GAKDEN WALKS AND EOADS. 



77 



ever, may be more properly discussed under the 

 heads of Eoad-making- and Maintenance. 



But the interception and removal of all earth 

 springs, and thus laying and keeping the foundation 

 of the road or walk dry, should precede any attempt 

 at making- either. Hence the thorough drainage 

 of the roadway is the first vital step in road-making ; 

 so important is this, that if not taken the others 

 should not be attempted. 



The deeper almost, in reason, the drainage can be 

 carried the better, as the thicker the strata of dry 

 soil beneath the roadway the better it will be, the 

 longer it will last, and the less road material need 

 be used to make and keep it good. The latter is a 

 point of the utmost moment, as dry earth on the spot 

 costs \drtually nothing, while stone or gravel may 

 range in price from three to ten shillings per square 

 yard ; and yet, bulk for bulk, dry earth forms as 

 strong a foundation as either. 



In practice, it is found that a layer of dry earth 

 under a road, from two to 

 four feet deep, generally 

 suffices for a solid founda- 

 tion for the road material. 

 Hence, a drain four feet 

 deep will generally be 

 found sufficient. This may 

 be formed either of tiles or 

 stones, and should be made 

 with more than ordinary 

 care, alike in regard to 

 material and fall, as it is 



obvious that it cannot be got at afterwards without 

 destropng the road or walk. (See chapter on 

 Draining.) 



The best place for the drain is the centre of the 

 road, and, unless in the case of very wide carriage- 

 roads, terraces, or walks, one drain will prove suffi- 

 cient ; where these, however, exceed twelve feet in 

 width, and the soil is very wet or adhesive, one drain 

 on each side may be necessary. 



The form of the earthy base of the road is the 

 next point claiming notice. As a general rule, there 

 is no sounder one in theory, nor safer one in practice, 

 than that it should be an exact counterpart of the form 

 of the surface, that is, slightly convex in the middle, 

 the degree of convexity being determined by the 

 width, a ratio of an inch to six feet being a good 

 proportion. The earth should then be made as 

 hard and smooth as possible, ramming in the soil 

 over the drain with the utmost care, so that its 

 subsidence should not destroy the form of the road 

 afterwards ; and so likely is this to happen, con- 

 solidate as we may by artificial means, that, where 

 practicable, it is safe practice to excavate and drain 

 the roadway on walks some time before they are 



Fig. 1.— Section of 



Convex Surface 



made. jSTeither must it be supposed that all roads 

 and walks need deep drainage. On light, sandy 

 soils, chalky gravel lands, the soil and subsoils 

 are mostly sufficiently dry to carry roadways or 

 walks, without this extra trouble and expense. But 

 in nearly all heavy loams and clays, the first cost of 

 thorough drainage will be found by far the least in 

 the end. 



The Surface. — As to the depth of road material 

 necessary, that varies somewhat according to its 

 quality and the nature of the base on which it rests ; 

 as already remarked, the drier the latter the less road 

 material will be needed. Its function is simple, not 

 compoimd. It neither carries nor is the road ; its chief 

 function, like that of iron rails on the line, is to reduce 

 friction to a minimum by its hardness, and prevent 

 the wear and tear of the foundation of the road. 

 Hence, the ratio of its thickness may be measiu'ed 

 by the degree of its impenetrability : the harder it 

 is the thinner it may be. 

 Thus, six inches of gTanite 

 on a dry base would form 

 a better road than sixteen 

 inches of mixed road mate- 

 rial of indifferent quality. 



Uniformity of hardness, 

 as well as of size and 

 thickness of road mate- 

 rial, are of the highest 

 importance to the stability 

 and uniform quality of 

 roads and walks. The importance of the first and 

 the last will be at once apparent to all. The impor- 

 tance of uniformity of size is but little understood 

 in theory, and still more rarely attended to m 

 practice. But a moment's consideration will show 

 that every time a carriage-wheel mounts on to the 

 summit of a stone larger than the average, it gains a 

 coign of vantage with which to come down with 

 such additional force as to scoop out a hole more or 

 less deep upon the general surface of the road. 

 Hence the tendency of all such roads is to become 

 worse and worse. The luts become deeper by every 

 undue momentum of the revohdng wheels, and the big 

 stones help to cut the smaller ones through, to the 

 utter destruction of the road. Uniformity of size in 

 the road material would remove the most potent and 

 ever-present destructive force from our roadways. 

 Uniformity of hardness is almost of equal moment. 

 Supposing granite here, and hard flints or brickbats 

 fm-ther on, the granite would become a powerful 

 means of smashing the latter into sheer uselessness, 

 all the sooner by the operation of the same causes 

 and laws as those already described. Similar evils, 

 though in lesser degree, would follow inequalities 



showing Level Ease, with 

 and Drain at Side. 



