APPENDIX. ROAD LOCOMOTION. 491 



the accuracy with which he estimated the resistances to which 

 loads were exposed on railways arising from friction and gravity, 

 led him at a very early stage to reject the idea of successfully 

 applying steam power "to common roads. In October, 1818, in 

 conjunction with Mr. Nicholas Wood, he made a series of 

 experiments on the resistances to which carriages are exposed 

 on railways, with a dynamometer of his own contrivance. This 

 dynamometer was chiefly remarkable for its simplicity, but it 

 will not bear comparison with others that have been contrived 

 and made use of subsequently ; it is, however, interesting as the 

 first systematic attempt to determine the precise amount of 

 resistance of carriages moving on railways. It was by this 

 machine for the first time ascertained, that the friction was a 

 constant quantity at all velocities. Although this fact had 

 been long before developed by Coulomb and was well known to 

 scientific men as an established fact, yet at the time when my 

 father made these experiments, the deductions of philosophers 

 were neither believed in nor acted upon by practical engineers. 

 Indeed, although the experiments of my father went directly to 

 corroborate the deductions of philosophers, it required a con- 

 siderable space of time to overcome the prejudices which then 

 existed among practical men. 



" It was maintained by many, that the results of the experi- 

 ments led to the greatest possible mechanical absurdities. For 

 instance, it was maintained, that if friction were constant at all 

 velocities upon a level railway, when once a power was applied 

 to a carriage which exceeded the friction of that carriage by the 

 smallest possible amount, that same small excess of power would 

 be able to convey the carriage along a level railway at all 

 conceivable velocities. When this position was put by those 

 who opposed the conclusions at which my father had arrived, 

 he felt great hesitation in maintaining his own views; for it 

 appeared to him at first sight really to be as it was put by his 

 opponents an absurdity. Frequent repetition, however, of the 

 experiments to which I have alluded, left no doubt upon his 

 mind, that his conclusion that friction was uniform at all 

 velocities was a fact which must be received as positively 

 established; and he soon afterwards boldly maintained that 

 that which, was an apparent absurdity was, instead, a necessary 

 consequence. I well remember the ridicule which was thrown 

 upon this view by many of those persons with whom he was 

 associated at the time. Nevertheless it is undoubted, that could 



