ON DRAUGHT. 451 



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

 of time, large quantities of materials, l:)Ut 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 in keeping clear all the drains, and even in scraping 

 little drains fronr 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 435) of tiie resistance of a waggon upon ditferent 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 explana- 

 tory of tlie object of rail-roads and their effects as regards diminishing 

 draugiit. 



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

 .he 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 longitudinal 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, with a gravelled road 

 between tiie rails. This is a rail-road. It evidently combines the advan- 

 tages of a good foot-hold for horses, with those of smooth and hard surfaces 

 for tlie wheels to roll upon. It requires, however, that the carriages should 

 be all nearly alike as regards the width and form of the wheels; and ex 

 perience has proved that such a road is not generally worth constructing 

 unless the traffic is sufficient to allow of carriages being built expressly tor 

 that or similar roads. This being the case, the form and dimensions of the 

 rails, and the general construction of the carriages, are uncontrolled by 

 any other consideration than that of diminishing draught. 



A considerable improvement upon this point may, therefore, be expected 

 in the railway, over the common road. The railway, as constructed upon 

 the plan at present conceived to be the best, consists of two parallel bars of 

 wrought iron, about two inches and a half broad on the upper surface, and 

 about six inches deep, placed at a distance of about five feet: these bars 

 are supported upon, and firmly fixed to blocks of stone, from one foot to 

 two feet square, and at intervals of three feet. 

 Fig. 40. 



_(i_ ci a> 



~—^- -^^^^^^—;^ FPq -^^^ 



ff-S 



a a a, jig. 40, represents a side view of these bars, of which J is a 

 section, c c c are the blocks of stone on which it rests. Fig, 42 is a per- 

 spective view of 51 pair of these parallel bars, consiituling together the 



