In the choice of materials, the expense of conveying them to the road must be taken into consideration, but it is often better economy to fetch good stone from a great distance than to use that which is less durable, though readily procured ; as, in addition to the expense of frequent repairs to a road formed with weak materials, great additional labour Is imposed upon the horses, which have to wear down repeated coats of fresh stones. This is one of the points in which the inex perience and ignorance of road surveyors have often been displayed, eases baring occurred in which an inferior material has been procured fro® • distance at great cost, while stone of excellent quality existed in abundance en the spot.
With vegans to the beet aim of the broken stone for the surface of a mad, both Telford and 31cAllam direct that no piece should exceed six or eight ounces in weight. In some districts the surveyors have been instructed to test the metal by a pair of scales and a 81Z-01111C0 • ht; but a more usual test is an iron ring i inches in diameter, attached to a handle, through which every stone should be small enough to par. Souse writers have recommended that one inch should be the maximum diameter, but it it only the hardest and toughest materials that will bear breaking so small without much waste. The piece% should be as nearly cubical as may be, and should on no amount be broken on the surface of the road ; nor is it well to do it on the heap, the beet method being to break one or two pieces at once ea a large block of hard stone, the pieces being held steady by the iron ring that servos as a gauge. A sitting posture is considered beet for theme engsged in breaking road-metal, an operation which, under the modern 'Teem of road waking, gives employment to a great number of hands. Attempts have been made to perform this operation by machinery, but mechanical oontrivances have not been found equal to manual labour. Pronged shovels are made use of in lifting the broken stone into barrows and carts, as they save labour by entering the heap with less resistance than ordinary shovels, and also prevent the admixture of earth with the metal.
The depth of metal on a paved foundation should be not less than 6 inches, and it should be laid on in two or three distinct layers, carefully' (Tread with broad shovels, and carriages should work on each till it is in some degree consolidated before another is laid over it. While the metalling is fresh, men should attend to rake it In the ruts as fast as they are formed, and to pick off any large stones that may have pre viously escaped notice, as they are sure to work up to the surface. The sides of the road may be covered with the smaller portion of the metal, separated by a sieve with meshes of an inch square ; and a layer of about an Inch and a half of clean gravel is oecationally added over the whole surface in order to ease the draught while the road is new, though its effect on the road is rather injurious than otherwise, nothing being needed to bind the metal together. liolling a road on which fresh materials have been laid is a reassure of doubtful utility, the moat effectual consolidation being produced by the working of carriages which are compelled to vary their tracks, and to run on the new metal, by placing wooden treaties across the road, and altering their position when necessary ; the road is frequently raked as long as any loose stones remain.
Where the traffic is not sufficient to justify so expensive a mode of formation as that which has been described, good roads may be formed with broken stone only, increasing In thickness from 6 inches at the sides to 12 inches in the centre. If nothing better than gravel can be procured, Parnell recommends that a coat of 4 inches be laid on the prepared bed, and worked over till pretty firm ; then a layer 3 inches thick, once screened, and finally three distinct layers of the gravel well riddled, and free from earth, clay, or atones exceeding an inch and a half in diameter ; the road, when completed, to be 10 inches thick at the sides, and 16 in the centre, where the strongest and best part of the gravel should be laid. The drainage must be particularly attended to in a gravel road. Among the inferior materials occasionally used is limestone burnt to a vitreous stato; but though formerly often used In districts where coal is abundant, it is not approved for carriage ways by modern roadmskerma In completing a road it Is necessary to form the side channels with care, and to provide against their being interfered with by branch or field roads. The foothpath, which is usually about 5 feet wide, may be made of gravel or broken sandstone, and ie required in the Holy. head road specifications to he level with the centre of the road, which is 6 inches above the sides. For fencing, walls are preferred where stone is plentiful, as they occupy leas space than hedges, and have t neat appearance. If the stone should be of favourable shape, such wally may be built without mortar, except in the coping; but it on the side of an embankment, the wall, should be always strongly built Witt mortar. A hedge-bank and ditch occupy a width of about 8 feet is ordinary eases, and the young quick% are protected by post and rail fencing; but where timber is scarce, it Is sometimes well to make the ditch and bank rather larger, so that the wooden railing may be dig pensed with. In cuttings and some other situations a mound or haul without a hedge forms a convenient fence, and these, as well as hedge banks, may be improved in appearance and durability by being awarded All (erases should be kept low, that they may not exclude sun and wind ; and for the same reason trees or buildingli that overshadow the road should be removed when practicable, The situation of tollgate, must be regulated by circumstances, but it is very desirable to Reek placing them either on, or at the bottom of, a bill, because such an arrangement is very liable to cause accidents. The gates, which when single, may be 15 feet, or, when double, without a centre-post 24 to 80 feet wide, are usually painted white, that they may ho readib seen at night. They should be well lighted, and supplied with con; fortable toll-houses, which, on some of the modern are erects in an ornamental style. Parnell advises the use of milestones of light coloured stone, and of larger dimensions than usual ; but cast-iron poet lave been extensively used, and on some cast-iron tablets 'mounted on stone. A convenient arrangement is a atone or post with wo tablets inclined towards the road, so that persons travelling in tither direction may sec the distance of the town which they are pproaching.