in 



vn. 



ROAD. 



131 



weight 



ro ... which an inferior material has been procured 

 great cost, while stone of excellent quality existed 







ord to the beet sue ot the broken stone for the surface of 

 a raw! bothTeMord and MoAdam direct that no piece .hould exceed 

 ITor otaht ounces In weight. In some distriota the surveyors have 

 been intUueted to tost the metal by a pair of scales and a six-ounce 

 mal test U an iron ring 2| inches in diameter, 

 through which every stone should be small 

 writers have recommended that one inch should 

 aster, but it is only the hardest and toughest 

 iiislsrishi that will bear breaking so small without much waste. The 

 KM An-ffH be a* nearly cubical as may be. and should on no 

 ieeooni be broken on the surface of the road; nor U it well to do it 

 on the BT-r. the best method being to break one or two pieces at once 

 en a sugeUock of hard atone, the pieces being held steady bv the iron 

 ring that serves as a gauge. A sitting posture ia considered beet for 

 Mr^Bnragrd in breaking road-metal, an operation which, under the 

 muJnu system of road-making, gives employment to a great number 

 of hand*. Attempt* have been made to perform this operation \<y 

 machinery but mechanical contrivances have not been found equal to 

 .^....1 Ubour. Pronged shovels are made use of in lifting the broken 



into barrows and carts, as they save labour by entering the heap 

 with less resistance than ordinary shovels, and alao prevent the 

 admixture of earth with the metal 



The depth of metal on a paved foundation should be not lees than 

 6 inches, and it should be laid on in two or three distinct layers, carefully 

 spread with broad shovels, and carriages should work on each till it is 



deg 



onsolidated 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 

 Uyer of about an inch and a half of clean gravel is occasionally 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 bring needed to bind the metal together. Moiling a road on 

 which freah materials have been laid is a measure of doubtful utility, 

 the most effectual consolidation being produced by the working of 

 carriage* 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 

 tides 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 stones exceeding an inch and a 

 half in diameter ; the road, when completed, to be 10 inches thick at 

 the aides, and 16 in the centre, where the strongest and best part of 

 the gravel should bo laid. The drainage must be particularly attended 

 to in a gravel road. Among the inferior materials occasionally used 

 is limestone burnt to a vitreous state ; but though formerly often used 

 in districts where coal is abundant, it is not approved for carriage- 

 ways by modern road-makers. 



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 is required in the Holy- 

 head road specifications to be level with the centre of the road, which 

 is 6 inches above the sides. For fencing, walls arc preferred where 

 tone is plentiful, a* they occupy less space than hedges, and have a 

 neat appearance. If the stone should be of favourable shape, such walls 

 may be built without mortar, except in the coping ; but if on the side 

 of an embankment, the walls should be always strongly built with 

 mortar. A hedge-bank and ditch occupy a width of about 8 feet in 

 ordinary exes, and the young quicks are protected by post and rail- 

 fencing ; but where timber is scarce, it ia sometimes well to make the 

 ditch and bank rather larger, so that the wooden railing may be dis 

 pemed with. In cuttings and some other situations a mound or bank 

 without a hedge forms a convenient fence, and these, as well as hedge- 

 banks, may be improved in appearance and durability by being swarded. 

 All fences should be kept low, that they may not exclude sun and 

 wind ; and for the same reason trees or buildings that overshadow the 

 road should be removed when practicable. The situation of toll-gate* 

 must be regulated by circumstances, but it is very desirable to avoid 

 placing them either on, or at the bottom of, a hill, because such an 

 arrangement is very liable to cause accidents. The gates, which, 

 when single, may be 16 feet, or, when donl.le, without a centra-post, 

 24 to 80 feet wide, are usually painted white, that they may bo readily 

 men at night. They should be well lighted, and supplied with com- 

 fortable toll-bouses, which, on some of the modern roads, are erected 

 in an ornamental style. Parnell advises the use of milestones of light- 

 coloured stone, and of larger dimension* than usual ; but cast-iron posts 



have been extensively used, and on some roads cast-iron tablets 

 mounted on stone. A convenient arrangement is a stone or post with 

 two tableU inclined towards the road, so that persona travelling in 

 either dir.i-ti.ni may see the distance of the town which they are 

 approaching. 



However well a metalled road may be made in the first instance, its 

 preservation in a good state depends greatly on prompt and judicious 

 repair. The mud that forms ou the surface in wet weather should bo 

 scraped off and formed into heaps at the side (avoiding the side 

 channels), until it ia sufficiently dry for carting away ; because, if left 

 on the surface, it would, while moist, soften the road and cause it to 

 break up, and after drying impede the running off of water from a 

 subsequent shower. This operation has been usually performed by 

 hand, but scraping- machines, patented by Messrs. Bourne and Harris, 

 have been introduced with partial success, and have been said to 

 diminish the labour fully one-half. The winter season, from October 

 to April, is considered the best time for the addition of fresh mate- 

 rials, which are laid on in thin coats, and should always be applied as 

 soon as any hollow capable of retaining water is observed. For the 

 purpose of keeping a supply of broken stone always at hand, dep6ts for 

 holding about twenty-four cubic yards of metal are formed by tho 

 road-side, at intervals of a quarter of a mile or leas, from which the 

 stone is taken to the required spot in barrows. When laid on the road, 

 according to Parnell, it is not necessary to pick up the old surface, aa 

 the new metal keeps the part under it wet and soft, and soon works in. 

 Me Adam, however, recommended breaking up the surface of th< 

 in every case where fresh stone is added. 



Stone and Iron Tramways. Though an improvement on ordinary 

 pavement, this description of road may be considered as a link be- 

 tween metalled and paved roads, stone tracks having been occasionally 

 applied to common roads, and with great benefit. Stone tramways 

 consist of wheel-tracks formed of large blocks of stone, usually granite, 

 the surface of which is made so smooth as to otter very little resist- 

 ance to the rolling of the wheels, while the space between the tracks, 

 being composed of broken stone, gravel, or rough pavement, affords 

 secure footing for the horses. Iron tramways, in which cast or wrought 

 iron plates are used instead of blocks of stone, have hitherto been 

 very little used on ordinary roads, though their superior smoothness 

 gives them a decided advantage, while their expense does not, as stated 

 by Macneill, at all exceed that of granite. Iron tracks are sometimes 

 made with a flat surface, but a slight concavity, as in WoodhouseV rail, 

 which tends to keep the carriages more accurately in the right course, 

 and is therefore an advantage when the vehicles used on the tramway 

 are nearly uniform in width. The granite blocks used for stone train- 

 ways are generally from 3 to 6 feet long, 12 to 18 inches wide, and 8 to 

 12 inches deep. Great care is necessary in bedding such large blocks ; 

 and the joints require nice adjustment. They are frequently laid end to 

 end without any fitting into each other, but it has been proposed to 

 dovetail the ends together, to insert a small stone as a dowel 1 

 two blocks, to use iron clamps, or to join the stones with oak tree- 

 nails. The granite tracks used on some steep ascents in the Holyhead 

 road are bedded on a pavement 8 inches thick, packed and grouted, and 

 a layer of 3 inches of broken stones not exceeding 1J inch in diameter; 

 a thin stratum of gravel, well rolled, being placed last of all to receive 

 the blocks. When they are laid, the centre and side spaces are filled 

 up with ordinary road material to the level of the tracks ; a row of 

 common granite paving-stones, about 6 inches deep, 5 wide, and 9 

 long, being laid along each side of the tracks to prevent loose materials 

 working on to thuin. Mr. Stevenson, in the ' Edinburgh Encyclopaedia,' 

 recommends the use of smaller stones, as being cheaper and less 

 liable to injury from vibration than those of the usual size. The 

 dimensions recommended by him are 14 inches deep, 18 inches wide 

 at the base, 12 inches wide at the top, and to 9 inches long. 

 The increased accuracy required in the numerous joints might pro- 

 bably counterbalance any advantage gained by the adoption ui 

 storfes. 



The great saving of power effected by the use of tramways for 

 ordinary carriages ia shown by numerous experiments, some of which, 

 tried on the granite tracks of the Commercial Road in London, ( 

 that a well-made waggon will run with increasing velocity, by the 

 force of gravity alone, down a mean slope of 1 in 155. this road a 

 loaded waggon weighing ten tons was drawn with apparent ease by 

 a single horse, up an ascent of 1 in 274, for a distance of about two 

 miles. On an iron tramway laid in 1816 by the Forth and Clyde canal 

 company at Port Dundas, near Glasgow, a horse, has taken n load of 

 three tons on a cart weighing nine cwt., up an acclivity of 1 in 15, 

 without difficulty, though he could not proceed with it on a common 

 causeway with an easy line of draught; and the carter. 

 that the horses take up three tons upon the iron tracks as easily 

 as they did twenty-four cwt. on the common causeway previously 

 used. 



In order to ascertain the comparative durability of different kinds of 

 stone!' .-.and for paving generally, Mr. Walker tried gome 



experiments on blocks laid in a toll gateway on the Commerci-il lovnl 

 tramway, the results of which were as follows : The blocks were 18 

 inches wide and 12 deep, and were laid down in March, 1830; and tin- 

 loss given in the table was ascertained after they had been in use 

 seventeen months, in August, 1831 : 



