SCIENCE OF THRESHING. 139 



Two short sounds with a short pause between them, 

 to go ahead or commence work. 



Three medium short sounds means to hurry, given 

 to indicate to those hauling grain that the machine is 

 about to wait for them. 



One long, continuous sound followed by three 

 shorter ones is a signal to the waterman that the 

 supply of water is about exhausted. 



A continuous succession of short and rapid sounds 

 denotes fire or other distress and should be responded 

 to by all within hearing of the call. 



No one should ever sound the whistle but the 

 engineer, as one unaccustomed to it cannot give the 

 proper expression to the sound. 



The stroke of the whistle lever should be full and 

 steady, and well timed. The valve should not be 

 opened too suddenly, but with a clean and steady pull, 

 and should be closed gradually. The spaces between 

 the sounds should be well timed and of equal length. 

 This will give expression to the sound, pleasing to 

 hear. An old thresherman once said he could tell the 

 character of the engineer by the way he sounded the 

 whistle. 



The tone or pitch of a whistle may be changed by 

 screwing the bell up or down. The lower down the 

 sharper the tone will be, and more piercing to the 

 ears of those near by. When the bell is farther up 

 the tone will be of lower pitch and can be heard at 

 a greater distance and is not so distressing to those 

 near by. When set in a position, it should be left so 

 and not changed without good reason, as the people 



