Information respecting Rail-Roads. 101 
employment of hard-stone tracks, alternating with spaces cover- 
ed by a softer material, appears to have been an early step to- 
wards this separation ; but the most advantageous form of it is 
found in the modern iron rail-roads. It is generally considered, 
that the day’s work of a horse on a rail-road, will be about 
times that of the same animal on a turnpike road ; but I do not 
know that it has been accurately ascertained, what may be the 
proportional intensity of the resistance on the turnpike, in its 
best condition, or that we have<at all the means of judging of 
the effect of substituting hard-stone tracks under the wheels. I 
should fear, that, though they may at first afford a tolerably 
appropriate surface, on which the resistance may be very much 
inferior to that presented by a turnpike-road, their good condi- 
tion could not endure long. Every one must have observed the 
rounded form assumed by the upper surfaces of the square 
blocks with which streets are paved, and that the abrasion of the 
angles leaves ultimately a very irregular surface. The inter- 
stices will be found deeper in the direction across which the 
wheels generally move ; since, from the elasticity of the paving 
material, and the ground which supports it, the angles of the 
stones are peculiarly exposed to the action of the wheels. We 
may expect that the same effect will be produced on stone- 
tracks ; and that they will, to a certain degree, present an irre- 
gular knobbed or undulating surface, incomparably less advan- 
tageous for traction, than that of the more perfect material of 
the iron railways. 
The advantage possessed by stone tracks in admitting the em- 
ployment upon them of wheels of the ordinary construction, is 
shared by the plate or tram rail-road ; and this renders that form 
superior to others, for many purposes. These tram-roads seem to 
be almost universally in use in the mineral districts of Wales. 
This preference is approved of, but without assigning any ade- 
quate reason for it, by Mr Overton, an engineer of that country *. 
The only shadow of an advantage claimed for the system is, 
that it presents a greater resistance on descents where retarda- 
tion is required. But this excess of retardation is continual ; 
and it is certainly preferable to get rid of it, and to produce, 
* Account of the Mineral Basins, &c. of South Wales, 
