Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/875

Rh CANAL 791 Having analysed each of these objections, and fully weighed the Arguments on which they were based, he came to the following con clusions as to the practicability of construction and maintenance: &quot; 1st, As regards the engineering construction, there are no works on the canal presenting on their face any unusual difficulty of exe cution, and there are no contingencies that I can conceive likely to arise that would introduce difficulties Insurmountable by engineer ing skill. &quot; Idly, As regards the maintenance of the canal, I am of opinion that no obstacles would be met with that would prevent the work, when completed, being maintained with ease and efficiency, and without the necessity of incurring any extraordinary or unusual yearly expenditure.&quot; &quot; Sai d Pasha died between the period of Sir John Hawkshaw s examination of the country and the date of his report. He was succeeded by his brother, Ismail, the present Viceroy or Khedive, who, alarmed at the largeness and uncertainty of the grants to the Canal Company, of the proprietorship of land which could be irrigated by the sweet water canal, and anxious to retire from the obligation of finding forced labour for the construction of the works, refused to ratify or agree to the concessions granted by his brother. The whole question was then referred to the arbitration of the late Emperor of the French, who kindly undertook the task, and awarded the sum of 3,800,000 to be paid by the Viceroy to the Canal Company as indemnifica tion for the loss they would sustain by the withdrawal of forced or native labour, for the retrocession of large grants of land, and for the abandonment of other privileges attached to the original act of concession. This money was applied to the prosecution of the works. &quot;The withdrawal of native labour involved very important changes in the mode of conducting the works, and occasioned at the time considerable delay. Mechanical appliances for the removal of the material, and European skilled labour, had to be substituted ; these had to be recruited from different parts of Europe, and great difficulty was experienced in procuring them. The accessory canals had to be widened for the conveyance of larger dredging- machines, and additional dwellings had to be provided for the accommodation of European labourers. Ultimately all difficulties were overcome, and the work proceeded.&quot; After the works had been nearly completed, the Lords of the Admiralty instructed Admiral Richards, the hydro- grapher, and Lieutenant-Colonel Clarke, R.E., to visit Egypt, and report as to the condition of the canal. These officers accordingly made a most minute survey of the canal and its terminal harbours, and issued a most interesting. report, 1 from the information contained in which the plan of the canal, Plate XXXVI., has been mainly constructed. From this plan it will be seen that the canal extends from Port Said on the Mediterranean to Suez on the Red Sea, and that, as shown by the section, it traverses a compara tively flat country. This route has been selected so as to take advantage of certain valleys or depressions which are called lakes, but were in fact, previous to the construction of the canal, low-lying tracts of country, at some places below the level of the Mediterranean and Red Seas. These valleys were found to be coated with a deep deposit of salt, and are described as having had all the appearance of being covered with snow, bearing evidence of their having been at one period overflowed by the sea. As will be seen from the plan, Lake Menzaleh is next to the Mediterranean, Lake Timsah about half-way across the isthmus, and the Bitter Lakes next to the Red Sea. Lake Timsah, which is about 5 miles long, and the Bitter Lakes, about 23, were quite dry before the cutting of the canal, and the water which has converted them into large inland lakes was supplied from the Red Sea and Mediterranean. The water 1 Report on the Maritime Caned connecting the Mediterranean at Port Said with the Red Sea at Suez, February 1870. began to flow from the Mediterranean in February 1869, and from the Red Sea in July, and by the beginning of October of the same year these vast tracts of country, which had formerly been parched and arid valleys, were converted into great lakes navigated by vessels of the largest class. It will be seen from the section that the surface of the ground is generally very low, the chief cuttings being at Serapeum and El Guisr, where the sandy dunes attain an elevation of about 50 to 60 feet. The channel through the lakes was excavated partly by hand labour and partly by dredging, and for a considerable portion the level of the valleys was so low as to afford sufficient depth without excavation. The material excavated appears to have been almost entirely alluvial, and easily removed ; the only rock was met with at El Guisr, where soft gypsum occurred, removable to a considerable extent by dredging, so that the canal works presented no physical difficulty. The whole length of the navigation is 88 geographical miles. Of this distance 66 miles are actual canal, formed by cuttings, 14 miles are made by dredging through the lakes, and 8 miles required no works, the natural depth being equal to that of the canal. Throughout its whole length the canal was intended to have a navigable depth of 26 feet for a width of 72 feet at the bottom, and to have a width at the top varying according to the character of the cuttings. At those places where the cuttings are deep, the slopes were designed to be 2 to 1, with a surface width at the water-line of about 197 feet, as shown in fig. 9, which Fio. 9. . --- 72 I l &amp;gt;, Cross-section of Suez Canal at El Guisr. is a cross-section at El Guisr; in the less elevated por tions of the land, where the stuff is softer, the slopes arc increased, giving a surface width of 325 feet. It will be understood that in the lakes the canal consists of a navigable channel of sufficient depth and breadth to admit the traffic, the surface of the water extending on either side to the edge of the lake. Fig;. 10 shows a cross -section at Lake &amp;lt;. 72 F* Fid. 10. Cross-section at Menzaleh. Mcnzaleh. The deep channel through the lakes is marked by iron beacons on either side, 250 feet apart, and the Admiralty reporters state that &quot; in practice it is found more difficult to keep in the centre while passing through these beacons, than it is when between the embankments.&quot; At every 5 or 6 miles there is a passing-place, to enable large vessels to moor for the night, or to bring-up in order to allow others to pass, all these movements being regulated by telegraph from Port Said, Ismailia, or Suez. Perhaps the most interesting question to the engineer is the action of the tide in the narrow channel between the two seas, and the observations made on this subject are given in the following quotation from the Admiralty report : &quot; The tidal observations which we were able to make were neces sarily somewhat imperfect from want of time, but they were mado at that period of the moon s age when their effect would be greatest ; the results show that in the southern portion of the canal, between Suez and Great Bitter Lake, the tidal influence from the Red Sea i.s felt, there being a regular flow and ebb, the flood running in for about seven hours, and the ebb running out for five hours ; at the Suez entrance, the rise at springs, unless effected by strong winds, is between 5 and 6 feet ; about half way from Suez to the Small Bitter Lake, a distance of 6 miles, it is under 2 feet; at the south end of the Small Bitter Lake, a few inches only; while at the south end of the Great Lake there is scarcely any perceptible tidal influence. We were informed by the authorities at Ismailia, that since the Great Lake has been filled, the level of Lake Timsah, which was