254 Olservations upon Wheel- Carriage Experiments, 



shackles of this green car, is 2 cnt/0 qv. 18 lbs. the enil>arra'-sing 

 body, &c. is therefore 2 cwt. Oqr. 13 lbs. heavier than the boily 

 of Scotch dray, with springs and shackles of this car ; to this 

 weight was added six and a quarter hundred weight, called 

 loading, making tivgether 11 cwt. 1 qr. 13 lbs. The real nature 

 therefore of this experiment is fairly stated, when described as 

 one carriage without springs, having 



Cwt. qr. lb. 



10 1 23 upon it; another with springs, carrying 



11 1 13 or additional loading, by use of springs, 



3 IS about the eleventh part of the load, pro- 

 vided the inaccuracies with respect tothe use of vien, the difference 

 in size of wheels, nnd the impossibility of equalization by the 

 mode resorted to, had not rendered the experiment indefinite. 

 The weight of loads as here calculated, when considered propor- 

 tionally to the weights of the carriages drawing them, is pretty 

 similar to the common cart or dray of six or seven hundred, 

 drawing a load of twenty or thirty. Had such an experiment as 

 this been tried upon a very bad and rutted road, I am inclined 

 to think that much useful information would have been received 

 by the public. 

 ' Experiment, No. 5, see annexed syllabus. 

 Here, as before, I have to point out unobserved dissimilarities. 

 I have not had anv opportunity of weighing these carriages — 

 they were said to be of equal weights, and exactly similar in 

 construction, but for the purpose oj equaliz.ation, as mevtioned 

 in Report, it was necessary to make the one heavier than the 

 other ; this would appear paradoxical ; it has however arisen 

 from a mistake — they did not exactly or reasonably correspond 

 in their construction — the one had the advantage of flexibility 

 by having fewer and weaker plates in its springs ; this dissimi- 

 larity caused the necessity of increasing the weights upon it ; 

 they therefore differed in weight, and in springs, and also in va- 

 rious minor though necessary considerations externally visible. 

 By the pliability of the slender perch when lengthened, too slight 

 to be used in ordinary, a further advantage was given to this 

 carriage, but without much ajjparciit operation ; it may, there- 

 fore, not very uineasonably have been suspected, during the ex- 

 periment, that the length of the ))erch was the countervailing 

 disadvantage. I will not however draw this or any precive con- 

 clusion v.ith respect to the facts siiigly or collectively — thev are 

 all too indefinite , the previous arrangements, particularly with 

 respect to tlie surface used in this case, do not a})pc'ar to me to 

 have been such as to show the nature of a long perch compara- 

 tively with that of a short one, I am oi' opinion that a long 



perch 



