OR, PLAIN TEACHING. 



103 



engine, 378. A condenser, 9, is 

 placed under and at a little dis- 

 tance from the cylinder, 8, with 

 which it communicates directly 

 by a pipe. For this purpose the 

 steam is withdrawn from the 

 cylinder, 8, by means of an air- 

 pump, 19. In the condenser, 9, 

 the steam is brought into con- 

 tact with cold water, or water 

 warmed only by the frequent 

 condensation of steam ; and for 

 the sake of economising fuel, this 

 water is sent again co the boiler 

 through the feed-pipe, 4. Imme- 

 diately above the air-pump, 19, 

 is the hot-well, 10, into which the 

 water from the condenser, 9, is 

 conveyed. The air-pump, 19, is 

 not merely useful in removing 



the condensed steam, but it draws 

 off gases which are generated in 

 the production of steam. We 

 see that water passes from the 

 boiler, 1, in the form of steam 

 through the steam pipe, 5, forces 

 the piston, 15, both up and down, 

 giving motion to the beam, 12, the 

 fly-wheel, 18, and all moveable 

 parts of the engine, and returns 

 again (though with some loss) 

 through the feed-pipe, 4, to the 

 boiler, 1. The whole of these 

 complicated operations depend 

 upon the expansive force of heat, 

 operating upon the particles of 

 water, and acting upon a me- 

 chanical contrivance by means of 

 pistons and VALVES. 



Other particulars connected with steam, and steam machinery, will be explained in our 

 description of the Locomotive and the Steam- ship. 



