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ITS HISTORY AND ANTIQUITIES.
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docks, of the following capacity, affording unrivalled facilities for the inspection and repair of ships :—
Length from gates to head : eastern 475 feet, middle 282 feet, and western 352 feet; length on blocks, 426, 252, and T48 feet; width of gates 80, 51, and 60 feet; depth of water over blocks, at spring tides 25, 15, and 21 feet, at neaps 21, 11, and 17 feet.
The water is pumped from these docks by steam engines capable of raising and discharging into the river 125 tons of water a minute, and owing to this exceptional accommodation, combined with the peculiarity to Southampton of a double high water, the un docking three large ships and docking three others on the same tide is a frequent occurrence. A few years since the fine troop-ship " Himalaya " tested this in a very practical manner. Sent from Portsmouth to be docked at Southampton, this vessel, 3,550 tons burden, 375 feet long, 30-3- in depth, and 46i feet in breadth, steamed into the tidal dock and was dry docked in the same tide. A double high water is so rare a phenomenon that a few words concerning it may prove interesting. The first high water at the full or the change of the moon is at 1 Oh. 30m., and the second at 12h. 45m., with low water at 4h. 20m. The rise at springs is 18 feet, and that at neaps 8 feet. After low water the tide rises steadily for seven hours, which may be considered the first high water; it then ebbs for an hour about 9 inches, when it again commences to rise, and in about an hour and a quarter reaches its former level, and sometimes higher, this being the second high water. This double high tide is believed to be caused by the Isle of Wight breaking up the Channel into the Solent and Spithead passages, since as long as the tide runs strong to the westward of Spithead the water is kept up at Southampton, save the slight fall already mentioned, but when the tide makes to the eastward of that point the water falls rapidly here.
Massive sheers, the front legs.each 110 feet high and the back leg of the tripod 140 feet, worked by a steam engine of 20 horsepower, are provided on the south-eastern side of the tidal dock, and have been tested with a hundred tons vertical lift, and 80 tons overhanging 35 feet from the dock wall. The length of the groove being 48 feet, the sheers may be run in and out in four minutes; they lift 20 tons at the rate of six feet a minute, and heavier weights in proportion. The rapid development of steam navigation, and the increase of Southampton's importance as a port of call, has led the Company to commence the construction of a new dock to enable steam vessels of the largest proportions to arrive or leave the port, shipping or unshipping goods, at any state of the tide. The first quay of this extension, now rapidly approaching completion, will be
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