ROUGH-AND-TUMBLE ENGINEERING 69 



ing i vr into a hot boiler will do it. For instance, 



out a boiler while in the field, and then refilling 

 MS time to get cool. 1 have seen an en- 

 gineer pour water into a boiler as soon as the escaping 



i would The flues cannot stand such t 



mem. y are thinner than the shell or flue sheet, 



and therefore cool much qui i contracting arc 



tlue sheet, and as a matter of course be- 

 to leak. A flue, when once started to leak, seldom 

 stops without being set up, and one leaky flue will start 

 others, and what are you going to do about it ? Arc you 

 going to send to a boiler shop and get a boilcrmaker to 

 come out and fix them and pay him from forty to 



hour for doing it? I don't know but that you 

 must the first time, but if you are going to make a busi- 

 ness of making your flues leak, you had best learn how to 

 repair them yourself. You can do it if you are not too 

 &et into the fire door. You should provide your- 

 vith a flue expander, a calking tool, and a machi: 

 hammer (not too heavy). Take into the firebox with you 

 a piece of clean waste with which you will wipe off the 

 of the flues and flue sheet to remove any soot or 

 ashes th ive collected around them. After this is 



done you will force the expander into the flues, driving 

 order to bring the shoulder of the expander 

 d of the flue. Then drive the 

 taper into the expander. By driving the pin in 



