Mr Adamson on Rail-Roads. 31 



126,000 tons conveyed one mile in 312 days. The performance 

 at the Hetton colliery, during the same period, amounted to 

 198,000 tons conveyed one mile. The difference arises from the 

 greater regularity of the hne in the latter case. The effect, in 

 the one case, is equal to somewhat more than that of three 

 horses ; and, in the other, somewhat more than four. The ex- 

 pence of neither of which, including that of their attendance, is 

 likely to amount to the annual cost of the locomotive engine. 

 But as the velocity in those cases is not much above the ordinary 

 rate at which a horse travels, this may be looked upon as far 

 under the rate of performance they are capable of attaining to. 

 For few of the items composing the whole expence, are increased 

 by increasing the speed of the engine, while its performance must 

 increase in the rate of the velocity ; so that a rate of speed may 

 be found at which conveyance by them, will be cheaper than by 

 horses moving at the velocity most favourable for their action. 

 But the great advantage of steam-power hes in the economy 

 with which quickness of motion may be produced. According to 

 Mr Wood's estimate, an engine, which, at the velocity of two 

 miles per hour, performs the work of four horses, w ill, at the 

 rate of six miles per hour, perform the work of twelve horses. 

 The increase of expence consequent on the increase of velocity, 

 has not yet, I imagine, been correctly ascertained. It is evident, 

 however, that it cannot approach to the ratio of the performances 

 at the higher and lower velocity. It is well understood, that 

 goods can be conveyed at a slow rate on a canal much cheaper 

 than by any other method ; and that as the motion is made 

 quicker, the superiority of the canal vanishes ; but in comparing 

 them with rail-roads, the rate which produces equal effects with 

 the same power has been stated at different values, generally, 

 however, lying between three and four miles per hour, and vary- 

 ing with the shape of the tracts and size of the canal ; for all ve- 

 locities beyond this, the advantage of the rail-road augments in 

 a high ratio. The system of water conveyance we must look 

 upon as nearly perfect; and the other as yet offering many 

 chances of improvement ; and from its applicability in some of 

 its many forms to all imaginable situations, and its success in 

 those wherein it has been attempted, we must esteem it eminent- 

 ly worthy of having its properties more accurately investigated. 



