172 Experiments for determinivg the [March. 



construction to the other, it will not keep pace with that of a better 

 construction, but it will in a short time be left behind, till at last 

 the better carriage will overtake the machine which carries the 

 pulley. Now if the carriages are replaced in their former situation, 

 that which appeared to be the best may have additional loading put 

 upon it by degrees till it nearly keeps pace with the inferior car- 

 riage ; so that after a sufficient number of trials, the advantage of 

 one over the other may be determined by weight. 



Tills is in fact weigiiing the draught of one carriage against the 

 draught of another ; and thus, taking any one carriage as a standard, 

 the comparative advantage of any number of carriages, ploughs, or 

 implements to be drawn by horses, may be accurately ascertained. 



13y this apparatus a cart with wooden springs was tried against a 

 common cart : both were in the first place weighed, and the lightest 

 had as much loading put into it as made it equal in weight to the 

 other. They were then fastened to the ends of a rope which went 

 round a pulley which was mounted, as above described, on another 

 carriage. After a number of trials, on a road which was neither 

 very good nor very bad, it was fairly ascertained that the cart on 

 wooden springs surpassed a common cart of nearly the same form, 

 and with wheels of nearly the same size ; and that it carried more 

 than one-fifth greater loading than the common cart ; that is to say, 

 the spring cart, loaded with seven men and a boy, kept pace with 

 a common cart loaded with six men, whose weights compared were 

 in the proportion above-mentioned. 



To prevent any mistake that might arise from the difference of 

 roughness in the different paths on which the carts ran, they were 

 placed alternately at each end of the road, without any material 

 difference being observed.* 



Distance from workmen skilled in working steel springs pre- 

 vented a comparison being made between them and wooden 

 springs. 



Having thus stated the result of an inquiry, which appears to me 

 of extensive utility, I beg leave to point out in general. 



That if one horse out of five which are now employed in 

 drawing heavy burdens could be spared, the saving to the nation 

 would be (according to the calculations of Mr. Ward, in his excel- 

 lent paper printed in the Third Report for 1809, of the House of 

 Comnjons' Committee upon Broad-Wheels and Koads) nearly three 

 millions sterling. 



That as the advantage of springs must be inconsiderable upon 

 smooth, sott, and sandy roads, their utility may perhaps be confined 

 to one-tnuh part of tlie roads in England, still they may save nearly 

 300,000/. annually to the nation, with all the advantages arising 

 from the greater supply of human food, which must arise from the 

 saving of land now appropriated to the maintaining of horses. Sup- 



• A similar experiment to what is above described was tried on a grarel walk 

 with models, and nearly tiie same results were produced. 



