256 Olstrvations upoii WJw^UCarriage Experitnenls, 



and the axle, is perfectly correct with respect to either a four- or 

 a two-wheeled carriage ; because a horse can apply more of hi» 

 strength, when his traces make an angle, than when they ap- 

 proach more to the horizontal, — but it has not any hearing upon 

 the question of the length of the perch or means of l)ringing for- 

 ward the hind wheels, because the direction of the force applied 

 to them is at all times governed by the parallel of the road and 

 position of the carriage. There are other more important con- 

 siderations, particularly with respect to mail-coaches, that would 

 be too tedious to enter into upon the present occasion. Advan- 

 tage would be derived, if it were possible to have the weight so 

 low as to act with less power upon the axle in the rut : and, al- 

 though this fact can be shown mathematically or experimentally 

 by an apparatus for the })urpose, yet from the impracticability of 

 it, with respect to roads, I shall not dwell upon it. 



Expcrhnenl, No. 7, see annexed syllabus. 



1 am not aware of any difference in the object of this experi- 

 ment from that of number 2, unless it be expressed by the use 

 of the word wooden ; but as no comparison was made between 

 wooden and steel springs, which in an agricultural point of view 

 1 very much lament, I shall not enter into that question, but 

 merely observe upon the facts in the manner they took place. 

 I am sorry that here, as in the former cases, I have to begin by 

 pointing out dissimilarities in the essential points. 



The equalization of these carriages, that was mentioned to 

 have previously taken place in private, must, as in the case of 

 experiment No. 2, have been deceptive for reasons somewhat 

 similar, as follows ; — 



Tile quantity of weight acting by the shafts upon the wheels, 

 that supported them in front to supply the place of horses, was 

 unascertained. Lifting by hand the points of the shafts, as at- 

 tentively done by Mr. Edgeworth, jun. was deceptive, because 

 in so doing he was obliged unavoidably to lift the metal ma- 

 chinery and front wheels. The shafts of Mr. Edgeworth's cart, 

 being supported by a larger wheel, were seven inches higher 

 than those of the other cart, which in front was lower than in 

 rear: this circumstance was a serious disparity, because their 

 ^xles were bended — two metal weights were previously fixed by 

 cords at the fore sloat of this cart, under the denomination, I 

 suppose, of equalizing weights ; placing these weights so far for- 

 ward had simply the effect of increasing the disadvantages this 

 cart already laboured under, particularly by the inferiority in 

 size of its front wheel. 



It is further to be observed, that the carts started from situa- 

 tions pretty level with each other: but at the termination or end 

 of the track, a point twenty yards from the western wall of the 



yard. 



