214 Kansas Academy of Science. 



As desirable forms of prinie movers in commercial plants the 

 gas- and oil-engines must be subjected to complete analysis that 

 shall include all conditions of first cost, depreciation, repairs, and 

 labor, as well as fuel cost. This we will now proceed to do with 

 our typical col^ton-mill. 



A single gas-engine of 1800 horse-power, to use natural gas, may 

 'be purchased for about $43 per horse-power ; foundations will cost 

 about $7; making the total cost of the engine, erected, $50 per horse- 

 power, or $90,000. This is somewhat less than the average first 

 cost of a water-power plant, but the difference is not likely to be 

 enough to inflaence appreciably the total investment in the mill. 

 Depreciation may be taken at four per cent, and repairs three per 

 cent, on $90,000, giving $6300 annually. Labor for attendance, one 

 •man, at $750 per year. Gas consumption will be about ten cubic 

 feet per horse power per hour, or 54,000,000 cubic feet per year of 

 3000 hours. With gas at 25 cents per 1000 cubic feet, the fuel bill 

 will be $13,500, and hence the total annual cost of power, $20,550. 

 This, when compared with the preceding calculations, giving $22,500 

 for water power and $38,000 for steam power, shows well for the gas- 

 engine. When installed with a suction producer, using coal for 

 fuel, conditions will be different. Actual figures for cost of pro- 

 ducers of this capacity are not available, but $10 per horse-power 

 will be a safe figure, which, with $2000 added to the cost of the 

 engine to provide for the slightly increased size necessary when 

 nsed with the suction producer, makes the total cost of the appara- 

 tus $1 10,000. It will be assumed that Arkansas anthracite coal will 

 be used, at $(3 per ton, and that the rate of fuel consumption will be 

 1.25 pounds of coal per horse-power per hour, which is a liberal 

 figure. This gives 3375 tons of coal burned per year, at a cost of 

 $20,250. Depreciation and repairs will be increased to seven per 

 cent, of $110,000, or $7700, and labor increased by two men, at $450 

 each per year, making total labor $1650 per year. This makes the 

 total cost of power $29,600 per year, or $7100 more than the cost of 

 water power. This excess is, however, but forty-five per cent, of 

 that occurring with the use of steam, and is $760 less than that 

 with water power with electrical transmission and motor drive. As 

 already noted, however, the power cost with the latter system may 

 be reduced under favorable conditions ; so it may fairly be stated 

 that costs are about the same for the hydro-electric system and the 

 gas-engine with suction producer. 



The first cost of the gas equipment is $50,000 less, however; so 

 ■that there would be a difference in dividends in its favor of over 



