ROAD. 



with three tons upon a level, inftead of two upon fuch a 

 declivity. The proportion of weight upon each wheel, ac- 

 cording to the declivity, will depend on the nature of the load- 

 ing of the cart, for the higher the centre of gravity of the 

 load is, the greater will that weight be on the lower wheel on 

 the fame declivity ; and therefore a cart loaded with hay, 

 draw, or wool, or any other bulky commodity, will be 

 more injurious to a convex road, unlefs when on the middle 

 of it, than the fame cart loaded with the fame weight of 

 ftone, lead, or iron, or any other weighty commodity which 

 lies low in a cart : and nothing can be more injurious 

 on fuch roads, than a ftage-coach loaded with outfide 

 pallencrers. But the deftructive confequences of allowing 

 carriages to heel much on any fort of road are even villble, 

 though in a (mail degree, he fuppofes, from the effec/t pro- 

 duced by a wheel going over a ftone, or any hard iubftance 

 lying in one of the tracks or ruts, in which cafe there will 

 foon be a deep hole formed by the wheel in the other track, 

 directly oppoiite to that ftone or fubftance which raifed the 

 other wheel. Every precaution ought, therefore, to be ufed 

 to prevent carriages heeling to one fide on any part of a road. 

 And he fuggefts, that the inconvenience, and in many cafes 

 the danger, of going on either fide of a convex road, makes 

 all waggoners, carters, coachmen, &c. keep always on the 

 middle, by which, on fuch roads, there is feldom any other 

 part ufed by wheel carriages, however wide the road may 

 be ; confequently, by the carriages being always confined 

 to the fame track, that part of the road foon gets out of 

 repair, and requires a conftant outlay of money to keep it in 

 proper order or condition for being travelled upon. It is 

 alfo added, that the method of forming and making the 

 convex roads, in the fir It inftance, appears to him very 

 abfurd. He fuppofes, that before any hard materials are 

 kid on, the road is generally formed in fomewhat a hollow 

 manner, rounded below, in which there are drains, or ditches, 

 on each fide : alfo the footways orhorfe roads when made high 

 enough. Thefe are alfo fometimes called the fummer roads, 

 on account, he fuppofes, of that being the only feafon they can 

 in general be travelled upon. The road forms a convex line, 

 about ten or twelve inches lower at the fides of it than the 

 footway and fummer road. After being thus formed and pre- 

 pared, the hai d materials, moftly confiding of broken itones, 

 are laid on, which, it is fuppofed, will fill up that fpace which 

 is the hollow m a convex line, and when finifhed, the whole 

 furface, from one fide to the other, forms one convexity ; 

 the footways or horfc roads being made a continuation of 

 the fame curve. And this is Hill with the idea, that all 

 the water that falls on the road will run into the drains on 

 each fide. But let any perfon, in wet weather, take a view 

 of a road thus formed, and he will find, that, in general, 

 however great the convexity may be, the water will ft and in 

 every rut and every imprefiion made upon it, efpecially if 

 the road has been long travelled upon ; that the Hones on the 

 furface are pulverized by heavy wheel carriages, and the wet 

 earth from below worked up among them. Alfo where the 

 road is but newly made or repaired, and the materials are 

 futficicntly porous to let through the water, it will then 

 lodge on the convex furface, in every imprefiion of a itone 

 or ether uneven part, particularly at the fides, where it is 

 dammed again by the footways, and thus the bed or found* 

 ation of the road is Itept conftantly moift, and ot courfe it 

 will very foon go out ot repair. By thi6 centinualmoillure 

 the (tones fink down into the foft earth] of which the bed of 

 the road is compofed, and this earth works up through the 

 harder material':, and occaGonsail that dirtinels generally on 

 the furface of roads in wet weather, although, perhaps, ten 

 or twelve inches in thicknefs of thofe hard materials had 



been at firft laid over it. Sometimes, indeed, there are 

 under-drains made through the footway, from the fide 

 parts, at every ten or fifteen yards diftai ce, to convey the 

 water into the ditches ; but even this is not found to aiifwer 

 the purpofe intended, for the intermediate (pact a loon 

 become fo impervious, that the water does not pats through 

 them to enter thefe drains, the wet earth being converted 

 into a fort of puddle, refembling what is ufed, in aquatic 

 works, tor the purpofe of preventing the moifture from 

 penetrating through, and confequently it lodges in all the 

 ruts and hollows on the furface, without pafiing off fo 

 quickly as fhould always be the cafe in fuch inftances. 



Befides this there is another manner of forming thefe 

 convex roads advifed in the Bedfordfhire Agricultural 

 Report, in which it is propofed to leave a hollow or vacuum, 

 as it is called, in the middle, to depofit the hard materials in. 

 The only difference that appears to be between this and the 

 method defcribed above, is, that inftead of the bottom of this 

 hollow being made convex, it is made flat, and alio deeper. 

 It is thought that this method is liable to the fame obje&ion 

 as the former, perhaps even in a ftronger degree ; befides, it 

 would require a much greater thicknefs of hard materials, 

 which are very expenfive, and thofe materials would be deeped 

 or thickeft in the middle of the road, where the wheuls of 

 carriages hardly ever go, confequently that part is not fo 

 liable to be cut up as the tracks in which wheels molt gene- 

 rally run, and produce their greateft effects. Mr. Marihall 

 feems, however, to think more favourably of this form of 

 road, efpecially for wet weather, affuming it as a found 

 pofition, that roads, in general, which are intended to lie tra- 

 velled in wet feafons, fhould be convex or Jhelving, not flat or 

 concave. It remains to determine the proper degree of con- 

 vexity of the hard line of road ; from the margin of which 

 the dry-weather line ought to (helve gently to the foot of 

 the hedge-bank ; fo that carriages may pafs freely, and 

 fafely, from one line to the other ; and in order that the ram- 

 water which falls on that fide of the lane may find its way, 

 eafily, into the channel prepared for it, which is, he con- 

 ceives, for a wet-weather road, to be regulated by a variety 

 of circumltances : as, firft, by the materials of which it is 

 to be formed : foft materials are molt liable to be worn into 

 ruts and hollows, and require to be laid up with a quicker 

 defcent for rain water, than hard materials, which require 

 lefs elevation or rotundity of furface ; and leaft of all a firm 

 even pavement. Secondly, that a convex road in the face of 

 a Iteep is to be laid up higher, with a given material, than 

 one on more level ground, on which rain-water has no other 

 tendency than to the fides ; whereas in the face of a deep, it 

 it may have an equal or greater tendency along the line of 

 road ; and is liable to be caught by the flighted imprcflions of 

 wheels ; and thus to wear channels, as may too often be I 

 from the top to the bottom of the hill. Even where the 

 furface of the road is perfectly fmooth, it may have twice 

 thediftance to run, before it reach the outer margin, that it 

 has on a level. And thirdly, that the degree ot convexity 

 is to be determined, in part, by the width of the road ; the 

 materials and defcent being equal. A wide road requires 

 to be formed witli gn ater fidewa) defcent thrin a narrower 

 one; which more readily fre i itfell from i lin-water, inaf- 

 much as the diftance is fhorter from the crown to the outfkirts 



ot the road in fuch i i! 



But thai the fri eing of a road fro ater is not the 



only object to bi kepi n vn v, nth > its convexity : 



the tale ., ,1 I larticularly thofe of 



burden, wl d up 



high, require to d. A carriage moves molt 



freely, and with the !• . rtion of draft, when the load 



Uea 



