122 Book of Locomotives 



is surrounded with water. From the fire- 

 box run numerous tubes, they number any- 

 thing from 150 to 350. At the smoke-box 

 they come to an end, and as we examine 

 this end of the boiler our attention is drawn 

 to something which we think must be a 

 trumpet that is judging by its shape. That 

 small trumpet is the lung of the locomotive ; 

 without it little could be done. The hot 

 gases, which we have mentioned as rushing 

 through those numerous pipes from the 

 fire-box to the smoke-box have a double 

 duty to perform. 



Not only do they add to the boiling capa- 

 city of the fire, but they are the chief means 

 of getting that fire to burn fiercely; the 

 tubes would be practically useless if it were 

 not for that trumpet. If we look at it closely 

 we notice that it is placed so that the mouth- 

 piece of the trumpet comes right under the 

 chimney, the bell mouth being at the bot- 

 tom. The real name of the trumpet is the 

 blast-pipe, through which the waste steam 

 from the cylinders is discharged to the 

 chimney. As the steam rushes up the blast 



