502 



RAII.IIOADS. 



should not content themselves with the biassed opinions of their own 

 eno-ineers, but look further for the impartial judgment of scientific 

 umpires. The talents of such men as Lardner, Babbage, Sheep- 

 shanks, and others might, with great advantage, both to engineere 

 and capitalists, be invited to pass judgment on the merits of different 

 proposed lines; and certainly with a fair view of them as national 

 undertakings, none should be allowed to run except by the shortest 

 and most convenient lines, irrespectively of the petty local interests 

 that too often, according to the present arrangement of parliamentary 

 committees, successfully oppose a line or portion of a line admirably 

 and with consummate skill adapted for railroad communication. The 

 proceedings before Parliament on the Brighton lines of railroad, in 

 particular, show very strongly the necessity of altering the system of 

 committee enquiries. 



As the consideration of the slopes or gradients on a railroad es- 

 sentially and mainly affects the cost of transport, we shall consider 

 it under that head, which we before said was the second element in 

 the gross expense. 



If the mere question of transport, without reference to velocity, 

 were at issue, a railroad would have no advantages over a canal. 

 It is the speed of transport which gives the former a superiority, and 

 which calls on the talents of the engineer to devise means for its at- 

 tainment, both by equalizing the road and providing, engines and 

 carriages of the greatest power and least resistance. . On the Liver- 

 pool and Manchester road an engine and train (gross average weight 

 about 100 tons) runs on a level at a rate of about twenty miles an 

 hour ; and we entertain little doubt that on a longer line of road a 

 o-reater speed might be obtained without a diminution of weight in 

 the train. Any variation from this level produces an increase or di- 

 minution of speed, varying in a constant ratio to the slope ; but the 

 gradients must be less than one in 300, unless, the mechanical power 

 and expense be increased and the weight [of the train diminished. 

 The greater is the angle of inclination the more disadvantageously 

 will the labour be expended, as the following table will show : — 



M'Neill's translation of M. Navier on the Mode of comparing Lines of Railway. 



It appears therefore from this table (on which considerable de- 

 pendence may be placed, both owing to the character of its author 

 as a government engineer of the highest reputation in France and 



