The principal dimensions are as follows:—

Feet. In.
Height of tower from the base to the gallery639
Height of lamp above the gallery110
Total height of the lantern300
Outside diameter at base, over stone moulding230
Outside diameter over cast-iron shell190
Outside diameter just below the cornice1311¼
Outside diameter of tower casing at light-room floor138¼
Outside diameter of gallery, to outer ends of brackets1910¼
Inside diameter of cellar, or basement story90
Inside diameter of each of the other four stories120
Clear height of cellar90
Clear height of each of the other four stories120
Total thickness of each floor09

The plates composing the cast-iron shell are curved, oblong, rectangular, and 1⅜ inch thick at the base, diminishing gradually to ⅞ inch at the top of the tower.

MAPLIN SANDS LIGHTHOUSE.

This lighthouse was erected in 1848, from the design of Mr. Halpin, engineer to the Corporation of Dublin.

Of lighthouses on piles we shall take as an example the Maplin Sands Lighthouse, designed by Mr. Walker, for the Trinity House Corporation, and erected in 1841.

It stands upon nine piles of wrought-iron, each 26 feet long and 5 inches in diameter: these are screwed 14 feet 6 inches deep into the sand, and secured by screw-blades of cast-iron, each 4 feet in diameter. One pile forms the centre of an octagon; the others are placed one at each of the eight angles. To the tops of the piles are firmly fitted hollow iron columns; the central one being perpendicular, the others bent, so that they incline inwards. They are braced together by radiating, diagonal, and horizontal rods. Each terminates at the top in a socket, into which is fitted a timber post of about one foot square. The posts, like the columns, are braced together, and form the foundation of the house, platform, and lantern.