ROUGH-AND-TUMBLE ENGINEERING 65 



or fusible plug, is a hollow brass plug or bolt, screwed 



the crown sheet or top of the fire box. The hole 



through the plug is filled with some soft metal that will 



less temperature than is required to burn 



iron. The heat from the firebox will have no effect on 



Me plug as long as the crown sheet is covered 

 with water, but the moment the water level falls below 

 the top of the crown sheet, thereby exposing the plug, this 

 soft metal is melted and runs out. This allows the steam 

 to rush down through the opening in the plug, puts out 

 the fire and prevents any injury to the boiler. All this 

 sounds very fine, but I am free to confess that I am not an 

 advocate of a fusible plug. After telling you to never al- 

 low the water to get low, and then to say there is some- 

 thing to make even this allowable, sounds very much like 

 the preacher who told his boy "never go fishing on Sun- 

 day, but if you do go, to be sure and bring home the fish." 



have no objejction to the safety plug if the engi- 

 neer did not kn*w it was there. I am aware that some 

 < require that all engines be fitted with a fusible plug. 

 I do not question their good intentions, but I do ques- 

 tion their judgment. It seems to me they are granting 

 a license to carelessness. For instance, an engineer is run- 

 ning with a low gauge of water, owing possibly to the 

 tanks heiner delayed lonprer than usual. He knows the 

 : M low. hut lie says to himself, "well, if the 

 o low I will only blow out the ^ d so 



