484 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



with and without expansion, but owing to a mistake in one of 

 the calculations the paper was laid aside, and stated that in his 

 opinion there was a saving of lY per cent by using steam at a full 

 stroke. He also read another paper relative to the United States 

 steam frigate "Wabash. 



Mr. Corlies stated that he claimed a power by which can be 

 regulated the • power of the engine, which was only a simple 

 adjustment. In the experiment made on two engines at the 

 Metropolitan Mills, he (Mr. Corlies), after looking at a card from 

 the engineers, said he could not do anything to improve them. 

 He also alluded to the Ocean Steam Mills and the James Mills, 

 and stated that a gentleman spoke to him the other day, and 

 stated that his engines were working at a half " cut-oflf," which 

 was giving him entire satisfaction. 



Mr. Seely. — I think it is time to hear a little from the other 

 side. The only thing for us to know is, what is claimed for the 

 " cut-off," and what is gained by the use of it. All machinery is 

 driven by force — force is what gives motion. If you put a weight 

 on the ground it remains without motion. You may have what 

 amount of steam you like in your boiler, but unless you open 

 your port you receive no gain from the use of it. In the old- 

 fashioned cylinder, where we do not use the " cut-oif," you drive 

 the piston to the bottom. If you want to save twenty-five per 

 cent, you must use the " cut-off; " and if you wish to get the 

 utmost work of an engine you must use the whole stroke. 



Professor Mason. — I have a particular engine which I desire 

 to work for the next three months, and I desire to know by what 

 means I can get the full amount of its power. 



Mr. Seely. — To do so, the stroke must be used at its full length. 

 It is well understood that the condensing engine is the most pro- 

 fitable, except in reference to friction. If you gain twenty-five 

 per cent, by the "cut-off," you may gain ten per cent, by friction. 

 Steam should be cut off in such a manner that at the end of the 

 stroke it lose all its power. 



Mr. Montgomery. — The full value of each foot of steam is well 

 understood. On 1212° of steam we get 10 atmospheres. The 

 Cornish engine had become valuable for pumping a certain amount 

 of water in a given time; it has the preference in England, and 

 also in this country. Some writers have attempted to state that 

 the loss from radiation is not very great, but this is a great 

 mistake. 



