i9io.] 



Wind Power. 



905 



maintenance, one realises the cheapness of this form of 

 power. 



Uses. — The chief uses of the modern windmill are for (1) 

 pumping and (2) power. Windmills for pumping are 

 employed to supply water for farms, estates and villages, and 

 are also used for drainage and irrigation purposes. A more 

 extensive use of the windmill in the two latter directions 

 would, in many instances, prove economical. Much land in 

 this country subject to unfavourable moisture conditions 

 could be rendered productive through the use of the windmill. 



Power windmills are mostly used for driving farm 

 machinery, and for the generation of electricity. Wind power 

 is particularly useful for such operations as charring, pulping, 

 grinding, churning, and sawing. For the production of 

 electricity specially constructed dynamos and storage batteries 

 are now manufactured and, with a proper plant, the applica- 

 tion of wind power in this direction gives most satisfactory 

 results. 



Principles of Construction.* — The main differences between 

 the pumping and power windmills lie in their strength and 

 type of gearing. Power mills usually exert a higher horse- 

 power than pumping windmills. The principles of construc- 

 tion are, however, much the same in both types. The older 

 patterns of windmills were provided with wooden wheels and 

 vanes and no governing arrangements beyond a brake. It 

 is characteristic of the modern mills to be provided with a 

 properly constructed steel wheel and spring governor. The 

 wheel has a framework composed of a bracket with numerous 

 arms, to which are attached the sails. Their length, width, 

 thickness, and distance apart, and the angle at which they are 

 set, all make a difference to the efficiency of the machine and 

 can only be determined after scientifically conducted experi- 

 ments. The wheel (Fig. I., IF) is kept at a suitable angle to 

 the wind by the vane (V) and governing arrangements. The 

 advantage of the spring governor (G) is made manifest 

 by watching a mill of the old type working in a gusty wind. 

 With every increase of wind velocity the rate of revolution 

 is suddenly increased, and the resulting jerky motion must 



* For an account of some of the different types of pumping mills on the market., 

 see /our. Roy. Agric. Soc, vol. 64, 1903. 



