ew Goes, tess

ee

fo the Firft Volume. 591

tended torife at the head 62 inches in its femicircnlar courfe, from-the line of refi to theline of equilibrium; then, as the length of the gate is to the diflance between the two hinges, fo will be 62 inches to double the horizontal diftance of two perpen- dicular lines, one falling from each of the hooks.”? Or“ take any other diftance of the hinges from each other, and the required extra length of the lower thimble may be found by placing the numbers 110 and 62 as the firft and*fecond terms of a rule of three proportion, and the new diftance of the hinges muft be the third term; the anfwer, divided by two, will be the fought-for horizontal difiance of the two perpendicular Jines falling from the haoks(adding the lof% in hanging the gate); the anfwer for the one is the meafure for the other*.” It is fuppofed that“ thefe general rules will find a tolerably accurate meafure in all cafes; for where a gate or wicket is fhort and light, the friction of the hinges will be lefs in two refpes, both by the diminifhed preffure on the hooks from the gate’s lightnefs, and the reduced diameter of the pivots, which will fupply what is wanting in the weight or momen- tum of the gate. On the other hand, when the gate is long and heavy, its increafed weight or momentum, and its length asa lever, will be oppofed to the additional friction‘of the hinges.” And“ in cafes where old hinges are badly made, with large hooks or deep thimbles, that difficulty is to be met by taking the proportion for the diftance of the two hinges from each other at five or ten inches more than it really may be, wita reference to the given table, or by adding fomething to the ufual horizontal diftance of the lines falling from the hooks. But when the thim- bles are of a long cylindrical form they are extremely apt to bind upon the hooks, and will fometimes put a dead ftop to the gate’s motion. With fuch thimbles the attempt of adding to the velocity of a gate’s fall may only increafe the binding or friction; and the remedy for this defe@, therefore, is to make the hooks much fmaller than the thimbles: in new thimbles, no form but that of annular, or ring- like, fhould be admitted.” By“ the lower thimble being furnifhed with a fcrew of equal diameter throughout its length, its extra length may be regulated to fo great a nicety as half a turn of the fcrew, and may either be let into the’ heel beyond the fhouldering, or lengthened out by a wather as circumftances require, in adapting it either for hinges, which are lefs than forty inches afunder, or the contrary, without the help of a blackfmith or any frefh forging, which is always troublefome and expenfive. And if a gate finks at the head, without any fault in the hanging-poft or hooks, the lower thimble may be lengthened out to bring the

gate upright, and the hooks remain unaltered+,” * Parker’s Effay on Gates.+ Ibid.% VOL< I, at