233 REPORT — 1841, 



The obvious tendency which this body of experiments had to support, a prin- 

 ciple — which the author of this Report had advanced and supported before 

 a Committee of the House of Lords in the year 1835, but which then and 

 ever since was declared by engineers to be paradoxical and absurd, and one 

 which had no foundation in practice — suggested the trial of one extended 

 experiment, by which the truth or falsehood of that doctrine would be put 

 beyond all doubt. The doctrine referred to vf&s, that a railway laid doivn 

 with gradients not exceeding twenty feet a mile would be for all practical pur- 

 poses, nearly if not altogether as good as a railway of equal length laid down 

 from terminus to terminus on a dead level. The grounds on which he advanced 

 this doctrine were, that a compensation would be obtained on the descending 

 gradients for the disadvantages of the ascending gradients. This compensa- 

 tion would be either in time, or power, or both, which would be saved in 

 the descent ; and he consequently maintained, that a railway graduated 

 within the limits proposed would be worked at as great an average speed, 

 and with as small an expenditure of moving power, as a dead level*. 



If the principle now advanced be admitted, it will follow that the whole 

 amount of inconvenience which would ensue from the adoption of eighteen 

 or twenty-foot gradients would be a variation in the speed of transport. The 

 average speed, the time of completing the journey, the expenditure of power, 

 the expense of maintaining the line, and supplying it with locomotive power, 

 would be the same. The great practical importance of these circumstances 

 is quite evident. 



To reduce this question to the immediate test of experiment, it was deter- 

 mined to prepare an engine and full train of twelve coaches loaded as such 

 a train would be in the ordinary traffic of a railway, and to run this train on 

 the railway from Liverpool to Birmingham and back, observing the moment 

 of passing each quarter-mile post, and obtaining thereby the actual speed 

 with Avhich each gradient, from one end to the other of the line, was ascended 

 and descended, and the speed on the levels. By taking a mean of the speed 

 in ascending and descending the gradients, it would be necessary, if the prin- 

 ciple maintained by the writer of this Report were valid, that this mean 

 should be exactly or very nearly equal to the speed on the level. 



The experiment was accordingly made on the 16th July 1839, and the fol- 

 lowing are the details of it : — 



Experiment with the Hecla Locomotive Engine. 



On a trip from Liverpool to Birmingham and back, with a load consisting 

 of the Tender and Twelve Second Class Grand Junction Carriages. 

 Weather fine and calm ; rails dry ; water in the tender warm. 



1 



* The principle here advocated has nothing in common with that of tlie undulating rail- 

 way proposed some years ago. That project had for its foundation a supposed advantage, 

 derivable from the acceleration of the load descending inclined planes of greater inclination 

 than the angle of repose; it was maintained, that the momentum thus acquired woidd com- 

 pensate for the steepness of the plane in the ascent, and it was essential to this project that 

 the gradients should exceed the angle of repose. It is, on the contrary, essential to the prin- 

 ciple maintained in the present Report, that the gradients should not exceed the angle of 

 repose. Tlie principle of what was called the undulating railway was evidently fallacious. 



