562 ON DRAUGHT. 



curved road, can bear only upon one edge, as in fig. 38. The conical wheels 

 Fig. 38. Fig. 39. st ^ * n use > although much in- 



clined at the axle, are never 

 sufficiently so to bring the lower 

 surface of the wheel even, hori- 

 zontal, and therefore are con- 

 stantly running upon the edge, 

 as in fig. 39, until they have 

 formed a rut coinciding with 

 their own shape. In a barrel- 

 led or curved road, the mischief 

 done will, of course, be great 

 in proportion to this curvature. This form is, therefore, mischievous as well as 

 useless. Six inches' rise in the centre of a road of twenty feet wide, is more 

 than sufficient to ensure drainage, if drainage is not effectually prevented by 

 ruts or hollow places, and less than this will suffice where the road is good, and 

 is kept in proper order. 



The hardness of the surface, the most important feature, will of course 

 principally depend upon the materials used, and the formation of the road, and 

 still more upon the state of repair in which it is kept. It is easy to form a good 

 road when the foundation is already laid by the existence of an old one : level- 

 ling the surface, applying a covering of eight or ten inches in thickness of 

 broken stones, having as few round or smooth surfaces as possible, the hardest 

 that can be obtained, and above all things securing good drainage, both from 

 the surface and from the bottom, is all that is required : but constant repair and 

 unremitting attention are necessary to keep a road thus formed in good condition. 

 These repairs and attention do not consist in laying on at certain intervals 

 of time large quantities of materials, but in constantly removing the sand 

 which is formed, and which, in wet weather, holds the water, and prevents 

 drainage ; in filling up as quickly as possible, with fresh materials, any ruts or 

 hollows ; and particularly in keeping clear all the drains, and even in scraj. ing 

 small drains from ruts, or such parts of the road as may contain the water, and 

 which it may not be possible immediately to fill up. 



By attention to these points, those who are interested in the preservation of 

 the roads, and the expenses attending it, will find that economy will ultimately 

 be the result ; and those who are interested in diminishing the labour and 

 expense of draught, we shall only refer again to the table (page 548) of the 

 resistances of a waggon upon different roads, from which they will see, that a 

 horse upon a clean road will do one-third more than upon one slightly muddy ; 

 more than four times as much as upon new-laid gravel ; and nearly seven times 

 as much as upon a heavy sandy road. 



No arguments that we can put forward can at all strengthen the effect that 

 such facts must produce ; and we shall, therefore, quit the subject of roads, 

 and conclude our observations on draught by a few words explanatory of the 

 object of rail-roads and their effects as regards diminishing draught. 



The great desideratum in the formation of a good road is the facilitating the 

 rolling of the wheels. We have shown that, for this purpose, a hard, smooth 

 surface is necessary ; and, as this is only required for the wheels, two longi- 

 tudinal tracks, of such surface, of proper width, are sufficient for the mere 

 passage of the carriage. If, therefore, there is a considerable traffic between two 

 points along a line of road, without much interruption from crossing, all the 

 qualities of a good road may be obtained in a very superior degree, by having 

 two parallel rails, or tracks of wood or iron, raised a little above the general level 

 of the ground. This is a rail-road. It evidently affords the means of attaining any 



