There are few departments of practical mechanics in which every individual, at some period or other of his life, is more immediately interested than in the management of roads and pavements. The mechanical theory of the motions of wheel-carriages, and of the nature of the frictions and resistances that they have to overcome, as relating to the ultimate objects for which roads are constructed, may naturally constitute the first section of an essay on this subject; the second will naturally comprehend the best arrangement of the means for attaining those objects, by the form and construction of such roads and pavements as appear to be the most eligible under various circumstances; and the third may be devoted to some historical illustrations of the principal roads which exist, or which have existed, in various parts of the world.

SECT. I.—Of the Objects of Roads.

The grand object of all modern roads is the accommodation of wheel carriages. The construction of footpaths and of bridle-roads is so simple as to require very little separate consideration; except that, in cities and towns, the convenience of the inhabitants requires that some pains should be taken to avoid dust, and has generally been a reason for employing pavements in preference to gravel roads, which might in some other respects be more eligible.

For facilitating the motion of carriages, the most essential requisite is to have the road as smooth, and as hard, and as level as possible. The wheels of carriages are principally useful in diminishing the friction of the materials; a dray sliding without wheels, even on a railroad of greased and polished iron, would have to overcome a friction as much greater than that of the wheel on its axle as the diameter of the wheel is greater than that of the axle. The wheels assist us also in drawing a carriage over an obstacle; for the path which the axis of the wheel describes is always smoother and less abrupt than the surface of a rough road on which the wheel rolls, and so much the smoother as the wheel is larger, since the portions of larger circles, which constitute the path in question, are less curved than those of smaller ones.

But in all common cases of roads not extremely hard, by far the greater part of the resistance actually exhibited by a road to the motion of a carriage, is that which depends on the continual displacement of a portion of the materials from their inelasticity, which causes them to exert a continual pressure on the fore part of the wheel, without rising behind it to propel it forwards by its re-action, as an elastic substance would do. Hence, in a soft sand, although the axles of the wheels may move in a direction perfectly horizontal, the draught becomes extremely heavy. The more the wheel sinks, the greater is the resistance; and if we suppose the degree of elasticity of the materials, and their immediate resistance at different depths, to be known, we may calculate the whole effect of their action on the wheel, and the force that is required to displace them, in the progressive motion of the carriage. Thus, if the materials were perfectly inelastic, acting only on the preceding half of the immersed portion of the wheel, and their immediate pressure or resistance were simply proportional to the depth, like that of fluids, or that of elastic substances compressed, the horizontal resistance would be to the weight nearly as two-fifths of the length of the part immersed at once, in the newly-formed rut, to the diameter of the wheel; or on a still more probable supposition respecting the greater resistance of the more deeply-seated parts of the rut, about half as much as this, or as about one-fifth of the length of the part immersed in the rut to the diameter. Thus, if a coach or waggon, weighing 60 hundredweight, supported by wheels 4 feet in diameter, formed a new rut an inch deep, in a smooth road, the length of the part immersed being about 14 inches, the resistance would, upon the lowest supposition that is at all admissible, be about one-seventeenth of the weight, and more probably about one-ninth or from 6 to 7 hundredweight at least; and if the rut were 2 inches deep, the resistance would be half as much more. But, on any supposition, the increased height, and even the increased breadth, of the wheel, is calculated to diminish the resistance, by diminishing the depth of the part immersed; thus, if a wheel were made four times as high, the length of that part immersed, considering the road as an imperfect fluid, would be doubled, and the resistance would be diminished, theoretically speaking, to about half of its former magnitude; and if the breadth were increased from one to eight, the length of the part immersed would be diminished to about a half, and the resistance would in this case also be reduced to a half.

In soft and boggy soils, as well as in sandy roads, this consideration is of great importance; and the wheels employed for removing heavy weights, in such cases, ought to be as high and as broad as possible consistently with sufficient lightness and economy. But whether a broad, and, at the same time, a low roller, possesses any advantages above a narrow coach-wheel, is a matter much more questionable: it must be remembered that a narrow wheel may often run between stones, where a broader wheel would have to pass over them; and there appears to be no theoretical reason for preferring a low roller, except with respect to a single pair of wheels, as affording a more convenient attachment for the shafts in a moderate inclination, which is both more favourable to the exertion of the horses, and more effective in overcoming the friction; since it has been demonstrated that the angle affording the most advantageous line of draught is exactly the same as the inclination of a plane along which the carriage would just begin to descend by its own weight on the same kind of surface. In fact, however, there is no necessity for fixing the axle-tree precisely in the line of draught; and the principal reason for having the fore wheels lower than the others is for the convenience of turning the carriage more abruptly. A practical road-maker has observed that a good road never suffers from narrow wheels with moderate weights not in rapid motion, but that it is equally worn by the rapid driving of heavy stage-coaches, and by the slow grinding of the conical rollers of overloaded, broad-wheeled waggons.

Such being the operations of the wheels of carriages on sandy or on rough roads, it is easy to perceive how much the hardness and smoothness of the surface must facilitate the draught; it is obvious also that the same qualities must be equally conducive to the durability of the road, since the inequalities will always cause the carriage to fall on it with a certain impetus after being elevated by the irregularities, and the same shock which strains the carriage will also tend to wear away the road still more where it is lowest; and, on the other hand, the resistance of the soft materials before the wheel will tend to tear up the road, as it causes the wheel to thrust them before it.

Details respecting roads have lost much of their interest since the general introduction of railroads; but in places where common roads are still much used it will be found now, as formerly, that the interests of the traveller and of the postmaster are somewhat at variance with respect to the qualities of a road. The French position keeps to the rough pavement as long as the aching limbs of the ladies in the carriage will allow them to be silent, except when, in going down hill, he saves himself the trouble of locking the wheel by bringing it to the soft edge of the ditch or kerneled; and the horses of the Parisian cabriolets, in their excursions to the suburbs, have sagacity enough to incline always to the pavement, when their drivers allow them to have a will of their own; while a single horseman, on the contrary, more commonly finds his steed on the gravel road, if he happen to leave him to his own direction. In Great Britain the roads are commonly managed by commissioners, who have no community of interest with the innkeepers; on the Continent they are under the immediate direction of the different governments, who also appoint the postmasters, while the carriages are almost as uniformly the property of particular individuals, who have no immediate influence on the management of the roads; and this diversity may perhaps explain in some measure the different systems of road-making which prevail on the opposite sides of the Channel. But it may be said of roads as of governments, "that which is best administered is best;" whether a very smooth pavement not too slippery, or a very hard gravel road not worn into great inequalities.

**Sect. II.—Of the Mechanical Formation of Roads.**

The only strongly-marked division of the different kinds of roads depends on their being paved or gravelled; but each of these classes admits of considerable diversity in the principles on which the road is constructed. The theory of pavement appears to be extremely simple; the stones, however, may be either small or large; the former being understood to be employed without previous preparation of their shape, as in the inferior kind of work which is called "pitching" in the west of England; the latter being more or less cut to fit each other, whether in the form of thick, rough blocks, not very remote from cubes, or of flat and smooth flagstones. In the cities of Great Britain the former are commonly used for horse-pavements, and the latter for foot-passengers; but in Florence the whole breadth of the streets is paved with flagstones placed diagonally, and in Naples the surfaces are nearly as smooth; in both these cases it is necessary to roughen the stones frequently with chisels wherever there is a hill or a bridge, in order to prevent the horses slipping, but in both cities the horses, from habit, are sufficiently sure-footed, even when running with some rapidity. In Milan both kinds of pavements are mixed in the same streets; the smooth in two double lines, for the wheels of carriages coming and going; and the rougher in the intermediate parts, for the feet of the horses, as in the British railroads. But in none of these cities is there much heavy traffic to wear these well-arranged surfaces into such inequalities as would soon be observed in the streets of London if they were so delicately formed; although, until this deterioration actually took place, the locomotion would be luxurious both for the horses and for the passengers, and only ruinous to the coachmakers. The Romans used large and heavy blocks for their roads, cutting them on the spot into such forms as enabled them to be best adjusted to those of the neighbouring stones, though seldom exactly rectangular in their surfaces; and even at Pompeii, where the ruts are worn half through the depth of the blocks, the bottom remains tolerably even, in a longitudinal direction, at least as much so as would be required for carts and other carriages of business.

Our more particular object, however, is, first, the consideration of gravel-roads rather than of pavements; the word gravel being here understood to mean in general all stone broken small, whether by nature or by art. The improvement of such roads has long been a subject of great interest with the agricultural and commercial inhabitants of Great Britain. It was soon after the year 1700 that a part of the charge of repairing roads was taken off the respective parishes through which they pass, and levied on the general traveller by means of turnpike-gates; but it was for many years a complaint that the roads were little, if at all, fundamentally improved by the expenditure of the money so raised. This complaint is very energetically advanced in a "Dissertation concerning the present State of the High Roads of England, especially of those near London, wherein is proposed a new Method of Repairing and Maintaining them;" read before the Royal Society in the winter of 1736-37, by Robert Philips, and printed in a small separate volume. The author's great object is to recommend washing the roads by a constant stream, if possible, and at any rate, washing the materials of which they are composed. In this respect, notwithstanding the existence of single roads so situated that the effects of water upon them have been very beneficially introduced, his plans for the universal employment of water have been altogether superseded by later experience; but he remonstrates, with greater propriety, against the practice, which has, however, continued to prevail so generally till of late years, of laying down large heaps of unprepared gravel, to be gradually consolidated into a harder mass, at the expense of the intolerable labour of the poor animals that are obliged to grind it down. As an illustration of the good effect of water, he mentions that even the sediment deposited by it at the bottom of Fleetditch, which was supposed to be a soft mud, and to require removal when the ditch was filled up, proved in fact to be a hard gravelly substance, which afterwards afforded an excellent foundation for the roads and buildings supported by it.

The attention of the public was afterwards directed to the subject of roads and carriages, by several essays which appeared in the Communications to the Board of Agriculture, and also in a separate form, under the names of Beaton, Wright, Jessop, Hall, Wilkes, Erskine, Ellis, Cumming, Whetley, Amos, and Booth. We may also refer to Sir Henry Parnell's Treatise on Roads; Telford's Reports; The Art of Constructing and Repairing Common Roads, by Henry Law, and Professor Mahan's Essay on Road-Making.

But the suggestions of these writers were in a great measure superseded by the success of Mr Loudon Macadam, a gentleman whose practice was marked by simplicity and economy, though he also had the merit of discovering that the simplest and cheapest methods, in particular cases, especially in that of boggy soils, are also the most effectual. The practical observations which are to be here inserted cannot therefore be so well expressed in any other form as in that of an abstract of Mr Macadam's own directions.

Mr Macadam's leading principles are (Remarks, p. 37), "that a road ought to be considered as an artificial flooring, forming a strong, smooth, solid surface, at once capable of carrying great weights, and over which carriages may pass without meeting any impediment."

He proceeds to give directions for repairing an old road and for making a new one, in the form of a communication to a committee appointed by the House of Commons, in the year 1819, with some subsequent corrections.

No additional materials, he observes, are to be brought upon a road, unless in any part of it there be not a quantity of clean stone equal to 10 inches in thickness. The stone already in the road, supposing it to have been made in the usual manner, is to be loosened, and broken so that no piece may exceed six ounces in weight; the road is then to be laid as flat as possible, leaving only a fall of 3 inches from the middle to the sides when the road is 30 feet wide. The stones, thus loosened, are to be dragged to the side by a strong heavy rake, with teeth 2½ inches in length, and there broken; but the stones are never to be broken on the road itself. When the great stones have been removed, and none are left exceeding six ounces in weight, the surface is to be made smooth by a rake, which will also settle the remaining materials into a better consistence, bringing up the stone, and letting the dirt fall down into its place. The road being so prepared, the stone that has been broken by the side is then to be carefully spread over it: this operation requires particular attention, and the future quality of the road will greatly depend on the manner in which it is performed; the stone must not be laid on in shovelful, but scattered over the surface, one shovelful following another, and being spread over a considerable space. Only a small part of the length of the road should be lifted in this manner at once; that is, about 2 or 3 yards; five men in a gang should be employed to lift it all across, two continually digging up and raking off the large stones, and preparing the road for receiving them again, and the other three breaking them at the side of the road. It may, however, happen that the surveyor may see cause to distribute the labour in a proportion somewhat different. The only proper method of breaking stones, in general, both for effect and for economy, is in a sitting posture. The stones are to be placed in small heaps, and women, boys, and old men past hard labour, may sit down and break them with small hammers into pieces not exceeding six ounces in weight.

In some cases it would be unprofitable to lift and relay a road, even if the materials should have been originally too large; for example, the road between Bath and Cirencester was made of large stones, but so friable that in lifting they would have fallen into sand; in this case Mr Macadam merely had the higher parts cut down, and replaced when sifted, and the surface kept smooth, until those materials were gradually worn out; and they were afterwards replaced by stone of a better quality, properly prepared. At Egham it was necessary to remove the whole road, in order to separate the small portion of valuable materials from the mass of soft matter in which they were enveloped, and which was carried away, at a considerable expense, before a good road could be made. But although freestone is by no means calculated to make a durable road, yet by judicious management it may be made to form a good road as long as it lasts. Whenever new stone is to be laid on a road already consolidated, the hardened surface is to be loosened with a pick, in order to enable the fresh materials to unite with the old. A new road, however well it may have been made, will always receive the impressions of the carriage-wheels until it is hardened; a man must therefore attend the road for some time, in order to rake in the tracks made by the wheels; that is, as long as any loose materials are left that can be so employed.

It is always superfluous, and generally injurious, to add to the broken stone any mixture of earth, clay, chalk, or any other matter that will imbibe water and be affected by frost, or to lay anything whatever on the clean stone for the purpose of binding it; for good stone, well broken, will always combine by its own roughness into a solid substance with a smooth surface, that will not be affected by the vicissitudes of weather, or disfigured by the action of wheels, which, as they pass over it without a jolt, will consequently be incapable of doing it any considerable injury. The experience of the year 1820 strongly confirmed the inutility and inconvenience of employing chalk with the stone. In January, when a hard frost was succeeded by a sudden thaw, a great number of roads broke up, and the wheels of the carriages penetrated into the original soil; in particular, it was observed that all the roads of which chalk was a component part became nearly impassable; and even roads made over chalky soils gave way in most places. But not one of the roads that had been thoroughly made after these directions was observed to give way.

The tools required for lifting roads are—1. Strong picks, but short from the handle to the point; 2. Small hammers, weighing about a pound, with a face the size of a shilling, well steeled, and with a short handle; 3. Rakes with wooden heads, ten inches in length, and with iron teeth about two and a half inches long, and very strong, for raking out the large stones when the road is broken up, and for keeping it smooth after it has been finished, and while it is consolidating; 4. Very light, broad-mouthed shovels, to spread the broken stones and to form the road.

Mr Macadam argues strongly against the old opinion of the necessity of placing a quantity of large stones as a foundation, in order to carry the road over a wet subsoil. He says, that whatever be the nature of the soil, if it be previously "made quite dry," and a covering impenetrable to rain placed over it, the thickness of the covering needs only to depend on its own capability of becoming impervious. Large stones, he says, will constantly work up by the agitation of the traffic on the road, and leave vacuities for the reception of water; and the only way of keeping the stones in their places is to have them of a uniform size. A rocky bottom causes a road to wear out much the faster [acting, probably, as a lower millstone in facilitating the operation of grinding]. "It is a known fact, that a road lasts much longer over a morass than when made over rock. In the neighbourhood of Bridgewater, for example, the materials consumed on a rocky road, when compared with those which are required for a similar road made over the naked surface of the soil, are in the proportion of seven to five." In the summer of 1819, upon some new roads made in Scotland, more than three feet of materials, of various dimensions, were laid down; and more than two-thirds of them, according to our author, were worse than wasted. In such an arrangement the water generally penetrates to the bottom of the trench made to receive the road, and remains there, to do mischief upon every change of weather. To prevent such inconveniences, it is necessary, in wet soils, either to make drains to lower ground, or to raise the road above the general level, instead of making a trench to receive the stones; and from the penetration of rain the solidity of the road itself must protect it. A well-made road, not quite four inches in thickness, was found to have kept the earth below it dry, in the parish of Ashton, near Bristol; but six, eight, or ten inches of materials are generally required to make a firm road, being laid on in successive layers of about two inches in thickness, all well broken, well cleaned, and well sized. Sometimes, indeed, a much greater depth of stone than this is required; in a road, for example, which was made from Lewes to East Bourn entirely upon Mr Macadam's principles, as much as three feet of materials were required in many parts before the road could be sufficiently consolidated; it was, however, ultimately so made, though at an expense of not much less than a thousand pounds a mile.

Mr Macadam maintains that the quantity of stone required for paving is fully sufficient to make an excellent gravel road in any part of the world; and in almost every case materials equally good can be obtained for roads at a still cheaper rate; commonly, indeed, at one-tenth of the expense of pavements. It is, however, in steep ascents that pavements are most objectionable.

The operation of washing gravel Mr Macadam has not found eligible, because it is more expensive than screening or sifting, and less effectual; for about London the common gravel is not capable of being cleaned by any ordinary washing, though the Thames gravel, where it can be procured, is generally clean and serviceable. Coarse gravel broken, he says, is preferable to fine, as it consolidates more perfectly into a single mass. The old practice of putting a heap of unprepared gravel along the middle of the road, and letting it work its own way gradually to the sides, he thinks every way reprehensible.

The objection to a very convex road is, that travellers only use the middle of it, which is therefore worn into three furrows by the string of horses and by the wheels; if the road is flatter, it becomes worn more equitably. Ditches, he observes, only require to be so deep that the surface of the water in them may be a few inches below the level of the road; the farmer often makes them dangerously deep, on account of the value of the mould that is dug out of them. Mr Macadam would prefer a bog to any other foundation for a road, provided that it would allow a man to walk over it; and he observes, that the resistance to the motion of a carriage would not be materially affected by the foundation, if the road were well made. From Bridgewater to Cross, a part of the road shakes when a carriage passes over it; yet the consumption of materials is stated to be less there than on the limestone rock in the neighbourhood. He does not use any faggots in such cases, nor any stones larger than six ounces in weight; and these never sink in the bog, but unite into one mass like a piece of timber, which rests on it. He makes such a road generally at three different times; and he always prefers working in weather not very dry. The surveyors are directed to carry a pair of scales and a six-ounce weight in their pockets, as a check upon the workmen.

Mr Macadam has generally found reason to approve the usual regulation respecting carriage-wheels; but he thinks broad wheels less advantageous to roads than is commonly supposed. He suggests that the tolls might always be fairly made proportional to the exact number of horses employed; except that the waggoners should be encouraged to harness them in pairs rather than in a line. The conical form of broad wheels he thinks very injurious. Clean flints from the sea-side are among the best materials for roads, and might often be procured cheap by canals; granite chipings also, brought as ballast, are excellent; and when the middle of the road has been well made with good stones, the sides may often be left for a few feet less abundantly provided with them, as they are naturally much less exposed to wear.

We have given details of Macadam's plan at considerable length, in order that the reader interested in the subject may form his judgment on a method of constructing roads which was at one time so popular as to threaten to supersede every other. Macadam's great rival in the art of road-making was Telford, whose method was directly opposed to that of Macadam, in requiring that every road should be laid down upon a hard, solid, carefully-prepared foundation; whereas Macadam, as it will have been seen, was indifferent whether the substratum were soft or hard, but of the two he rather preferred the former. Telford was accustomed to regard as the real road, not the surface upon which animals and vehicles moved, but the foundation or sub-road, which, if properly preserved, would last for ever; and in order to preserve it properly, it was covered with suitable materials, renewed from time to time, on which were expended the action of the horses' feet and carriage-wheels, as well as of the weather. This method was adopted with great success on the Holyhead road, the Glasgow and Carlisle road, &c.; and the public had abundant opportunity of testing the merits of the two rival schemes. It is scarcely necessary to say which eventually prevailed. Considerable credit, however, is due to Macadam for improved details and economy in the art of road-making; and we now proceed to describe some of the more important features of Telford's practice. In the first place, the road having been properly levelled, and, where necessary, drained, a regular bottoming of close-set pavement was constructed. The object was to secure the greatest degree of hardness consistent with the materials at hand; and this method is stated to be less expensive than a thick coating of broken stones, while six inches of broken stones is sufficient when laid on pavement. Any kind of common stone may be used for the pavement; and if the stones are laid with their broadest faces downwards, and stone chips be well driven into the interstices, the earthy bed of the road will not be pressed up so as to mix with the coating of broken stones. When this coating is consolidated it will form a solid, uniform mass of stone, and will be very superior in hardness to one of broken stones mixed with the earth of the sub-stratum. On a road of this kind the power required to draw a wagon was 46 lbs., while on a road made with a thick coating of broken stone laid on earth it was 65 lbs., and with a thick coating of gravel laid on earth it was 147 lbs. In places where stone is scarce, but gravel and lime are abundant, concrete may be used for the solid foundation of the road; it should be spread to the depth of 6 inches, and upon this, 6 inches of good hard gravel may be placed in two courses, 3 inches at a time. By using concrete, a good solid road may be formed with round, pebbly gravel, and other materials not well adapted to road-making. The gravel should be free from clay and dirt, and consist of stones and sand, the latter sufficiently abundant to fill up the spaces in the former. Five or six parts of the gravel are to be mixed with ground, unslaked lime, when sufficient water must be added to slack the lime. It is to be well mixed up, and thrown at once into its place and trimmed to the proper form. Just as the concrete is about to set, the first layer of broken stones or screened gravel is to be put on. The broken stones on the surface will quickly wedge together, but round and pebbly gravel stones must be mixed with some binding material, to fill up the interstices and prevent them from rolling about. This binding material is useful in making the road solid; but it makes it spongy in wet weather, and serves to break it up after a thaw. In chalk districts that material may be used for the foundation, but it should be placed at such a depth as to be out of reach of frost. In soft and boggy ground, the foundation should be laid with bushes or bundles of faggots. The best road-metal for the surface should be hard and tough, for which purpose whin-stones, basalts, granite, and beach pebbles are well adapted. Flint is hard but brittle, and is easily crushed; and so also, for a contrary reason, the softer sandstones. The limestones are retentive of water, and are apt to split during a thaw, but the harder and more compact varieties may be used. When gravel is the only road material, it should be screened, and the fine stuff or hoggin be reserved for footpaths. The larger stones should be broken, and the screened gravel be spread to the depth of 6 inches. When new roads are opened, men should be employed to keep every rut raked in as soon as it is formed, and guards or fenders should be placed so as to make the carriages pass over every part of the road in turn.

In every road provision must be made for drainage. Surface-drainage is assisted by a gently-convex transverse section. There should be a ditch on each side to carry off all the water that may fall upon the road. Between the footpath and the road, at distances of about 60 feet, drains of tiles or pipes should be formed under the footpath for conveying the water into the ditch. If the surface be properly drained, very little water will find its way to the substratum unless this be a strong clay or wet peat, in which case a system of under-drainage must be adopted, and trenches or drains be formed across the road at distances of 20 or 30 feet.

In improving an old road, it is often desirable to straighten its course by cutting off corners and bends, or to improve the level by avoiding or lowering hills, and embanking valleys. It is also desirable to increase the width and make it uniform throughout; the transverse section must be corrected, ruts filled up, and the side ditches cleaned and deepened; trees and hedges too near the road must be cut down, and mud-banks removed. In improving an old road by the common method of heaping on new materials, there is a wasteful expenditure of means; for most old roads usually contain abundant material if properly lifted and applied. Roads should be scraped clean in wet weather, and watered in dry; the fences should be as low as possible, and placed far on the sides of the road, so as not to intercept the sun and wind.

In forming roads through the streets of a busy town, it is even more important than in the country to secure a good foundation. This may be of concrete or of broken stone, or the old road may itself be the foundation, for which purpose the stones must be taken up and laid down again to the proper cross section; and upon this, stone pavement may be laid, some kind of coarse mortar being used. Granite is the best paving-stone, especially that from Guernsey and Aberdeen, as it does not become polished by wear. Next to this the hardest varieties of limestone and freestone may be used. The stones should be in rectangular blocks from 8 to 15 inches in depth, about 18 inches in length, and 3 or 4 inches in width. Narrow stones are found to wear better than wide ones. The courses should break joint, and should abut against a firm kerb on each side of the road. The courses should be commenced on each side and worked towards the centre; the joints between the stones should be thin, and the last stone should fit tightly so as to form a key to the whole. The stones should be well rammed down with a heavy punner, and a thin grouting of sand and lime should be poured over the surface, unless the superior plan be adopted of bedding the stones in mortar. Where the road is inclined, the pavement should be laid so as to give horses a hold for their feet; for which purpose the stones may be sloped so as to form a series of ledges or steps, or a course of slate about an inch less in depth than the stones may be inserted between the courses.

Roads have been paved with wooden blocks, but they have in many cases failed for want of a solid foundation, the absence of which caused them to form numerous pits and cavities, and they were also found to be very slippery in wet weather. Some years ago, wooden pavements were in such favour in London, that most of the great thoroughfares were so paved. A large number of patents were taken out for new forms of blocks, and machinery for preparing them, and also for combining and laying them down. Contracts were also entered into for terms of years; so that long after wooden pavements had fallen into disfavour they continued to be used. When these roads were new and in good condition, they were easy to the horses, pleasant to the travellers, and especially so to the inhabitants of crowded thoroughfares, from the cessation of noise. After the wooden roads had been given up, a noiseless wheel was attempted,—that is, a wheel with a band of vulcanized india-rubber let into the tire. Asphaltum roads have also been tried, for which purpose the soft earth is well rammed, and a coarse concrete laid; upon this a finer concrete; and lastly, the asphaltum applied in a liquid state, and before it is quite set covered with sand, slate-dust, plaster of Paris, or powdered chalk, rubbed in with a flat heavy tool of wood; or, for a rough pavement, a clean, sharp grit is used. This kind of road answers tolerably well where the traffic is not considerable, but it is liable to soften under a hot sun, and to exhale a very disagreeable odour. Sect. III.—Of the Roads of different Ages and Countries.

The ancient Incas of Peru seem to have been the greatest road-makers in the world. The story told by Montaigne (iii. vi., p. 206) of a road in Peru, from Quito to Cuzco, 300 leagues long and 25 paces broad, made of stones 10 feet square, with a running stream and a row of trees on each side, seems to have been literally true. "It was conducted," says Prescott in his History of Peru, "over pathless sierras covered with snow; galleries were cut for leagues through the living rock; rivers were crossed by means of bridges that swung suspended in the air; precipices were scaled by stairways hewn out of the native bed; and ravines of hideous depth were filled up with solid masonry." In Italy only, the Romans are said to have made more than 14,000 miles of road, which was generally executed with great care and labour; and many of their roads still remain as the foundation of the most favourite routes of Italian travellers. The more than Roman despot of modern times was as much a Roman in his road-making as in the selfish character of his general policy; and in proportion to the duration of his destiny he performed more than all the Appii and Flaminii of antiquity. Whatever his merits may have been, the beneficial effects of his measures remain; and those who have profited by his improvements have no right to criticise his motives with too great severity.

Of the great roads diverging from the gates of ancient Rome, about twelve have been enumerated by antiquaries, and twelve more branched off from these at a small distance from the city; eighteen others commenced in different parts of Italy, and in the whole there are at least fifty, which have been distinguished by appropriate names, without including the military roads through the distant provinces; such, for example, as in England were distinguished by the name of streets, of which many traces yet remain in different parts of the country.

Directly to the sea the Romans travelled by the Ostian Road; along its shores to the north-west by the Aurelian, and to the south-east by the Appian. Next within the Aurelian was the Flaminian, then the Salarian, the Nomentanian, the Tiburtine, the Praenestine, the Lavican, and the Latin; and then the Appian, which was the most ancient of all, having been made as far as Capua, in the 442d year of the city, accompanied to a considerable distance by an aqueduct. The Aurelian road was made in the year 512; the Flaminian about 538.

I. The Flaminius Road still affords the great northern approach to Rome by the Porta del Popolo; it led to Feligno, Ancona, and Rimini, and was continued by the Emilian to Bologna, and thence to Aquilegia, near Venice; the present mountain route from Bologna to Rome is still facilitated by the remains of the ancient structures. Besides the Emilian Road, the Flaminian was also connected with the Cassia, leading to Modena; the Clodia to Arezzo, Florence, and Lucca; there were also six other branches of less note, each named after its founder.

II. III. The Salarian and the Nomentanian roads lay to the east of the Flaminian; the former, from the Porta Salara, led through the country of the Sabines by Rieti to Hadria; the latter, from the Porta San' Agnese, went north-eastwards to Nomentum.

IV. The Tiburtine Road led from the Porta Tiburtina, now San Lorenzo, to Tivoli, with a branch on the right called the Gabian. The large blocks which were employed to form this road, near the town of Tivoli, in ascending from the river, are still in their ancient places; they are accurately fitted together, and present a surface sufficiently smooth, after having been in use for about 2000 years.

V. VI. VII. The three next in order all met at Anagnis, 24 miles beyond Praeneste or Palestrina. The Praenestine, from the Esquilin gate, now called Porta Maggiore, on account of the magnitude of the ruins of the aqueduct of Clodius, with which it is incorporated, led by Aquinum to Praeneste; the Lovian led from the same gate, more to the right, by way of Beneventum; and the Latium road, from the Porta Latina, went first to Comitium, and from Anagnis proceeded to join the Appian near Capua.

VIII. The Appian Road is well known, from the minute description of Horace's progress in his journey to Brundisium, as from the eagerness with which a modern traveller reckons the stages that he has completed on his way to Naples, without a visit from the bandits that infest it. Its length is the extent of this road, from the Colosseum to Capua, was 142 Roman miles; and it was continued 238 miles farther to Brundisium by Julius Caesar. It was constructed with large stones, or rather rocks, joined together with great care; and it is said to have had a foot-pavement, 2 feet wide on each side, besides the agger, or principal mass of stones in the middle, and the two marginal parts, which were probably unpaved.

IX. The Ostian Road led from the Porta di San Paolo, near the Tiber, in a straight line to the mouth of that river.

X. The Aurelian, from the Porta Aurelia, a gate which was near the Holm Adrian, or Castle of San Angelo, led by Laurentum to Centocelle, or Civita Vecchia, and then by the Via Sacra across the Alban hills, as far as Arles in Provence. This seems to have been the oldest passage into Gaul; it was improved by Pompey the Great under the name of the Strata Romana. Several other passages over the Alps are also particularized in the Itinerary of Antonine on the roads from Milan to Arles; from Milan to Vienne in Dauphino, either by the Grecian or by the Cottian Pass; the former north, the latter south of Montcenis; from Milan to Strasbourg; and from Milan to Mentz.

XI. XII. The Triumphal Road began from the Capitol, and went over the Tiber into the country beyond the present site of the Vatican. We may consider as the last of the twelve great roads, originating from Rome, the Caudina, leading due north from the Porta Pinchiana on the Monte Pincio.

Among the less remarkable roads about the metropolis of the ancient world were also the Campanian, the new and the old Valerian, both leading by Tivoli, to the Adriatic; the Tuscanal, the Alban, the Ardeantine, on the right of the Appian; the Laurentine, a little more to the right; Pliny's villa being mentioned as accessible from either of these last; the Portuenis, from the Porta Portuense, Tresveneria, leading to Ostia; and the Aurel Nora, beginning from the Porta Janicul, now Porta San Pancrazio, and leading towards Civita Vecchia.

Whether on the foundations of the ancient roads, or in any new lines that have been prepared in modern times by the magnificence of the pontiffs or of the princes, the great roads of Italy are at present almost universally well made and well repaired. In Lombardy, indeed, and throughout the immense plain that extends from the Alps to the Apennines, they are quite as good, in summer at least, as those in England. The cross roads of Italy are, however, greatly neglected; for it is in fact almost exclusively in Great Britain that private and individual exertion supersedes the necessity of public munificence. The intercourse of Italy with the rest of Europe has been greatly facilitated by the improvements made in the two great passages over the Alps by the authority of Bonaparte. The more useful of these improvements are probably those which have been effected on the southern side of Montcenis, since they enable the traveller to pass with little danger or difficulty at all seasons of the year; the more magnificent are the works at the Simplon, which, however, are not completely secure from the danger of avalanches, whenever fresh snow is lying on the ground. The Apennine portion of the Aurelian road has also been greatly improved by some still more recent operations, so that carriages may now pass with comparative ease and safety from Lucca to Genoa; though, for one stage near Sestri, it is not thought advisable for the travellers to retain their seats within them.

The general declivity of the new road over Montcenis is 1 inch in 15 or 20; and it is never greater in the steepest part,—that is, in the fourth and fifth turns that wind up over Lanslebourg.—than 1 in 12. (Derrien, Notice Historique et Descriptive sur la Route de Montcenis.) The road over the Simplon was executed jointly by the French and Italians, under the government of Bonaparte, from 1801 to 1803. The greatest declivity is 1 inch in 29; so that an English stage coachman might trot his horses up almost the whole way. The longest gallery or tunnel is about 500 feet under ground. The roads in France are generally rough in their original formation, and still rougher from want of care in repairing them, as the traveller feels to his cost in passing over the primitive mountains in the south of that country, where the roads are certainly very different from those which are made by Macadam across a bog; although some of the more recent French and Flemish pavements, as long as they remain unimpaired, are truly excellent. In Germany they have few pavements; and the roads, except in sandy countries, are generally kept in good repair,—that is, in the south and the west of Germany. Mr Cripps informs us that the great roads in Sweden are beautiful; they are very slightly convex, and made of granite broken to the size of a walnut. The roads of the British Islands are excellent, and in most cases still retain their utility as feeders to railways.