In the first place, as regards durability, the objection would be removed to a considerable extent by employing a good foundation, and laying the metal carefully upon it, providing for the proper drainage of surf and substratum as men tioned above, for the lodgment of water either above or below such roads is very injurious, and tends, perhaps more than anything else, to their destruction. having obtained a good foundation, the next point is to cover it with a hard compact crust impervious to water, and laid to a proper cross section, so that it may be speedily drained and no water be allowed to I remain on the surface, which, besides its inconvenience to passengers, is very destructive to the surface of the road. A practice has come into vogue of late, of covering the road when made, with a binding composed of the grit col lected off the road in wet weather, and by the operation of water-sweeping. The binding is laid on regularly and watered until the new material is firmly set, which it does very quickly, and when the binding is of good quality and properly laid on, it assists its formation very considerably, and altogether improves the condition of the road and econo mizes the material, for it saves the wear and attrition of the new stone. Some road-makers object to this binding on the ground, that it destroys or rots the road, and that when the road is set it has to be carted away again ; but this is only the case where improper binding is used, such as is swept from streets which are not properly cleansed, and there fore consists principally of mud, and not of grit, or rather of grit so mixed with dirt as to be for the most part useless for binding. This method of binding a road removes in part the objection which is made against the resistance occasioned by the louse stones of a newly-laid broken road.
We alluded just now to the cleansing of roads, and it is a matter which deserves considerable attention, and is appli cable to every variety of road ; a dirty road is a constant source, only not of inconvenience, but of expense, for scarcely any thing destroys a road more readily than dirt. And not only is this the ease, but the tractive power also required on a dirty road is twice as great as that required on a clean one: when we come to add to this the Ilairrige done to property by the mud in wet weather, and the dust in dry, we shall be able to form some notion of the waste occasioned by dirty roads.
The best method of cleansing roads is by water-sweeping : a method of watering and sweeping combined, the roads being first watered and then swept, by which means the road is thoroughly washed from its impurities. The watering is usually carried on by means of a water-cart, but a more effectual means, as far as the cleansing of the road is con cerned, is atIbrded by the hose and jet. The sweeping is mostly effected by hand, and in some places this method is carried on systematically, which is an improvement upon the old practice ; but of all methods offered to the public, that of Whitworth's sweeping-machine, is the most effective, and in the end, we believe, the most economical, By this machine an endless chain of brooms is male to revolve by the motion of the wheels, and to sweep the dirt imtnediately from the roads up an inclined plane into the cart. without
fear of splashing, or any other annoyance to the public, which is a vast improvement on the old practice of stacking the mud or dust up in heaps, and letting it remain in that state until the carts come round, during which period a considerable por tion of it had probably been spattered about by the traffic, or blown in all directions by the wind, and even then passengers must expect to be bespattered by the negligent manner in which the refuse was carted away. This machine, too, presents other ' advantages, in the width of the brooms, and the uniform pres sure exerted throughout, a pressure which can also be regulated as occasion demands. Water-sweeping by this machine is, we venture to assert, one of the best, if not the best method of cleansing roads, and our assertion is supported by facts. It has been objected that water-sweeping removes the material of the road, but the contrary has been proved to be the case. .Mr. Smith, the eminent surveyor of Birmingham, says, " I have found that the use of sweeping-machines, with the proper employment of water, has reduced the amount of material required for the repair of roads in Birmingham one-third, viz., from '20,000 to 13.000 cubic yards; the first named amount is the average of seven years preceding the introduc tion of the machines, the latter of the three years subsequent." On the of March, 1S4S, some experiments were made upon the subject in the Quadrant, llegent-street, the road being then covered with a thick coating of dust, which was causing great as well as injury to the road, but could not be removed by scraping without removing also much of the new stone to which it adhered, It was determined to sweep half of it dry, and half after proper watering. This was done, and the sweepings removed were washed, to sepa rate the refuse from the stony matter mixed with it ; one third part of that which was taken dry consisted of coarse grit which would have been useful on the road ; one-twelfth part only of that which was removed in the form of slop was Story matter, and that was so completely pulverized as to be of scarcely any use—it had done its work. After the two per tions of the road had been cleansed, the difference between them was very striking. That which was swept dry was still covered with adhesive matter, which, together with the stones to which it adhered, was lifted by the wheels, the whole road being rough and uneven. The portion which had been swept with water was perfectly even and smooth. On the 2•1th both portions Nvere swept, but only one quarter as much dirt was taken from that which had been water-swept as from the other. On the 2Gth it rained, and three times as much slop was taken off the part of the road which had not been water-swept on the '22nd. The preservative effect of water-sweeping by machine was most striking, by the decidedly better condition of that portion of the road cleansed in this effective manner.