8^ 6i30MEtER. 



^ . . ^ arbor of which another screw of brass B is formed, which 



Description of i-. ■. iS rxr r i 



an Odometer, acts upon the brass wheel C. (Fig. I * PI. III.) This wheel 



or instrument Q serves ^Iso as a dial-plate, and is divided into miles, 

 the ground halves, quarters, and furlongs; the figures indicating the 

 passed over by. miles are nearly three quarters of an inch long, so as to 

 a carnage. be qnite distinct; they are pointed out by the index D, 

 which is placed as represented in the plate, in such a 

 \ manner as to be easily' seen from the carriage. 



These two brass wheels arc mounted by the irons E E 

 upon a block of. wood F, eight inclies long, two inches 

 thick; and five inches broad. This block may be screwed 

 tipon the axletree-bed by two strong square-headed 

 wood-screws. If the carriage permits, this block should 

 be fixed obliquely on the axlctree-bed, so that the dial- 

 plate may be raised up toward the eye of the person 

 booking out from the carriage. 



II is a ratchet wheel attached to the arbdr of the wheel 

 A, which, by means of the click I, allows the wheel to. 

 be set with a key or handle fitted to the squared end o.f 

 the arbor at K. L is a long spring screwed on the block; 

 it presses on the wheel A, to prevent it from shaking by 

 the motion of the carriage. A small triangular spring is 

 put under the middle of the dial-plate wheel for the same 

 purpose. 



If the wheel of the carriage is exactly five feet three 

 inches in circumference, the brass toothed wheel which it 

 turns should have twenty teeth, and that which serves as 

 . a dial-plate should have eighty ; it will then cbunt five 

 niiles. If thje carriage wheel is either larger or smaller, 

 a mile should be carefully measured on a smooth road, 

 and the number of turns which the carriage wheel makes 

 in going this mile may easily be counted by tying a piece 

 of fine packthread to one of the spokes and letting the 

 -<vheel, as it moves slowly forward, wind up the pack- 

 thread on its nave. When the wheel has proceeded a 

 half or a quarter of a mile, unwind the string and count 

 the number of turns which it has made. 



By the addition of another Avheel of eighty-one teeth 

 placed under the dial-plate wheel and moved by the screw 

 C, with a proper haird fitted to it, and proper figures on the 

 dial-plate, this machine would couaj: four hundred miles, 



\ • B0RI>Cr 



