A Treatise On The Principles And Practice Of Harbour Engineering

BREAKWATER CONSTRUCTION. 175 tide ns long as possible ont of the water, and to get a course closed up in one operation. When the masoury had been brought up three courses, the tide was considered to be mastered. The helmet divers had two gantries ap- propriated to their work, and the masons had four. The masons came out at noon and at midnight, and it was always low water at that time; therefore nearly half of the wall above low water was built in the night. The average day’s work for each mason was 6| cubic yards, and no piecework was permitted.” The diving work was always ended in August, and the building up to the quay level in September, while the promenade was generally finished before Christmas. The rate of progress gradually increased from 300 linear feet to 600 linear feet of wall per annum. Mole or Jetty at Zeebrugge.1—The outer portion of the jetty at Zeebrugge is constructed in solid concrete, and it has a foundation composed LONGITUDINAL SECTION Mm CROSS SECTION Fias. 146-149. METAL FRAMEWORK of monoliths, or blocks, 82 feet long by 24J feet wide in the portion flanking the quay, and by 29t feet in the portion beyond, the heights ranging from 23 feet to 30 feet according to the level of the foundation bed. These concrete blocks are inclosed in an iron framework caisson, which served as an outer shell. The plating in sides and floor is j inch thick. Lattice beams 3| feet high stillen the bottom ; eighteen frames strengthen the sides; and on the underside is a rim or edge 18 inches deep. The caissons were manufactured in the workshop adjoining the site, the various parts being conveyed to the block-yard at the inner harbour by means of railway trucks, from which they were unloaded by an overhead land traveller or gantry. 1 Vide “ Les Ports et le canal maritime de Bruges,” par M. L. Coiseau. Mémoires de la Société des Ingénieurs civils de France. Bulletin de décembre, 1904.