basins, which rises 75 feet above canal water-level, it follows the tidal part of the Lower Eider. The canal passes mile to the south of the town of Rendsburg, and after touching the Lake of Flemhude, the water-level of which has been lowered 23 feet, follows the Upper Eider and reaches Kiel Bay at Holtenau, at the point where the old Eider Canal entered. Description of Baltic Canal.—The canal has a length of 613 miles, of which nearly two-thirds is straight. Since the average rise of the tide at the mouth of the Elbe is 8 feet 10 inches, and the water-level of the Baltic in Kiel Bay varies considerably with the wind, it was necessary to close the ends of the canal by locks, to avoid too rapid currents through it, Fig. 15, Plate 6. The waterlevel in the canal corresponds with the average level of the Baltic, which differs little from the ordinary half-tide water-level at the mouth of the Elbe. The Baltic locks generally stand open, and are only shut when the water-level rises or falls 13 feet from the mean. The Brunsbüttel locks are opened during each ebb, and allow the water in the canal, according to the tide, to fall down to 13 feet below ordinary low-water level; but when this level is reached, they are closed, so as to prevent too strong a current in the canal. The locks are closed during the flood-tide, to prevent the entrance of the Elbe water, which is heavily charged with mud. During each ordinary tide, from 3,924,000 cubic yards to 5,232,000 cubic yards of water flow from the canal into the Elbe, with a maximum velocity of 4.9 feet per second, and clear out the mud and other sediment deposited in the outer harbour by the flood-tide. The bottom of the canal has, therefore, been given a fall to the Elbe for 37 miles. The depth of the canal, at the lowest water-level, is 27 feet 10 inches; and the breadth at the bottom, on the straight portion, is 72 feet, Fig. 16, Plate 6. To a height of 10 feet above the bottom, the side slopes are 3 to 1; above this they are 2 to 1 up to 23 feet, at which level there is a horizontal berm, varying from 8 feet to 31 feet in width, according to the nature of the ground. The lower parts of the side slopes are made flatter than the upper, with a view to a possible deepening of the canal to 29 feet. The wetted cross-section of the canal is 454 square yards. The sharpest curve on the canal has a radius of about 50 chains; and the width R on all curves is increased according to the formula, b = 26 100' where b and R are expressed in metres. There are six passing places for large vessels, each 492 yards long and 65 yards wide. In constructing the canal, 105,950,000 cubic yards were exca vated; and at times 66 excavators and dredgers, 94 locomotives, 582,756 tip-wagons, and 270 tugs and other vessels were at work. The maximum number of men employed was 8,900, in June, 1892. Special difficulties were encountered in cutting the canal through the marshy lowlands, where it was necessary first to tip sandbanks into the marsh, and then excavate the canal through them. At each end, at Brunsbüttel and Holtenau, there are two locks side by side, having an extreme length of 712 feet, an available length between the gates of 490 feet, and width of 82 feet, Figs. 17 to 20, Plate 6; but, as the Elbe locks stand open for several hours each tide, and the Baltic locks nearly always, the length of the ships using the canal is not restricted to 490 feet. At Rendsburg, a lock, 223 feet long, 65 feet wide, and 18 feet deep, connects the cana) with the Lower Eider. At this point there are two railway swingbridges and a road swing-bridge; and two single-line railway swing-bridges cross the canal elsewhere. The swing-bridges have unequal arms, and leave a clear opening of 164 feet across the canal; and they, and also the gates, sluices, and capstans of the locks at Brunsbüttel and Holtenau, are worked by hydraulic power. The two high-level bridges at Grünenthal and Levensau have single spans of 513 feet and 536 feet respectively, and give a clear headway of 138 feet; and each carries two lines of railway and a roadway over the canal. The canal is lighted at night, for the passage of vessels, by electric glow lamps, arc lamps being considered too dazzling. Sixteen-candle power lamps are placed 13 feet above the waterlevel, 73 yards apart on the sharpest curves, up to 274 yards on the straight portions. The end locks and their approaches are specially well lighted by incandescent lamps of from 25- to 60-candle power, and shaded arc lamps on the water side. The works were commenced in 1888, and the canal opened in 1895. The cost of the works amounted to £7,800,000. SHIP-CANAL BETWEEN DORTMUND AND THE HARBOURS ON THE EMS.1 The canal from Dortmund to the Ems is part of the proposed waterway between the Rhine, Weser, and Elbe, and connects the coalfields and manufactories of Westphalia with the port of Emden, situated at the outlet of the River Ems into the North Sea. 1 Centralblatt der Bauverwaltung, 1893, p. 389; 1894, p. 507; 1895, pp. 230, 509, 522, and 533; and 1896, pp. 42, 278, 302, 308, 320, 332, 333, and 575. Route of the Canal.-The canal, which is to serve barges up to 600 tons carrying capacity, commences at the important manufacturing town Dortmund, where considerable dock works have been constructed, Fig. 21, Plate 6. At Henrichenburg, 9 miles from Dortmund, the level of the canal is raised 46 feet, which is surmounted by a canal-lift. From this point there is a branch to Herne, where there is an important mine. The canal continues for 42 miles at the higher level to Münster, cutting through the water-partings of the rivers Emscher, Lippe, and Stever. The Lippe and Stever are crossed by massive aqueducts, each having three equal spans of 69 feet and 41 feet respectively, approached by canal embankments, reaching a height of 49 feet. A short branch connects the docks at Münster with the canal. At 4 miles to the north of this town, the fall of the canal towards the river Ems commences. The middle reach, 21 miles long, is reached by two locks, and terminates near the village of Bevergern. It crosses the Ems by a lofty aqueduct with four openings of 39 feet. From Bevergern the proposed "Mittelland" Canal is designed to branch off to the Weser and the Elbe, via Osnabrück and Hanover, Fig. 21, Plate 3. The third lock lies behind Bevergern; while the descent to the Ems is made by six locks near the village of Gleesen. To economise water, the last of these locks, which has a depth of 21 feet, is provided with a side pond on each side, the two ponds having together a capacity of two-thirds that of the lock. The canal follows the Ems for a short distance, and then enters the Ems or Haneken Canal, built in 1824, and now widened and deepened, which it follows for 11 miles. Above Meppen, the canal follows the Hase, a canalised tributary of the Ems, and then again enters the Ems, which is canalised to Papenburg, on which length there are five needle weirs. A further use of the Ems was impossible, owing to its winding course. Papenburg is the terminus for the smaller sea-going ships, but cannot be reached by the larger vessels. At Oldersum, 183 miles further down, the Ems increases greatly in width, and the water is at times too rough for the canal boats, so that from this point a lateral canal has been built to Emden, Fig. 21, Plate 6. Large extensions are now being made to the port at Emden. The canal, including the branch canal to Herne, has a total length of 174 miles, of which 115 miles are canal proper, 38 miles the canalised and regulated Ems, and 20 miles the open Ems. Description of Dortmund Canal.-The canal is 98 feet wide at the water-level, 8 feet deep and 59 feet wide at the bottom in cutting, and 11 feet deep and 46 feet wide at the bottom in embankment, which alteration of cross-section effects a reduction in the quantity of material required for the banks. The slopes, from 31 feet under water to 31 feet above the water-level, where subjected to wash and the effects of frost, are 3 to 1, and below this they are 2 to 1. The relative area of the wetted cross-section of the canal to that of the ships using it, is 4 to 1. There are eighteen locks and a canal-lift near Henrichenburg; and it is necessary to provide water for the upper half of the canal to its entrance into the Ems. The pumping-station is situated where the canal crosses the Lippe, and is capable of lifting 60,480 cubic feet of water from the river into the canal. Owing to the scarcity of water, the locks, as far as the entrance to the Ems, are constructed to take only one vessel at a time, and have an available length of 220 feet, a width of 28 feet, and a depth of 10 feet over the sills. The locks on the widened Haneken Canal, and on the canalised Ems, where plenty of water is available, are 541 feet long, 33 feet wide, and 81 feet deep, and can take a tug and a train of canal-boats. All streams crossing the canal are carried underneath in culverts. The canal is crossed by about one hundred and twenty bridges, nearly all of which have a single clear span of 102 feet. Near Meppen and Lingen there are two swing-bridges, as it was impossible to raise the roads for carrying them over the canal by a fixed bridge. The canal cross-section on the three aqueducts crossing the Lippe, Stever and Ems is reduced to 59 feet by 10 feet. The upper part of the canal, from Dortmund to the Haneken Canal, 87 miles in length, is fed by pumps from the Lippe; while from Münster to Bevergern, it is fed with water from the Ems by pumps calculated to supply 31 cubic feet per second. In connection with the canal-lift at Henrichenburg, there are pumps delivering 163 cubic feet per second from the Dortmund-Henrichenburg portion of the canal. This canal-lift, with a height of 46 feet, is considerably larger than those hitherto constructed at Anderton, Fontinettes, and La Louvière, lifting vessels of from 100 to 400 tons, for here vessels of 600 tons are dealt with. The lift chamber at Henrichenburg consists of a trough or box having a clear inside length of 230 feet, a breadth of 28 feet between the guides, and containing 81 feet depth of water; it is hung from a bridge, and rests upon five cylindrical floats 27 feet in diameter. The five floats are arranged in a row under the longitudinal axis of the trough, and each moves up and down in a shaft filled with water. They are entirely immersed, and their buoyancy exactly equals the weight of the trough and its contents. Since the whole is normally in equilibrium, weight added to the trough causes it to sink, and a reduction in its weight causes it to rise. This disturbance of the balance is effected in the first place by causing the trough to rise to a little below the level of the upper reach of the canal, so that water from this reach will flow into it; and in the second case by stopping it before it reaches the lower level of the canal, so that water will flow from it into that level. This operation is regulated by two screwed shafts on either side, which are driven by an electric motor at exactly the same speed. These screw spindles pass through nuts fixed to the sides of the trough, which they serve to keep level, and, in the event of a sudden alteration in the buoyancy of the floats, would support it. The cost of the canal was £3,725,000. At Dortmund, Münster, Papenburg, Leer, and Emden, extensive dock works are being constructed, those at Dortmund costing £271,250. THE ELBE-TRAVE CANAL.1 In 1391-98 a canal was made connecting the Elbe with the Baltic, the locks on which accommodated vessels up to 62 feet long, 10 feet beam and 1 foot 5 inches draught. The construction of the North Sea and Baltic Canal made the bringing of this waterway up to modern requirements of vital importance to Lübeck; and in 1873 preliminary works for the new Elbe-Trave Canal were commenced. Description of Canal.-The canal in course of construction leaves the Elbe at Lauenburg, then follows the valley of KnikemühleBach, passes over the Berlin-Hamburg railway above Büchen station in the valley of the Delvenau, enters the Mölln Lake, and then follows the valley of the Stecknitz to the port of Lübeck, Fig. 22, Plate 6. The canal is 42 miles long, and its upper reach is 17 miles long; the portion descending towards the Elbe is 7 miles, and that towards the Trave, 18 miles long. The water-level of the upper reach is 24 feet above the mean water-level of the Elbe, and 40 feet above the mean water-level of the Trave. Three locks surmount the difference of level on the Elbe side, and six that on the Trave side. The breadth of the canal is 105 feet at the water-level, and 72 feet at the bottom; and the depth of water is 6 feet. The 1 Centralblatt der Bauverwaltung, 1894, pp. 500 and 521. |
