124 ROUGH-AND-TUMBLE ENGINEERING 



the horse-power of an engine; make yourself so fam- 

 iliar with it that you could figure any engine without 

 referring to the book. Don't stop at this, learn to 

 figure the heating surface in any boiler. It will en- 

 able you to satisfy yourself whether you are working 

 your boiler or engine too hard or what it ought to be 

 capable of doing. 



SOME THINGS TO KNOW 



Q. What is fire? 



A. Fire is the rapid combustion or cunsuming of 

 organic matter. 



Q. What is water? 



A. Water is a compound of oxygen and hydrogen. 

 In weight 88 9-10 parts oxygen to 11 i-io hydrogen. 

 It has its maximum density at 39 degrees Fahr.. 

 changes to steam at 212 degrees, and to ice at 32 de- 

 grees. 



Q. What is smoke? 



A. It is unconsumed carbon, finely divided, escap- 

 ing into open air. 



Q. Is excessive smoke a waste of fuel ? 



A. Yes. 



Q. How will you prevent it? 



A. Keep a thin fire, and admit cold air sufficient 

 to insure perfect combustion. 



Q. What is low water as applied to a boiler' 



