The Martello tower, off the Spit Isle of Grain, erected by Messrs. Kirk and Parry, of Sleaford, Lincolnshire, is completed, and was on Saturday officially given up to the Ordnance authority at Sheerness. The tower has been nearly two years in erection, and is completed within the time specified by the Board of Ordnance.
The peculiar construction of this tower gives it the facility of firing the guns (which are to be of the largest calibre) on traversing centre pivots, so as to do execution in the fair-way of the rivers Thames and Medway. With the latter river this tower forms a crossfire with the Sheerness Battery guns, sufficient to sink any ships attempting to pass. The tower is struck from seven different centres, in order to get stability to the available parts thereof. The average thickness of the solid masonry is 12 feet. The outer dimensions are 63 feet by 71 feet, underneath is a barrack room capable of accommodating 30 gunners, and an officers private room.
The basement story contains the following rooms; viz, ordnance store, provision store, barrack store, regimental store and magazine, the latter being encased with an entire coat of asphalte.
The whole of this basement is lined with nine-inch brickwork, all being within a 12-feet wall of masonry. The estimated cost of this tower is about £14,000, exclusive of its foundation of piles, which support solid balks of timber, with York landings, being filled in to a depth of 6 feet with cement. The extreme height of the tower is 41 feet 6 inches.
From the exposed situation of the tower, which is subject to the sea and weather, great difficulties were experienced during the winter months in proceeding with the work.
From the Launceston Examiner (Aus) 16 February 1856.