THE ROYAL ARTILLERY INSTITUTION. 
223 
fire, than exists in the case of the faces and casemated flanks of bastioned 
fronts. 
A heavy and well protected fire of artillery from a fortress will no doubt 
compel a besieger to make a more frequent use of mining operations than 
has hitherto been customary. A more general employment of countermines 
may therefore be fairly considered as another consequence of the improve¬ 
ments in Artillery. In the last edition of the French “ Aide Memoire du 
Genie,” the construction of branches and chambers by means of borers, 
similar to those used for artesian wells, is advocated. In favourable ground 
7 0 ft. may be bored in four hours, and a chamber formed without difficulty 
capable of holding 400 lbs. of powder. M. Piron, in the work before alluded 
to, conceives (and probably with justice), that great advantage to the defence 
will arise from a large use of these artesian mines. 
Coast Batteries. 
With regard to the third point which it was proposed to notice, viz. 
changes in coast batteries, the use of uncovered masonry in parapets, embra¬ 
sures or the fronts of casemates in positions near to which an enemy's ships 
could advance, must to a large extent be abandoned, constructions of iron, 
or of masonry protected with iron being substituted; the thickness of 
earthen parapets in similar positions must be largely increased, and shields 
of iron used, as before pointed out, for strengthening earthen embrasures. 
Positions from which any long channel could be enfiladed, and which would 
have formerly been considered too distant, might now be advantageously 
occupied by earthen or other batteries. 
The adoption of iron for casemate fronts, and of iron screens for 
strengthening earthen embrasures, disposes of a difficulty which formerly 
gave a ship a certain advantage over a shore battery, viz. the large opening 
of the embrasures of the battery compared with the small ports of the ship's 
side. It now of course becomes practicable to make the one as small as the 
other. 
The exterior opening of existing casemate embrasures, which in some 
amounts to as large an area as 54 square feet, yet admitting a hori¬ 
zontal traverse of only about 40°, might by a judicious use of iron throat 
pieces, combined with that of Colonel Colquhoun's raised racer and ima¬ 
ginary pivot, be reduced to 10 square feet, or even less, without impairing 
their lateral range. 
Having now r touched upon some of the principal changes in works of 
defence which appear to me to be called for by improvements in Artillery, I 
will conclude by expressing the hope that an interesting discussion may 
ensue, and by thanking the Committtee of the Institution for providing these 
opportunities for debating upon professional subjects. I do not know that 
I need apologize for the brevity of this paper, for I think that a short paper 
followed by a full discussion is more interesting than the contrary. 
