A Treatise On The Principles And Practice Of Harbour Engineering

74 HARBOUR ENGINEERING. phragms at. intervals strengthen the conerete work. The Mouchel pile is light and easy to handle. The reduction in strength is such as to be practically inappreciable, and does not affect the utility of the pile. Ficis. 67.—Mouchel Hollow Pile. Figs. 68. —Johnston Pile. The Johnston pile (fig. 68) differs from the preceding in that the longi- tudinal rods are replaced by angle bars at the corners of the pile. These are bound together by flat bands and coiled steel wire. The Chenoweth pile (fig. 69) is constructed on totally different lines. A sheet of iron mesh is bent round a longitudinal axis in the form of a continuons spiral, forming a cylinder which is surrounded and filled with concrète. The Williams pile (fig. 70) consists of a central rolled steel joist sur- rounded at intervals by steel wire hoops and having cambered longitudinal stiffeners. Moulding’. — Reinforced conerete piles may be moulded either vertically or horizontally. For the former method, it is claimed that it results in greater uniformity in density throughout any horizontal layer, while the latter method is characterised by greater convenience. The advantage gained by vertical moulding is of questionable validity—there is no reason why horizontally moulded piles sbould not be absolutely homogeneous—and, in any case, it cannot be said to compensate for the greater trouble of moulding in that way and the higher cost involved. In horizontal moulding a box is formed of the dimensions of the pile, but