264 



and, thirdly, crystals which he had now seen for the first time, 

 six-sided tables, often very thin and transparent, and resembling 

 cystine in appearance. They were accompanied in the speci- 

 men by thicker rhombic tables, more or less modified, and he 

 considered them all modifications of rhombohoedrons. 



He also exhibited crystals of oxalate of lime from the vege- 

 table kingdom. Prof. Bailey called attention some time since to 

 the large amount of oxalate of lime existing in the bark of certain 

 trees, the {)rincipal ingredient of the ashes of which was carbon- 

 ate of lime, a salt arising from the decomposition of the oxalate 

 and other organic salts of lime. This excretion from the human 

 body Dr. Bacon has noticed to be quite common in Boston, but 

 it cannot be due to the use of water containing lime salts, for the 

 Cochituate water is now almost universally used, and this, it is 

 well known, is one of the purest of pond waters. He would 

 not even consider a small amount of oxalate of lime deposited 

 from the urine as a morbid indication, for this salt is so insoluble 

 that a precipitation of it in a certain quantity may be regarded 

 as not inconsistent with health. 



An ingenious instrument, in brass and steel, for mak- 

 ing fine sections of "wood and other articles for micros- 

 copic examination, was presented by Edward C. Cabot, 

 Esq., and the thanks of the Society voted for the dona- 

 tion. 



September 16, 1857. 



The President in the Chair. 



Mr. Charles Stodder read a paper on the vibrations 

 caused by the falling of the water over the dam at Had- 

 ley Falls, as follows : — 



A paper was read at the Montreal Meeting of the American 

 Association for the Advancement of Science, on the vibration 

 caused by the falling of the water over the dam at Hadley Falls, 

 The same matter has been the subject of discussion in this 



