ON RAILWAY CONSTANTS. 24? 



by curves of a mile radius, is inappreciable, and therefore curves of a much 

 shorter radius may be safely laid down. 



10. That the mean amount of resistance to railway trains being so much 

 above the estimate heretofore adopted by engineers, and the resistance from 

 curves being so much less than their estimate of it, the practical principles 

 on which they have generally acted in laying out lines of railway will require 

 serious modifications, all of which fortunately will have a tendency to diminish 

 the expense and difficulty attending the construction and the working of rail- 

 ways. 



In consequence of the low estimate of the resistance and the high estimate 

 of the effect of curves, which engineers in general have heretofore adopted, 

 great expense has been incurred and difficulties encountered to obtain flat gra- 

 dients and straight lines. In some cases the gradients have been so levelled as 

 not to exceed from four to six feet per mile, and the lines have been rendered 

 so straight, that the curves nowhere have so short a radius as a mile. From 

 what has been proved in the present Report, it is evident that such lines of 

 railway will afford no practical advantage over those which have been laid 

 down with gradients of sixteen, twenty, or even twenty-five feet per mile, and 

 on which curves of a mile or less radius have been allowed. 



The writer of this Report cannot conclude it without acknowledging the 

 liberal assistance he has received from the Grand Junction Railway Com- 

 pany, who supplied engines, carriages, and waggons, without charge, for the 

 experiments ; also from the Liverpool and Manchester Railw'ay Company, who 

 allowed many of the experiments to be made on their line. 



Mr. Hardman Earle of Liverpool, has also been of the greatest assistance 

 in conducting the experiments, several of which were suggested by him. 



Similar acknowledgements are also due to Mr. Edward Woods, engineer to 

 the Liverpool and Manchester Railway Company. This gentleman super- 

 intended and directed many of the most Important experiments, and subse- 

 quently reduced and tabulated them, when the writer of this Report was pre- 

 vented by professional business from being present. 



Report on Railway Constants. By Edward Woods. 



In the first Report, by Dr. Lardner, of the Committee appointed by the 

 British Association to investigate the mean values of the resistance of trains 

 moving upon railways, published in the eighth volume of the Transactions 

 of the Association, the various modes proposed for ascertaining the amount 

 of resistance to the tractive power were described, and their relative merits 

 discussed. 



The methods alluded to were — 



L By the dynamometer. 



2. By observing the motion of a load down an inclined plane, sufficiently 

 steep to give accelerated motion. 



3. By putting the load in motion on a straight and level line of railway, so 

 as to impart to it a certain known velocity, and then observing the rate of 

 its retardation. 



4. By a combination of the two preceding methods, as resorted to by Le 

 Comte de Pambour. 



5. By a plan proposed by Dr. Lardner, viz. selecting two inclined planes of 



