Richmond daily Whig. [volume] (Richmond, Va.) 1842-1861, 1861-06-29
From the London Army and Navy Ga,ette. Nav Il

From the London Army and Navy Ga,ette May IS.
The rev principle OF casting large 60 s-holow in
stead of solid-by OF curren. cf water intro
duced into the which forms the mould Of the bore
thus cooling from interior has been successfully applied
10 the manufacture OF monster at the Fort Pit
Foundery, Pittsburg in the United States Of America
il is found practically that guns of large csbre cast by
the ordinary solid method have not the requisite strength
to bear the strain in rrg owing to the fact that melted
iron shrilkl in COOLING the process Of sodifyDg not
heirg Simultaneous Throughout; the mass but progressive
from the sufsce iuwards Ia consequence of the strong
compression termed the fstcooed portions
1t is obvious that, independently of hawa and cavities
about the surface Of the bcre who're the greatest strength
and hardness required the metal is there the asI
dense and tho least hard of the whole mass; and it
mainly o"iag to this fact that guns become soon un
serviceabls by the ensrgsuen of the bore round the
seat Of the bal after prolonged firing The Of COM
resson tie outer crust OF the gun essss the Internal
Cors Of he charge and after certain number Of rounds
with ull charges the gun bursts The greater the
Of the casting the greater the Irregularities of structural
arrangement and the unfit the gun becomes to
st the strain OF explosion. Hence the hitherto pr4ci
cal limit to the cstro Of cast iron gum no nation hay-
ing yet succeeded in manu.c uring safe and service
able guns of more than ten inches cslbre.
BY the usT process of c0oiug late. nally the metal
sbcu: ths bore in of compression, and the
terror in a state Of tens0r which, in fact is what il
ought TO be- in Cr3e to obtain the greatest 9Th OF
the whole thickness oi metal when suhected TO internal
strains. Moreover the metal about bore first cool
ID will be- it should BE-, the hardest and denscst On
the old systen Of the inequalities produced
in the pysicL sructure of the metal ID well known
that beyond a certain limit little increase Of
strength s 10 the gun by increasing s thickness OF
metal and that on this account, practical limit has
hitherto been placed TO the manufacture OF cannon OF
very large cahbre, which would he found incapable
O; Tess,iig hs Great siTens TO which h,d
subjec new era in the casting OF iron Cannon has
commenced. and We proceed TO describe the lat
Ia al.
process
The monster gun, better, perhaps known by the
Of the l5-ineh gun has the following Dimensions
Is total length il Is feet 10 niche gressost exterior
diameter feet across the breech iuing down TO IS
inches at the muzze The thickness Of metal behind the
epsodtl chsmper IS 25 inches and l6t nctes at the
junction OF the bore with the chamber timing Gown TO
inches st the muzze. The weight OF this enormous
piece Of ordnance is nearly 30 tons. The solid Gs-
FOUNDER the heaviest caNtron guu of our service,
reighB about forr Ions fifteen hundred weight
The lJ.nch gun is usod a. Fortress Monroe upon an
iron pnts carriage, running up and rscoiug in
the usual msnuer, and hes shells OF two csssfs. The
fret. to be used where the greatest possible explosive e
feet is wanted of the minimum thcl Ut ilces) ad
miss ole TO endure the shock Of the &C. about 30J
pounds weight aiming about eigb;ceu pounds Of pow
der The second, for batterng purpose RAG wall Of
FIVE inches thickness and weighs Al pounds. There is
sso solid shot of the enormous weight OF As pcund9:
but for the already mentioned connected With
solid castings OF large masses is very doubtful is
pacticabe cast satisfactory sod shoi OF this fiaa
ster The Nindsge allowed is onc-,enth OF an inch.
M,jor Barnard, of the American Engin sr, rho has
published most interesting INT OF this cannon,
gives the following summary OF the practice carried
with il in the experimental uisl,: la five tfial' at
1000 yards with thirty I've pounds Of powder, the lat
rrA teTsiions ooI6ued within 6ge yards On either
.le of target The vertical Deviation probably duo to
varying initial yeoci.ies pcrhapa to diaronce 10
the weight of the shells ranged yad- zach
a. fairy a.. Of
ed powder the initial velocity found 10 be 32s feet
yer second The greatest range attained, with iae
mum elevation OF q deg. 30 min, Was 5,72O yards,
Si,h time Of fight Of twenty seven seconds.
Such Immense charges, however, produce far less
strain Oh The gun than might be supposed owing to the
nature of the powder used aud described in the Official
report "l4rgegained," and as Rodmans perforated
cake pOwje The former II OF l0hs inch cube 10 the
-as Of its gf.iE; the latter is compressed into scd
cakes It oon.ijerabs pressure and perforated with
holes to admit to ke flame The o. ct Intended
by this Improvement i4 to rcGrd the burning analogous
10 the plan adopted by Sir William Armstrong; SLOW
burning POWDER and thus reduce the excessive STRAIN
which all guns subject with fine grain powder end
which, by the number Of angles presented TO the gGcs
Of asmc irfsmad almost insantaneously and before
the heavy prc ce is started from s sea-. This result
i estimated by pressure guGge introduced inio the
chamber of the gun. The comparative initial pressures
Of the pcrforat,d cake" large grained, and common
canton powder, a;e estimated to have sbou. the
ratio of one-geventb one third, and unify-a result of
very great Importance in s bearing upon the practcs
by of using csst-ron guns Of extraordinary cabres.
# will be interesting tLs point, 10 notice the per-
formance Of TIE Eagsh monster gun, better known
too Horsfall gun, mounted Scuthsea Castle Ports
mouth; this being the largest piece Of ordinance thoro
made in this country The weight Of this gun about
twenty-five TONS and it throws solid shot OF about 800
pounds Of weight One hundred and thirty rounds have
been f-cd wnh charges OF forty aud fifty pounds of
powder and With eighteen degrees Of elevation, range
o. i.tle 5000 yards obtained. But that the
cannon Was uuable stand these proof charges COM
para.ivcly oder.te for its cabre known 20 be
strongly suspected by the Director General Of Artillery
srd this opinion confirmed By the discovery Of a
crack OF over three uches ia length in the ch'mber
when searched and examined lately by Captain Freetb,
Assistant Inspector of Artillery 1t is probable that it
will be sgau subjected to proof at an early date The
The Am.r rcsn inch had up to the date OF
the Ia -. reports fred $50 rounds with full charges
and 1T The 300h round whom the last search made,
the most delicate tests applied to the bore failed to in.
dcate the slightest enlargement or deterioration Of any
Lind.