136 Improvements in the Construction, of Steam- Engines. 



communicate alternately with a condensing vessel, into 

 which a jet of water is admitted to hasten the condensation, 

 or the condensing vessel may he cooled by any other means 

 calculated to produce that effect. Things being thus" ar- 

 ranged, when the engine is at work, steam of high tem- 

 perature is admitted from the boiler to act by its elastic 

 force on one side of the smaller piston, while the steam 

 which had last moved it has a communication with the 

 larger steam vessel or cylinder, where it follows the larger 

 piston now moving towards that end of its cylinder which 

 is open to the condensing vessel. Let both pistons end 

 their stroke at one time, and let us now suppose them both 

 at the top of their respective cylinders, ready to descend; 

 then the steam of forty pounds the square inch entering 

 above the smaller piston will carry it downwards, while the 

 steam below it, instead of being allowed to escape into the 

 atmosphere or applied to any other purpose, will pass into 

 the larger cylinder above its piston, which will take its 

 downward stroke at the same time that the piston of the 

 smaller cylinder is doing the same thing; and while this 

 goes on, the steam which last filled the larger cylinder, in 

 the upward stroke of the engine, will be passing into the 

 condenser to be condensed during the downward stroke. 

 When the pistons in the smaller and larger cylinder have 

 thus been made to descend to the bottom of their respective 

 cylinders, then the steam from the boiler is to be shut off 

 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 cylinder 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 ; 

 the steam, which in the downward stroke of the engine 

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

 and the communication between the bottom of the larger 

 cylinder and the condenser shut off; and so on alternately, 

 admitting the steam to the different sides of the smaller 

 p ston, while the steam last admitted into the smaller 

 cylinder passes alternately to the different sides of the 

 larger piston in the larger cylinder, the top and bottom of 

 which are made to communicate alternately with the con- 

 denser. . 



" hi an engine working with the improvements which 

 have been ju>t 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 one side of Its piston, by the conden- 

 sation 



