40 Description of the First Steam-Engine. 



prevent the return of the water ; vino the cold water pipes, 

 and n the cold water cock ; the dotted lines bze represent 

 the cold water fountain, which is here supposed to he imme- 

 diately behind the engine, and the water in it standing nearly 

 upon a level with the top of the cold water vessel?. Fig. A. 

 is a ^round-plan of the fountain, where mno represent the 

 cold water pipes, n the water cock, and F the reservoir. 

 Fig. 3. represents a section of the two cocks, which are in 

 every respect similar ; the black circle ab c represents the 

 key of the cock, and the black shaded part the passage 

 through the key ; the dotted circle r stu the shell or body cf 

 the cock, the two dotted lines t z the pipe that leads from the 

 boiler, the two dotted lines sz the pipe that leads to the right 

 hand water vessel, the two dotted lines z u the pipe that leads 

 to the left hand water vessel, and the curved dotted line x zy 

 the top of the boiler. 



From an inspection of Fig. B. it will appear, that by a quar- 

 ter turn of the key of the cock Tc, (Fig. 1.) the steam may 

 either be directed into the right or left hand water vessel, 

 and, in like manner, by a quarter turn of the key of the cock 

 n, cold water may be permitted to pass into either of the 

 vessels. 



Suppose the fire burning, and the boiler sending forth 

 steam, and the key of the cock k turned so as to permit the 

 steam to enter into the vessel abed, then will the steam drive 

 out all the air of that vessel up the force pipe x ■ x x x, and 

 occupy its place, steam will then be seen to issue from the 

 noselto of the force pipe. When this is observed, the key of 

 the steam cock k must be turned, to permit the steam to pass 

 into the vessel efgh, and, at the same time, the key of the 

 cold water cock n must be also turned, to permit the water from 

 the fountain to be forced into the vessel abed, (by the pres- 

 sure of the atmosphere,) as the steam therein condenses with 

 the cold water ; and when the vessel abed is filled with wa- 

 ter, and the vessel efgh with steam, the key of the steam 

 cock Jc is to be turned back into its first position, which will 

 again permit the steam to pass into the vessel abed, to act 

 upon the surface of the water in that vessel, so as to drive it 

 up the force pipe x x x, and, at the same time, the key of the 

 cold water cock n must also be turned, to permit the cold wa- 



