310 



ENGINEERING. 



lake, and lowered the level of the neighbor- 

 ing lakes. The outlet canals connecting Oke- 

 chobee 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 Jake had 

 fallen 5 feet. At that time 380,000 acres had 

 been redeemed. The excavation was done en- 

 tirely 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. In connection with the New Barns- 

 ley railway, running to the Yorkshire collier- 

 ies, 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 construc- 

 tion contains 10^ acres, giving the city a to- 

 tal area of wet-dock accommodation of 133 

 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 cais- 

 son at the entrance. The sea-bank between 

 the basin and the river is 1J 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 creo- 

 soted 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 ap- 

 pliances,' 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 ad- 

 vantage is that it takes only two men to oper- 

 ate 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 in- 

 cline 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 21| feet of 

 water on the sill ; the larger one is 512 by 81 

 feet, with 19 feet of water. The pumping- 

 engines 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 Rhse- 

 tian 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 me- 

 tres, 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 in- 

 dependent of the South German railroads over 

 which the traffic has hitherto had to pass. 

 Starting from Innspruck, the new line is car- 

 ried along the right bank of the Inn to Lan- 

 deck. At that point the difficult part of the 

 work began. From Landeck to St. Antoine, 

 where the road enters the tunnel, the total 

 rise is 1,721 feet. The gradient in the valley 

 of Rosanna is one in forty. The distance 

 between Landeck and Bludenz, the other ter- 

 minus of the road, on the opposite side of the 

 Arlberg in the Austrian province of Vorarlberg, 

 is 35 miles. This section is a mountain rail- 

 road 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 in- 

 stead 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 sys- 

 tem as the machines employed in boring the 

 Mont Cenis and St. Gothard tunnels. A se- 

 ries 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 succes- 

 sion by compressed air. The machines were 

 actuated by turbines at the end of the gallery. 

 The chisels penetrated the rock from !$ to 2 

 metres. The holes were then filled with dy- 

 namite and the blast exploded, lengthening the 

 drift about 1J metre. The perforators moved 

 on wheels. The compressed air was applie'd 



