Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/606

582 ROACH (Leuciscus rutilus), a of the of s (Cyprinidæ) and of the  Leuciscus, which comprises also the,, and. It is one of the most common es of  north of the, and extends northwards as far as. Its  are in a single series, five or six on each side. The body is generally rather deep, its greatest depth being about one-third of the total length, the not included. The are large, from forty-two to forty-four along the lateral line, seven or eight series being above it, and three between the lateral line and. The first dorsal rays are inserted vertically above, but not in advance of the root of the. The is supported by from twelve to fourteen rays. The general colour is y, in adult es with a red tinge about the lower. Roach spawn from to, and frequently produce hybrids with other allied es, such as the  and the. They never attain to a large size, a roach of 1 ℔ being considered an unusually large fish. As a - this is not held in esteem; but by the pleasure it affords to a large class of humble  it rivals any of the  es which give more pretentious, and has properly been made the subject of a special work, The Book of the Roach, by Greville Fennell.  

ROADS STREETS. The earliest roads about which anything definite is known are those of, one of the oldest of which and the most celebrated for the grandeur of its works—the —was commenced in roads are remarkable for preserving a straight course from point to point regardless of obstacles which might have been easily avoided. They appear to have been often laid out in a line with some prominent landmark, and their general straightness is perhaps due to convenience in setting them out. In solidity of construction they have never been excelled, and many of them still remain, often forming the foundation of a more modern road, and in some instances constituting the road surface now used. It is consequently possible, with the help of allusions of, to follow the mode of construction. Two parallel trenches were first cut to mark the breadth of the road; loose was removed until a solid foundation was reached; and it was replaced by proper material consolidated by ramming, or other means were taken to form a solid foundation for the body of the road. This appears as a rule to have been composed of four layers, generally of local materials, though sometimes they were brought from considerable distances. The lowest layer consisted of two or three courses of flat s, or, when these were not obtainable, of other s, generally laid in ; the second layer was composed of rubble of smaller s, or a coarse ; the third of a finer, on which was laid a  of polygonal blocks of hard  jointed with the greatest nicety. The four layers are found to be often 3 or more in thickness, but the two lowest were dispensed with on. The paved part of a great road appears to have been about 16 wide, and on either side, and separated from it by raised  causeways, were unpaved side-ways, each of half the width of the paved road. Where, as on many roads, the surface was not paved, it was made of hard, or s or s set in. Sometimes and  were used instead of, and it would seem that where inferior materials were used the road was made higher above the ground and rounder in cross section. Streets were paved with large polygonal blocks laid as above described and footways with rectangular slabs. Specimens are still to be seen in and. There are no traces of influence in the later roads in, but in  the  method appears to have been followed to some extent when new roads were constructed about the. A foundation of stones on the flat was laid, and over that two layers of considerable thickness, of larger and smaller stones, bordered by large stones on edge, which appeared on the surface of the road. In  set the foundation-stones on edge and reduced the thickness of the upper layers, and his method was generally followed until the influence of  began to be felt. A French chaussée with accotements still retains some resemblance to the old roads.

The almost incredibly bad state of the roads in towards the appears from the accounts cited by Macaulay (Hist., c. iii.). It was due chiefly to the state of the, which compelled each to maintain its own roads by statute labour, but the establishment of  s and the maintenance of roads by  do not appear to have effected any great improvement. At the time of Arthur Young’s six s’ tour in the roads would seem to have been almost as bad as ever, and it is doubtful if there was much improvement up to the. The roads were generally managed by ignorant and incompetent men until  and  brought  principles and regular system to their construction and repair. The name of is associated with a pitched foundation, which he did not always use, but which closely resembled that which had been long in use in, and the name of  often characterizes roads on which all his precepts are disregarded. Both insisted on thorough and on the use of carefully prepared materials, and adopted a uniform cross section of moderate curvature instead of the exaggerated roundness given before; but, while  paid particular attention to a foundation for the broken,  disregarded it, contending that the , however bad, would carry any weight if made dry by  and kept dry by an impervious covering. was engaged more with the repair of old roads than with the construction of new ones, and, though it is not possible to agree with all his doctrines, the improvement which he effected in road management and maintenance was great and lasting.

of Roads.—A road should be as short as possible between two points to be connected, but straightness must often be sacrificed to avoid difficulties and expense and to secure good gradients. The latter should be as easy as practicable, having regard to the to be traversed, and it is desirable that there should be a ruling gradient than which none should be steeper. On a level macadamized road in ordinary repair the which the has to put forth to draw a load may be taken as one-thirtieth of the load. But in going the horse has also to lift the load, and the additional  to be put forth on this account is very nearly equal to the load drawn divided by the rate of gradient. Thus on a gradient of 1 in 30 the spent in lifting is one-thirtieth of the load, and in ascending a horse has to exert twice the force required to draw the load on a level. In descending, on the other hand, on such a gradient, the vehicle, when once started, would just move of itself without pressing on the horse. A can without difficulty exert twice his usual  for a time, and can therefore ascend gradients of 1 in 30 on a macadamized surface without sensible diminution of, and can  freely down them. These considerations have led to 1 in 30 being generally considered as the ruling gradient to be aimed at on first-class roads, though 1 in 40 has been advocated. adopted 1 in 30 as the ruling gradient on the road through, and there are only two gradients steeper, in places where they were unavoidable. All unnecessary rises and falls should be avoided, but a dead level is unfavourable for, and on this account 1 in 100 to 1 in 150 is the flattest gradient that is desirable. Such slight rises and falls are probably rather favourable than otherwise to ease of draught by s. In transverse section, roads in the generally comprise the -way, a space on each side, on one or both of which there may be a footpath, then the s, and outside all the es. The width of the -way may be from 15, which allows of the easy passage of two, to 30 or 50