o BULLETIN 173, U. S. NATIONAL MUSEUM 



efficacious when the wheels were turned by the wind, were in use in 

 Tibet and Mongolia in very early times, and Heron of Alexandria 

 {Treatise on Pneumatics, c. 150 A. D.) described a light, wind-driven 

 organ pump. That the wind mill originated in the East and was 

 introduced into Europe by the Crusaders returning from the East 

 is now generally accepted. This theory is supported to some extent 

 by the fact that windmills were known in Persia in the tenth century 

 and in England and France in the twelfth century. The earliest 

 authenticated record of a windmill in the West is of one at Haberdon 

 in England in 1191. Records following this show that within the 

 next 50 years windmills were erected very generally in Europe. 



The details of construction of the first windmills are purely con- 

 jectural. The first records are of mills that were complete in the 

 essential elements of a horizontal shaft carrj-ing sails at the outer 

 end, a downward or vertical shaft that carried the millstone at its 

 lower end, and some crude gearing (at the upper end of the vertical 

 shaft and the inner end of the horizontal shaft) to transmit the 

 motion of the sail shaft to the vertical shaft. Though not 

 shown in the earliest drawings, it is assumed that the first 

 mills also had a means of raising or lowering the millstone 

 to vary the grain size of the meal being ground. To these elements 

 no improvements are known to have been added until the fifteenth 

 century. A heavy beam pressed against the sail shaft was used as 

 a brake in the first part of the sixteenth century, and by the end of 

 the century the curved brake band of pliable wood applied to the 

 rim of the driving wheel (suggested by da Vinci about 1500) was 

 used. The improvement of setting the sail shaft at a slight angle 

 to the horizontal was suggested about 1557 by Dardan, and the 

 internal features of the mill were practically complete by the end 

 of the sixteenth century. 



Externally the construction of the windmill has been determined 

 by the necessity of housing the mill material equipment and operators 

 and at the same time permitting the mill to be faced in the direction 

 of the wind from any quarter. Some presume that the original wind- 

 mill was built upon a boat in order that it might be turned about 

 easily to meet the wind, but the earliest windmills alluded to were 

 on land, and it is believed that the problem of facing the mill about 

 was solved before the first was built. The most primitive mill con- 

 sisted of a light boxlike house built upon a central post, which was 

 supported by a timber tripod base that rested upon the ground and 

 could be turned round, base and all, to face the wind. Later, in the 

 fourteenth century, the central post was let into the ground and fixed, 

 and the mill turned upon the post. Following this the turret-post 

 mill was constructed in which the boxlike structure was erected upon 

 a masonry tower, in which larger milling facilities could be housed 



