ON THE RESISTANCE OF ROAD VEHICLES TO TRACTION. 



837 



Gravity Trials. Speed Observatiotis. 



Mean 



Daimler Motor Company, London. 



16-77 



io-2s 



16-77 



6-23 

 4-46 



7'04 



68-9 

 43-2 

 54-4 



1 in 38 

 1 in 52 

 1 in 41 



111 



in 45 



Lancashire Steam Motor Company, Lcylandi 



381 

 396 

 400 

 400 



-ton 



400 



168 

 192-5 

 2O0 

 200 



Steam Carriage and Waggon Company, Chiswich. 



200 

 200 



14-4 

 15-0 



13-89 

 13-33 



16-77 

 16-77 



3-00 

 2-76 



77'0 

 78-4 



1 in 29 

 1 in 29 



1 ill 25 



1 in 29 



NoTi':. — In Iliin 3 with tlie Daimler car tlie engine but not the gearing was disconnected. In linn 8 

 with tlie Lcyland fcai- the engine was disconnectCu. 



it will be sfeeh that the l)ainiler car had the least friction, viz., ^-jth 

 of its -weight, or 51 lb. per ton. The Thornycroft car had a friction of 

 ._,',, th of its weight, or nearly 78 lb. per ton. The Leyland car had a 

 friction of J.-th of its weight, or nearly 88 lb. per ton. With the engine 

 disconnected the Daimler car had a friction amounting to ^^ of its 

 weight, and the Leyland car had a friction amounting to j'-ji'd of its 

 weight, or 67 lb. per ton. 



From the difficulty of getting the speed quite accurately, and also to 

 some extent because the method of calculation is approximate, probably 

 these results are not quite so trustworthy as those obtained in the follow- 

 ing manner, in which the friction is calculated from the distance from 

 starting to stopping. 



Friction calculated from distance of running from starting to stop- 

 ping. Let s be the total distance the car ran, and h the fall of level in 

 that distance. Then h:s is the gradient due to friction, and corresponds 

 to i/y in the previous calculation. 



A table of the results of the observations calculated in this way 

 differed only slightly from the previous results. 



X. Experimentu by Professor H. S. Hele-Shaw, F.R.S.,for the Royal 

 Lancashire Agricultural Society, 1897. 



Professor Hele-Shaw made a number of experiments for the above 

 Society at their show held at Southport, 1897. Among other results he 

 obtained the tractive force for agricultural waggons and cai'ts, on turf and 

 roads. 



The following is a brief summary of the results obtained ; — 

 1902. z 



