197 



ties of substances lighter than water; it being only necessary to hold 

 them down by a pin or wire. By the usual method, the operation is 

 complicated. The following are a few duplicate results, given to 

 show the uniformity which is attainable by this mode. 



These figures correspond sufficiently with the results given in 

 books; which, however, very commonly disagree, even at the first 

 decimal; chiefly because of the want of homogeneity, or uniform 

 compactness in substances operated upon. 



It will be objected to this process, that it is going back to the first 

 crude idea of Archimedes, and rejecting subsequent improvements. 

 It may claim, however, to be a refinement upon that philosopher's 

 bath-tub; and if the operation is easy, and the results are good, not 

 much further need be said. For specimens of very small size, and 

 high density, the balance would be preferable; but the genuineness of 

 a gold coin, as small as the half-eagle, is easily determined by the 

 cup. And to demonstrate, to a class of learners, the principle of 

 specific gravity, this is evidently to be preferred to the weighing in 

 water, which is an after-thought of some complexity. 



Staled Meeting, June 20. 



Present, eleven members. 



Prof. Frazer, Vice-President, in the Chair. 



Letters were read: — 



From the Etat Major of the Corps of Mining Engineers of 

 Russia, dated St. Petersburg, Feb. 25, 1855;— from the Impe- 

 rial Society of Naturalists of Moscow, dated 1-13 August, 

 1855; — from the Imperial Academy of Sciences at Vienna, 



