TRANSACTIONS OF ■ SECTION G. 869 



cannot be said to express anything very definite, and certainly aiford no guidance 

 whatever as to the resistance of self-propelled vehicles at various speeds. Again 

 in recent years large sections of cities have been paved with asphalte and wood, 

 while the laying of setts or stone pavements has undergone considerable modi- 

 fication, which is readily seen by an examination of a modern street and one of ten 

 or fifteen years ago. Another modern development is the introduction of solid 

 indiarubber and pneumatic tyres, which were at first regarded merely as a luxurv, 

 but have now proved to be an important factor in the life of the vehicle, as well 

 as of its resistance, this being so much the case that eftbrts have from time to time 

 been made to introduce the use of indiarubber tyres upon traction engines. 



Beyond the foregoing points, which have not been brought under investigation 

 in connection with the resistance of vehicles, no attempt appears to have been 

 made to ascertain the extent to which the various factors of resistance relatively 

 affect the whole result. Now it is evident that as the higher speeds are used, and 

 the weights are increased, vibration and shock become more and more important ; 

 thus the resistance due to the rim of the wheel, and the ways in which it can be 

 met by mechanical contrivances, must be regarded as quite a different problem from 

 that of the springs attached to the body of vehicles, and some distinction must be 

 made between the resistances as aflfected by each of the foregoing. 



Enough has been said to show that there is not only matter for an inquiry 

 which would be welcomed by makers of road vehicles, especially of self-propelled 

 road vehicles, but that such an investigation, if it is to be of any real vakie, must 

 be thorough, and requires not only some expenditure of money, but cannot well be 

 undertaken by any single individual. The great interest which was excited by 

 the paper read by Mr. Thorneycroft at the last meeting at Dover of the Briti.sh 

 Association, and" the previous communications which have passed between the 

 author and the Tresident of this Section, who is himself a higli authority upon 

 the question of roads, have led to this matter being brought forward with the 

 idea of forming a committee of the British Association for the investigation of 

 road resistance. 



In order to facilitate the work of the Committee, a summary of previous investi- 

 gations in this subject has been prepared, which can be laid before the members, if 

 it is formed. Some preliminary experiments have also been made with a view to 

 obtaining some idea of the nature of the apparatus required, and the amount of 

 expense likely to be entailed. 



Preliminary Experiments, 



Allusion has been made to the fact that all the previous experiments have been 

 performed by means of the traction of horses : it seemed with the introduction of 

 powerful motor cars it might be able to pull steadily any vehicle at any required 

 speed. Thii idea really forms the chief feature of the proposed experiments, as it 

 is evident that if one motor car is not sutticient two or more could be harnessed 

 to the vehicle which is to be drawn. In order to ascertain how far this idea was 

 practicable, Mr. J. A. Holder, of Birmingham, who owns a 12 h.p. Daimler car, 

 was kind enough to visit Liverpool, and on Tuesday, AVednesday, and Tliursday, 

 July 17, 18, and 19, a series of experiments, in which the author was assisted by 

 two former students, Mr. Humfrey, B.Sc, and Mr. Cormack, B.Sc, were made, 

 Mr. Holder's autocar towing the author's New Orleans Voiturette. These 

 experiments took place over roads of asphalte, wood, setts, and macadam in the 

 neighbourhood of Liverpool, both level and up the steepest gradients which could 

 be found, viz., Everton Brow, the details of which were given in a wall diagram. 

 It will not serve any useful purpose at present to give the detailed results of these 

 experiments, as they were obviously iucomplete, and pointed to the absolute 

 necessity of more elaborate apparatus of a self-recording nature ; but it may be of 

 interest to explain the apparatus actually employed, so as to indicate what will be 

 required to insure satisfactory results. 



The apparatus consists of two parts, which were illustrated by wall diagrams 

 (1) a dynamometer, and (2) a speed indicator : 



Dynamometer. — This consisted of an ordinary spring balance, the back of 



