, 1864-11-29
i Wrouglt.Iron Shield for the Cron.
atadt DefenseA,

! The London Herald has the following ac
| coutn Of anew device Of defensive warfare, o.
which some mention has already been made ::
The wrought-iron. shield for the Cronstadt
nefenses was shown on Saturday afternoon ia
the guests Of Sir John D. Hay and the Millwall
60 at distance Of 100 yards, it might be takei,
for m ordinary work Of masonry some forty
or fifty feet long, and ten or twelve feet high.
with three embrasures in the usual places.
Close inspection, however, dscloses the suc-
cession OF iron layers or bars, twelve inches
BY twelve inches, extending third Of the
and nut fastcnings at the butts to The rear.
such is the front VieT-a view, by the way,
which goes to show that unless special knowl-
edge were possessed Of the material with
which an e!eny's works were faced, it would
be impossible, in war, to say whether the ma.
tcriAl is brick, stone or Iron.
The exact measurement Of the front is 4316
feet by 10 feet md the 12-inch by 12-inch iron
layers or bars weigh COO pounds yard. The
side or end views Of the shield reveal the chief
mysteries Of construction. The sides or ends
resemble IN inclined capital letter 4, tho
front Of the shield being the upright Or verti-
cal arm Of the letter, and the rear bnttresses
the inclined arm Of the letter. Between the
inclined and vertical or upright arms of the
letter arc the elements of strength and cohe-
sion. First Of all; It is seen that the twelve
inches By twelve inches Of wrought iron layers
or bars Of the face or front of the shield, CO.
here by dovetailed projections and reccsscs-
the modified tongue and groove Of wood
1ooring-such as were first adopted in the
Thorneycroft iron wall. The tongue and
groove keep the taceor front Of the shield TO-
Eether, and face:or front cohesion ia obtained
10 the rear buttresses in simple, and as it
appears, an efficient manner.
The plan is as follows: At the back of
each Of the face or front layers or bars q dove
tail tongue projection has been rolled to cot-
respond with the tongue projection which fits
into. the grove, to form the face or front wall,
The back dovctail tongue, be it observed, is.
like the other, homogeneous portion Of eacl,
layer or bur. The back doyetai1 tongue Of
each layer or bar is then fitted, and firmly
keyed into the d0yetails Of corresponding
upi isht on the face Of the rear butresses ia
secure the Whole. Nothing could be simpler,
and as has already been stated, the cohesion
long sustain the pounding Of heavy ordnance,
is point on which no opinion need be offered i
because experiment can alone determine.
The rear bnttrcsses are four in number.
at the base four feet and at the top
eighteen inches. Such is the side or end views |
Of Tue shield Views revealing q simply con-
trived cohesion Of the heaviest mass Of !
wrought iron that has ever been put together. |
Standing, last of all, in the inside Of the /
shield, the three embrasures first attract at- |
tention. They are four feet in height, By two
feet two inches in breadth and the weakness
which they give the shield is compensated By
vertical box bnttrcsses, one on cach aide Of |
Zach embrazCre. These box buttresses, at the |
sides Of the embrasures, arc distinct, and in
addition to the four rear huttresses already
named. The box buttresses at tho sides Of
he cmbrasurcs merely compensate for the
Weakness Mt the embrasures, and to do so I'll
:icntly they hare doyetails Oh their face which
It and lay into the dorctalls, IN. the rear, of
he front myers or. bars.
: Near the shield Is stationed short but
nassire 600 FOUNDER iron carriage for the
anne destination as the shield: The carriage
s for q gun with trunnions, and the rear Of
he gun rests ona great double screw, which,
n addition to eleynting the gun, acts in place
# compressor to check recoil. The new
method Of compression for rceoa Is simple,
Fhether it answers practically. It is com
,ression by sheer resistance from the screw.
he screw tightening the wheels Of the gun.
a1riagc to the gun platform. The uainiRRum
# rccoil Is anucipated,'