ABSTRACT OF PROCEEDINGS — APPENDIX. XXXV11. 



cement mortar, and at present the work is satisfactory 

 and likely to remain so. The thickening and heightening 

 of the dam were begun after the talus or apron had been 

 completed. Sir Benjamin Baker came to the conclusion 

 that the ouly satisfactory method of building the thickening 

 in contiguity to the old dam, so as to form the whole into 

 as homogeneous a structure as rubble masonry built in such 

 a climate would permit, was to keep the old and the new 

 parts separate until such time should elapse as might 

 permit of the new work reaching the same temperature 

 stage as that of the old part, when the space between 

 could be filled with cement grout consisting of 1 of water 

 to 1/2 of Portland cement. 



The Grand Barrage, or Delta Barrage as it is more fre- 

 quently called, is situated at the head of the delta north 

 of Cairo. It was originally built by a French engineer, 

 M. Mogel, but it failed to hold up even a moderate head 

 of water. The failure was due to careless construction 

 rather than to the design. It consists of two separate 

 works across the heads of the two branches of the river — 

 the Damietta and the Rosetta. There are three main 

 canals which take off above the barrage, which with 

 numerous branches irrigate the delta. The restoration of 

 this great work was undertaken by Sir J. Fowler and Sir 

 B. Baker and consisted in lengthening the aprons of 

 masonry up and down stream, covering the old floor with 

 a layer of concrete 4 feet thick over which was laid a 

 pavement of ashlar masonry under the arches and over a 

 portion of the down-stream apron ; also a row of piles was 

 added to the up-stream apron. The foundations of the 

 barrage were further consolidated by means of cement 

 grout under pressure. By means of these additions the 

 barrage was able to hold up 4 metres, bit it was decided 

 to reduce this to 3 metres, and subsidiary weirs were con- 



