360 PROCEEDINGS OF THE AMERICAN ACADEMY 



Professor Horsford directed attention to instances of spon- 

 taneous combustion of saw-dust, used to catch the dripping 

 of oil from machinery. 



Professor Jeffries Wyman read a paper on the anatomy, 

 and especially the muscular system, of Troglodytes Gorilla. 



Mr. Folsom exhibited a specimen of the smallest ancient 

 gold coin known. It bears the head of Jupiter Ammon, and 

 is of an age anterior to B. C. 500. The only other specimen 

 known is in the British Museum. 



Professor Agassiz presented his views of the tertiary de- 

 posits, as consisting, in each of its three great divisions, of a 

 greater number of successive deposits, and these of a much 

 more distinct character, than is generally thought. He ex- 

 pressed his conviction, not only that the tertiary shells which 

 have been regarded as identical with existing species are 

 specifically different, but also that in some cases shells of 

 successive beds of the same formation, which have been taken 

 for the same, really belong to two, three, or more species. 



A discussion respecting the evidences of synchronism be- 

 tween distant deposits of the same epoch ensued between 

 Professor W. B. Rogers and Professor Agassiz. 



Professor W. B. Rogers exhibited a stereoscopic slide, 

 which, by a simple contrivance, enabled the observer to rotate 

 two equal slips of ivory on a black ground in such manner 

 as to give them any desired inclination to one another, 

 thereby causing the resultant visual figure to assume various 

 perspective attitudes in the vertical plane, and, by alternate 

 convergence or divergence of the slips, giving it a vibrating 

 motion in that plane. This arrangement he offered as the 

 simplest experimental means of illustrating the principle of 

 visual relief, as produced by combining the twin pictures 

 of a stereoscope. He made some remarks in continuation of 

 former observations in regard to the theory of vision by the 

 successive combination of corresponding points, as maintained 

 by Sir David Brewster, and described a further experiment 

 which he regarded as wholly incompatible with that theory. 



