Public ledger. [volume] (Memphis, Tenn.) 1865-1893, 1868-12-09

fully equal in its effects TO the English
l2-inch gun with seyenty-six pounds OF
English powder. The two projectiles
from the rife were 685 pound steel and
a 658 pound chilled.iron shot. From the
l5-iDch gun three 480 pound steel and
one 450 pound cast.iron shot were fired.
Three Of the six blows upon the iron of
this target were the most powerful that
have been produced by modern artillery,
aud two others only inferior to these.
But the target was erected and the ex-
periments made with other objects than
to test this particular shield. Your own
remarks, November 20, on our coast
wise forts certainly make prominent
enough the necessity for experimental
firing; indeed your very first paragraph
suggests reasons to fire even at so anti
quated material as granite, which are
not invalidated by your subsequent state
ment that "solid masonry crumbles be-
fore the fire of l5-inch and 20-inch guns
brought to bear at that short range which
the monitor may establish for itself with
impunity. Suppose we grant this fact,
and then submit that earth shall be sub
stituted. In that case we have ciphered
out of existence millions of dollars
expended on granite walls in times gone
by"
We may indeed have ciphered the
money out of existence, but not the
works themselves. There they are, and,
perhaps, may yet have certain important
uses, though, as you rightly state, they
are founded on antiquated systems.' A,
any rate it ia the duty of the engineers
to test that point. And l feel confident
that every engineer would most gladly
| substitute "earth for crumbling gran
ite far more gladly, indeed, than to re
sort to material so costly as iron and,
as yet, so unsatisfactory. Earth is the
cheapest of all materials and the best
possible medium to resist cannon shot
Let any one, however, look at 10 inch
| or a 20-inch gun mounted behind or
earthen parapet and he will recognize
that those who load and direct these pom
derous weapons are scarcely protected al
all, and this defect is not remesied by
forming an esrthen embrasure. Unless,
therefore, the battery be very high, earth
alone is entirely inadequate as protec
ton for guns or gunners. Again, it FIRE
quently occurs that very limited but most
important sites are to be occupied, such
as the artificial sites at Spithead, Eng
land, and many on our own coast, which
afford insu fficient space for the requisite
number of guns in ordinary earthen bat
teries, and which are so low that such
batteries are quite inadmissible.
A. al 90 II of
remark, "a very serious question how
far (if at ally iron may wisely be employed
to advantage in covering forts or parts oi
forts, and particularly to protect guns
gunners and gun-carriages from the tre-
mendous artillery of modern naval war
fare" One thing about this question is
certain: the amount of money it requires
is immense, and such structures cannot
be entered upon without some reasonable
confidence that this enormous expendi-
ture will not only be adequate at the
present day, but that it will not, like
granite construction, be utterly made
quate to resist the improved weapons oi
another year. You are doubtless ia
miliar with the recent experiments al
| Shoeburyness, at least as they are ex'
hibited by the accounts of the London
Times In the Gibraltar" the " Ply
mouth" the Experimental /" Tor " War
| Office ~ and the Millwall shields you
have seen the trials of the most elaborate
constructions of this kind that human art,
aided by protracted study and experi'
mental research, has as yet been able to
make. Without commenting upon the
success or failure of any one of these
structures, / will only ask you to con-
ceive an American 20-inch gun of just
double the power of any of those actually
used directed against them
Such is the "dilemma imposed upon
u.s." and you are quite right in the use oil
the pronoun. 1t is not dilemma for
"engineers alone, but for the nations
which it concerns. 1t is quite common
| to attribute to engineers certain
"opinions which they ara warned they
must change" Until, however, some
thing is established with regard to future
construction, we must try to make the
best use OF such means as we have, and
including among them earth obstruc-
tions, torpedoes, floating batteries, etc.
and, though last, perhaps not least, the
newly devised carriage, which | should
call the Moncrisf we're it not that a
model by an American engineer ofi
Ger, on precisely the same principle, has
been in existence for many years, aud
that other plans to accomplish the same
purpose have been under study, and even
trial, with us during the last year or two.
| am, very respectfully, ETC.,
j. B. BARNARD,
Col ofEugineers, Brew. Msj. Gen. U.S.A.
.
The above remarks apply to all the nrinEs
| Reduced charges were used 70 begin with
afterward increased TO mdriBaa, but as the gun.
were really at 120 and $50 yards. the accuracy
was always almost perfect, and such bits could
! not probably be made BY hostile feet in .