IMPROVEMENTS IN CON- STRUCTING ARMOUR FOR SHIPS AND FORTIFICATIONS
Year: 1862

page_text: .PROVISIONAL SPECIFICATION left by Carl Johan Laurentz Leffler at
the Office of the Commissioners of Patents, with his Petition, on the 17th
December 1862.
I, CARL JOHAN LAURENTZ LEFFLER, of Gefle, in the Kingdom of Sweden,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN CON-
STRUCTING ARMOUR FOR SHIPS AND FORTIFICATIONS," to be as follows:-
This Invention has for its object "Improvements in Constructing Armour for
Ships and Fortifications." For this purpose I employ bars of a width sufficient
to form the thickness of the armour, and I place them the one on the other, so
that the edges of the bars form the face of the armour; so far the arrangement
is similar to what has before been proposed, but I do not as is now usual form
rivet or bolt holes through the bars, as such holes greatly weaken the bars, nor
do I otherwise connect the several bars the one to the other throughout their
whole length so as to prevent their yielding when struck independently the one
of the other, for a rigid mass is more easily penetrated by a shot than one that
is able to yield to the blow, but I secure the bars at their ends by causing
them to enter grooves in metal ribs or frames which are attached to the main
frame of the ship or structure, these ribs or frames are formed of metal bars
rolled in one piece to the required grooved form, I do not attach the grooved
ribs or frames to the main frame by through bolts as this would weaken the
frames, but I form recesses in the grooved ribs or frames to receive the heads
of bolts, and these bolts where a timber backing is employed passed through
this backing to the frame behind. I do not either as heretofore make the

page_text: bars of which the armour is formed either entirely of iron, or entirely of steel,
but I make each bar a compound bar, a bar of steel and a bar of iron welded
together, then the iron is sufficiently tenacious to resist breakage, whilst the
steel will protect the iron from being cut through by the shot, or in place of this
arrangement alternate bars of iron and steel may be employed. The top bar of
the series I form much stiffer and thicker than the others, so that it may be
able to keep the other bars in their places, thus the top bar becomes in fact a
narrow armour plate, and it may be secured by through bolts in addition to the
grooved ribs or frames before mentioned. Where the bars employed are of
considerable length, and consequently their flexibility if supported only at the
ends excessive, I limit this to any required extent by forming dovetailed
grooves at intervals in the back of the armour (or series of bars) and driving
bars or keys of corresponding form into these grooves.
In constructing armour plates, I form a pile of alternate plates of iron and
steel laid the one on the other until a sufficient thickness is obtained, and I
weld these altogether, and such armour plates may be secured in their places
by means of grooved 'rib's or frames retaining their ends, these grooved ribs or
frames are rolled to the shape required, which causes them to be much
stronger than they would be were they built up by riveting together several
separate bars.
Ribs or frames of grooved metal rolled in one piece may also be employed
for securing ordinary armour plates to the frame of a ship or structure.