THE ROYAL ARTILLERY INSTITUTION. 
235 
although with most probably some inequalities, the tensions and compres¬ 
sions have so adjusted themselves that the whole thickness of the chase is 
more or less effective, and that perhaps a somewhat undue strain of the 
explosion is transmitted to the exterior plies; a far better fault than that it 
should be concentrated towards the interior. 
In April, 1855, whilst those mortars were in progress, Lord Palmerston 
sent for me and asked what was doing as to mortar vessels to carry them. 
No orders for anything of the sort had been given. His Lordship directed 
me to consider the design of mortar vessel I should propose, and to place 
myself in communication with Sir Charles Wood, Bart., then First Lord of 
the Admiralty, which I did on the 20th April, 1855, having a good while 
previously worked out the scheme of mortar float which I then designed and 
submitted, and as to which I had several interviews with Admiral. Sir 
Baldwin Walker, B.N., and Mr. Watts, Constructor to the Admiralty, 
resulting from which I was requested to obtain tenders for the construction 
of two of these floats. 
Obstacles of official routine prevented anything further being done until 
so late as nearly the end of July, 1855, when I deemed it right to inform 
Lord Palmerston of the fact. Peace soon after put an end to the matter. 
No account of these large mortar floats has before been published. A 
model of one of them, as well as an accurate model of the 36-inch mortars 
themselves, as finally constructed, have been placed by me, on loan, in the 
museum of the United Service Institution, Scotland Yard, London. 
The general idea of one of these floats may be conceived as a hollow, flat¬ 
decked, square slab, built of iron, made up chiefly of horizontally aggregated 
hollow cubes, each of 8 ft. on the side, the outer ranges all round these being 
of half cubes, with prismoidal spaces outside these again to be filled with 
sand and sawdust mixed. The mortar in the centre of the deck, ranging 
diagonally, and its bed, with elastic material beneath it, bearing not upon 
the deck but upon the keelsons at the bottom. In rear of the mortar and 
below deck a pair of high-pressure engines, with independent twin screws, 
their shafts set at angles of about 35° to each other, so as either to propel, 
steer, or shift in azimuth only. 
The following is the general description of those designs submitted by 
me 
{Copy). 
General description of Floating Mortar Batteries, upon a new construction, proposed 
to carry the 3 Q-ineh Mortars now preparing. Submitted to the Admiralty by 
Robert Mallet, C.F., 1855. 
Each mortar battery may be viewed as a square redoubt afloat, 7 5 ft. square 
over all; armed with one very powerful mortar, and with five 32-pr. long guns; 
having a draught of water, in fighting trim—with engines at work, fuel, stores, 
ammunition, armament, and crew on board—of only 7 ft. 
The principal objects held in view in designing this form of floating battery 
have been:— 
1. The greatest obtainable steadiness upon the water, so as to admit the best 
practice at long ranges with the 36-inch mortar. 
