78 



CASSELL'S POPULAR GARDENING. 



of thickness : one part of the road would be ■worn 

 through before the others ; the drawing strain on 

 the horses increased, and unequally distributed; 

 and the amount of friction, that is, thS power of the 

 road to resist the passage of the load over it, greatly- 

 augmented. 



Smoothness and hardness of surface are the next 

 points of most moment. The more perfectly these 

 qualities are developed the mor^ nearly will the road 

 itself be rendered waterproof, and consequently the 

 greater its force of resistance, and the longer it will 

 resist the wear and tear of traffic. Fortified by rest- 

 ing on a solid dry base, and the materials of the 

 roads compacted into a solid mass of uniform quality, 

 they become well-nigh indestructible under ordinary 

 traffic, while the smoothness and hardness of surface 

 reduce the friction to a minimum. Such roads, with 

 biit slight repairs, last a lifetime ; whereas, those 

 indifferently made are ever on the anvil of constant 

 ' repair, and seldom or never in good condition. 



AU these general principles of construction apply 

 equally to much-frequented walks as to roads, and as 

 the former have often to bear pony and hand carriage 

 traffic for invalids and children, and in larger places 

 not seldom regular carriage traffic, it is equally im- 

 portant that they should be well made. Besides, the 

 qualities here indicated are almost as important for 

 pedestrian as for carriage traffic, and the strain of 

 crowds of people on the walks of public and private 

 gardens upon fSte and open-day occasions, now for- 

 , innately so common, is as great if not greater than 

 that arising from moderate carriage traffic. 



Construction. — The following practical instruc- 

 • tions regarding construction will be equally applicable 

 to first-class walks, and roads. The drainage and pre- 

 paration of the ground have already been described. . 

 Instead of foUowiug the line of surface, some, how- 

 ever, prefer to make the base or earth line level or 

 slightly concave instead of convex ia the centre 

 (a b. Fig. 1). This is supposed to insure more tho- 

 rough drainage, the water falling from each side of 

 the road into the middle and so into the drains. Per- 

 haps, indeed, this form is more generally adopted than 

 any other. In the illustration only one drain is shown, 

 and that at the side. But, where needful, another 

 could be carried along the other side. From the posi- 

 tion of the overflow drain under the grating, it will be 

 seen that this may be carried along under the centre of 

 the roadway, and thus help to drain the road, as well 

 as be placed in the best position for running drains 

 into it from either side, as may be needful. The 

 drains immediately under the gratings are carried 

 deeper than the overflow drains for the collection of 

 sediment, which can readily be removed, so as to 

 prevent the main drain from being silted up. The 



prompt removal of surface water by some such 

 means as this, is of immense importance in insm'ing 

 the stability and durability of roads. The convex 

 surface also enables rather more material to be used 

 on the crown of the road, where it is said there is 

 the most friction. This, however, is doubtful, and 

 runs contrary to one of the vital principles already 

 advanced — uniformity of thickness of road material 

 over the entire surface. 



Then as to the depth of materials. As wide a 

 range exists in practice as that included between 

 nine and eighteen inches — a foot on 'a solid dry soil 

 base is ample, nine inches being a good average. 

 As to materials, anything from small fagots to the 

 hardest granite, iron-slag, and the most binding con- 

 cretes and gravel, is used. 



In situations where fagot-wood is plentiful and 

 road material scarce and dear, a layer at least four 

 inches in thickness of fagots may be used' with 

 advantage. Covered over with road material, and 

 thus excluded from air and water to a great ex- 

 tent, it is astonishing how long the sprigs of trees 

 and shrubs will last under a roadway, and how 

 noiseless and elastio such roads continue for a period 

 of from twenty to thirty years. But the use of this 

 — relatively to good stone such perishable material 

 — is almost confined to carriage-drives and roads 

 through woods, &c. 



A more common base for roads is a layer of ballast 

 or burnt marl or clay. This is hard and porous almost 

 as brickbats, forming a capital secondary base on the 

 dry earth. Builders' refuse, the waste slag, clinkers, 

 &c., from iron furnaces and foundries, and stones of 

 all sorts, the harder the better, should follow. Roads 

 subjected to heavy traffic should have a surface 

 stratum of from four to six inches deep of pure 

 granite, or other hard stones, such as greenstone, 

 porphyry, basalt, &c. ; neither can these stones be 

 broken too small for the surface — from one and a half 

 to two inches in diameter, the pieces weighing from 

 four to six ounces, being the largest that should be 

 employed. Where a surfacing of gravel is used 

 over the granite, as is mostly tho case in carriage- 

 roads, the pieces may approach to double these 

 1 weights and sizes. But the smaller the stones oh the 

 surface, the sooner they will blend into an impervious 

 and impenetrable mass, and the longer the road will 

 last. A road nine inches or a, foot deep, with a' 

 layer of burnt earth and of hard stones of ^ unequal 

 size, the lower being the largest, and each laj'er as 

 nearly as may be of uniform-sized stones, either with 

 or without a surfacing of gravel, would be virtually 

 indestructible under ordinary traffic, and with the 

 slightest attention to repairs. 



As soon as finished, rake perfectly smooth ; water 

 heavily should the material and weather be dry, 



