34 SCIENCE OF SUCCESSFUL THRESHING 



frequently opens, it is an indication that the fireman is 

 either careless or unable to control his fire. 



The best way to check the rise of steam is to start the 

 injector, but if the boiler be too full, the damper may be 

 closed. Another way is to open the fire door about an 

 inch, leaving the damper open, but the door should never 

 be held open more than this amount. This will do no 

 harm to tubes or boiler, but while the engine is running 

 the door should never be opened when the damper is closed. 

 When the engine is to be shut down for any length of time 

 the smoke-box door may be opened to check the fire. 



Some grades of coal will form clinkers that cover the 

 grates and shut off the air supply. These must be kept 

 out by removing through the fire door, but do not use the 

 poker when it can be avoided, or keep the door open longer 

 than is necessary, since stirring the fire only makes matters 

 worse. When troubled with clinkers, make it a point to 

 clean the fire at noon or at any time the engine may be 

 stopped. The tubes should be cleaned at least once a day. 



One or two of the bricks for straw burners can be used 

 to advantage in burning coal. They make better combus- 

 tion with poor coal, render the fire easier to control and by 

 maintaining a more uniform heat in the fire-box, are easier 

 on the boiler. 



How to Fire with Wood. The manner of firing with 

 wood depends entirely upon the fuel, and must be learned 

 by experience. When the wood is soft, or the sticks small 



