Imágenes de páginas

ing of the canal off Port Tewfik: deepening of the basin of Port Tewfik ; and the continuance of the masonry-work. They at the same time suggested the advisability of cutting a second canal parallel to the first, in anticipation of a still greater traffic. This scheme was the subject of the negotiations between M. de Lesseps and the British Government. The section of the Suez canal is too small for vessels of such dimensions as are now built for the Indian and Australian trade, irrespective of the question of overcrowding and blockades. The passage is too narrow and shallow to allow them to steer properly, particularly at such a slow speed as five knots an hour, the maximum in the present canal. It was on this account that the English ship-owners, in their conferences with M. de Lesseps in the latter part of the year, urged the necessity of enlarging the section of the present canal as more pressing than that of separate channels for vessels going in opposite directions. He promised to meet their views and have the plans for the improvements drawn up on the basis of an enlargement of the present canal, which will take precedence, and a correspondingly larger sectional area in the projected parallel passage. Isthmus of Corinth Canal.—The Isthmus of Corinth canal, which was begun in the spring of 1882, and is expected to take four years, proceeds with greater rapidity since the introduction, in the autumn of 1883, of gigantic steam-excavators constructed in France. The length of the canal is 6,342 metres. Its depth and width are the same as those of the Suez canal. It will save ships from the Adriatic trading with Greece, Turkey, the Danube, or the Black sea, as much as 185 marine miles, and those from the Mediterranean and Atlantic about half that distance. At present 5,800 large steamers and 300 war-vessels, besides a large number of sailing-craft, sail around Cape Matapan every year, enough to furnish the canal, to begin with, a traffic of nearly 6,000,000 tons. The site of the new town of Isthmia, at the AEgean outlet of the canal, is exceedingly healthful. There was no mortality among the workmen from climatic causes during the first year's operations. Sahara Sea.—M. de Lesseps, after a personal examination of the route of the canal with which Commandant Roudaire proposes to inundate the chotts of Tunis and Algeria, declared his adhesion to the project, which he has favored from its inception, and aided in its preliminary stages. The chotts, or alkaline basins, depressed below the level of the Mediterranean, extend in an irregular chain from Gabes to the town of Biskra in the desert, 300 miles inland. The large lake which would be formed by flooding the depressed area would be not less than 2,000 or 3,000 square miles in extent, and deep enough to float the largest vessels, which could enter easily by the nearly straight canal. The creation of such a landlocked sea

would render fertile a broad belt of desert-land to the north, constituting the whole interior of Algeria and Tunis, where there are numerous fresh-water wells, and where nothing but rain is wanted to make the soil exceedingly productive. The cutting would be through sand, except in some places where a calcareous rock is met with ; which, however, is hardly more

than sufficient to furnish materials for break

waters, piers, and buildings. The total cost is estimated by M. de Lesseps at 150,000,000 francs, and the time to complete it five years. Panama Canal,—The works on the Panama canal are progressing, though, from the inability of M. de Lesseps to raise a new loan in the spring, it is evident that the feasibility of carrying out some important features of the original plan is doubted. The reports of the director-general, M. Dingler, on the excavations are encouraging. The quantity of earth to be removed is placed at 100,000,000 cubic metres, instead of 80,000,000 as previously estimated; but the absence of the expected rock excavation, and the looseness of the soil, reduce the estimated cost from 10 francs a metre to about one third of that rate. Much of the excavation is done by negro laborers, who work more cheaply than the machines which were brought for the purpose. M. de Lesseps estimates the total cost at 500,000,000 francs, not including the reserve fund of 100,000,000 francs for unforeseen expenses. He asserts positively that the canal will be completed within the five years originally calculated, which end in 1888. The proposed high dam in the valley of the Chagres is one of the most dubious features in the canal plans. The reservoir at high water is to cover an area of 6,750 acres, and contain 1,000,000,000 cubic metres of water. The directory has abandoned the idea of building the canal without locks, and determined to make a lateral canal and three locks at Panama. The total length of the canal from the Atlantic to the islands of Naos and Flamenco, where it joins the Pacific, is 74 kilometres. It is divided into 12 sections, the most important of which are Colon, Gorgona, Obispo, Emperador, Culebra, and Paraiso. On all the sections 30 steam-excavators, 40 locomotives, and 800 tip-wagons were at work in the autumn. The force of laborers was then 10,000 men, which number was expected to be augmented at the beginning of the fine season in December to 15,000. About two thirds of the grand cutting between Obispo and Paraiso was excavated by Oct. 15th. It is expected that in 1884, when all the machinery will be on the ground, the excavations will proceed at the rate of 4,000,000 cubic metres a month. On Oct. 15th the harbor-works at Colon were nearly completed. An entire town had sprung up there, with numerous workshops and warehouses, and connecting railroads for the distribution of material. The terre plein and breakwater were finished. A cutting was opened at the spot called Monkey Hill, with the object of filling up the lagoons at the bottom of the bay of Colon, in order to improve the sanitary conditions. The 120 horse-power dredgers remove, each of them, 6,000 cubic metres of earth a day. The machines of the Franco-American Trading Company, which were built in Lockport, N. Y., excavate 2,000 metres. This company has contracted to dig the Pacific opening from the mouth of the Rio Grande to Paraiso within the term of two years. Florida Ship-Canal.—A project for a tide-water canal across the upper part of the Florida Peninsula has been taken up by a company formed for the purpose. The commercial prospects of this canal are more encouraging than those of the again intermitted Cape Cod cutting, for the 800 miles of navigation which it will save were described by Commodore Maury as being as dangerous as any in the world. The annual losses from wrecks on the southern coast of Florida are computed to amount to $5,000,000. A saving of 1 per cent. in insurance is therefore counted on. The commerce which goes through Florida Pass annually is said to be three times as great as the traffic of the Suez canal. The route selected is from a point on the Suwanee river, to a point above Jacksonville on the St. John's river—a distance of somewhat over 60 miles, The estimated cost is $20,000,000. The Iron Gate.—The removal of the obstructions in the cataracts and narrows of the Danube, called the Iron Gate, at the point where the Austro-Hungarian, Servian, and Roumanian boundaries meet, was attempted in 1781, and again in 1834. The scheme has been deferred up to the present in pursuance of the protective policy of the Austrian and Hungarian Governments, which feared the competition of foreign manufactures, and even of American grain. In 1883 it was again taken up, and arrangements were made for the final execution of this important and difficult work of engineering. On June 4th, an accord was reached between the Austrian and Hungarian ministries, in a conference at Vienna, by which the Hungarian Government undertook the regulation of the river. The agreement of Servia and Roumania was obtained. The cost is to be reimbursed by the levy of tolls for the period of ninety years. The various estimates range from 10,000,000 to 22,000,000 florins. The general plan which was adopted was worked out by the American engineer MacAlpine. Diversion of the Syr Darya.—Schemes for changing the course of the Syr (Jaxartes) and that of the Amou (Oxus) have been under the consideration of the Russian Government for some time. Both of the principal rivers of Turkestan have followed different channels at different periods. The partial diversion of the Syr into the bed of the Jany Darya is a work of no great difficulty, as it was accomplished by the Kara Kalpaks about 1760. The river

was turned into its former course by means of a dam constructed in 1837 or 1838, by order of the Khan of Khiva, to prevent the Russians from using it as an avenue of approach to his capital. In 1853 the Russians broke the dam and allowed the waters to flow into the dry bed of the Jany Darya, but finding that the Syr Darya was rendered too shallow for steamboat communication, they restored the work. In 1883 a channel was reopened, and the water soon penetrated as far as Irkibai. Whether the main volume of the river can be diverted into the new course, and whether it can be made to flow into the Amou or the Sea of Aral, is still doubtful. The work already accomplished will restore fertility to a large portion of the Kizil Kum desert, and improve the military and caravan communications with Khiva and the Amou Darya station. Drainage of Lake Okechobee.—The reclamation of swamp - lands on an enormous scale has been undertaken in Florida by an association of American and English capitalists. The Florida Land Improvement Company, organized by Hamilton Disston, of Philadelphia, in addition to 4,000,000 acres of State lands which were obtained by purchase, selected, and in great part resold, one half being taken by an English syndicate and several hundred thousand acres of the remainder by other purchasers, received authorization to drain the Okechobee district, covering 11,000,000 acres, on terms giving the company for its service one half of the land reclaimed. There are some sections in the overflowed lands, as well as in the pinelands of Southern Florida, which are supposed to be as well adapted to the cultivation of sugar as any soil in the world. The cane can be harvested in saccharine maturity, as the region is south of the frost-line; but whether it will propagate itself for a succession of years by ratooning, as in Cuba, is not yet established. These lands are also suitable for jute, which is grown in Florida of a superior staple and luster. The feasibility of draining Lake Okechobee was established in 1879, in a survey ordered to be made by the Federal Government. Col. Meigs, who conducted the survey, calculated the level of Lake Hickpochee, connecting with Lake Okechobee, to be 22 feet above mean low tide. A survey made in 1881 demonstrated that the elevation of Lake Okechobee above the low-water level of the Atlantic ocean was 25 feet. When Lake Okechobee overflows its banks and backs the waters of its numerous tributaries, submerging the entire surrounding country, a portion of the overflow finds its way into the Gulf of Mexico by sluggish and tortuous channels through Coloosahatchie river and other outlets. The company began to cut a canal from the Coloosahatchie in January, 1882, and made connection with the lake on Dec. 10, 1882. A steady current set through this channel, which relieved a large surface of swamp-land adjacent to the lake, and lowered the level of the neighboring lakes. The outlet canals connecting Okechobee with the Coloosahatchie river are to be made navigable. The first one made is 52,000 feet long. The company next deepened and straightened the Kissimmee and Little rivers which connect the Tchopekaliza lake with Okechobee. Canals 6 feet deep were cut, and a current was obtained of 2+ miles an hour. By May, 1883, the level of the upper lake had fallen 5 feet. At that time 380,000 acres had been redeemed. The excavation was done entirely with steam-dredges. Hull Harbor Improvements.-The new dock at Hull is intended to meet the growing demands of a port which, next to London and Liverpool, has the largest commerce of any in the British Islands. ln connection with the New Barnsley railway, running to the Yorkshire collieries, the new dock enables Hull to become a large coal outport. The Humber brings ships of deepest draught up to Hull at any state of the tide. Besides the river Hull, which winds through the town and constituted the old harbor, but which is available only for small vessels at high water, there were seven wet docks with a total area of 76% acres. The new basin, called the Alexandra dock, is 46% acres in extent, and a new one in course of construction contains 10+ acres, giving the city a total area of wet-dock accommodation of 1334 acres. The Alexandra dock will accommodate the large vessels engaged in the grain-trade with California and India. To construct it, 150 acres of the foreshore were reclaimed by embanking, of which 100 acres are occupied by the wet dock and two graving docks, their quays, warehouses, roads, railways, etc. The works have a frontage on the river of 6,000 feet, and a depth of 3,500 feet. The dock is 2,300 feet long by 1,000 wide. It is entered through a lock 550 feet long and 85 feet in width, having three pairs of gates and a caisson at the entrance. The sea-bank between the basin and the river is 14 mile long, being composed of 200,000 tons of chalk, faced with stone, with an outward slope of one in two. The trumpet-shaped entrance, 360 feet wide, is formed by timber wharves built upon creosoted piles. The depth over the sill is 34 feet at high spring-tide. There are two jetties 400 feet long, and one of 450 feet, within the dock. All the cranes, capstans, and other appliances, as well as the gates, valves, and sluices, bridges, and hoists, will be worked by hydraulic machinery. This is already applied in a novel manner in the work of excavation. A hydraulic navvy is used, which is capable of removing 600 to 700 cubic yards of earth a day. Unlike the steam navvy, it can not be thrown out of order by giving it more work than it can do, as it stops when driven beyond its capacity, so that it can not get strained. Another advantage is that it takes only two men to operate it. It is self-acting, depositing the earth in tip-wagons on either side as fast as they can

be unloaded and brought up again. Hydraulic power is used also in drawing the barrows which bring the excavated material up an incline to the banks, where it is used for filling up. The larger of the two graving docks is 550 by 65 feet at bottom, with 214 feet of water on the sill; the larger one is 512 by 81 feet, with 19% feet of water. The pumpingengines used in emptying the dry docks are employed also in maintaining the water in the main dock at the proper level, the supply being drawn from an inland stream which is freer from sediment than the Humber. Arlberg Tunnel.-The headings met in the great tunnel through the Arlberg in the Rhaetian Alps on Nov. 14th. The tunnel is nearly 6% miles long, taking rank immediately after the St. Gothard and Mont Cenis tunnels. The exact length of the new tunnel is 10,270 metres, that of the Mont Cenis tunnel 12,323, that of the St. Gothard tunnel 14,900. The object of the work is to shorten the distance between Austria and Switzerland, and to give Austria direct communication with the railroad systems of Western Europe and render her independent of the South German railroads over which the traffic has hitherto had to pass. Starting from Innspruck, the new line is carried along the right bank of the Inn to Landeck. . At that point the difficult part of the work began. From Landeck to St. Antoine where the road enters the tunnel, the toti rise is 1,721 feet. The gradient in the valley of Rosanna is one in forty. The distance between Landeck and Bludenz, the other terminus of the road, on the opposite side of the Arlberg in the Austrian province of Vorarlberg, is 35 miles. This section is a mountain railroad all the way. The Panznau valley is crossed by a bridge of three arches, each of 197 feet span. The tunnel first planned by Gen. Nordling, who surveyed the route, was a smaller one higher in the mountain; but the Austrian Government determined not to spare expense in a work of so great political and commercial importance, and the tunnel was made longer, in order to lessen the grades, and wider, so as to accommodate two tracks instead of one. The work of boring began in June, 1880, on the Austrian side. On the Swiss side the heading was started in September of that year. The perforators used on the Austrian side were percussion drills, constructed on the same system as the machines employed in boring the Mont Cenis and St. Gothard tunnels. A series of 20 or 25 chisels, covering a space of 7 square metres, were driven into the face of the heading with blows imparted in rapid succession by compressed air. The machines were actuated by turbines at the end of the gallery. The chisels penetrated the rock from 14 to 2 metres. The holes were then filled with dynamite and the blast exploded, lengthening the drift about 14 metre. The perforators moved on wheels. The compressed air was applied under a pressure of five atmospheres through flexible tubes. On the Swiss side the new Brandt perforator was employed. This machine excelled the performance of the Ferroux apparatus used at the other end, which is the latest improvement in the percussion perforator. The new perforator consists of six or eight veritable drills, with a diameter of 70 millimetres, which bore into the rock with a rotary movement under a hydraulic pressure of from 60 to 100 atmospheres. The difference in the speed at which the work proceeded in the different Alpine tunnels shows the progress made in boring machinery. The Mont Cenis tunnel advanced at the rate of 3,637 feet a year; the St. Gothard at the rate of 5,474 feet; and the Arlberg at the rate of 7,080 feet. The improvements reduce the expense in a still greater ratio, the Arlberg tunnel having cost only $750 per lineal metre, as compared with $1,250 per metre in the St. Gothard, and $2,000 in the Mont Cenis works; although a part of this saving was due to the relative shortness of the Arlberg bore. The work of carrying away the excavated material in mountain tunneling is as difficult, and consumes quite as much time, as that of excavating. The gases from the explosives render this task unwholesome and sometimes dangerous. In the Arlberg the miners escaped ill effects by covering their mouths and nostrils with sponges steeped in vinegar. At first, owing to the hardness of the rocks on the western side, and to the inflow of enorInous quantities of water, the stipulated rate of progress, about ten feet a day, could not be made; but after the water was subdued the advance was more rapid than the prescribed speed. The gallery was driven on a level with the bottom of the tunnel, and not, as formerly, on the Belgian system, i. e., on a level with the top. The cost of the tunnel itself is estimated at 18,000,000 florins, including the premiums earned by the contractors for early completion, in which premiums they allowed their workmen to share. The cost of the whole line will be about 40,000,000 florins. Mersey Railway Tunnel.—The headings of the tunnel under the river Mersey met in the center before the end of the year. Though insignificant in length, the river being less than a mile broad at that point, this tunnel is a work of great difficulty, owing to the low level at which it has to be carried under the deep waters of the Mersey, the toughness of the new red sandstone, the amount of pumping necessary to remove the immense quantity of water which perforates through this porous rock, the work of lining the gallery to stop this inflow, and the precautions which were necessary against a possible fault in the geological formation and the inrush of water from the river. Fortunately, the stratum was found to be continuous. The roof of the tunnel is separated from the bed of the river by a thickness of 30 feet. The length of the tunnel is 1,753 yards.

The seven-foot heading was excavated partly with Col. Beaumont's boring-machine, which was set for ; inch per revolution, equal to # inch per minute, which was a slower speed than was made in the gray chalk of the Channel tunnel. Through this seven-foot drift. way the water which entered flowed down the

incline to the shaft at each end and was got

rid of by means of the steam-pumps. The tunnel was excavated at a higher level, the work proceeding at some distance in the rear of the advance of the drift-way. The tunnel is semicircular, and has a breadth of 26 feet and a height of 20 feet above the rails, the radius of the curve varying from 40 feet at the base to 13 feet in the arch. The gallery, as it was quarried out, was lined all round with massive walls of brick and cement. The heavy blocks of stone, which were blasted out with gelatine, were removed on cars in a constant rotation. On the Cheshire side, where the Beaumont borer was used, a compressed-air locomotive of Col. Beaumont's invention was employed to remove the excavated rock. Hitherto the only connection between Liverpool and Birkenhead, where the railroads of Cheshire and Wales converge, has been by ferry. Various plans for carrying a railroad across the Mersey, by a high bridge or a tunnel, have been proposed by engineers before. The tunnel ài. constructed is the shortest and most direct route, one end emerging in the center of Liverpool, and the other in the center of Birkenhead. The grades are consequently heavy. The tunnel is expected to be opened to traffic in 1885. East River Bridge. — The suspension-bridge over the strait called the East river, which separates New York from Brooklyn, on Long Island, was completed and formally opened on May 24th. The project of a bridge to connect the two cities and furnish safe and rapid communication, was originally brought forward by William C. Kingsley, President of the Bridge Trustees, and Henry C. Murphy, his predecessor in office. Mr. Kingsley selected the site, and had plans and estimates prepared, as early as 1865. The Bridge Company was organized in 1867, with a nominal capital of $5,000,000, the amount of the preliminary rough estimate of the engineer, $500,000 of which was subscribed by citizens who formed the company, $3,000,000 was to be furnished by Brooklyn and $1,500,000 by the city of New York. In 1875 the bridge was made a State work, and placed in charge of a board of trustees. John A. Roebling, the originator of wire suspension-bridges, was the engineer. His estimates in 1867 made the cost of the bridge $7,000,000, and of the approaches $3,800,000. The estimated time of construction was five years. A commission of bridge engineers approved his plans. Congress passed an act in 1869 authorizing the construction, and in June of that year the Secretary of War decided that it would not impede navigation, providing

« AnteriorContinuar »