Mance: Quarry Industry of Southern Indiana 93 



Locomobiles cost from $60 per horse-power in the 75 

 horse-power units to $47.50 per horse-power in units of 600 

 horse-power. That is, a 75 horse-power locomobile would cost 

 $4,500 while a 600 horse-power unit would cost approximately 

 $28,500. The two letters can be compared by adding one-third 

 to the horse-power consumption to give the kilowatt consumption. 

 This method of figuring will give a comparatively accurate 

 result. The second letter is as follows: 



Dear vSir: 



We have you favor of the 29th ins t., and would state that a 100-kilowatt 

 single-cylinder engine, with 120 pounds steam at throttle, will give a steam 

 consumption per indicated horse-power per hour at full load of 26 pounds, 

 and at one-haK load of 28 pounds. 



Inasmuch as you will have boiler and line losses, and the steam will come 

 to the engine somewhat wet, and inasmuch as you have the friction loss 

 of the engine and the factor of generator efficiency to be taken care of, 6 or 

 7 pounds of coal per kilowatt hour is as low as you should figure. 



It takes about 600 pounds of coal to bank a 150 horse-power boiler all 

 night, and this should be added in. 



With good oiling system, the engine should not consume more than 

 one dollar's worth of engine oil per month; and the cylinder oil should not 

 cost more than 30 cents per day. 



If you are going up into the larger sizes, if you installed a compound 

 engine you could cut about l}/2 pounds off the coal consumption per kilowatt 

 hour. 



Another economical type of engine for ordinary power genera- 

 tion is the oil engine. In this type of engine oil is burned in the 

 cylinders the same as gas is burned in the gas engine. Several 

 general types are in the field; the main difference between them 

 lies in the method of preparing the oil charge for ignition and 

 firing the charge. 



Oil engines offer a cheap method of producing power in 

 medium-sized plants, but the one drawback is the dependence 

 of the operator on the prices fixed for oil by the company con- 

 trolling the output in this country. 



The onl}^ oil engine plant in operation in the stone belt at the 

 present time is the one run by Harding and Cogswell at Elletts- 

 ville. The engine in use is a 40 horse-power Fairbanks-Morse 

 and^ is giving excellent satisfaction. The cost of power in this 

 plant will be taken up in the part of this study which deals with 

 the cost of power. 



Another type of prime mover that is of interest in connection 

 with any discussion of power, especially power in large plants, 

 is the steam turbine. Steam engines are of two general classes: 



