Vide Tables of Ricochet practice, [pages 73], [79], [80].
FASCINES.
Fascines are bundles of wood of various lengths, according to the purposes to which they are to be applied.
Fascines for a revetment should be strong, and well bound. When small brushwood is used, they are made 6 feet long, and 7 inches in diameter, and are firmly bound with four or five withes, or gads.
The gads are made of tough twigs, first twisted until the fibres separate, the smaller end is then turned round, so as to form a loop, or noose. To make a fascine 6 feet long, the workmen set up three fascine horses on the same level, and in a right line.
(A fascine horse is formed with two pickets, each 5 feet long, driven about 1 foot obliquely into the ground, so as to cross each other at right angles 2 feet above the surface of the earth; and they are fastened together at their point of meeting, with cord, three or four-thread spun yarn, or gads.) The brushwood, stripped of all its leaves and smaller branches, and which should be from half to one inch in diameter, and 5 or 6 feet long, is then laid on the fascine horses, the thick ends being placed alternately at each end. The large stuff must be used to form the exterior, and the smaller twigs the interior of the fascine. Before binding the fascine, it must be compressed with a fascine choaker, which consists of a cord, or chain, equal in length to one and a half times the circumference of the fascine, fastened at one end to a lever 5 feet long and 2½ inches in diameter, with a loop at the other end, into which, after passing the chain round the fascine near the part to be bound, a lever, similar to the one already described, is inserted, and the brushwood is squeezed tightly together until the gad is tied. The fascine must be compressed in a similar manner before each gad is fastened. The weight of the fascine is about 33 lb. Three men can make a 6 feet fascine in twenty minutes. Two of the workmen place the brushwood, while the third prepares the gads. If large brushwood can be procured, the fascines should be 18 feet long, the strength of the revetment being materially increased by diminishing the number of joints. When the fascines are 18 feet long, they are made nine inches in diameter, and the gads are placed 18 inches apart, the fascine horses being one yard apart. This fascine weighs about 2 cwt. Four men can make an 18 feet fascine in two hours, or, if the wood be cut and brought to them, they can make four fascines in that time. They require 3 bill-hooks, 1 saw, 1 fascine choaker (each lever about 6 feet long), and 6 fascine horses. Three men prepare the brushwood, and lay it on the horses, while the fourth makes the gads.
The revetment is formed in proportion as the parapet is raised, the first fascine being half buried in the banquette, with three pickets driven vertically through it, each picket being from 3 to 4 feet long, and from 1¼ to 1½ inches in diameter at the thickest end. The second row of fascines is then laid a little in front of the first, so as to form the required slope, and three pickets are driven through each fascine; the extreme pickets through the fascine previously laid in the direction of the slope, the other perpendicular to the slope.
The joints of the different rows of fascines should be so broken, that no two adjoining joints may be in the same line, and the ends of the fascines at the angles should alternately be flush with, and be inserted in the parapet; care being taken to lay the fascines so that the ties of the gads may be concealed in the parapets. Six rows of large fascines are sufficient to form the revetment of a parapet, the upper row being covered with a layer of sods, the grass upwards. When fascines of seven inches in diameter are used, eight rows are required.
GABIONS.
Gabions are cylindrical baskets open at both ends, and are very commonly used to revet parapets. For the interior of parapets they should be 3 feet in height, and diameter. The common gabions are 2 feet in diameter, and 2 feet 9 inches high.