There is no doubt that a roadway paved with granite or whinstone setts, upon a hard concrete foundation, presents a most enduring pavement, costing but a few pence per annum in repairs[54] and cleansing, and in other respects it answers nearly all the requirements of traffic except in two very important particulars--it becomes very greasy and slippery under certain conditions of the weather after having been laid any time, and it is an intolerable nuisance in any great thoroughfare, from the incessant din and clatter arising from the wheels of vehicles and the iron shoes of the horses striking upon it; so great is the noise in some thoroughfares thus paved, that tradesmen are compelled to keep their doors and windows tightly closed in order that they may be able to conduct their business, and it is known to injuriously affect the nerves and health of persons who are obliged to live in the vicinity of such streets. It is a bad pavement too for horses to travel upon, the jar upon the legs of the unfortunate animals soon telling upon them. Great improvements, however, have in recent years been introduced to correct these faults. The setts are now made very narrow, about 3 inches in width, or 4 setts to 14 inches including the joints: this gives a better foothold for the horse, the hoof having but a little way to slip before being arrested by a joint; it also lessens the noise, and helps besides to prevent the edges of the stones becoming worn or the pavement wearing unevenly. Running the joints with an asphaltic composition instead of ordinary grouting has also materially conduced to deaden the noise. Taking the question of cost into account--and cost of this description of paving, be it remembered, is considerably affected by weight, when carriage of the stone has to be considered--the following sizes of stones may be taken as satisfactory.[55] Depth 6 to 8 inches Width 2¹⁄₂ „ 3 „ Length 5 „ 9 „ The following table,[56] showing the number of square yards that 1 ton in weight of different sizes of granite setts will cover, may be of use, but this must vary with the specific gravity of the stone employed. Depth. Width. Square yards. 5 inches × 3 inches covers 4¹⁄₃ 6 „ × 3 „ „ 3²⁄₅ 4 „ × 4 „ „ 5¹⁄₃ 7 „ × 3 „ „ 3 The question of the best class of stones to employ as a paving material must to a great measure depend upon local circumstances, but it is important to select such stones as are very hard and durable, but which will not wear smooth and slippery nor round by reason of the chipping off of their edges. Nearly all granites are suitable for this work, but Carnarvonshire syenite[57] is said to be the best material that can be used, although, being denser than granite, it is heavier and consequently more expensive.