20 SCIENCE OF SUCCESSFUL THRESHING 



wicking, with which it was packed, was forced, by the 

 tightening of the packing-nut, over the lower end of the 

 glass, practically shutting off the water. 



Broken Water-Glass. In case the water glass breaks 

 when the boiler is under pressure, shut both valves to stop 

 the escape of steam and water. The engine can be run by 

 gage-cocks until a new glass may be obtained. If a new 

 glass be at hand, it may be put in at once, but care should 

 be taken to heat it gradually, for if the steam be turned on 

 suddenly, it will break. 



Injectors. The injector has, of late years, reached 

 such a state of perfection as to make it the most conven- 

 ient of all the types of boiler feeders. Although economi- 

 cal in itself, it does not equal, in ultimate economy, a pump 

 used in connection with a heater. The question naturally 

 arises : if it be economy to use a heater in connection with 

 the pump, why not with the injector as well? Were the 

 feed water from the injector piped through the heater, but 

 little would be gained thereby, because the injector delivers 

 water so hot, that it would absorb but little additional heat 

 during its passage through the heater. Consequently, the 

 pump, with heater, is the more economical because it util- 

 izes heat from the engine exhaust (which would otherwise 

 be wasted), to heat the water, while the injector heats it 

 by means of live steam taken from the boiler. It is not 

 usual, therefore, to pipe the feed water from an injector 

 through a heater. 



