62 ROUGH-AND-TUMBLE ENGINEERING 



PART FOUR. 



STEAM GAUGE 



Some engineers call a steam gauge a "clock." I sup- 

 pose they do this because they think it tells them when 

 it is time to throw in coal, and when it is time to quit, 

 and when it is time for the safety valve to blow off. If 

 that is what they think a steam gauge is for, I can tell 

 them that it is time for them to learn differently. 



It is true that in a certain sense it does tell the engineer 

 when to do certain things, but not as a clock would tell 

 the time of day. The office of a steam gauge is to enable 

 you to read the pressure on your boiler at all times, the 

 same as a scale will enable you to determine the weight 

 of any object. 



As this is the duty of the steam gauge, it is necessary 

 that it be absolutely correct. By the use of an unreliable 

 gauge you may become thoroughly bewildered, and in 

 reality know nothing of what pressure you are carrying. 



This will occur in about this way : Your steam gauge 

 becomes weak, and if your safety is set at 100 pounds, it 

 will show 100 or even more before the pop allows the 



