CATALOG OF THE MECHANICAL COLLECTIONS H 



carried forward a series of experiments that led to the perfection of 

 the solid wheel mill wdth curved steel blades. This type of wind 

 wheel was not Perry's invention, but his design (the aerometer) was 

 far in advance of all others, with an efficiency of 25 percent, about 

 80 percent better than any prior windmill. Perry is said to have 

 •done for the windmill what Poncelet did for the water wheel. 



Recent developments in windmill design have had to do principally 

 with the application of aerodynamic principles to the design of wind- 

 wheel vanes. The airplane-propeller type wind wheel is used in some 

 of the direct-connected wind-electric sets, while the Kumme system 

 employs a wind wheel of a few very large vanes or sails similar in 

 design and construction to an airplane wing. In these latter ones 

 the blade is free to move about the arm that carries it, and its pitch 

 is regulated by the wind itself. The most radical in appearance of 

 all the modern windmills are those that employ the rotor principle 

 or "Magnus effect" for their operation. These may have a wind 

 wheel made up of a few arms supporting small light rotor cylinders 

 or may consist only of one large vertical cylinder rising directly from 

 the ground and designed to be used upon the top of some wind-swept 

 hill. 



By far the greatest number of windmills in the United States have 

 been used for pumping water, a service to which the windmill is well 

 suited because large quantities of water may be pumped and stored 

 during periods of steady winds, to be drawn upon and used at any 

 time regardless of the wind. An analogous service in which the 

 windmill is now successfully applied is that of generating electric 

 power, which, like water, may be stored (in batteries) during steady 

 winds to be used when needed. Wind-electric generator sets are now 

 used extensively in the lighting of isolated airway beacons and farms. 

 A very early suggestion of this use of wind power is shown (below) 

 in the model of a wind-electric system made by Moses G. Farmer 

 as early as 1880. 



MONITOR WINDMILL, 1881 

 Plate 5, Figxire 1 



U.S.N.M. no. 300687 ; original patent model ; transferred from the United States 

 Patent Ottice ; photograph no. 18219A. 



This model was submitted with the application for the patent 

 issued to L. H. Sparks, August 30, 1881, no. 246247. 



This is one of several similar designs that constitute the bulk of the 

 windmills in use in this country. The mill has the solid type of wind 

 wheel (in which the slats are rigidly fixed), a rudder vane for holding 

 the wind wheel in the direction of the wind, and a governor for main- 

 taining a uniform speed of the mill in varying winds. The governor 

 consists of a safety vane normal to the direction of the wind and 



