126 ROUGH-AND-TUMBL! BIKING 



A. Because if he is deceive 1 1>\ it. it shows he has 

 neglected something. 



Q. What is meant by Priming?" 



A. It is the passing of water in visible quarr 

 into the cylinder with the steam. 



Q. What would you consider the first duty of an 

 engineer on discovering that the water was foaming or 

 priming? 



A. Open the cylinder cocks at once, and throttle 

 the steam. 



Q. Why would you do this? 



A. Open the cocks to enable the water to escape, 

 and throttle the steam so that the water would settle. 



Q. Is foaming the same as priming? 



A. Yes and no. 



Q. How do you make that out? 



A. A boiler may foam without priming, but it < 

 prime without first foaming. 



Q. Where will you first discover that the water i< 

 foaming? 



A. It will appear in the glass guage. the glass will 

 have a milky appearance and the water will seem to ]>< 

 running down from the top. There will be a snapping 

 or cracking in the cylinder as quick as priming be<r 



Q. What causes a boiler to foam? 



A. There are a number of causes. It may come 

 from faulty construction of the better ; it may have insuf- 



