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wheel, arbor, pinion, hand, twelve and fig

PERAAIBULATOR, a machine for measuring distances upon the ground. Ls external figure is shewn in figs. 1 and 2, Plate Perambulator. A B is a maho gany wheel, strongly framed and hooped with iron, that it ma) not wear, it turns in a handle, I) E, which the operator holds in his hand, and thus wheels it along upon ground. At F is a piece of mechan ism to register the number of revolutions the wheel has made. The pivots of the wheel work into pieces of brass let into the two arms of the handle, I) E; on the end of one of its pivots, a small pinion, a, (fig. 3) is fixed, this turns another pinion, h, upon a long spindle, d, which conveys the motion to the machinery at F (fig. 2) ; both pinions have eight teeth, therefore the spindle, d, turns in the same time as the great wheel, A B. This spindle is let into the wood work of the handle, as is shewn in the dotted line, d, (fig. 2), and has a square hole in its end to receive the end of a short arbor, e, (fig. 4), which is an enlarged plan of the wheel work ; this end has an endless screw on it turning a wheel, f; below this wheel, on the same arbor, is a pinion turning a wheel, h, and lower still is another wheel (hidden by f), turning a pinion, g, on whose arbor is the small hand, i, shewn in the plan of the dial plate. The wheel, 11.„ has a pinion on its arbor, immediately above it, turning k, which has a pinion above it, turning /, whose arbor is a tube, and put over the orb of h ; this tube has a short hand, rn (fig. 5), fix ed on it. The long hand, 71, is fixed to the arbor of the wheel A; this arbor is not made fast to the wheel, but to a circu lar plate, p, against which the wheel fits, and to which it is held by a pin put through the arbor beneath it, by this means the hands can be turned round to set them, without moving the wheel Is ; a pin is fixed in this wheel, which a, every revolution, lifts and lets fall a hammer, r, to strike the bell, t, and thus give notice of the hand having completed its revolu tion. The great wheehis half a pole in

circumference, and the wheels a b, being equal, the endless screw turns once for every half pole the instrument is wheeled along the ground ; the screw is so cut, that it turns the wheel,./, once in twenty four turiis of the great wheel equal twelve poles. The lower wheel on its arbor has thirty six teeth, and turns 8., of twelve teeth, three times as fast, or once for four poles ; this is equal to one chain, and the circle of the hand, t, (fig. 5) which it car ries, is divided into one hundred, each equal one link ; the pinion on the arbor of f has twelve teeth, and h, which it turns, has forty, it will turn once fbr 34- times of f, or 31 times 12 poles = 40 poles 1 furlong, the dial of the hand, n, which it carries, is divided into forty, each equal one pole, and by the pin in the plate, p, it strikes the bell once each revolution. The pinion of eight on the arbor of h, turns k, of sixty-four once for eight furlongs, and its pinion of six, drives / of seventy-two, once round for twelve of lc., or ninety-six furlongs, equal twelve miles. The hand, in, fixed to its arbor, points out these dis tances on a circle divided into twelve for miles, and subdivided into eight for fur longs. A. small scraper is fixed to the frame to prevent the wheel gathering dirt, and thus enlarging its circumference.

In wheeling a machine along a road, care should be taken to avoid all sudden holes or hills as much as possible, with out deviating from the straight line.

The bell, by striking, is ofgreat use to point out every furlong which might other wise be passed unnoticed.