Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 3, 1802).djvu/143

123&#93; LOC rent levels, and thus evenhially saved 3 because their apertures may be opened and closed at plea- sure, so that only the sixth part is required for the passage of boats. The particulars of this ingenious contrivance are inserted, and illus- trated with engravings, in the 3d vol. of the Repertory of Arts, &c. Another patent was granted, in 1798, to Mr. James Fussell, for his invention of a machine or balance-lock, serving to raise or lower boats on canals ; an account of which appeared in the 1 1 th vol. of the work before quoted. Locked Jaw. See Jaw, LOC [12: LOCKING-POLE, an ingeni- ous piece of mechanism, to be affixed to the wheels of waggons or other carriages; when descend- ing steep hills. As many distressing accidents happen from carts over-powering the shaft-horse, when proceeding down declivities, Mr.THOM AS CoL- LEY laid before the Society for the Encouragement of Arts, ice. a con- trivance for preventing such casual- ties; in consequence of which, he was rewarded with their silver me- dal. The foUovving cut represents this useful invention ; A, The hollow, which lies on the nave of the wheel. B C, The chains, that clip the felly of the wheel. D, Tiie fiont part of the pole, shod v/ith iron ; and which is far- ther strengthened by a rib of iron, that is rivetted along its side, as is indicated by the black line, in the cut. In order to apply this locking- pole, the chain C is put round the felly of the wheel ; the pin B is passed through the last link of C, and turned back through the mov- able ring c: thus the wheel is secur- ed, ajid any waggon, however laden, may descend the steepest hill with safety. To prevent the locking-pole from breaking, Mr. Colley da'e£ls it to be made of the stem of an ash- tree, the spurns, that is, the begin- ning of the roots of which, have not been cut off in felling. He farther remarks, that if a horse, which has been accustomed to such situation and to descents, be put in the shafts, the animal will be so much inclined to hold back, that it will be ex- tremely difficult to make him draw. This exertion, however, is abso- lutely necessary ; as otherwise the chain-horse, which should always be linked to the locked side, will be obliged to pull an unnecessary weight, occasioned by his being considerably lower tlian the jxiintj of the shafts. Lastly, in conveying the locking- pole from one declivity to another, it is to be placed between the lowrr part of the cart and the axle-tree, while the smaller end is to be buckled with a strap fixed under the body of the cart, on the driving side. LOCUST, or Gryllus Locusta, L. a family of inse6ts, natives of Asia and Africa, where chiefly two