94 Mr Edgeworth on a Machine for Measuring Distances. 



myself of It. Gout's patent pedometer, which is of litde accu- 

 rate use in the pocket, worn as a watch, for counting the 

 number of steps in walking. 



I placed this pedometer horizontally in the elbow of the 

 gig : It was there secure, concealed by a little door covered 

 with cloth, so that the dial-plate was not easily discovered, ex- 

 cept by a person who knew the opening. The difficulty in 

 the machinery was to communicate motion to the pedometer, 

 which being in the body of the gig, and of course on springs, 

 was subject to constant alteration of distance from the wheel ; 

 but as the springs played in nearly a perpendicular direction, 

 I passed through the side of the gig, an upright spindle, 

 which came some inches below the axletree. The lower end 

 was bent in a crank shape, and this crank came in contact with 

 a pin of about half an inch diameter, that was driven in to the 

 nave near its circumference. 



Round the spindle there was a helical spring, which slight- 

 ly urged the cranked part against the axletree, but every time 

 the wheel revolved, the pin in the nave pushed the crank out 

 for a few inches from the axletree, and it returned to its place 

 by the action of the spring as the pin receded. On the top of 

 the spindle was placed a lever of about two inches long, a lit- 

 tle above the level of the pedometer ; this acted against the 

 short perpendicular arm of a crooked lever, the long horizon- 

 tal arm of which lifted up the handle of the pedometer, and 

 by this means caused the hand to advance one division on the 

 dial-plate. Now, this horizontal arm was elastic, and allowed 

 the motion, communicated from the nave, to be much more 

 than was necessary for raising the handle ; the elastic lever 

 was also bent by the motion, so that no jolting should cause 

 any variation in registering the number of revolutions. In 

 fact, this idea of allowing by elasticity an overplus of motion, 

 and of placing the whole machinery on springs, arc the only 

 new principles in this little contrivance. 



It will be best to have a mile measured accurately on a 

 straight road, then, by driving backwards and forwards a few 

 times, and taking the mean of the number of revolutions which 

 the wheel performs in the mile, a table can easily be formed 

 for any carnage, whatever -nay be die size of the wheel, 



