868 REPORT — 1900. 



Particulars were given as to the number and capacity of refuse destructors in 

 Bradford, and a complete description of the Hammerton Street destructor, and the 

 results of a seven days' test on this destructor were supplied. 



The utilisation of the residuum or clinker from the destructors, its use in 

 mortar making, and the clinker-crushing and screening machinery were described. 



A short account was also given of the utilisation of the steam produced by the 

 destructors, and a description of a new destructor in course of erection at Southtield 

 Lane. 



FRIDAY, SEPTEMBEB 7. 

 The following Papers were read : — 



1 . Resistance of Road Vehicles to Traction. 

 Bn Professor Hele Shaw, LL.D., F.R.S. 



About the time of the general introduction of railways considerable attention 

 was directed to the nature of the resistances encountered by vehicles upon the 

 common road, and the researches of Correze, Edgeworth, Coriolis, Morin, Tredgold, 

 Dupuit, and others must be regarded as having thrown considerable light upon the 

 subject. From time to time recently others have done work in this direction, but 

 there is no doubt that the attention directed to traction on railways has thrown 

 the scientific investigation of the subject of common roads almost entirely into the 

 background. During the last few years, however, it has been realised that there 

 was a great field for the development of traction, and particularly by mechanical 

 means upcm the common roads, and the improvement which has been quietly 

 taking place in the construction and maintenance of roads is a feature of national 

 importance. Not only is the condition of the pavements in the cities and towns 

 much improved, but in out-of-the-way districts, such as in the hilly parts of 

 Cumberland and Westmorland, the use of steam rollers by the County Councils 

 has etfected vast improvement in the state of the roads. Various causes have 

 contributed to this result, but it is worthy of notice that whereas when the 

 coaching days became comparatively a thing of the past the roads fell into neglect, 

 so now the increasing number of cyclists and tourists who visit country places 

 are an appreciable factor worthy of consideration and encouragement by the 

 local authorities. The recent remarkable and growing development of motor 

 vehicles with a legal limit of speed as hiofh as twelve miles an hour, and the 

 generally increased speeds of tram-cars in cities owing to the introduction of 

 electricity and steam, give some reason for thinking the general rate of speed on 

 common "roads may reach, or even exceed, the present legal limit applying to motor 

 vehicles. As showing the mechanical possibilities in this direction, it may be 

 pointed out that quite recently in France between forty and fifty miles an hour 

 has been salely maintained for more than 300 miles upon the common road. 

 Such a speed — or anything approaching to it — would not be allowed in this 

 country, but the fact remains that it is possible with safety. With heavy traffic 

 the legal limit for a self-propelled waggon of about two tons tare, capable of carrj^- 

 ing several tons, is no less than eight miles an hour, and the heaviest traffic with 

 a tare limit of vehicle of three tons, probably carrying a load of eight or ten more, 

 is as high .as live milfs an hour. 



These facts, and the introduction generally of mechanical propulsion, point to 

 th« necessity of having a fairl^' complete knowledge' of the resistance of common 

 roads of various kinds upon diiferent classes of vehiclea moving at dillerent speeds. 

 In the brief historii-al account ^iven by the author of what has hitherto been 

 dune in this direction it will be seen that the experimental means of traction has 

 without exception — as iar as the author is aware — been limited to traction by 

 horses ; and as at any rate the earlier experiments were made with the view of 

 horse traction, only two speeds were taken into account, viz., walking and trotting. 

 Considering the variation in speed of horses under these two conditions, these terms 



