Engineering Wonders of the World
Volume I

398 ENGINEERING WONDERS OF THE WORLD. Fig. 16.—CAST-IRON LINING FOR SLUICES. Stoney principle. The other 50, acting on the sliding surface principle, are used only under a small head of water. As to dimensions, 140 sluices are 23 feet high by 6 feet 6 inches wide, -and the remainder half that height by the same width. The levels of the sluice sills vary to suit the varying level of the river bed. The aggregate width of the openings, 427 yards, is about equal to the width of the Thames at Westminster Bridge, and the maxi- mum flood discharge through these sluices is twice the flow over Niagara Falls. To meet the needs of river traffic, a series of four locks, each 260 feet by 32 feet, has been provided on the left bank of the river. These ck can be used throughout the year. The passages to the locks, and the locks themselves, were exca- vated for the most part out of the solid granite of the west abutment of the dam. There is a drop of about 20 feet between locks. The gates, worked by hydraulic power, range in height from 26 feet 3 inches to the abnormal height of 59 feet. The two largest weigh 105 tons each. They are suspended from above, and moved out from their recesses and across the passage in much the same way as a slid- ing coach-house door is moved. The carriage from which a gate depends runs on friction rollers over ways carried across the lock on a bascule bridge. The total length of this navi- gation channel is miles. Owing to exceptionally low Niles and poor floods (both favourable to foundation building), and to the effective use made of these condi- tions, the contractors for the Assouan Reser- voir and Assiout Barrage were able to com- plete their work one year within contract time. Despite the fact that the rocks in the cata- ract at Assouan had withstood the scouring action of the flood for ages, it was found, after the reservoir had been in use c £ XT x xi • Aprons, tor a tew seasons, that the ir- regular bed of the river, just below the dam, on which the water issuing from the great sluices poured, could not withstand the con- tinued shock indefinitely. To meet the un- usual circumstances of the case, and to render the part affected capable of withstanding per- manently the action of the water at the out- flow, protecting aprons were constructed in the following manner :—All loose and defec- tive rock was removed, and the hollows so formed filled in with masonry, which was then built up to the level of the sluice outlets. In places these aprons attained a maximum thick- ness of 37 feet, and were extended down- stream for a distance of 200 feet. Altogether, 350,000 tons of masonry were used in their F’g. 17.—HORIZONTAL SECTION OF A STONEY SLUICE, SHOWING ROLLER BEARINGS* AND STAUNCHING ANGLES.