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you have adopted; and, as one individual concerned, I beg leave to offer you my most sincere congratulations thereon.
“ CYRUS J. COATSWORTH.”
ROADS MADE WITH A FOUNDATION OF RUBBLE
STONES, AND A SURFACE OF BROKEN STONES.
A useful road may be constructed by making a foundation with rubble stones, and laying broken stones or gravel upon them.
The stones should be reduced so as not to have any of them more than four pounds in weight; these should be laid in a regular bed, to the depth of seven inches in the middle and four inches at the sides, supposing the road to be thirty feet in breadth ; a coating of small broken stones should then be laid on in the way directed when a pavement is used.
If the subsoil be clay, a course of earth, of any kind that is not clay, of the thickness of six inches, should be laid upon the clay, to prevent it from rising and mixing with the stones.
A road made according to the rules here given will not be a very expensive one: it will answer for cross turnpike roads, and other roads that do not communicate between large towns and collieries.
This plan is much superior to, and not more expensive than, the next plan.
A ROAD MADE WHOLLY OF BROKEN STONE.
A road may be constructed, suitable to light carriages and little traffic, by forming a level bed on the natural soil, and putting upon it a body of broken stones, of twelve inches in thickness in the middle, and six at the sides. The stones should be laid on in successive layers, taking care to let each layer be worked in, and consolidated, before a fresh one be laid on. If the subsoil is clay, a course of earth should be laid upon it, as proposed in the last plan.
Roads of this description are not sufficiently strong for great thoroughfares. This plan, however, having of late been recommended as greatly superior to all other plans by persons who profess to be experienced and scientific road-makers, a number of turnpike trustees have adopted it; but experience has fully established its unfitness for roads of great traffic, in comparison with those made with a proper foundation. The reason is very obvious; for if a coating of small broken stones be laid on the natural soil, the weight of carriage wheels passing over it forces the lower course of the stones into the soil, while the soil is forced
into the interstices between them; the clean body of stones, first laid on to make the road, is thus converted into a mixed body of stones and earth, and, consequently, the surface of the road cannot but be very imperfect as to hardness. It is necessarily heavy in wet weather, on account of the mud the earth makes on its surface; and, in
warm weather, on account of a quantity of dry dirt.
A road made on this plan will require, for two or three years after it is said to be finished, the expenditure of large sums in new materials to bring it into any thing like even an imperfectly consolidated state; and, after all that can be done, such a road will always run heavy, and break up after severe frosts; for, as the natural soil on which such a road is laid is always more or less damp and wet, it will necessarily keep the body of materials of which the road is made damp and wet; in consequence of which, the surface of the road will wear down quickly. Hard frosts will penetrate through the materials into the under soil, and, when thaws take place, break up the whole surface.
It is in this way that the ruinous state of most roads, after severe frosts, is to be accounted for.
The following Post Office bulletin, which appeared in the London newspapers of 27th February 1838, will serve as conclusive testimony in favour of strong roads, and against those made “ with materials of an uniform size from the bottom,” laid on the natural soil ; these being the roads to which the Post Office alludes.
“ General Post Office, Tuesday, one o'clock.The mails, during the last two or three days, have again been seriously retarded in their arrival, owing to the heavy fall of snow, especially in the north, and the generally rotten state of the roads. One Glasgow and one Edinburgh mail are still due. The roads in the west of England and on other lines are so rotten that the wheels frequently sank to the nave.”
ROADS MADE WITH GRAVEL.
In a country where no stone can be got for making a road, and nothing better than gravel can be procured, the following plan of employing it may be adopted :—When the bed of the road has been formed, a coating of small gravel should be laid on, four inches thick, over its whole breadth; carriages should then be let to run upon it, and the ruts should be raked in as soon as they appear. When the first coat of gravel has become tolerably firm, another coating, once screened, should be laid
three inches thick, over the whole surface, and the ruts raked in as before. When this second coat of gravel is consolidated, a third should be laid on, three inches thick: this coat of gravel should be well riddled, and cleansed from all earth or clay, and all pebbles exceeding one inch and a half in diameter should be broken before they are laid on the road. This process should be repeated until there is a body of gravel laid on the road sixteen inches thick in the middle, and ten at the sides, so as to form a convex surface rising six inches from the sides to the centre. The strongest and best part of the gravel should be put on the middle fifteen feet of the road, and the smaller gravel on the sides. In all roads of this description the greatest care must be taken to drain the subsoil by a sufficient number of cross and mitre drains, communicating with the main drains. If this is not attended to, it will be impossible to form a good carriage way.
A road made with gravel in the way here recommended will be much stronger than gravel roads usually are; but it will be much inferior to one made with stone materials. The roundness of the stones prevents them from becoming consolidated by pressure, so as to form a perfectly hard surface; and when the gravel consists of limestone, flint, freestone, sandstone, or other kinds of weak stone, it is so rapidly pulverised, that the friction produced by wheels passing over it adds greatly to the labour of horses.