S~T- -.fe 



DOUBLE-ACTING ENGINE CITV SAW-MILLS. 



THE STEAM ENGINE. 



CHAPTER II. 



17. Method of regulating the activity of the furnace. 18. How steam is 

 made to produce a mechanical effect. 19. The cylinder and piston. 

 20. Metallic pistons. 21. Estimate of the force with which the piston 

 is moved. 22. Transmission of this force. 23. Piston rod. 24. 

 Cocks, valves, and slides. 25. How employed. 26. Stroke of the 

 engine. 27. Effective pressure. 28. Supply of steam to the cylinder. 

 29. By valves. 30. By slides. 31. Seaward' s slides. 32. Single 

 cock. 33. Four-way cock. 34. Low and high pressure, more pro- 

 perly called condensing and non-condensing, engines. 35. Objections 



LARDNER'S MUSEUM OP SCIENCE. c 17 



No. 57. 



