Proceedings of the Polytechnic Association. 985 



gas. There are a series of eleven arches, just large enough to go 

 through, and a couple of gas burners are under each. 



New Geate Bar. 



Mr. J. 1^. B. Carver exhibited Mr. N. B. Schofield's corrugated 

 grate bar. The bars are corrugated longitudinally, with a corrugated 

 narrow bottom, which prevents its warping. 



Dr. P. H. Yanderweyde thought the plain bar would answer as well 

 as this. He did not see how the corrugation improved the bar. 



Dr. D. D. Parmelee said that the quality of the cast-iron has much 

 to do with the trouble of grate bars. While crystallized iron is the 

 best material for making these bai's, and not the cast-iron that melts 

 at a low temperature. There is more in the quality of the iron than 

 in the form of the grate bar. 



Kew Cash Deawer. 

 Mr. E.. B. Zwallen exhibited a cash box, with secret drawers, of an 

 improved construction. The invention was closely examined, and its 

 simple mode of security was warmly approved. 



Model of a Tunnel under the East Kuvee. 



Mr. Edwin Ferguson presented a model of his method of laying a 

 wrought iron tunnel in sections for the East river, to be laid on the 

 bed of the river. Each section consists of two cylinders, with eliptical 

 cross section, one within the other, firmly connected together. The 

 cost to build this tunnel would be two and a half millions dollars. 

 The tubes or cylindei-s are to be made of boiler iron, and can be put 

 down in any required length, and laying on the bed of the river, will 

 not damage anything whatever. 



Mr. B. J. La Motte exhibited a model and read the following paper 

 on 



Proposed Ieon BRrooE ovee the East Biver. 



In every enterprise, two things must be well considered : The 

 amount of good it will do on one side, and tlie amount of evil it 

 will do, or may do, on the other side. If the amount of good and 

 evil will nearly balance each other, then it is just as well in such a 

 case to let the enterprise alone. 



It appears to me that the contemplated bridge over the East river 

 lias some points highly objectionable connected with it ; but the prin- 

 cipal one of these will be its great height from the water level, being 



