trial by the spirit level, there is a slight degree of convexity.'-Etidence, p. 39.

The remaining evidence is that of some of the most experienced road-engineers and surveyors. From this we shall extract what we think most important to the remarks which we shall offer to our readers upon the laying out, the formation, and the maintaining of roads.

In the original laying out of roads, we are glad to find in favour of some degree of curvature, such good authority as that of Mr. Edgeworth.

To follow the mathematical axiom, that a straight line is the shortest that can be drawn between two points, will not succeed in making the most commodious roads; hills must be avoided, towns must be resorted to, and the sudden bends of rivers must be shunned.'It may perhaps appear surprising, that there is but little difference in length between a road that has a gentle bend, and one that is in a perfectly straight line. A road two miles long and perfectly straight can scarcely be found any where; but if such a road could be found, and if it were curved so as to prevent the eye from seeing farther than a quarter of a mile of it, in any one place, the whole road would not be lengthened more than one hundred and fifty yards. It is not proposed to make serpentine roads merely for the entertainment of travellers; but it is intended to point out that a strict adherence to a straight line is of much less consequence than is usually supposed.'-Edgeworth, P. 12.

We wish this observation could be impressed on those merciless annihilators of rural scenery, the Commissioners of Inclosures. We were perhaps a little disposed to smile at the following passages of Mr. Paterson, though we admit the justness both of his illustration and of his reasons,

'The difference between going over a hill, and round the bottom of it, is not, in point of distance, quite so much as is generally understood. Place, for instance, an egg upon a table: then, from the one end to the other, trace a line upon the shell exactly on the horizontal plane: between the same extreme points of the egg, trace a line over the top of it directly in the vertical plane; and the length of those two lines will be found to be exactly equal. The same observation will apply, in a greater or lesser degree, to the forming of roads over hilly ground.'There is another remark in favour of the curved line in general, which it may be proper to attend to. Every traveller knows by experience, that in going but a mile or two of a road that is formed on a straight line, the sight of such a distance before him oppresses his mind with fatigue, and he thinks it long till he arrives at the end of his prospect. Or rather, the eye of the traveller taking in such a large prospect at once, the distance appears less than it really is, as is the case in looking over an expanse of water, or an extensive plain. So that in proportion as hope is encouraged by the deceiving prospect, in like proportion

will he experience disappointment and fatigue as he becomes gradually undeceived by the real length of the road in travelling along it. But in going the same distance of a road that is diversified by several windings, his mind is diverted from the fatigue by the change of scenery that opens to his view, at every turn or winding of the road; so that while he moves along, if he is not amused, he feels it, at any rate, less tiresome than in the former case.'

Inspired, we presume, by the beautiful passage of his countryman on the tide of human time,' Mr. Paterson goes on to moralize on the journey of life: we have neither time nor taste to follow him in his ambitious but desultory course, and must therefore be contented to jog on in more sober guise.

How much may be effected by science and skill in diminishing the obstruction occasioned by hills, is exemplified in the evidence of Mr. Telford, engineer of the Holyhead road, under the parlia mentary commissioners.

'On the Welsh part of that road,' he says, 'the inclinations were formerly (in many instances) as much as one in six, seven, eight, nine and ten; the width at the same time frequently not exceeding twelve feet, without protection on the lower side.' Now the longitudinal inclinations are in general less than one in thirty; in one instance for a considerable distance there was no avoiding one in twentytwo, and in another for about two hundred yards, one in seventeen; but in these two cases, the surface of the roadway being made peculiarly smooth and hard, no inconvenience is experienced by wheel carriages.'

In the formation of roads, one of the most prevailing faults is that of giving them too great a convexity: a fall of three inches, Mr. M'Adam says, from the centre to the side, is sufficient for a road thirty feet wide. The inefficacy of the convexity for the purpose of draining the roads is pointed out by Mr. Edgeworth.

In all these schemes for carrying off water from the roads by the inclination of the ground it seems to have escaped the attention of those who proposed them, that no lateral inclination of the ground, consistent with the safety of carriages, would empty a rut of three inches deep. So far from this being the case, whoever attends to the fact will find, that even down a moderate slope, where any dirt remains upon the roads, the water will be obstructed.'-' In fact,' he continues, roads become dry by evaporation; and where they are exposed to sun and wind, the effects of heat and ventilation are more powerful than any surface drainage that could be accomplished.'-p. 14.

All the materials, of which the surface of the road is formed, should be broken small. The reason for this is thus given by Mr. M'Adam.

'It seems an obvious proposition, that the materials of which a road is to be composed, should be reduced to such a size as shall enable carriages to pass over without striking against them, so that they may be

6 4

consolidated

consolidated by a perpendicular pressure. The size of the stones must be proportioned to that part of the wheel, which will form the point of contact upon a smooth level surface; and this will be found to be about an inch square. When the stones of a road exceed the size of this bearing, the wheels of carriages will keep them in constant motion, and prevent their consolidating, because when a wheel rests only on one part of a stone, the other part rises; or if the stone be so large that the wheel does not pass over, but strikes against it, besides the impediment presented to the carriage, a great damage is done to the road. From this it appears that every stone above a specified size is a positive disadvantage in road-making. Upon a road made of wellordered materials, wheel carriages will pass over without any jolt or shake; and consequently without that action and re-action between the wheels and the stones, which is the real cause of the present bad state of the roads of Great Britain. A rough road can only be a road made of large stones; and as neither use nor change of weather can produce them, the defect must be entirely the work of the road-maker.'-Mem. p. 5.

Mr. Edgeworth agrees with him. (p. 20.) No stones larger than an inch and a half diameter should be suffered to remain on the road; when much inaccuracy in this respect is suspected, an iron ring may be employed as a gauge.' Mr. Paterson recommends a ring of a diameter of two inches, or two inches and a half. Mr. M'Adam has the stones broken to the weight of six ounces.

• Do you find a measure or ring through which the stones will pass a good method of regulating their size?-That is a very good way; but I always make my surveyors carry a pair of scales, and a six ounce weight in their pockets, and when they come to a heap of stones, they weigh one or two of the largest, and if they are reasonably about that weight they will do; it is impossible to make them come exactly to it.' -Report, p. 24.

In breaking stones for roads,' Mr. Edgeworth says, the best method is to have them broken by a person sitting, and using small hammers.-A hard stone may serve for an anvil, and the stone to be broken may be advantageously held in a forked stick.' (p. 20.) Mr. M'Adam recommends the employment of women and children in this operation, and adds that his recommendation applies to all materials universally. Round gravel and round pebbles never make a tolerable road: but broken stone will combine by its own angles into a smooth solid surface, that cannot be affected by the vicissitudes of weather.'

But though all our authorities agree in the necessity of forming the surface of the road of stone broken small, there is some discordance among them as to the foundation, especially in a swampy soil. When the substratum of a road is unsound,' says Mr. Edgeworth, (p. 18.) it should be covered with faggots of brushwood, with the branches of fir trees, or with furze and,

heath.

heath. Flat stones, if they can be had, should then be laid over the faggots, and upon them stones of six or seven pounds weight, and lastly, a coat of eight or ten inches of pounded stone.' Mr. Paterson says, if the bottom be soft and wet, the bottom metals should be much larger than the top;' though he mentions. cases in which the large stones will work their way to the surface. Several of the intelligent surveyors examined by the Committee agree in these opinions, and Mr. Telford recommends covering a foundation of clay with vegetable soil. Mr. M'Adam however appears to set this question at rest. In answer to the questions,

'What depth of solid materials would you think it right to put upon a road in order to repair it properly ?'-- He replies, I should think that ten inches of well consolidated materials is equal to carry any thing.'

"That is, provided the substratum is sound?-No;-I should not care whether the substratum was soft or hard; I should rather prefer a soft one to a hard one.'

'You don't mean you would prefer a bog?-If it was not such a bog as would not allow a man to walk over it, I should prefer it.'

'What advantage is derived from the substrata not being perfectly solid?—I think when a road is placed upon a hard substance, such as a rock, the road wears much sooner than when placed on a soft substance. The road in Somersetshire between Bridgewater and Cross is mostly over a morass, which is so extremely soft that, when you ride in a carriage along the road, you see the water tremble in the ditches: on each side; and after there has been a slight frost, the vibration of the water from the carriage on the road will be so great as to break the young ice. That road is partly in the Bristol district. I think there is about seven miles of it, and at the end of those seven miles, we come directly to the limestone rock. I think we have about five or six miles of this rocky road immediately succeeding the morass; and being curious to know what the wear was, I had a very exact account kept, not very lately, but I think the difference is as five to seven in the expenditure of the materials on the soft and hard;'-though the hard road lies higher.

But in forming a road over a morass, would you bottom the road with small or large stones?-I never use large stones on the bottom of a road; I would not put a large stone in any part of it.'

'In forming a road across a morass, would you not put some sort of intermediate material between the bog and the stone?—No, never.'

Would you not put faggots ?—No, no faggots.'

How small would you have the stones?-Not to exceed six ounces in weight.'

'Have you not found, that a foundation of bog sinks?—No, not a bit of the road sinks: and we have the same thickness of materials on the one as on the other.'

'If a road be made smooth and solid, it will be one mass, and the effect of the substrata, whether clay or sand, can never be felt in effect

by

by carriages going over the road; because a road well made unites itself into a body like a piece of timber or a board.'—Report, p. 23.

Having observed symptoms of incredulity in some members of the Committee, Mr. M'Adam, on a subsequent examination, corroborated the above statement by the testimonies of Edward Whitting, surveyor of the road alluded to, and by that of R. Phippen, Esq., the treasurer; the former of whom asserts that the general strength of the road is from seven inches to nine, and that he has always considered five tons of stones on the morass, equal to seven over the hills.

Where the road is carried through a wet or springy soil, Mr. Paterson's method of draining is simple, and not very expensive. 'Run,' says he, (page 24.) 'a drain along the middle of the road all the way, from two to three feet deep, as narrow as it can possibly be dug, filling it with stones up to the surface of the road, making those at the bottom of a pretty good size, probably from six to eight inches in diameter. From this leading drain make a branch here and there, to carry off the water to the canals on the sides of the road.'

Attention to these canals or ditches is obviously of considerable importance. In order to obviate the danger occasioned by them Mr. Walker recommends their being formed on the field side of the hedge. In a length of road over a marsh where the ditches were obliged to be wide and deep, I ordered,' says he, 'some cuttings of willow to be stuck into the road side of the ditch, which are now so thick and strong, as to be a complete security from all danger.'-We are acquainted with many formidable causeways, where we should rejoice to see this practice adopted.

When a road is well formed, and covered to the depth of eight or ten inches with well-broken materials, the next object is to maintain it in good repair. And here the whole art and mystery consists in constant scraping when the weather is wet and dirty; in continually filling the ruts, (that all the metals, as Mr. Paterson expresses it, may be subjected to equal fatigue,) and in giving free access to sun and air, by cutting the hedges and stripping the trees by the road side to a certain height; though not to such a degree as is too often practised to the destruction of the timber, and the utter annihilation of all picturesque beauty. When fresh materials are necessary, they should be laid on while the road is in a moist state, and immediately after it has been scraped.

After travelling in a sultry day through clouds of dust, we have often congratulated ourselves upon entering the region of watered roads. This, however, Mr. B. Farey, surveyor of Whitechapel Road, tells us is very injurious, if practised before May and after August, as the water separates the stones and makes the road

spongy