340 Patent for certaui Improvements 



from the top, and admitted to the bottom of the smaller 

 cylinder, and the communication between the bottom of 

 the smaller and the top of the larger cvlinder is also to be 

 cut off, and the communication to be opened between the 

 top of the smaller and the bottom of the larger cylinder j 

 the steam, which in the downward stroke of the engine 

 filled the larger cylinder, being now open to the condenser, 

 and tlie communication between the bottom of the larger 

 cylinder and the condenser shut off; and so alternately ad- 

 mitting the steam to thedlficrent sides of the smaller piston, 

 while the steam last admitted into the smaller cylinder 

 passes alternately to the ditlerent sides of th^- larger piston 

 in the larger cylinder, the top and bottom of which are 

 made to conununicate alternately with the condenser. In 

 an engine working with the improvements which have been 

 just described, while the steam is admitted to one side of the 

 piston in the smaller cylinder, the steam on the other side 

 has room made for its admission into the larger cylinder on 

 on^ side of its piston, by the condensation going on on the 

 other side of the large piston which i.; open to the con- 

 denser; and that waste of steam which takes place in en- 

 gines worked only by the expansive force of steam, from 

 steam passing the piston, is prevented; foi* all steaui that 

 passes the piston in the smaller cylinder is received into the 

 larger. In such an engine, where it may be more conve- 

 nient for any particular purpose, the arrangement maybe 

 altered, and the top of the smaller made to conmiunicatc 

 with the top of the larger, and the bottom of the sm?il!er 

 with the bottom of the larger cylinder; in which case the 

 only difference will be, that when the piston in the smaller 

 cylinder descends that in the larger will ascend, and while 

 the latter de&cjnds the former will ascend ; which for some 

 particular purposes maybe more convenient than the ar- 

 rangement before described. 



2dly. As the difficulty of giving a proper degree of strength 

 to large cylinders, and the cases for the same, which are to 

 be exposed to the action of strong steam, increases in pro- 

 portion as their size is augmented ; instead of employing, 

 besides the smaller cylinder or steam measure, one cylinder 

 only of large diameter in steam-engines of great power, I 

 sometimes prefer substituting for the latter cylinder two or 

 more cylinders of smaller diameter, but of such dimension!? 

 that their capacity, and the area of the pistons worked in 

 them, are equal to the area of the one piston, and the ca- 

 pacity of the one cylinder which otherwise would be ne- 

 cessary; and such substituted cylinders are made to com- 

 municate 



