24 WATER POWER OF HALIFAX COUNTY, NOVA SCOTIA : 



of light loads to full loads. AVitli the steam i^laiit, on the con- 

 trary, the items of coal, labor, etc., increase rapidly with the 

 load factor, and hence the cost per horse-power per annum 

 increases in almost the same proportion. 



The cost of attendance is the most serious outlay in small 

 stations. It means, generally, the pay of at least three men, and 

 occasional extras — not less than $2,000 per annum, even for a 

 very small plant. At 100 kilowatt capacity this would come to 

 at least $20 per kilowatt per year, which added to the other 

 charges, is pretty nearly prohibitive. At 200 kilowatt capacity, 

 the oj^erating charge gets down to reasonable figures. In a 

 rough estimate, one Avill not go far wrong in saying that fin- 

 electrical purposes a water power of 250 to 300 horse-power on 

 steady flow is worth considering. Anything below this is of 

 little account, except for local utilization, and the usefulness of 

 the power increases rapidly above this point. 



If the situation is favorable for storage, a good deal can be 

 done with small streams ; but unless the above amount can be 

 made available without going to heavy expense, there is not 

 much that can be done. If two or more such powers are avail- 

 able they can be often worked together to advantage. There are 

 powers near the limiting size that have been passd over as too 

 small, and these are the o'nes which ought to be carefully looked 

 after in the interest of small places and small inthistries. 



The fundamental fact that faces the engineer of a hydro- 

 electric plant is that the total amount of hydraulic power avail- 

 able is, once for all, a fixed quantity. Of the rain that falls in 

 the drainage area of the stream a certain proportion finds its 

 way into the stream and that is all that is there available. Tak- 

 ing a series of years, too, the distribution of this available water 

 through the year is approximately uniform, so that one can 

 state broadly the total normal power per year, and that its dis- 

 tribution through the year follows a certain power curve. In 

 some streams this curve is very regular, in others extremely 



