§90 Additions and Corre&ions

interfere with the velocity of the gate’s fall, becaufe the hooks are the centre of motion upon which all adjuftment, as to the gate’s fall, depends, the places of the thimbles influencing only the upright pofition of the gate when faftened. The numbers of 58, rather furpafs the precife meafure of their refpeCive fides of the triangle, but are nearer to the truth in calculation than any workman could attain uy applying thefe directions; for in neither cafe do they exceed their true meafure _ fomuch as ,!, of an inch, and therefore in the one the clear fum of 4 inch is affamed _. for general purpofes; and fhould the hinges be lefs than 4o inches afunder,+ inch will be rather too much; or were they to be more than 40 inches diftant from each other,+inch, on the contrary, would be rather too little for the jufl proportion. It is certain that a fmall{pace muft be loft in hanging agate, though the hooks and thimbles be made with great exaCtnefs; for the weight of the gate will draw the upper thimble to bear upon the hind part of the upper hook, and will prefs the lower thimble again{t the fore part of the lower hook; this muft be trifling when the hinges are well fitted, and no allowance is qpede for it, becaufe the lower thimble gains as much upon the upper one by their being placed+ inch, thatis+ inch each, out of the plane of the gate’s extenfion, as appears by the difference of the fides of the triangle, numbered+24 and 1+ equal—1, inch by the meafure 43, which is aflumed, but really about= inch more, as ftated above, or on the whole equal to+ inch, which is a good general equivalent for the lofsin hanging a gate, and will ufually be fufficient to preferve the upright pofition of the gate when faft- ened, without having recourfe toa wafher at the lower thimble*.” It is remarked that the*‘ velocity as above given to the gate’s fall will be amply fufficient without any care of oiling the hinges; but the effect of wind cannot be counteracted in gates by any good confiruétion of the hinges; for were a velocity given to a gate’s fall equal to the refiftance of fo powerful an agent, the gate would foon want repair, from the confiant violence of its fhutting, and be fo much the heavier in the hands of a horfeman: befides, when a firong wind blew in the fame direétion as that of the gate’s fall, no man on horfeback would be able to withftand its force; and well con. firucted gates are moft liable to be a@ted upon by wind, from their wide extent of furface. But if paflengers are fo carelefs as to leave gates open under fuch cir- cumftances, there will be one fatisf&aQion remaining; that is, as foon as the wind ceafes, the hinges muft refume their property, and the gates fafien of themfelvest.’ Various directions are given, by which the new pofition of the hooks may be found when the hinges of gates are more or lefs than forty inches afunder. In proofof the accuracy of which,“ fuppofe a gateto be 110 inches long, and that it is in-

* Parker's Effay.+ Ibid.