AMERICAN INSTITUTE. 487 



being sent. The greatest vibration was at 10 o'clock A. M.,and 10 o'clock 

 p. M., and were always least felt one hour later. 



IRON. 



The trial of cannon has been made in the United States, as follows : The 

 gun, 32 lbs., cast vertically, and about 18 inches longer than necessary, so 

 that the lighter impurities may rise to the top as so much scum, then sawed 

 off, then bored of an exact calibre and perfectly polished, so that the shot 

 has no point of unequal pressure ; then ascertain by thermometer the tem- 

 perature of the gun, put in a small charge of powder, one wad and one ball, 

 discharge it, clean it, let it cool to its first temperature. (Before the first 

 loading try its tone with a hammer !) Then try the tone again, and so on to 

 full proof. If the tone has not materially changed, the gun may be fired 

 one thousand times, after Avliich percussion rapidly disintegrates the metal. 



Commodore llodgers ordered an experiment on percussion before a com- 

 mittee of Congress, of which I was one. A man struck the trunnion of a 

 thirty-two pounder with a sledge hammer, while Com. K. counted the blows. 

 At a certain number, he remarked to us, a few more will break it off'. We 

 examined the trunnion, and saw no signs of fracture, any more than before 

 the first blow, but it broke as predicted. 



There is no better test than the tone or ring of the metal ; it is precise as 

 the tuning fork of a piano tuner. 



It is very valuable to railway work, and should be applied to every 

 working part before a start for any considerable run. 



Some similar test may be applied to boiler plates. Let each plate be 

 subjected to a scientific assay, for it is of infinitely greater importance than 

 our assay of gold and silver, for the latter can o?ily totcch otir pockets, 

 while the want oi t\ie for iner destroys thousands of precious lives! 



Each plate, when duly proved, should receive the stamp of the assay ofGce, 

 and to counterfeit that should be punished by hanging ! 



Nature forms timber of given strength ; man finds it very diflicult to imi- 

 tate her works ; but I do believe that each plate can^e proved. 



H. Meigs. 



ELEMENTARY BODIES. 



Faraday simplified chemistry — found but few original elements. Sir John 

 Herschell, the other day, in the chair of the British Association, remarked, 

 " that the formulae of chemical notation, for chemists are not algebraists, 

 and are becoming more and more repulsive. As the atomic formulae indicates 

 numerical relations, the aggregate weights of the several atoms in each 

 group, and the groups in each compound, it is distressing to the alge- 

 braist to find that he cannot interpret a chemical formulge — according to 

 the rules of arithmetic. I am slow to believe in similar generalizations," 

 &c. 



Note by Meigs. — I object to the admission of the term "atom " in sci- 

 entific language. We cannot form a conception of an atom. The infinite 

 dixiisibility of matter multiplies every attempt to ^-onceive of an original 



