relative to Exper'tmenls on JVhcel-carriages. 87 



Then 2 qis. being added to the carriage with springs, it preceded 

 the other carriage, the elliptic springs being thus brought more 

 perfectly into play. 



The gross weights of each carriage, when reduced to pounds, 

 were nearly as follows: — The carriage with springs lOOSlbs. 

 The carriage without springs 62."-51l)s. From these experiments 

 it appears, that in the first place there was but little diiference 

 between elliptic and grasshopper springs, except what arose from 

 the difference of their weight ; and in the next place it appears, 

 that the gross difference of weight carried by the carriages, with 

 and without springs, was nearly as 19 to 6. 



But to show the exact advantage of springs in these experi- 

 ments, the weight of tiie wheels and axletrees of both carriages 

 must be deducted from the gross weight, because the wheels and 

 axletrees were moved independently of the springs, only the 

 Avcight incumbent on the axletree and wheels being liable to the 

 effect of the springs. The medium weight of the wheels and 

 axletrees of each of these carriages was nearly 250 lbs. which 

 being deducted from the gross weights of each carriage, leaves 

 7.>81bs, for the one, and i'^731bs. for the other; tiie proportion 

 being nearly I to 2, 



Comparison of wooden with steel Springs. 



Ctrl. </rs. lbs. 



A carriage with wooden springs, carrying ..330 



Ditto without springs 22 7 



To each of these must be added the weight of the carriage, 

 after deducting the weight of the wheels and axletrees, viz. 145!bs. 



Making the carriage with wooden springs .. .. 5G21bs. 



That without springs 432lbs. 



Nearly in the proportion of 3 to 4 ; and in this state the car- 

 riages kept together when moving with a velocity supposed to 

 be about five miles an hour. 



At the ilow rate at which a horse draws a loaded cart, the 

 carriage with Wooden springs carried 3 cwt. 2cps. Olbs. being 

 one quarter less than when moving at a quicker rate. 



Hence it is apparent that the steel springs had some advan- 

 tage over the wooden springs, and that wiien the force of a m.in 

 was employed to draw a carriage with and without springs, the 

 advantage was not only seen but felt. 



Experiments upon Joitr-wheelsd Carriages, ■ivith and without 

 Springs. 

 Two four-wheeled carriages, as nearly similar as might be, 

 were placed upon 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 raided to the 



F i licit^iiL 



