1839.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



387 



Table V. 



Table VII. 



Table VIII. 



Table IX. 



meanwhile we may state the results, from which it would appear, that 

 as considerable an error has been conunitted in overrating the amount 

 of resistance dne to friction, as in underrating the whole resistance. The 

 formula-, established by Dr. Lardner, have been ajiplied to a limited nnmljcr 

 of experiments performed under diflTerent circumstances, and the results 

 agree in giving the friction a value amounting to from five to six pounds a 

 ton of the gross weight. How widely this differs from the common estimate 

 may be perceived when it is stated, that that estimate is from nine to eleven 

 pounds i)er ton. Mr. Woods, the engineer of the Liverpool and Manches- 

 ter railway, has ajijjUed a method of calculation to one of M. de Pamhonr's 

 experiments, by which the resistance from friction is obtained very nearly 

 free from the effect of atniosi)heric resistance, but it is not the method used 

 by Dr. Lardner. The result obtained by Mr. Woods is the same as that 

 olitained by Dr. Lardner. 



Dr. Lardner read at the meeting a comnumication from M. de Pamboiu-, 

 stating, that that gentleman bad been engageil in similai- inquii-ies, as to the 

 amount of the friction and the atmosiiheric resistance, with a view to cor- 

 rect, in the forthcoming edition of bis work on Locomotive Engines, any 

 errors which might have existed in the former edition, and the results which 

 M. de Pambour stated, that be obtained for the friction, were the same as 

 those obtained by Dr. Lardner and Mr. Woods. 



Dr. Lardner proceeded to say, that the results of this extensive course of 



experiments coiTohorated and fully established a doctrine which he had ven- 

 tured to advance before a committee of the House of Lords in tlie year 

 1835, but which was then and subsequently pronounced to be paradoxical, 

 absurd, and one which could have no jnactical truth. That iloctrine was, 

 that a railway laid down with giadicnts, from sixteen to twenty feet a mile, 

 would be for all practical purposes nearly, if not altogether, as good as a 

 railway laid down, from terminus to terminus, upon a dead level. The 

 grounds on wliich be advanced this doctrine were, that a compensating effect 

 would be produced in descending and ascending the gradients, and that a 

 variation of speed in tlie train would be the whole amount of inconvenience 

 wbicli wouhl ensue ; that the time of performing the journey, and the ex- 

 penditure of power required for it, the expense of maintaining the line of 

 way, and supplying locomotive power, would he the same in both cases ; 

 that, therefore, he thought that no considerable capital ought to be expended 

 in obtaining gradients lower than those just mentioned. He stated that he 

 was assailed with the most unsparing ridicule when he advanced this doctrine, 

 and that up lo the present hour, so far as he knew, it had never been 

 adopted or assented to by any practical man in tlie country. He saw, how- 

 was ever, its comjjlete verification and establishnient in tlie residts of these ex- 

 periments, and determined on making an pxpr-rimpii/nm critcis, which should 

 put its truth beyond all question. The variety of gradients on the railway 

 extending lietween Liverpool and Biiniinghani, offered a favourable theatre 



