OF ARTS AND SCIENCES. 295 



Professor Eustis remarked, that he had carefully surveyed 

 the track of the tornado, and had made a plan of it, in which 

 he had laid down the prostrate trees and other important ob- 

 jects in their exact positions, as determined by an accurate 

 survey. Having formed no theory upon the subject, he had 

 made his observations without bias from that cause. He com- 

 pared the general appearance of the track to that which would 

 be produced by a heavy body of enormous size, moving for- 

 ward with great momentum, so as to throw down every obsta- 

 cle in its path. In one or two places only, the position of the 

 prostr^e trees indicated the action of a rotating force. In one 

 place a tree was twisted 180° at the height of ten feet from 

 the ground. Professor Eustis mentioned another fact, which 

 he referred to the direct agency of electricity ; namely, that a 

 hole as large as a silver half-dollar, with its edge well defined 

 and free from cracks, though slightly fused, had been made in 

 a pane of glass in an inner window. A considerably smaller 

 hole was found in the window curtain, opposite to the large 

 hole in the glass. 



Professor Horsford presented a paper, " On the Permeability 

 of Metals to Mercury," in which, after remarking on the re- 

 searches of Daniel and Henry, he gave an account of a series 

 of original experiments, with a view to the elucidation of the 

 laws of this phenomenon. The following is a summary, in 

 his own language, of the results at which he arrived : — 



1. The specific gravity of lead is increased by saturation 

 with mercury. 



2. The velocity of the mercury diminishes as the length of 

 a saturated bar increases, and in a kind of geometrical ratio. 



3. The progress is more rapid in cast than in drawn lead. 



4. The total height to which the mercury attains is greater 

 in cast than in drawn lead. 



5. Gravity facilitates the flow of mercury from above down- 

 wards. 



6. The mercury which passes through a siphon-shaped bar 

 of lead contains lead in solution. 



