The results are almost identical with those of General Morin. 



IX. Extract from the Report of Professor W. C. JJnwin, F.R.S., on the 

 Tr-ials of Self-moving Vehicles at Biriaingham made before the lioyal 

 Agricultural Society, 1897. 



Some experiments were made on the competing vehicles to determine 

 the vehicle friction. 



The method adopted was to allow the oars to run down hill by gravity 

 (the motor being idle) and noting the speed acquired and the distance in 

 which they came to rest. 



The cars, fully loaded, were taken to a hill on the road between 

 Bassett's Pole and Bonehill. This portion of the road was levelled and 

 marked out in 100-foot distances. 



The total weights of the cars and loads in these trials were the 

 following :— 



Daimler 2 43 tons. 



Lancashire fi'49 „ 



Chiswick *'-57 ,, 



Method of Trials. — Eacli car was brought to one of the marked dis- 

 tances on the descending gradient, generally the point .300 feet from A, but 

 in Trial 3 at 400 feet from A. The car was then gently started from rest 

 and allowed to descend the hill by gravity. As it passed over the 200-foot 

 length from B to C the time of passage was taken. The car was allowed 

 to come to rest, stopping generally at a point beyond C, but in two trials 

 a little short of C. From the speed over the base B C one measure of the 

 friction can be obtained. The mean gradient from start to stop is another 

 measure. 



The following formula was used for calculating the friction from the 

 speed observations : — 



7 «' 



where 2240/ is the friction of the car reckoned in lb. per ton, h tlie 

 fall in feet from the point where the car started to the middle point of 

 the base B C, and s the distance from the starting-point to the middle 



point of B C . 



1 If is the c^radient due to the friction ; that is, the greatest gradient 

 on which the car would stand without moving, or if put in motion would 

 run without acceleration. 



The following table gives the values of the friction calculated from 

 the observations : — 



