POLYTECENIC ASSOCIATION PROCEEDINGS. 697 



all the steam made must pass upward and then downward into the 

 steam chamber. This chamber is slightly cone-shaped 5 the water 

 entirely surrounds it and nearly fills the boiler; thus, a compara- 

 tively small quantity of water is exposed to great heating surface. 

 The inner cone is connected with the outer shell of the boiler, so 

 as to give the shell greater strength. 



UNIVERSAL BOILER ALARM GUAGE. 



Mr. T. C. Banks, of Wallingford, Conn., exhibited a model of his 

 steam gauge, designed for protecting flue of boiler by preventing 

 low water, and thus also preventing explosions. When the water 

 falls in the boiler it also falls in a tube attached to the outside of 

 the boiler, but in connection with its water space. Consequent to 

 this falling of the water is the entrance of steam, which expands 

 the tube longitudinally, and draws a movable plate connected with 

 one end of spring, which moves a valve that admits steam to the 

 whistle, thus giving notice that the water is too low in the boiler. 

 A similar gauge can also be used to indicate when water is too high 

 in the boiler. 



After some discussion on the merits of this alarm gauge, the 

 Association adjourned. 



October 10, 1867. 

 Prof. S. D. TiLLUAK in the chair; J. Wyatt Rkid, Esq., Secretary. 



The Chairman presented the following summary of scientific 

 news: 



BBONZE AND STEEL ORDNANCE. 



The French government are now testing guns having an interior 

 of steel and an exterior of bronze. It is supposed such cannon 

 combhie the maximum of wear with the minimum of liability to 

 explosion. 



NTTRO-GLTCERINE FOR BLASTING. 



The summit tunnel on the Pacific railroad has just been com- 

 pleted. The work was expedited about twenty-five per cent faster 

 than it could have been, had not nitro-glyceriue been made on the 

 spot and substituted for gunpowder. 



