Home >> Encyclopedia-of-architecture-1852 >> Onument Of Lysicrates to Or Urbino 1trbin >> Peram Lator

Peram Lator

wheel, teeth, index, distance, stock and yards

PERAM LATOR, (from the Latin, perambulo, to trax el) an instrument f11' the measuring of distances, and in frequent use ILr measuring distances on roads, for settling disputes concerning the charges of the drivers of hackney carriages, and other purposes. It consists principally of a heel, upon which it runs, and an index which shows the number of turns of such wheel, reduced into miles, furlongs, poles, and yards.

The carriage or stock is made of wood, and is about 3 feet long. At one end is a handle for the person who uses it, and the other is furnished with sockets in which the axle of the wheel turns ; this end of the stock has the centre part removed, by which are left two arms between which the wheel works. Upon the stock, and just in front of the handle, is the dial-plate, with its two hands by which the distance is registered. The wheel is S feet, 3 inches, or pole in circumference. Upon one end of the axis of this wheel is a sunalt pinion, which woks into a smaller pinion at the end of a rod, which passes up the stock or carriage to the winks beneath the dial-plate. Motion is communicated by means of this rod to a worm or mierometer screw, which turns mice round for each revolution of the carriage-wheel of the perambulator. This worm works into a wheel of 80 teeth, vi hich is moved forward one tooth fur every pole, and caries a hand or index, which makes one revolution for 40 poles or one furlong. On the axis of this wheel, is a pinion of S teeth, which works into a wheel of 40 teeth, and on the axis of this second wheel is a pinion of 10 teeth, which moves a wheel of 160 teeth. This last wheel carries another hand, which makes one revolution for 80 of the former. These hands are arranged in the same manner as the hour and minute hand of it watch, so that the three cir cles on the dial-plate are all concentric. The first of these circles is divided into 220. and the second into 40, the n mber

of yards and poles contained in a furlong; the figures in these circles are read if by the first intentioned index, that which is attached to the wheel of 80 teeth. The third circle is din ided into 80, the number of furlongs in 10 miles, and to this circle belongs the index attached to the wheel of 160 teeth. The distance is ascertained by reading off the figures in the reverse order in which the circles are given above ; divide the number on the first circle by 8, and you will have the distance required in miles, furlongs, poles, and yards. The instrument is furnished with a stop or strap, so that after the distance is measured, the perambulator may be conveyed without the index being altered.

Unlike the pedometer, it requires no regulating, and the only risk of its giving the distance incorrectly, if well con structed, is passing over rugged and uneven roads, which will of course cause the index to show more than the true distance. In general, however, fin- shot distances, this error is very trifling.

When about to commence a measurement, the wheel should be furred round until the first mentioned index points to VO on the elide of yards. Some are provided with a click and racket, by which this may be done with much less nimble than by the wheel.

There are other instruments for the same or similar pur poses, bearing different names, as way/Pixer and odometer, lint the construction of all of them is very similar.

Way wiser is the name generally given to that Bent of the instrument a h'ich is applied to a carriage, in which. by a slight adaptation to one of the wheels of the carriage, the instrument is made to register the number of turns of such wheel, in the same manner as the perambulator.