THE ROYAL ARTILLERY INSTITUTION. 
79 
MEMORANDUM BY THE DEPUTY DIRECTOR OF WORKS, ON THE RESULTS OF 
EXPERIMENTS UPON A CASEMATED STRUCTURE OF GRANITE, WITH 
IRON SHIELDS AT THE EMBRASURES, CARRIED ON AT SHOEBURYNESS 
IN MAY AND NOVEMBER, 1865. 
1. Before considering the results of these experiments, I will refer briefly 
to the successive improvements that have been adopted of late years in 
casemates for sea defences, and especially in those lately constructed in this 
country. 
Old constructions of casemates . 
2. Bigs. 1-6, Plate I., and Pigs. 1-6, Plate II. represent the con¬ 
struction of casemates and embrasures adopted in the sea defences of the 
principal ports of the chief maritime powers previous to the year 1861. 
The dimensions of the embrasures will be seen on the plates.* 
The front walls of these defences have been constructed in some places 
of the stone of the locality, in some cases faced with granite; in places where 
stone is comparatively costly, they have been built wholly of brickwork. 
English. 
3. Excepting the old castles of the time of Henry VIII., at Portland, 
Walmer, Deal, and Hurst, &c. the only casemated sea defences which have 
been constructed in this country previous to the last five years, are at or 
near Portsmouth. Blockhouse Port and the Point Battery (see Pigs. 1, 2, 
Plate I.), on either side of the entrance to the harbour,—part of Port 
Monckton,—and a work at Cliff End, Needles Passage (see Pigs. 3, 4, 
Plate I.), are casemated, 
Except at Cliff End, where the work is wholly of brick, the outer walls of 
these are built of Purbeck stone". 
French, 
4. At Cherbourg (Pigs. 1-3, Plate II.) the casemated works are 
constructed of rubble walls built in horizontal beds, with a stone of 
laminated structure, and faced with granite. 
5. At Cronstadt (Pig. 4, Plate II.) the exterior walls are, it is believed, 
chiefly of granite, and with smaller embrasures than those at Portsmouth 
and Cherbourg. 
At Sebastopol (Pig. 5, Plate II.), Port Nicholas and the other works 
were constructed of magnesian limestone (Pierre des Steppes), the front 
walls having facings of coursed work, with rubble backings, not of a very 
sound description. 
* Blates I. II, IV. face p. 88. 
