IMPROVEMENTS IN THe Manufacture OF PROJECTILES
Year: 1882

page_text: LETTERS PATENT to Thorsten Nordenfelt, of Saint Swithin's Lane, in the
City of London, for an Invention of "IMPROVEMENTS IN THe Manufacture
OF PROJECTILES
"
PROVISIONAL SPECIFICATION left by the said Thorsten Nordenfelt at the
Office of the Commissioners of Patents on the 23rd February 1882.
THORSTEN NORDENFELT of Saint Swithins Lane in the City of London,
"IMPROVEMENTS IN THE MANUFACTURE OF PROJECTILES."
The object of my invention is to construct projectiles of iron or steel coated or
covered with a softer metal for the following special purposes.
1st To prevent by means of the softer metal the hard projectile from damaging
or wearing out the grooves of the rifling.
2nd To enable me to use a projectile closer up to the gauge of the calibre of a
gun than can be done if the hard metal is without such softer covering, as
the projectile might might stick in the bore and cause an explosion.
3rd To ensure better centreing of the projectile in the bore, and consequently
a steadier flight through the air than can be attained with the larger play
which is necessary if the projectile is not covered with softer metal.
4th To give if required rotation to the projectile by means of the softer metal
covering by letting it enter into the grooves of the rifling.
In order to do this I make the parts or parts of the surface of the iron or steel
projectile which have to be coated with the softer metal sufficiently even or polished
and I clean these parts by dipping the projectile into acid; then I insert the
projectile into a bath of copper or tin and apply electricity from a galvanic battery
or from an electrical machine-By this means I cause copper or tin to be deposited
on and to adhere to the surface of the projectile to the desired thickness for the
purposes above nained.
If I wish the coating of copper or tin to give rotation to the projectilo I make it
hicker in one or more parts of the projectile than in the other parts.
Or I put a disc or one or more rings of copper or brass round the projectile of
uch a diameter as to fill up the bore completely and then put on the coating over

page_text: this disc or rings, by means of the copper or tin bath; the coating put on in the
copper or tin bath assists in fixing this disc or rings on to the projectile.
If I wish to put a partial covering only on to the projectile I cover the remaining
parts with a suitable varnish to prevent the electro deposit taking place on the
parts which I do not wish to have coated with copper or tin.
If I wish to have the coating or covering of softer metal thicker in some parts
than in others I put the coating on first of the required thickness over the whole
projectile, or over the parts which I wish to have thinly covered; then I put
varnish over the parts I wish thinly covered, and put the projectile again into the
electrical bath and apply a thicker covering to the unvarnished parts.
By using a bath of copper or tin for coating projectiles with a softer metal I have
a more perfect means than any hitherto resorted to for centreing and rotating
projectiles and the objects can be attained more cheaply than can be done by any
other means.

page_text: the
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thorsten Nordenfelt in the Great Seal Patent Office on
22nd August 1882.
THORSTEN NORDENFELT of Saint Swithins Lane in the City of London.
"IMPROVEMENTS IN THE MANUFACTURE OF PROJECTILES."
"
The object of my invention is to construct projectiles of iron or steel coated or
covered with a softer metal, for the following special purposes;
1st To prevent by means of the softer metal the hard projectile from damaging
or wearing out the grooves of the rifling.
2nd To enable me to use a projectile closer up to the gauge of the calibre of a
gun than can be done if the hard metal is without such softer covering, as the
projectile might stick in the boro and cause an explosion.
3rd To ensure better centering of the projectile in the bore, and consequently a
steadier flight through the air than can be attained with the larger play, which is
necessary if the projectile is not covered with softer metal.
4th To give, if required rotation to the projectile by means of the softer metal
covering by letting it enter into the grooves of the rifling.
In order to do this I make the part or parts of the surface of the iron or steel
projectile which have to be coated with the softer metal sufficiently even or
polished and I clean these parts by dipping the projectile into acid; then I insert
the projectile into a bath of copper or tin and apply electricity from a galvanic
battery or from an electrical machine.-By this means I cause copper or tin to be
deposited on and to adhere to the surface of the projectile to the desired thickness
for the purposes above named.
If I wish the coating of copper or tin to give rotation to the projectile I make it
thicker in one or more parts of the projectile than in the other parts. Or I put a
disc or one or more rings of copper or brass round the projectile of such a diameter
as to fill up the bore completely and then put on the coating over this disc or rings
by means of the copper or tin bath, the coating put on in the copper or tin bath
assists in fixing this disc or rings on to the projectile.
If I wish to put a partial covering only on to the projectile I cover the remaining
parts with a suitable varnish to prevent the electro deposit taking place on the
parts which I do not wish to have coated with copper or tin.
If I wish to have the coating or covering of softer metal thicker in some parts
than in others I put the coating on first of the required thickness over the whole
projectile, or over the parts which I wish to have thinly covered; then I put
varnish over the parts I wish thinly covered, and put the projectile again into the
electrical bath and apply a thicker covering to the unvarnished parts.
**
By using a bath of copper or tin for coating projectiles with a softer metal I
have a more perfect means than any hitherto resorted to, for centering and
rotating projectiles and the objects can be attained more cheaply than can be
done by any other means.
In order that my said Invention may be most fully understood and readily
carried into effect I will proceed to describe the drawings hereunto annexed.

page_text: rotation as the projectile travels along the barrel. c is a covering of the softer
metal applied over the cup. If it be desired to produce the cup 6 by deposition
from a coating bath the projectile having been thoroughly cleaned is immersed in
the coating bath to the depth to which it is desired that the deposit should extend,
the electrical connections are made and the metal deposited from the solution until
it attains the requisite thickness. Or the surface may be varnished excepting
those parts on which the cup is to be produced and then the projectile may be
more deeply immersed in the coating bath. When a cup of the desired thickness
is formed the projectile is removed from the bath and the varnish is thoroughly
cleaned off before the next operation. Or in place of producing the cup by
electrical deposition a cup of the softer metal produced by casting or stamping
may be forced on to the base end of the projectile. The cup having been formed
or applied, the outer covering c, is then produced over it by electrical deposition
as already described in respect to the cup b. The covering c, extends over all the
parts of the projectile which can come into contact with the interior of the barrel.
Figure 2 represents a section of a projectile in which a base cup is not employed,
but in place thereof there are rings of the softer metal to take the rifling. d d are
these rings, they may be produced by electric deposition whilst the other parts of
the surface of the projectile are covered with varnish; or they may be rings cut
from a tube of the softer metal and forced on to the body of the projectile. The
outer covering c, is produced over the rings as already described.
Figure 3 is a section of a projectile similar to that shown by Figure 2 but
furnished both with base cup and ring.
Figure 4 is a section of a projectile which has first received a thin coating of the
softer metal by electrical deposition, sufficient to protect the projectile from rust:
and which has then been provided with a base cup b, and an outer covering c by
the means already described.
Having thus described the nature of my said invention and the manner of
performing the same I would have it understood that I claim :-
First, My improvements in the manufacture of projectiles of iron or steel,
consisting in the production thereon of base cups b, coverings c, and rings d by
the electrical deposition of a softer metal, substantially as described.
Second, My improvements in the manufacture of projectiles of iron or steel,
consisting in the application thereto of base cups b, or rings d, of a softer metal
than the body of the projectile, and securing the said cups or rings by an outer
covering of the softer metal produced by electrical deposition, substantially as
described.
Third. My improved projectiles, substantially as described.
In witness whereof I the said Thorsten Nordenfelt have hereunto set my
hand and seal this Fourteenth day of August in the year of our Lord