early roads and road-making—edgeworth and m’adam’s systems of roads—stevenson’s system of roads—cast-iron and stone tracks.

writing at an early date, mr. stevenson has given the following sketch of roads and road-making:—

“in early periods, when every family formed a kind of community within itself for providing the necessaries of life, it is obvious that there could be little communication with distant parts of the country, and there was, therefore, no use for roads, which, long after the establishment of towns, must have continued in the state of footpaths and horse-tracks. the bulky articles of fuel and building materials are likely to have given rise to the first idea of a sledge, the precursor of the wheel-carriage, which ultimately led to the construction of anything like a regular path. the first roads of britain appear to have been the military ways of the romans. some remains of these are still to be seen in various parts of the kingdom, and even in the immediate vicinity of the city of edinburgh. it is, however, quite astonishing how slow the progress of improvement in road-making seems to have been, and especially its adaptation to economical purposes; although all classes must have felt an equal interest in the formation of roads, as both the landed proprietor and the citizen were to be mutually benefited by thus laying open the country. but it requires the accumulated wealth of ages to produce improvements65 so expensive. it is long before the mind can be brought to approve of any radical change of habit, however advantageous; and the scale adopted in the first instance is often so circumscribed, that the whole measure requires to be extended and even to be changed a second, and perhaps a third time, in keeping pace with the public demands for improvement.

“it is well known, that even so late as about the middle of the last century, almost the whole land carriage of scotland, and a great part of england, was conducted upon horseback, the animals employed being termed pack-horses. to the horse-tracks thus produced, and which in the first instance were formed without regard to steep acclivities, are to be ascribed the evils which we now labour under, as attendant on the laying out of our roads for the modern improvement of wheel-carriages. nor was it till after much practice and the application of scientific principles, long after the introduction of carriages, that we were induced to improve the line of draught and adopt level tracks of road, although perhaps more circuitous.

“in great britain the road department, after much experience, is now brought into a system by which the highways are made and upheld by dues directly levied on those who travel or use them,—excepting, indeed, such roads as are situated in very remote parts of the country, where the government, with the most enlightened policy, has either executed the works directly by the troops upon the peace establishment, as in the case of general wade’s army, or given aid towards the original formation of extensive lines of road, for opening the more remote districts of the country. there is, perhaps, no better criterion for judging of the prosperity of a country than by its public improvements; and were this subject considered in all its bearings, we should hardly be able to quote any stronger evidence of internal riches and true greatness, than we find connected with the subject of its public roads. it appears from a very general or cursory calculation,66 which the reporter has made, that the highways of great britain and ireland, independently of the almost innumerable parish and private roads, extend to about 25,000 miles. the expense of these, including bridges, etc., on a very moderate calculation, may be stated throughout the kingdom at the rate of ￡800 per mile, which is equal to no less than the aggregate sum of twenty millions sterling. now, to what branch of political economy can we look with more certainty and propriety than to such splendid examples of the substantial wealth and resources of a country? for until a kingdom is traversed and laid open by roads, its government must be weak, and its people remain in a state of comparative poverty.

“but in so extensive a concern as the system of roads, involving so great an expense, we may naturally look for small beginnings and very gradual advancement. accordingly, we find in the first formation of highways, before their utility could be fully understood or experience had shown the benefits of science in the practice of the engineer, the early road-maker only increased the breadth of the horse-track, and strewed it over with gravel from the neighbouring brook. indeed, we know that so late as the year 1542, even the streets of london were formed in this way; and it is said to be established by the records of parliament, that when the new system of road-making was first proposed to be extended beyond the region of a few miles from that metropolis, such was the mistaken policy and narrow-minded views of the immediate proprietors, that the measure was strenuously opposed by those who wished to make a monopoly of the supplies for the metropolis, as detrimental to the established order of things.”

the names of richard edgeworth, f.r.s., and john m’adam, are well known in connection with roads—mr. edgeworth writing in 1813, mr. m’adam in 1816. both men had, it appears, given attention to the subject before the end of the last century. mr. edgeworth says:—“i67 have visited england, and have found, on a journey of many hundred miles, scarcely twenty miles of well-made road. in many parts of the country, and especially near london, the roads are in a shameful condition, and the pavement of london is utterly unworthy of a great metropolis.”

mr. m’adam had been much struck by the entire want of system that existed in the management of roads at that early period, and strongly urged the necessity of a reform in road management as a pre-requisite to road improvement. he urged the laying out of the roads of the country into separate districts, with the appointment of road trustees to manage them—the appointment of chief and assistant road-surveyors to superintend them—and a new system of accounting and finance,—all under statutory regulations; and it cannot be doubted that in all this mr. m’adam did good service, which was recognised in 1823 by parliament voting a sum of money to him for having introduced a system of “repairing, making, and managing turnpike roads and highways, from which the public have derived most important and valuable advantages.”

it appears to me, however, that all that is said in mr. m’adam’s first edition of his book on road-making, in 1816, is of so general and vague a nature that he cannot have known of mr. stevenson’s work at an early part of the century.

from mr. stevenson’s reports it appears that he was much employed in road-engineering in the counties of edinburgh, stirling, linlithgow, perth, and, indeed,68 generally throughout scotland, extending as far north as orkney and shetland; and without raising any claim to priority of design, i give the following extracts from reports made by him in 1812 and 1813, after he must have had at least several years’ previous study and practice of road-making, which i think clearly show that mr. stevenson, if not the original, was at least an independent inventor of the system of road-making which is termed “macadamising.”

in a report to “the honourable the committee of the trustees for the highways and roads within the county of edinburgh,” dated 1812, he says:—

“it may not, however, be considered altogether out of place to notice that the pieces of stone composing the road-metal in common use are perhaps one-half, and in some instances two-thirds, larger than is suitable for the best condition of a road. road-metal of a small size consolidates by the pressure of weighty carriages, when stones of the size commonly used are either pounded under the wheel or forced into the road. it would therefore be desirable, as an experiment upon the large scale, to lay one of the most public roads in the county to the extent of one fourth of a mile with stones broken much smaller than is customary.

“in some instances, especially within a few miles of edinburgh, it might be worthy of consideration by the honourable trustees of this county how far cast-iron cart-tracks might not be advantageously laid upon the roads. some years since the reporter got two or three yards’ length of these iron tracks brought from the shotts ironworks, where they have been used for years with much advantage, and, it is believed, with economy. these cart-tracks would cost about ￡2000 per statute mile, including upholding by the iron-founder for one year. it would be interesting to have also a69 trial made of these in some very public road, although it were only to the extent of two or three hundred yards.”

again, in a report to “the honourable the trustees for the bridge of marykirk,” also in 1812, he says:—

“in the annexed specification of road-makers’ work, the reporter makes some alterations upon the common and ordinary method of breaking and laying road materials, by reducing the road-metal to a more uniform size, and using a course of gravel, if it can be procured, or even of clean sharp sand, as a bottoming for the broken stones. a road composed of stones of various sizes can never be brought into that smooth and uniform surface, which is so much to be desired, for the moment the pressure is brought upon one of these out-sized stones, it must either be crushed under the wheel or be forced by repeated attacks into the road, and thereby it displaces the surrounding stones, and in either case admission is given to the surface-water; a pit is immediately formed, and every succeeding wheel widens the breach, until the road is rendered impassable. to counteract this very common effect, arising chiefly from the very vague manner of defining the dimensions of road-metal by bulk or even by weight, the reporter provides that the trustees shall furnish a riddle or screen, the meshes or openings of which are to be of such dimensions that a stone measuring more than one inch and a half upon any of its sides cannot pass through it.”

fig. 12.—section of one half of roadway.

mr. stevenson’s specification of the regent road in edinburgh is fuller, and is in the following terms:—

“the cross section (shown in fig. 12) of the metalled road to be the same in all respects as that already described for the causewayed70 roadway. but the cross section is to rise from the interior brows or slopes of the paved channels to the centre of the roadway, at the rate of 1 in 25. the bottoming of the road is to be of broken stones from the excavated matters of the calton hill works; the pieces of stone not to exceed five or six lbs. in weight; to be laid by hand in a compact manner to the depth necessary for preparing the road for the upper strata, viz., a layer or stratum of clean sharp sand four inches in thickness, laid all over the surface, and forming a bed for the upper or road-metal stratum, which is to be seven inches in thickness, and to consist of broken stones taken from the quarries of salisbury crags, or the lands of heriot’s hospital, as may be finally agreed upon. the road-metal is to be broken into pieces of such dimensions as to pass freely through a screen, to be provided by the commissioners, the meshes of which shall not exceed one inch and a half square. the whole to be finished with a ‘top-dressing’ of sea-gravel, in such a manner that none of the road-metal shall appear on the surface of the roadway when it is completed.”

these extracts, so far as i have been able to discover, contain the earliest proposals and precise specification of the construction of road now known by the familiar name of “macadamising,” and i dismiss the subject with the following candid quotation from mr. stevenson’s memoranda, in which he says:—

“it may be well to notice that in 1811 i specified road materials of the size as nearly as may be of road-metal, which afterwards became what is called ‘macadamised roads.’ i am not sure if i was before mr. m’adam in this respect; at all events he had the great merit of introducing the system of smooth roads. when i first proposed this method, i think, to the trustees of marykirk, they objected to it upon the score of expense.”

71 as regards the iron cart-tracks suggested for trial by mr. stevenson in his report to the edinburgh road trustees, already quoted, he subsequently matured his views and described them in the article “roads” in the edinburgh encyclop?dia, where he proposed to use stone tracks as a “smooth and durable city road,” which he describes as follows:—

“the individual component stones of the wheel-tracks, hitherto, very partially in use, extend from three to four feet in length, are about ten or twelve inches in breadth, and eight or ten inches in depth. the stones of the tracks recommended by me, on the other hand, are of a cubical form, measuring only from six to eight inches in the lengthway of the track, and twelve to fourteen inches in depth, eighteen inches in breadth at the base, and twelve inches at the top or wheel-track. the stones are therefore proportionate in all their dimensions, for unless they contain a mass of matter corresponding to their length, they will be found to want strength and stability. it would hardly be possible to keep slender stone-rails in their places, and hence the chief benefit of a connected railway would be lost. on the other hand, very large materials are difficult to be got, and are also more expensive in carriage and in workmanship than stones of a smaller size. the italian wheel-tracks are composed of stones two feet in breadth, and of various lengths. to lessen the risk of horses falling, these broad stones are kept in a rough state, by occasionally cutting grooves with a pick-axe upon their upper surface. a mode of paving with large blocks of granite, chequered or cut in this manner, has been tried in some of the streets in london. in order, however, to give pavement of this kind the necessary stability, the blocks would require to have their dimensions equally large on all sides, the expense of which would be too great. but cubical stones of the size now recommended may be procured at a moderate price, and72 throughout a great range of country; while the tracks, if properly laid, will actually be more stable than if blocks of larger dimensions were employed. for we may notice that a carriage-wheel rests or impinges even upon a less surface than one inch of its track at a time, in the course of each revolution round its axis; hence, it may be conceived to produce a kind of compensating effect, connected with the use of small stones, which prevents the tremor from being communicated beyond the limited sphere of each particular block, and, consequently, extending only a few inches. this system of paving i originally proposed for the main street of linlithgow, forming part of the great western road from edinburgh to stirlingshire, and a correct idea of the proposal will at once be acquired by examining fig. 13. by using tracks of this description—giving the stones a proportionally broad bed, and laying them upon a firm foundation (which is indispensable)—we should have our streets and the acclivities of our highways rendered smooth and durable, avoiding the expense and inconvenience of the common road, and also the irksome noise and jolting motion of the causeway.

“the tracks may be formed of granite, whinstone, or any of the hard varieties of rock capable of being hammer-dressed.”

fig. 13.—section for road metal. section for causeway.

specimens of these stone tracks were laid in edinburgh, in terms of mr. stevenson’s specification, on73 south bridge street opposite to the college, and in the pleasance, and a third specimen was laid by the road trustees on liberton hill, which still remains after a lapse of half a century.

subsequently to this mr. walker laid similar tramways in the commercial road, london, and as is well known, they have been pretty largely used in the principal towns in italy.

for a “city road,” as mr. stevenson termed it, the system he proposed has certain advantages, inasmuch as carriages with any form of wheel may use it, and this freedom of use admits of any amount of traffic being accommodated, carriages having the freedom of passing from the stone track to any part of the road. the introduction of iron “street tramways” may, however, be said, for the present, to have taken the place of all other plans for improving city passenger traffic.