146 ROUGH-AND-TUMBLE ENGINEERING 



have, if allowed to run freely from the boiler, can o 

 come boiler pressure and enter the boiler without 

 culty. Since the injector makes use of atmospheric ] 

 sure in lifting water it is evident that its limit, theoreti- 

 cally, is the same as that of the pump. Practically about 

 20 feet is its limit of vertical lift. Ejectors and syphons 

 arc instruments which make use of the injector principle 

 for lifting water from a lower level and delivering it to 

 a higher. These machines are made with large jets and 

 are suitable for handling large quantities of water. They 

 have not the forcing capacity of injectors. 



OIL 



It is very difficult to advise any one what brand of oil 

 to use. The same kind of oil is sold in various parts of 

 the country under different trade names. Furthermore, 

 oil is adulterated in a great variety of ways. There is 

 probably more fraud practiced in connection with lubri- 

 cating oils than anything else the engineer has to deal 

 with. The fraud in this line can be compared only with 

 the fraud in food products. It is a very easy matter to 

 adulterate an oil because very few engineers know how 

 to test an oil or really know a good oil from a poor one. 

 There are thousands of engineers who understand the 

 mechanical side of engineering very well, but who are en- 

 tirely ignorant in regard to oils. The fact that an oil 

 has considerable body or vicosity is no index of its purity 



