THE BOILER 115 



gasket. When the hand-hole plate is in place, the nut 

 should not be screwed down too tightly, when the engine 

 is cold, as the gasket may be injured so that it would not 

 stand steam pressure. It is best to screw up the nut only 

 moderately tight when cold, and turn it up a little more 

 with a wrench when steam begins to show on the gage, 

 and then a little more from time to time until the steam 

 gage shows working pressure. In this way, the rubber 

 has a chance to soften with the heat and adapt itself to the 

 iron surfaces. 



Cleaning the Tubes. The tubes should be cleaned at 

 least once each day, whether in burning coal, wood or 

 straw. The tube scraper is adjustable, and may be set 

 out while in the tube by turning the rod to the right. 

 Turning the rod to the left decreases the size of the 

 scraper. Soot is a very poor conductor of heat, and even 

 a thin coating of it affects the efficiency of the boiler to 

 a considerable extent. It is therefore, essential to keep 

 the scraper well set out, so that all the soot will be removed. 



Expanding and Beading the Tubes. Leaky tubes 

 should be fixed the first time the engine cools. When the 

 steam no longer shows on the gage, remove the ash-pan 

 bottom and grates ; also the bricks, if the engine be a straw 

 burner. If the leaks be only slight ones, they may be 

 stopped by simply using a beading tool. To do this clean 

 the end of the tube and the tube sheet and place the long 

 or guiding end of the tool within the tube. Use a small 



