Year: 1862




turret war ship She is to be clothed amid
ships with thick iron plates, which are to cx-
tend about five feet below the water line
and she will have three great revolving gun
turrets on deck, and powerful iron bca( or
ram on her bow. This beak resembles a
huge axe and is formed Of plates 30 feet long
Al inches thick, thus making nine inches Of
iron on the front edge. Each Of the revolv-
ing gun turrets will be 20 feet inside diameter
and the sides will be formed of eleven courses
of inch iron plates


These plates are laid over and rivctcd to
one another in such n manner as to "break
| Joints" and vertical plates are also boltcd to
| the several courses SO as to secure the whole
in the most rigid and perfect manner. These
gun towers, for the Roanoke, are now being
constructed at the Novelty Works in this
city, where tho plates for them, likewise
those for the armor are bent to the proper
curves. Each plate for turret is about nine
feet in length by forty inches in width and
an inch in thickness. Two courses of rivet
holes are punched out in each, and they are
all bent cold in a powerful hydraulic press.
The bed plate of tho press is of a concave
form, and the top block is of convex form.
A plate to be bent is placed upon the con-
cave bed plate of the press, and when prop
erly adjusted, the pump forces up three
rams under it, and the plate is reduced to
the proper curve against the top block. The
pressure to which each plate is submitted to
give it the proper curve is 100000 pounds.
BY this method of bending the turret plates
cold there is perfect uniformity and accuracy
secured for the whole. The turrets for the
Roanoke will be of a superior character, but
only six courses of plates have as yet been
laid on two of them.


The bending of the thick plates for the
ram. and also for the sides of the frigatc, is
quite different and difficult operation to
perform, compared with those Of the gun
towers. Each Of these plates has to be bent
to the proper curve to suit its own particu,
lar place on the vessel, and not only the
| broadSide, but the edges also must be bent to
suit the particular curves. The bending OPP
crati0ns are under the charge of Mr. George
Bonniwell, an intelligent young shipwrght.
| All these plates are hammered iron, and are
furnished by several companies in PcnnSvl-
vania, New York and Massachusetts, When
| they arrive they resemble huge, straight iron
slabs, varying in length from eleven TO TWEEN.
ty-two feet, and in breadth from twenty-five
to twenty!our inches, and their average
thickness is four and half inches. One of
eleven and half feet in length weighs 4, ,240;
one Of twenty two feet in length weighs over
four tons. Such masses Of iron are difficult
to move about, and the operation connected
with bending them are necessarily tedious
and troublesome and they require great care
and skill to conduct properly. OF course
it is impossible to bend such masses Of iron
cold, hence each plate is first heated to near
ly white heat in a long furnace, shaped
something like . bakers oven, with move
| able arch cover.


The press for bending is quito different
from the one used for turret plates. Out
wardy it resembles long, strong iron screw
press, used for pressing wooden cloth. Its
top block, or platcn is moved up and down,
but its bed is fixed and very solid. A dudg-
con hydraulic jack at each end supports and
moves the block up and down. The bed,
upon which the heated plate is laid, Is form
ed Of series Of adjustable bolster blocks,
each Of which is capable Of being set by
screw to any desired height on either side,
and at any desired angle to suit the bend to
be given to plate which is compressed be-
tween the descending top block and the adj
Unstable bed. \ plate is first placed in the
furnace, and it is then raised to nearly n
white heat. The cover Of the furnace is now





then siezed by powerful crane, secured on
carriage. The heated plate is now lifted,
the crane carriage moved back and the plate
swung around and placed in the press,
where it is perfectly adjusted to obtain the
proper curves. The huge top block is then
forced down, squeezing the great mass Of
iron into the desired shape


In about half an hour the plate has acquir-
oil npt cpt. ;t Il. t,iyn l,,
to have its edges plancd, when it is fit for
boiling to the frgate. The bolt holes are all
drilled. 1t requires a large number of men
to move such great heavy masses Of iron, and
from the time glowing plate is lifted out of
the furnace until it is secured in the press
the scene is one of extraordinary activity and
excitement, as the plate requires to be placed
in the press as expeditiously as possible be-
fore it becomes cool. The metal Of these
plates appears to be first class, but until
| within few days past they were furnished
very slowly by the different contractors. The
plating of the Roanoke will now proceed
with greater rapidity still she will not be
finished for several months to come. We
are told that this frigate is expected to OBJ
tain speed of about ten knots an hour
If she makes nine knots we shall be agreea-
bly, disappointed. AS the Roanoke will sit
very low in the water, we hope that proper
arrangements will be made for ventilation on
the main deck. The defects Of the Galena
and Monitor 50 clearly pointed out in the
Scientific American of last week, by an intel
ligent correspondent, will be reproduced in
the Roanoke, rendering her very deficient as
'sea boat" unless this advice is heeded-
Scientific daaerican.





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