciences. Jn this state the two 
first forces are still sensible; but, if by a diminution of pres- 
