280 



ENGINEERING. 



yard. "When completed, it will have a river 

 frontage of over 3 miles. 



The western part of the continuation of 

 Glasgow harbor, called Stobcross Docks, was 

 opened in September. These works when 

 completed, in three or four years, will cover 

 over 60 acres 33 acres of water and 27 acres, 

 or 3,344 lineal feet, of quayage. There will be 

 3 basins. Their average depth is to be 20 feet 

 at low tide. The basin just completed is the 

 largest one 695 feet wide at the broadest 

 part. The estimated cost of the whole works, 

 which were planned by James Deas, is 1,600,- 

 000. The basin now opened is called the 

 Queen's Dock ; it is a tidal harbor, the entrance 

 being 180 feet wide. A swing-bridge crosses 

 the entrance, which, although weighing 800 

 tons, is moved from one side to the other in a 

 minute and a half by its hydraulic machinery. 



Two new forms of floating docks have been 

 devised by Clark & Standfield, an English firm 

 of engineers. One is a tubular dock, similar 

 to the usual rectangular floating dock, but 

 capable of being towed in rough weather, and 

 of docking laden vessels or large iron-plated 

 war-ships. Its bottom consists of 6 or 8 par- 

 allel longitudinal tubes, connected transversely 

 by an iron framework, the 2 outer tubes, 

 which support the sides of the dock, running 

 up higher than the others, and having a flat 

 upper -side, forming a box-girder, on which 

 are fixed the vertical cylinders, which form 

 the sides of the dock. Some of these hollow 

 cylinders are perfectly tight, and some have 

 valves for admitting or expelling water ; those 

 in the centre contain the engines and pumping 

 apparatus. The dock is provided with a new 

 kind of rest for the ship, consisting of inflated 

 cushions of many thicknesses of canvas im- 

 bedded in India-rubber, supporting every part 

 of the bilge and sides of the ship as evenly as 

 though she were riding in the water. The air- 

 cushions can be removed from the parts re- 

 quiring repairs. The principle of this floating 

 dock with air-cushions might also be applied 

 in ship-floats for lifting vessels over shoals and 

 bars into rivers and harbors, or conveying iron 

 men-of-war through ship-canals, like that of 

 Suez. The other novel device of the Messrs. 

 Clark & Standfield is the gridiron depositing 

 dock, whose chief advantage over the ordinary 

 kinds of dry-docks is, that a number of vessels 

 can be docked and repaired at the same time. 

 It lifts the vessel out of the water, and deposits 

 it high and dry upon a staging of piles and 

 timber, which can be made long enough to 

 receive any desired number of vessels. It is, 

 therefore, adapted to the needs of a naval ar- 

 senal for a means of preserving gunboats and 

 war-vessels from the decay which attends 

 them if kept in water. The float consists of 

 pontoons of boiler-plate, about 3 feet apart, 

 running crossways to thenhip^s keel, which 

 are divided within into hollow compartments. 

 The pontoons are some 10 or 12 feet broad, 

 and 12 to 18 feet deep ; the side of the dock 

 joins the pontoons together; and in some of 



its hollow chambers are contained the engines, 

 boilers, and pumps. It balances the weight 

 of the vessel when on the dock ; and is fur- 

 nished with an outrigger, consisting of a broad 

 pontoon, which holds the dock upright when 

 submerged. The transverse section of the 

 dock is like the letter L. The spaces between 

 the pontoons fit in between the rows of piles 

 which form the stage ; and when the ship is 

 safely deposited and braced, the pontoon float 

 is lowered from under the bilge and retired. 

 This floating dock, like the one before de- 

 scribed, is provided with air-bags, for the pro- 

 tection of the vessel from strains. All the 

 numerous compartments in the dock are pro- 

 vided with separate pipes and valves, which 

 are brought to a centre, and controlled by the 

 director, who knows by the indicators the 

 amount of water in each chamber, and is able, 

 with the valves and pumps, to keep the dock 

 always on a level. The same inventors have 

 proposed a dock for the raising of sunken 

 ships. It is to descend over the vessel; and 

 from the projecting feet grapnels are to be 

 pressed under the keel of the ship by the in- 

 flation of air-bags behind them. Then, from 

 the hollow compartments the water will be 

 pumped until the hull is brought to the sur- 

 face. Another new type of a floating dock 

 has been worked out by Ercole Lauria, an 

 Italian engineer. An iron or oaken pontoon, 

 larger than the vessel to be docked, and capa- 

 ble of floating it, is filled with water, and in- 

 troduced under the keel of the ship, and then 

 emptied gradually, the vessel adjusting itself, 

 when the pontoon is at the proper level, to its 

 cradle, which rests upon beams of iron, whose 

 ends project beyond the sides of the pontoon. 

 The pontoon is then towed into a dock, and 

 again sunk, while the projecting beams rest on 

 ledges of masonry, thus holding the vessel sus- 

 pended ; the pontoon is again introduced under 

 the hull when the repairs are accomplished, 

 and the same floating and sinking operation is 

 repeated. The interior of the pontoon is di- 

 vided into 12 compartments, furnished with 24 

 India-rubber tubes, half of which are filled with 

 water to sink the pontoon, and half with air 

 to buoy it. The time necessary for docking a 

 ship would be about 6 hours. 



The water-supply of Lyons, France, is de- 

 rived from filtering galleries and reservoirs in 

 the gravel-bed which forms the centre of the 

 Khdne's valley, below the city. The filtering 

 surface covers 7,700 square yards. The floors 

 of the galleries are 10 feet below the low-water 

 mark of the river. The supply, in times of 

 low water, has been only 6,500,000 gallons 

 daily. To increase this supply, it was judged 

 to be useless to extend the galleries; but, it 

 being ascertained that below the conglomerate 

 beds underlying the gravel there was another 

 stratum of fine, porous gravel, this conglom- 

 erate rock has been pierced by 7 octagonal 

 wells, lined with cast-iron framing, 6 feet in 

 diameter, and 26 feet deep, sunk from the bot- 

 tom of the filtering galleries. These wells 



