on Experhnetits Upon PFheel-carriages. 95 



\vere of equal draft, moving at a quick rate. At a slower rate 

 judged to be about 2f miles an hourj the wooden springs car- 

 ried 3 cwt. 2qrs.— being Itjr. less. 



The Efficacy of Springs in aiding Animal Exertion. 



A man drew, with his utmost exertion, a two-wheeled car- 

 riage with wooden springs blocked, which was loaded with 2 cwt. 

 a given space in nine seconds ; — 1 cwt. 2 qrs. were added and 

 the springs permitted to play; — with a similar exertion, he drew 

 it over the same space in 8^ seconds. 



N. B. It is to be observed, that in all these experiments the 

 load on the guide-rail was made as nearly the same as could be 

 judged by lifting ; but in order to ascertain how far a diflcrence 

 in this respect might affect the results, the following experiment 

 was made. — In a carriage having the entire load 9cwt. 2 qrs. 

 7 lbs. the weight on the guide-rail was 40 lbs. ; the carriage was 

 just put in motion by a weight passing over a pulley of 14| lbs. 

 when the load on the guide-rail was only 20 lbs. the carriage 

 was put in motion by 14 lbs. 



On Four-wheeled Carriages. 



Two four-wheeled carriages, as nearly similar as possible, were 

 placed on the wooden platform. They were constructed in such 

 a manner that the load on either of them might be placed within 

 eighteen inches of the ground, or raised to the height of three 

 ft-'et and a half, or even eight feet above the road. The distance 

 between the fore antl hind axletrees in these carriages, was nine 

 feet nine inches, and they were so made, that each of them could 

 be shortened so as to bring the fore and hind axletrees within 

 six feet of each other. Of these two carriages, one had the 

 springs allowed to play, the other not. The first was loaded 

 with 8 cwt. the other with G cwt. Both were connected with 

 tiie peirameter, and the carriage with springs carrying the 8 cwt. 

 preceded the other. 



The sj>rings of the former carriage were prevented from act- 

 ing, and t!;e carriage loaded with G cwt. ; the springs of the 

 other carriage were made free, and it was loaded with 8 cwt.; 

 when this carriage preceded. This experiment proved tliat the 

 draft of these carriages was the same. 



The springs of both carriages vvere then made free, and the 

 axles of one of them brought within six feet of each other ; 

 those of the other carriage remaining at nine feet nine inches 

 asunder. The weight of both was brought to an equality, and 

 both were loaded at bottotn. 



'J'he 



