IM- PROVEMENTS IN MANUFACTURING GUNS, CYLINDERS, AND OTHER HOLLOW BODIES
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by François Garnier at the Office
of the Commissioners of Patents, with his Petition, on the 25th
October 1871.
I, FRANÇOIS GARNIER, of La Mulatière, near Lyon (France), Iron
Master, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN MANUFACTURING GUNS, CYLINDERS, AND OTHER HOLLOW BODIES,"
to be as follows:-
The object of my Invention is to manufacture guns, cylinders, and
other hollow bodies of iron with a lining or interior of steel, and without
the intervention of moulding and fusion.
The Invention is based on the application of the metallurgical rules
and principles which are necessary in order to preserve in the com-
position and combination of the two metals, iron and steel, all the
properties of expansion and resistance inherent in the nature of each of
them.
The essential feature of the Invention lies in the mode of preparing
the iron body or cylinder in which the tube of steel to form the interior
or lining has to be inserted. This mode of preparation consists in the

page_text: employment of bars or bundles selected and combined in a particular
manner as herein after described with the object of rendering the iron
body or cylinder capable of great resistance in all directions while
preserving the advantages of the malleability and tenacity of the metal,
which are so important in the manufacture of guns, cylinders, and
analogous articles. The iron bars or pieces are of special form, and
easily shaped by rolls, but before being thus operated upon they should
be hammered in order to deprive them of all heterogeneous particles
more particularly those parts to which the steel has to be united or
welded.
This preliminary operation having been finished I proceed to the
following three operations:-
1st Operation. A bar of iron issuing from the rolls is cut at its two
ends to the desired length by means of a circular saw or otherwise,
and while it still possesses sufficient heat. I roll or twist it into the form
of a spiral cylinder, that is to say, it is twisted into close spirals so as
to form a cylinder. Upon this cylinder I roll or twist in like manner
a second spiral cylinder from a laminated bar, the twisting being in the
opposite direction to that of the first bar so that the lines of the two
spirals cross each other.
2nd Operation.-I apply outside the two spiral cylinders iron bars
arranged like the staves of a cask, the number varying according to the
size or calibro of the cylinder. The two spiral cylinders of iron one
within the other and covered with thesc iron bars constitute a hollow
iron pile or bundle perfectly cylindrical. I weld this pile or bundle
under heat at its two ends, and I then place it with a mandril in a
reverberatory furnace heated to the temperature of welding white. As
soon as the iron has reached this temperature I withdraw it from the
furnace and submit it to the action of a steam hammer, by which and
proper tools it is shaped into the requisito forms and dimensions.
3rd Operation.—When the iron has been thus properly welded and
shaped, and before it loses its heat, I introduce a steel tube into the
interior. The whole is then returned to the furnace with, a mandril of
proper diameter, and by intense heat and by hammering the steel is
welded or united to the iron, and these two metals now form one compact,
body of perfect homogeneity.
All the foregoing operations being thus finished it is only requisite
to submit the hollow piece to the action of the lathe.

page_text: The mode of manufacture above described gives the metal such a
power of resistance that in the case of guns a considerable quantity of
the metal may with safety be removed at the breech by making deep
grooves thereon so as to lighten the gun.