Page:Report from the Select Committee on Steam Carriages.pdf/214



Mr. John Macneil. 6 September, 1831. those that are imperfectly formed with gravel, flint or round pebbles, without a bottoming or foundation of stone pavement or concrete, are on the contrary much affected by changes of the weather. In the formation of such roads, and before they become bound or firth, a considerable portion of the sub-soil mixes with the stone or gravel in consequence of the necessity of putting the gravel on in thin layers; this mixture of earth or clay, in dry warm seasons, expands by the heat, and makes the road loose and open, the consequence is, that the stones are thrown out, and many of them are crushed and ground into dust, producing considerable wear and diminution of the materials; in wet weather also, the clay or earth, mixed with the stones, absorbs moisture, becomes soft, and allows the stones to move and rub against each other when acted upon by the feet of horses or wheels of Carriages. This attrition of the stones against each other wears them out surprisingly fast, and produces large quantities of mud, which tend to keep the road damp, and by that means increases the injury.

Supposing the actual wear or deterioration of a road to be represented by 100, and that only Coaches. Vans and Waggons have passed over it during any given period, in what proportion would you estimate the effects; first, of atmosphere; secondly, of the Carriage; thirdly, of the horses?—This question can only be answered in a general way; do two lines of road would probably give results at all similar; much will depend on the manner in which the road is constructed, the materials of which it is composed, the care bestowed on its drainage, and whether it be in an open situation or shaded by trees; if the road be properly made, and in an open situation, the injury arising from the atmosphere will be little, compared with the actual wear caused by the wheels of Carriages and the feet of horses, probably not ten per cent, during the year; whereas on weak roads in clay countries every shower loosens the materials of which the road is composed, and causes considerable wear, perhaps thirty per cent, or even more in some