New-York tribune., 1867-08-22
THE XV-INCH GUN At SHOEYBURYNESs
To the Editor Of The Tribune.


SIR: May | ask of you the favor to publish
few remarks on your editorial 'The Rodman Gun st
shoeyburyness," in your issue of the 10th inst.
First with respect 10 relative power and quantity or
powder used the l5nch gun in the late trials against
the target HOu say 1.-THE charge used was GO pounds OF
American pOwderthat Is TO say 10 pounds more than tho
ordinary charge"
The ordinary charge is co pounds Of No. cannon pow
der But tho powder used on this occasion was what
called mammoth" powder, 80 pounds OF winch
reckoned equivalent TO only 35 pounds OF No.
powder and the charge used on the Shoeyburyness trial
was therefore, equal only pounds Of the latter
Is pounds less than the ordinary service charge.
This settles the question or powder ana proves con-
cusiyey that not only would very slight increase IN
velocity have put even east-ron shot clean through
this formidable target but also that the gun has repeat
edy impaired TO its shot 40 per cent more oS
than the late experiment on the English trial ground
then tried with go shot OF chilled iron and charge OF
Now simple calculation shows that the co 70 of "mam-
moth grain powder used in the l6inch guns equals in
guns the American navy And the 9nch English shot
only bored hole 10 inches deep, while the l5nch sph0r.
cal ball pierced huge hole i'll the tough Snch plate, and
bucked and injured the target over an area oi seVerai
feet
that with iron shot and at seventy yards range II could
not hurt the best OF the British irOncads and that
with steel shot (Which are not part OF ITS e49pnens
vessels which would successfully resist
It," The following extract from The London Mechanics
aGa-ne OF June % reliable authority on such SUBJECTS
The effects Of these alike important every cOunty in
their penetration The Warrior and L, Gor.
classes would certainly os h Gs1Ig i tS INV we b % ave s S
IL E whether they Hercus
ought keep these missiles out but she not yet shoat"
And this the opinion given on the strength of trials
in which cent less than the actual power Of the
gun used. Hence the following remark from the
same article:
But there is no doubt that ee gun would fTe %A1 rounds Of T. 70 Of
teay probably that the 81 charge having proved
crush the thick plates the extra 10 10 poSdet
would have pele completely through the wood bakns
great deal more remains be said tins subject,
but the above clearly shows that 5-neh round shot
with an initial velocity OF less that 200 rect per secohd'
can walk through nearly all the English and French non
clads and that with velocity OF l0Oo leet- bearing Ia
increases as the square OF seeutt
will 90 through any European brOadside lrOnclad.
A. fbe iron lads Kalamazoo class protect every
eXpOsed portion OF their huls, and no less
than IA inches OF iTon and viii carry l5noh guns
0Onch necessary, 10 does not likely that III " the
british and American irOnclads should go INTO
ton against each other should be blown out OF tho
water before had knocked single hole III our enemys
huls" In.
Ne,c- YORK, Aug. 10, 1867
TOur correspondent gives authority for his state
ments respecting the quality of the powder used at
the ShOeburyness trial Ii said in several of the
English reports that the gun and powder were
bought together in this country for tho purpose OK
the trial and that the powder was that ordinarily
used with the ROdman gun IN the American navy
THIS NAV hayebeen an error and l. n. may be rignt.
Ii So good deal OF allowance must be maze iol Ilo
unsatisfactory performance of the gun at SnOepury
ness The statements of The Mechanics magazine, nav
inQ been published month before the tial nave no
particular bearing the present case ana ouI CoI
Iresnondent's epnon that the American lo-lnch gun
aid more damage TO the target than the EhgIlsn
a ;ncb 10 entirely unwarranted by the facts. WI hat
the Rodman cannon might do WIN heayler
cbaroes of powder we do not undertake TO predict.
So far as actual experiment goes there can DO no
doubt that the English have beaten it-EDI