BOUGII-AND-TUMBLE ENGINEERING 



steam to escape ; or if the gauge becomes dogged, the pop 



blow off when the gauge only shows 90 pounds or 



less. This s really more dangerous than the 



former. As you would most naturally conclude that your 



safety was getting weak, and about the first thing you 



would do would be to screw it down so that the gauge 



would show 100 before the pop would blow off, when in 



you would have 1 10 or more. 



So you can see at once how important it is that your 

 gauge and safety should work exactly together, and there 

 t one way to make certain of this, and that is to test 

 your steam gauge. If you know the steam gauge is cor- 

 rect, you can make your safety valve agree with it ; but 

 never try to make it do so until you know the gauge is 

 reliable, 



HOW TO TEST A STEAM GAUGE 



Remove it from the boiler and take it to some shop 

 where there is a steam boiler in active use; have the engi- 

 neer attach your gauge where it will receive the direct 

 steam pressure, and if it shows the same as his gam 



usonable to suppose that your gauge is correct. I f the 

 engineer to whom you take your gauge should say he 



or a lit <r, then go some- 



where else. I have already told you that I did not 



to guess at anything about your engine T want you 



