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63. To perfect them it is necessary that ye angle E A Q be 30 degrees, and then ye proportion of ye force of ye wind should be in ye concave in regard of ye convex, as 4 to 1 as hath been explained in ye rules of ye fall of bodys at ye end of ye treatise of percussion of ye 3d edition: We may moreover make ye faces C N, C L movable and B E, B Q, that they may fall a little close to ye sayl C D, and that they may open to ye others wch would augment ye proportion; it is necessary also to put these 6 sayls two to two one upon ye other diameter, ye force of ye windmill be 10 times 100 and that of ye watermills 2 times 466 pounds when ye wind goeth 12 feet in a second, and ye currant of water 4 feet, we may make ye like calculations for greater or lesser swiftness of ye water or wind, and for greater or lesser sayls. Some have attempted to make horizontal mills wch may turn with all all winds; I ahve seen of three sorts. [[image: Drawing of four trapezoidal panels each folded at right angles in the middle and top left panel labeled L I D C; bottom left panel B C N M; top right panel H Q A B; bottom right panel B A F E. A straight vertical line separates the left panels from the right.]] The first had their sayls concave and convex according to an angle of 45 degrees as is seen in ye figure. A B is ye height of ye concave, and C D ye height of ye convex, ye wind blowing betwixt these two will not act after ye same manner. For it will slide on both sides from ye crest C D along ye plains C L and C N, and will not act but as 8 to 5 2/3 whereas incountering ye concave and not being able to slide away it will act by all its force, as if it had a cloth streched upon E Q H F, and so it will act by all ye force of its shoc and as 8 and there being 6 like sayls there would be allways 3 wch would receive somewhat less by one third of ye impulse than ye 3 others wch would necessarily turn ye wheels, but with a little force or else they must be made excessively great, and so they could not be sustained and would be in danger to be carried away by an impetuous wind. To perfect them it is necessary that ye angle E A Q be 30 degrees, and then ye proportion of ye force of ye wind should be in ye concave in regard of ye convex, as hath been explained in ye rules of ye fall of bodys at ye end of ye treatise of percussion of ye 3d edition: We may moreover make ye faces C N, C L movable and B E, B Q, that they may fall a little close to ye sayl C B, and that they may open to ye others wch would yet augment ye proportion; it is necessary also to put these 6 sayls two to two one upon ye other that they may receive ye wind ye better and then these mills may produce near ye same effect, as those we have spoken of: The second sort had ye breadth of its sayls in a verticall situation, but ye sheet wch elevated them was movable frames wch on one side would rest entirely against ye extremity of ye wood wch would compass them about when ye wind should blow against them and so they would there receive all ye effort; but on ye other side they would give place to ye wind turning upon ye pivots, and having nothing to stop them, and by that means one part of ye wind would pass between ye opening there made wch would give much less force than ye other side, and ye wheel would necessaryly turn. But it would turn feebly and [[strikethrough]] and [[/strikethrough]] when ordinary windmills would turn by a moderate wind, this would not turn at all or very gently, because there would not remain 1/4 of ye force more in ye side wch ye wind would strike entirely, than in ye other, wch would proceed from hence that ye wood and ye cross parts would there receive as much on one side as on ye other, and ye movable frame of ye side wch they would open would not hinder their falling a little by their weights, and being incountered by ye wind wch would sustain them being never elevated to an horizontal height: But they would open only half a little more or less; wherefore they would be useless for ye most part of ye time and would not grind but with violent winds: The third manner was by covering ye half of ye number of sayls by a semicylindrick circumference of tin or some other light matter wch was directed straight to ye wind by a great weather cock a great way distant from ye center of ye engine,
Transcription Notes:
mandc: Reviewed, added more detaile image description.
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