THE ROYAL ARTILLERY INSTITUTION. 
213 
CUPOLAS AND POETS. 
By EBANCIS DUNCAN, M.A., Lieutenant, Boyal Artillery. 
FELLOW OF THE GEOLOGICAL SOCIETY, AND D.C.L., 
KING’S COLLEGE, N.S. 
In the first paper on this subject, which appeared in the "Proceedings” of 
the B.A. Institution,* my object was more to generalize on the advantages of 
the plan I proposed; and to record the ideas which, from their simplicity, may 
have existed in the mind of any artilleryman or engineer, who has given the 
subject consideration. The notice taken of the former article by some of the 
military papers, encourages me to pursue the subject more into the region 
of details, and to enlarge on such of the advantages formerly mentioned, as 
seem of the greatest importance. 
In an article which appeared in a recent periodical,! the writer labours, and 
successfully, to prove that old fortifications cannot resist new guns. But he 
at the same time goes on to quote the report of the Commissioners of the 
National Defences, that " the considerations respecting the progress, which is 
being made in the production of ordnance of increased power, tend to show 
that in all probability the relative value of forts opposed to ships will be 
greatly increased.” This same opinion was expressed in my former paper, 
by saying "that fortresses evidently derive a higher ratio of benefit from 
improvements in artillery, when these improvements involve heavier guns 
and larger charges, than either ships, or armies in the field.” But in entering 
on details on such a subject, the duty of the writer is to show the means 
by which such superior advantage is to be obtained, and when obtained, how 
to be most effectually employed. 
In concluding the last paper, hints were thrown out as to the immense 
advantages to be derived by the use of the cupola on martello towers; and 
I shall best enlarge on these by illustration. The martello tower is most 
appreciated on a coast, round a harbour, or on an extended frontier like that 
of Canada. On a coast, as in a fortress, we must value the strength of the 
defences, as being not greater than their weakest point. So that, if we fortify 
one hundred miles of a coast accessible to an invading force, and leave twenty 
undefended which are equally accessible, we may consider the whole coast 
as far as resisting the landing of an enemy is concerned to be virtually 
undefended, and the expense of the incomplete defences to be practically 
thrown away. But there is a limit to the money a nation can expend in its 
fortifications, nor can it enclose itself within regular lines of fortification 
like a Chinese wall. Here then the martello tower comes in, and by placing 
[VOL. III.] 
* Tide p. 107. 
f Colburn’s United Service Magazine. October, 1862. 
M 
