570 PRACTICE OF AGRICULTURE. Part 111. 



our principal roads, at least upon all their acclivities which exceed a greater rise than at 

 the rate of 1 perpendicular to 26 horizontal feet ; an undulating line of road which 

 obliges the carrier, in most instances, to modify his load to one half of what his horse 

 can take along the more level parts. It is likewise proposed, that the leading streets of 

 all towns and villages situate upon the principal highways should be laid with these 

 stone tracks. The traveller would then glide smoothly along, instead of being accom- 

 panied with a thundering noise and jolting motion most unpleasant to himself and the 

 inhabitants of the respective places through which he passes. 



3540. The advantages of stone tracks in roads " cannot be better exemplified than by noticing an experi- 

 ment made in presence of some of the Directors of the Forth and Clyde Canal Company, upon a set of 

 cast-iron tracks, laid upon an acclivity rising at the rate of about 1 in 15 to Port Dundas, near Glasgow. 

 Here one horse actually drew up a load of three tons on a cart weighing nine cwt. In this case, the horse 

 proceeded up hill without much apparent difficulty till he reached the top, and was about to enter on the 

 common causeway, when he could proceed no further, although the road had now become level. The 

 carters frequenting this road agree that their horses had formerly greater difficulty in taking up twenty- 

 four cwt. on the causeway, than was now experienced with three tons. How great, therefore, must be the 

 beneficial effects of such an immense acquisition of power, as even the partial introduction of wheel- tracks 

 is calculated to aflTord to the traffic of the country !" 



3541. Mr. Stuart Menteath of Ctosehurn " has had single-horse waggons with four wheels applied to the 

 ordinary purposes of his estate. These waggons are constructed upon the principle of those of Switzerland ; 

 they are ten cwt. on which a horse, weighing about eleven cwt., takes a load of thirty cwt. between Edin- 

 burgh and Closeburn, a distance of sixty-six n.iles. This gentleman, whose knowledge in such matters is 

 extensive, estimates, that if wheel-tracks were laid upon the principal acclivities of the road, as above 

 recommended, his horses could work with a load of about two tons." {Stevenson's Plan for Track Roads. 

 Edin. 4to. 1826, p. 4.) 



3542. Planked roads are formed over morasses ; or in particular cases by laying down 

 a flooring of flanks, on which carriages pass for temporary purposes. A permanent kind 

 of road of this description has been made by weaving (or wattling) an endless hurdle of 

 the breadth of the road, and covering it with a coating of gravel or broken stones. The 

 advantage of this mode is, that the road may be made on a bog before the substratum 

 dries, and even if it is so soft as not to bear a man. By the time the hurdle rots, the 

 base will be consolidated and fit to bear any thing. 



3543. Rail roads are roads exclusively for the use of carriages, and are characterised by 

 a rail, commonly of iron, but sometimes of wood or stone, laid along the track of each 

 wheel, in order to produce the effect of a perfectly even surface. There is also a recent 

 invention of this kind, named a suspension railway, which, under particular circumstances, 

 promises very considerable advantages. In general the carriages for such roads have 

 their wheels low, and of a particular construction to fit the rails ; but in some cases the 

 rails have grooves for the use of common narrow wheels. Such roads are almost ex- 

 clusively in use at coal and other great mineral works ; but it has lately been proposed 

 to introduce them as side roads to the more public highways, for the purpose of loco- 

 motive steam-engines, and it seems highly probable that this may be done before long on 

 several of our main roads. (See Sect. V.) 



Sect. II. Line of Direction, or laying out of Roads. 



3544. Before carriages of burthen were in use, little more was required than a path upon 

 hard ground, that would bear horses. All marshy grounds were therefore shunned ; the 

 fords of rivers were resorted to, and the inequality or circuit of the road was of much less 

 consequence, that when carriages, instead of pack-horses, began to be employed. When 

 carriages were first employed, they probably were light and narrow, and did not require to 

 have roads of any considerable breadth or firmness ; and when roads had once been thus 

 traced, indolence and habit prevented any great exertions to lay them out in better lines, 

 or to repair them in any manner beyond what present convenience absolutely required. 

 When heavier carriages and greater traffic made wider and stronger roads necessary, the 

 ancient track was pursued : ignorance and want of concert in the proprietors of the 

 ground, and, above all, the want of some general effective superintending power, conti- 

 nued this wretched practice. {Edgeworth on Roads, p. 3.) At length turnpikes were es- 

 tablished, and laws passed investing magistrates with authority to alter established lines, so 

 that now the chief obstacle to the improvement of the lines of public roads is the expense. 



3545. In laying out roads, a variety of circumstances require to be taken into consi- 

 deration ; but the principal are evidently their line or direction, and its inclination to the 

 horizon. 



3546. The most perfect line, according to Marshal, is that which is straight and level. 

 But this is to be drawn in a country only which is perfectly flat, and where no obstruc- 

 tions lie in the way ; joint circumstances that rarely happen. Where the face of the 

 country, between two points or places to be connected by a road, is nearly but not quite 

 level, by reason of gentle swells which rise between them, a straight line may be perfect, 

 may be the most eligible under these circumstances : but where the intervening 

 country is broken into hill and dale, or if one ridge of hill only intervenes, a straight 

 line of carriage road is seldom compatible with perfection. In this case, which is 

 nearly general, the best skill of the surveyor lies in tracing the midway between the 



