ON THE BELFAST HARBOUR. 123 
In the year 1858 a commencement was made towards the regular deepen- 
ing of the navigable channel from the Holywood Lighthouse to the upper end 
of Donegall Quay. The improvement made by the dredging, which con- 
tinued from 1858 to 1861, was such that vessels with a deep draft-of water 
were enabled to get up to the lower end of the Victoria Channel without 
lightening their cargoes, as they had hitherto done, two miles lower down the 
river, in order to enable them to take a berth at the quays or to enter the 
docks ; and steamboats were also enabled to reach their berths at all times 
of the tide. The next works of magnitude which were undertaken by the 
Belfast Harbour Commissioners were commenced in the year 1864, and con- 
sisted of the construction of a floating dock and tidal dock on the county 
Antrim side of the harbour, and a graving or dry dock and tidal basin on the 
county Down side of the harbour. ‘These may be said to be the first really 
important works, apart from the deepening of the harbour, which were 
undertaken since the year 1847. 
Unlike the previous mode of constructing the wharves with timber, the 
Commissioners were advised in these cases to resort to the use of stone as a 
building material. On the county Antrim side of the harbour, where the 
ground for foundations is of such a treacherous nature, the entire works had 
to be built upon bearing or supporting piles. On the top of the piles a layer 
of concrete two feet in depth was laid, on which the superstructure was 
raised. The walls are generally of the section shown on the contract 
drawing, and are built of rubble stonework, faced with random rubble. On 
the county Down side of the river, the nature of the soil being firm hard 
sand, no artificial foundation was necessary. On both sides, however, the 
precaution has been adopted of driving a row of sheet piles, 6 inches thick, 
along the face of the work, to preclude the chance of the foundations being 
undermined by dredging or other causes. 
These dock works, though commenced in the year 1864, were not all com- 
pleted till the year 1871. The Hamilton Graving-Dock and Abercorn Basin 
were, however, finished and formally opened by the Lord Lieutenant in the 
year 1867. 
The Abercorn Basin is 725 feet in length by 635 feet in breadth, having a 
water-area of 121 acres. The average depth of water in that basin is now 
about 11 feet at low water, and a canting space secured in the harbour which 
will allow a vessel of 600 feet in length to turn upon its own centre as a 
pivot. The cost of this basin was £23,163, 
The Hamilton Graving-Dock is in length at top 470 feet, and at bottom 
4517 feet. It is 84 feet 6 inches broad at coping, and 50 feet broad at 
bottom. The coping is 15 feet above datum, and the level of sill at entrance 
is 5:60 feet below datum. The entrance of the dock is G0 feet in width, and 
the depth of the dock is 22 feet 9 inches below coping. It is provided with 
a caisson gate, which can be used as a bridge or road for horse-and-cart 
traffic when set in place. A powerful engine and centrifugal pump, with 
pumping machinery, is provided for clearing the dock of water when requisite 
for repairing vessels. The cost of this graving-dock, including mooring- 
paals, paving, gas- and water-pipes, capstans, paals, &c., amounted to £33,756. 
_ Of this, £2376 was expended on the caisson; and a further sum of £5140, 
not included in the above, was expended on the engine and pumping 
machinery and buildings in connexion therewith. 
The works on the county Antrim side, comprising the Spencer Dock, 
Dufferin Dock, and entrance-basin, were formally opened by Earl Spencer, 
Lord Lieutenant of Ireland, in the year 1872. The Spencer Dock is a tidal 
