32 SCIENCE OF SUCCESSFUL THRESHING 



Testing and Repairing the Heater. If you suspect 

 that the heater leaks, on engines with independent pumps, 

 it may be tested as follows : First drain the exhaust space 

 by opening the cock ; then start the pump, but let the engine 

 stand still. If water continues to issue from this cock, it 

 shows that the heater leaks. Repairs are easily made by 

 removing the heads. The tubes in either style of heater 

 may be tightened or renewed if necessary, in exactly the 

 same manner as those in the boiler. 



