DARTMOUTH LAKES POWER. DOANE. 23 



If the cost can be kept in the neighborhood of $100 per 

 horse-power, the outlook for an economical short transmission 

 is good, since this means an annual charge of no more than 

 $10 or $12 per horse-power for the motive power. The cost of 

 wheels and generators with their equipment will ru'n generally 

 from $25 to $30 per kilowatt in cases where raising trans- 

 formers are not needed, the usual case for small powers. All of 

 this can be approximated very readily, as also can the cost of 

 the necessary buildings. 



The heaviest charges in small work come in the operating 

 expenses and in the pole line. Pole lines for light wires need 

 not cost more than $250 to $300 per mile, exclusive of wires 

 and right-of-way. The latter, in working on a small scale, is 

 commonly along the highway, so that the cost is small ; but the 

 cost of wire, ulnless the line is short, may add considerably. 

 Still, at a given voltage, the cost of copper per kilowatt trans- 

 mitted is a constant, and the only relatively fixed item is the 

 cost of stringing, which varies only slightly with the size of wire 

 until the larger sizes are involved. For mechanical reasons, 

 however, it is not desirable to string wire smaller than E"o. 4 or 

 No. 5, so that the minimum cost of conductor is somewhere 

 about $500 per mile. Fortunately, the depreciation charge 

 against bare w r ire is practically negligable, and wire of this 

 minimum size will carry comfortably the output of the class of 

 plant considered. 



In hydro-electric plants the operating expense is largely one 

 of fixed charge, while with steam plants it is made up of fixed 

 charges coupled with variable items of coal, water, oil, waste 

 and incidentals. With the hydro-eleetric plant, consequently 

 the cost per horse-power per year is almost constant, regardless 

 of whether supplied one hour a day or twenty-four hours a day. 

 Repairs are about the only variable, and they may be coinsidered 

 as increasing in direct proportion to the load factor. Labor, oil, 

 waste, etc., are nearly the same, irrespective of the proportion 



