92 SMALL WATER SUPPLIES. 



Brake horse-power should be considered, and the 

 makers should be bound to provide an engine of that 

 power under the circumstances under which it will 

 work. The indicated horse-power, a quantity upon 

 which steam-engine builders place much reliance, is 

 quite unsuited to the rating of gas and oil engines, 

 and is in all cases unreliable. Indicator diagrams are 

 only taken for the purpose of ascertaining the work- 

 ing of the valves, etc. 



We now proceed to investigate the ways in which 

 small pumps are economically driven. For country 

 work, where no electricity or gas supply is available, 

 the oil engine or producer-gas engine at once pro- 

 vides a solution of the problem. Those made by 

 first-class makers are reliable machines, and small 

 oil engines will generally work well on ordinary 

 lamp oil (Royal Daylight Brand), which can be ob- 

 tained in most localities. For larger engines which 

 use more oil, it may be prudent to lay down a plant 

 capable of using cheap crude petroleum, which when 

 bought in large consignments provides very cheap 

 fuel. 



Where continuous working will be the rule, one 

 cannot do better than install a producer for the 

 engine of the suction type, if anthracite coal can be 

 obtained at a moderate price. Any ordinary intel- 

 ligent working-man can look after the producer., 

 which, when started (they take about half an hour to 

 light up and start), will work for hours with only 

 casual attention. Most makes of gas engine are 

 similar to each other ; it is hard to say which is the 

 best maker. Each claims special advantages for his 

 own engine. A typical example is given in fig. 77. 



