PROCEEDIN'GS OF THE POLYTECHNIC ASSOCIATION. 511 



Mr. Babcock. — Wilcox took out the economizer and reduced 

 the lost space to the smallest amount. By using the economizer, 

 the heat is sufficient to expand the air. 



Mr. Garvey inquired of Mr. Babcock what his authority was 

 for stating the specific heat of the air to be one-fourth that of 

 steam ? If the proper data were taken, it would be found that 

 the caloric engine was far less economical than the steam engine 

 in theory as well as in practice. 



Mr. Babcock said he could not give the name. One gave the 

 specific heat of air compared with water, to be 36-100; another 

 set it down as 22-100. 



Mr. Garvey. — The caloric engine was ably handled by Barnard, 

 in Silliman's Journal, but the analysis did not show such advan- 

 tages in favor of the caloric engine as Mr. Babcock deduced. 



Mr. Babcock. — All the power that is lost in the compression of 

 the air is made up for in the stuffing of the engines. 



Mr. Dibben thought the caloric engine effected a saving only 

 in fuel ; after that, he did not see its benefit. The great prob- 

 lem to be solved now is to cast the cylinder bottoms thin. It is 

 found that the thicker the cylinder bottom is the more liable it is 

 to crack. 



Mr. Howell stated that the best work of the Cornish engine 

 was, for three lbs. of coal, one horse power. He said the last 

 number of the Cornish engine gave 60,000,000 lbs. foot power 

 per bushel of coal of 94 lbs. 



Mr. Seely said it seemed strange to him that Mr. Ericsson 

 should desert his engine. Mr. Babcock says that Mr. Wilcox has 

 taken out his regenerator and it was found that it would scarcely 

 move. It is known to have been taken out in other engines, and 

 they have worked well without it. Heat has four times the effect 

 on air than it has on water. Let them put the friction brake on 

 their engine of a cold morning, and they will find a result simi- 

 lar to the one found in the Cornish engine. He thought an actual 

 trial would be better than speculation. 



Mr. Babcock stated that an 18 -inch Ericsson engine without 

 the economizer, would not run light over 60 revolutions per min- 

 ute. He had seen the Wilcox engine run with the economizer 

 over 200 revolutions per minute. 



Mr. Fisher thought that before going to trial, their plans ought 

 to be discussed. He stated that the first idea of a regenerator 

 was the respirator for persons having delicate lungs ; the next 



