Proceedings of the Polytechnic Association. 793 



passes through the flame and divides it, wlierebj it is daiined an 

 increased quantity of oxygen is furnished to the flame. He stated 

 that twenty-seven per cent of gas is saved by tliis improvement. 



Mr. C. E, Emer}^ remarked that this addition to the burner seemed 

 to make tlie light unsteady. Some time ago a piece of perforated 

 mica was phiced in the flame of gas, and an increase of light of from 

 two to three per cent was effected. 



Dr. J. B. Rich said the way in which the most perfect combustion 

 is attained, is by using an Argand burner, one and a half inches in 

 diameter, with some ninety holes in it. He found that, when the air 

 was admitted in a tine stream, the best efiect was produced. 



Mr. C. E. Emery stated that, causing the air introduced into the 

 furnace of a steam boiler to vibrate, made it evolve more heat, although 

 there is no more air admitted at the time. 



Dr. L. Feuchtwanger exhibited specimens of the sulphuret of mer- 

 cury, from a new mine just opened at Nappa county, California. 



Hoosic Tunnel. 



Dr. D. D. Parmelee gave the following description of nitro-glycerine 

 in relation to the Hoosic Tunnel : 



"When completed, the Hoosic tunnel will be about five miles in a 

 direct line through and nearly at the base of the mountain. The 

 highest point of earth above the grade of the road passing through it 

 will be 1,768 feet. 



The work is divided into two sections, one commencing at the east 

 side of the mountain, and the other at the west side. At the present 

 time a little more than a mile is completed of the east end, and very 

 nearly a mile of the west end ; about three miles are, therefore, yet 

 to be drilled, blasted, and carried out at the ends of the tunnel, to join 

 the two sections, and complete the work. This, it is estimated, will 

 require not more than five years, nor less than three, according to the 

 nature and stratification of the rocks. At the east end the workmen 

 all pass in and out at the main entrance, as there are no shafts. 



The drilhng is accomplished by compressed air engines brought in 

 through tubes leading from air pumps, which are worked by water 

 power obtained by damming the Deerfield river. The work is progress- 

 ing somewhat faster here than at the west end, as the rock is not so 

 hard, and much more easily removed. The west section presents 

 more subjects of interest than the east end. It is two miles from 

 North Adams, Mass. The entrance commences in earth, the sides 



