ROUGH- AN D- TUMBLE ENGOIBDUKG 59 



the engine by creating back pressure. We will illustrate 

 If you close the exhaust entirely the engine 

 will being true, you can readily under- 



i that partly dosing it will weaken the engine to a 

 pertain extent. So, remember that the nozzle has some- 

 .: to do with the power of the engine, and you 

 can see why the fellow that makes his engine clear 

 own flues is not the brightest engineer in the world. 



While it is not my intention to encourage the foolish 

 habit of pulling engines, to see which is the best puller, 

 iiould you get into this kind of a test, you can show 

 the other fellow a trick by dropping the exhaust nozzle 

 off entirely, and no one need know it. Your engine 

 will not appear to be making any effort, either, in making 

 the pull. Many a test has been won more through the 

 shrewdness of the operator than the superiority of the 

 engine. 



The knowing of this little trick may also help you out 

 of a bad hole some time when you want a little < 

 And this brings us to the point to which I 



facial attention. The majority of engineers, 

 when they want a little extra power, give the safety 



Now. I have already told you to carry a good head 



vam. anywhere from 100 to 120 pounds of steam is 



good pressure and is plenty. If you have your valve set 



