Continuous Hurdle.—If conditions permit the revetment to be built in place, the hurdle is made continuous for considerable lengths. The pickets may be larger; they are driven further apart, 12 or 18 inches, and the brush may be heavier. The construction is more rapid. The pickets are driven with a little more slant than is intended and must be anchored to the parapet. A line of poles, with wire attached at intervals of two or three pickets, will answer. The wires should be made fast to the pickets after the wattling is done. They will interfere with the weaving if fastened sooner. Two men should make 4 yards of continuous hurdling of ordinary height in one hour.
Brush Revetment.—Pickets may be set as above described and the brush laid inside them without weaving, being held in place by bringing the earth up with it. In this case the anchors must be fastened before the brush laying begins. The wires are not much in the way in this operation.
Plate 34.—Gabion.
Gabion Making.—A gabion is a cylindrical basket with open ends, made of brush woven on pickets or stakes as described for hurdles. The usual size is 2 feet outside diameter and 2 feet 9 inches height of wattling. On account of the sharp curvature somewhat better brush is required for gabions than will do for hurdles. The gabion form is made of wood, 21 inches diameter, with equidistant notches around the circumference, equal in number to the number of pickets to be used, usually eight to fourteen; less if the brush is large and stiff, more if small and pliable. The notches should be of such depth that the pickets will project to 1 inch outside the circle. The pickets should be 1-1/2 to 2 inches in diameter, 3 feet 6 inches long, sharpened, half at the small and half at the large end.
Plate 35.