Wind-mills.—The date of the invention of the wind-mill is not defi nitely known, although authorities generally concur in the belief that it is comparatively recent. Mabillon mentions a diploma of the year 1105 in which a convent in France is allowed to erect water- and wind-mills (molendina ad ventum). Many were built in that century. In the year 1332 a proposition was made to the Venetians to build a wind-mill. In 1393 the city of Spires caused a wind-mill to be erected, and sent to the Netherlands for a person acquainted with the method of grinding by it. A wind-mill was also constructed in 1442 at Frankfort. Wind-mills were used in the East only in places where no streams of water existed.
In the Middle Ages the natural right of man to employ water and wind as he pleased was frequently questioned. It is related that at the end of the fourteenth century the monks of the monastery of St. Augustine, at Windsheim, in the province of Overwissel, desired to erect a wind-mill, but were forbidden by a neighboring lord, who claimed that the wind in that district belonged to him. The bishop of Utrecht, however, to whom appeal was made, declared that no one but himself and the church at Utrecht had control of the wind in his diocese, and by letters patent dated 1391 he granted full power to the monks to build for themselves and their successors a good wind-mill wherever they chose.
The Old at Nantucket (pl. 3, jig. 7), built in 1746, was made chiefly of oak timber which grew on the island. With half-spread of sail it will grind fifty bushels of corn per day; doubling the width of sail over the arms will increase the grinding capacity proportionally. The mill-bouse is fixed, while the wind-wheel, together with its shaft and cog wheel, that engages in the trundle on the millstone spindle and the roof that covers them, is turned around to face the wind; this is accomplished by means of the tail-beam with a wagon-wheel on its end, as seen in the illustration. Tins wheel is worked around by hand, and is anchored in the required place. This mill was used for semaphore signalling in 1779 to warn American vessels coining in of the whereabouts of the English. Prior to its erection three other wind-mills had been built on the island, the first in 1723.
The (fig. S) is constructed by setting perpendicularly into the earth a strong post, which is held securely upright by several oblique braces. The upper part of the post is rounded and passes through a cir cular collar in the flooring of time lower chamber, and into a socket fixed in one of the strong- cross-beams of the flooring of the upper chamber, which must sustain the whole weight of the mill-house, and by means of a pivot or gudgeon on that part of the post which enters the socket the whole machine can revolve horizontally, to face the wind. The interior arrangement of a post-mill is shown in the Figure. The upper chamber
contains the operating mechanism, which consists of a horizontal shaft or axis, on whose end is a cog-wheel the trundle on the spindle attached to the upper millstone. The lower stone is somewhat larger than the upper stone. The corn is fed from the hopper through a spout, which is shaken by the revolutions of the square end of the spindle. The flour passes from the stones through the tunnel at one side, and thence to the chest, in the lower chamber. By a suitable mechanism the stones can be adjusted the proper distances apart and the null can be stopped and started at will. The bags of corn are drawn to the top of the mill by a rope wound about the axis of the shaft.
in the construction of grain-mills were gradually effected from time to time during the course of the Middle Ages, and in common with the progress of culture in general. It was not, how ever, until an impetus was given to invention by the enactment of the first British patent laws, early in the seventeenth century, that the im provements made by one or other individual mechanic became known beyond the precinct of the inventor's mill-house or the narrow limits of his native locality. It was but natural that under the incentive offered by the crown-patents many an old idea should be resuscitated and made the subject of patent-right.
In 1637 there was granted to George Mandy a patent for an invention relating to the " makinge, tryminge, selling, and putting out to hire of a new form of mills for the grindings of corn," etc. In 1682 letters-patent were issued beginning, " Whereas wee have Beene informed by our trusty and well-beloved John Joachim I3echer, Doctor of Lawes, that liee, with greate charge and study, bath found out and discovered A New Way for the makein,g- and erecting of,floating mills upon the River Thames and all other Navigable Rivers, for the Grinding of all sorts of Grainc," etc. In 1786 a patent was granted to Walter Taylor for "a machine in which the grinding surfaces are made of cast iron in form similar to the surface of the stones used by millers, such cast-iron grinding surfaces having grooves or furrows to admit of the flour passing. Steel cutters also may be fixed in the grooves." In 1827, Robert Vazie secured a patent for a mill which is described as follows: "The conical corn-mill operates, by means of two inverted concentric cones, by means of steel or other metal, one rotating on a vertical axis within the other, the external surface of the inner cone and the internal surface of the outer being grooved or chan nelled spirally in opposite directions to form the grinding surfaces, to and between which the grain is fed from a hopper above, and when ground falls from the open end or apex of the outer cone into a receptacle beneath."