9io 



Wind Power. 



[FEB., 



mechanical horse power — the capacity of a machine to work 

 at the rate of raising 33,000 lb. 1 ft. high in 1 minute, and 

 this expressed in animal power is equal to the work done by 

 two horses weighing 1,000 lb. each. Two such animals 

 doing 10 hours' work per day would develop power at the 

 rate of 1 H.P. mechanical. Thus we have a machine, costing 

 at the most £$o, and practically no annual expense, having 

 the same power as a couple of animals costing in the first 

 place at least £30 apiece and demanding not only an annual 

 expenditure for food and attendance, but an allowance for 

 depreciation and risk. Further consideration, of course, 

 reminds one that animal power possesses many valuable 

 features which are absent from such a machine as a windmill ; 

 but assuming that the horse were required like the windmill 

 for, say, pumping alone (by tread or sweep power), it is 

 obvious for many reasons that wind is by far the more 

 economical power to employ. 



Comparison of wind power with human labour leads to 

 similar conclusions. It requires nearly 10 men to exert con- 

 tinuously in a normal day's work power equal to 1 H.P. 

 A 12 ft. mill is capable of pumping at the rate of raising 

 3,300 gallons of water 1 ft. high in 1 minute, where a man, 

 working at a pump, can only raise water at the rate of 300 

 gallons 1 ft. high per minute. 



Nevertheless, where there is very little work of the windmill 

 type to be done, say, not more than a few T days each year, 

 it would not be economical to expend capital on a windmill, 

 even though per unit of power it be much cheaper than animal 

 power. When to employ wind power can only be determined 

 by a consideration of the conditions of each particular case. 



Description of Diagrams, 



Fig. I. — Wheel head, w, wheel ; G, spring governor ; v, vane ; IS, internal spur ; 



SP, spur pinion ; cs, centre shaft. 

 Fig. II. — Foot gear, c, slip couplings; hs, horizontal shaft. 



Fig. III. — Pump gear. cs, centre shaft ; cg, crank gear ; SP, spur pinion 

 engaging internal spur ; s, crank shaft which connects piston rod. 



Fig. IV. — Side view of tower. SB, horizontal steel braces; CB, diagonal cable 

 braces. 



