156 GH iKD-TUMBLB ENGINEERING 



ly t hat this Ixjok would n. >t he filled up with scientific 

 theories, that while they \\ere \ ery nice they would do 

 no good in this work. Now I am aware that I could 

 have made a book four times as lai this, and 



had it would not be as valuable to the beginner at it is 

 now. 



l-'rom the fact that there is not a problem or a q 

 tion contained in it that any one who lias a common 

 school education can not solve or answer without re- 

 ferring to any text book, the very best engineer in the 

 country need not know any more than he will find in 

 these pages. Yet I don't advise you to stop here. L 

 the top if you have the time and opportunity. Had I 

 taken up each step theoretically and given formula 

 bles, rules and demonstrations, the young engineer would 

 have Income discouraged and would never have read it 

 through. He would have become discouraged because 

 he could not understand it. Now to illustrate what I 

 mean, we will go a little deeper and then still deeper, 

 and you will begin to appreciate the Dimple way of put- 

 ting the things which you as a plain engineer are inter- 

 ested in. 



For example on page 139 we talked about the 

 working pressure of different sized boilers. It was most 

 fikely and natural for you to say. "How do T find the 

 safe working pressure " Well, to find the safe work- 

 ing pressure of a boiler it is first necessary to find the 



