114 SCIENCE OF SUCCESSFUL THRESHING 



tube-sheet. Wash the boiler thoroughly with a hose, using 

 as much pressure as possible. Most of the sediment will 

 be found around the "water-leg" and along the bottom of 

 the barrel. In some localities, sediment lodges against 

 the fire-box tube-sheet, causing the tubes to leak. When 

 this happens, a plug is necessary in the boiler barrel above 

 this sheet so that the sediment can be washed off with 

 a hose when the boiler is cleaned out. 



Packing Hand-Hole Plates. After the boiler has been 

 cleaned, the hand-holes must be re-packed, for it seldom 

 happens that a gasket can be used the second time. For 

 re-packing, it is best to use the purchased gaskets, which 

 can be bought cut ready for use. If preferred, they may 

 be cut from sheet rubber packing by the engineer. Other 

 substances, such as sheet asbestos, card-board, straw- 

 board, or rubber belting are sometimes used, but the most 

 satisfactory material for this purpose is two-ply sheet 

 rubber, which is about one-eighth of an inch thick. The 

 gasket should be cut so as to fit closely around the flange 

 on the plate and should lie flat. Before the hand-hole plate 

 is replaced, the nut should be oiled and screwed back and 

 forth the whole length of the thread on the bolt, using a 

 wrench if necessary, until it may be easily turned with the 

 fingers. The inside of the boiler plate and the face of the 

 hand-hole plate, where the packing touches, should be 

 scraped as clean and smooth as possible. Care must be 

 taken in inserting the plate, to prevent displacing the 



