4*72 transactions of the 



Polytechnic Association op the American Institute, 1 



October Qth, 1859. } 



S. D. Tillman, Esq., in the chair. John Johnson, Esq., Secretary, pro 

 tern. 



Mr. Seeley hoped that, if there were any exhihiters present, they would 

 come forward and explain their articles to the Association. No one re- 

 sponded to the invitation. 



Mr. Tillman then called attention to the only specimen of a rotary 

 engine in the Fair. He had seen but one on exhibition, and yet he con- 

 sidered the invention of a reliable rotary engine a desideratum. The air, 

 or caloric engine, too, deserved examination. 



Mr. Bruce observed an apparatus on exhibition which was intended for 

 manufacturing gas from wood. He would like to obtain information on 

 the practicability and economy of the manufacture. 



Mr. Butler considered the wood gas as by no means economical for city 

 use, where wood is dear and coal cheap, in comparison, even if the gas 

 from wood be equal in illuminating power to good coal gas, 



Mr. Seeley considered the apparatus required for the manufacture of 

 wood gas as too expensive for private use — too difficult to be operated, and 

 not in any sense equal to other and better sources of illumination. For 

 city purposes, it was not at all adapted. Coal gas was better and mare 

 cheaply procured. 



He wished to start a discussion, and would, therefore, offer a few words 

 on the Hot Air Engiyie. He considered it by far the most important 

 novelty at the Fair, because it can be applied to so many uses where steam 

 is inapplicable. We do not want a steam engine to work a few sewing ma- 

 chines in a factory, or to do the small amount of work required on ordinary 

 farms nor in many other places where a small amount of power is required. 

 For all such places the Caloric Engine seems well adapted. It requires 

 little attention — only to keep the fire burning — and is a reliable source of 

 power when only light work is to be performed. Doubtless with the same 

 amount of coal more power would be generated in the steam engine. Its 

 economy, therefore, is not to be looked for in the consumption of coal, but 

 in its requiring little or no attendance, 



Mr. Stetson. — The Caloric Engine is worthy of study and improvement, 

 for thouo-h not as economical as the steam engine in the consumption of 

 fuel it is much needed where a small amount of power cannot be obtained 

 without a distinct engine. In every third house in our large cities, power 

 is wanting in small amounts which it would be absurd to tit up separate 

 engines for ; and in such cases, economy of fuel is only a secondary consid- 

 eration to the employment of a cheap motor in place of manual labor. To 

 a large steam boat company a saving of fuel amoun'ang to 3 or 4 per cent, 

 would be important, but such is not the case where only a small amount of 

 power is wanted. The Caloric Engine uses about ten pounds of coal per 

 hour for each horse power. This is not economical, yet it compares favor- 

 ably with some small steam engines. Steam engines use from 3 pounds to 



