A NEW OR IMPROVED MANUFACTURE OF BILLIARD BALLS AND SIMILAR OBJECTS
Year: 1876

page_text: LETTERS PATENT to Gustav Magnus, of Berlin, Prussia, for the Invention of
14
A NEW OR IMPROVED MANUFACTURE OF BILLIARD BALLS AND SIMILAR
OBJECTS."
Sealed the 8th August 1876, and dated the 11th February 1876.
PROVISIONAL SPECIFICATION left by the said Gustav Magnus at the Office
of the Commissioners of Patents on the 11th February 1876.
GUSTAV MAGNUS, of Berlin, Prussia. "A NEW OR IMPROVED MANUFACTURE OF
BILLIARD BALLS AND SIMILAR OBJECTS."
The object of this Invention is to produce a new material which shall be cheaper
than ivory and at the same time quite as suitable for billiard balls and similar
articles. Various materials have been proposed but none have hitherto proved
suitable; efforts have more especially been directed towards the production of a
material having india-rubber for base. After three years of constant and expensive
trials I have at last succeeded in inventing a material for and mode of manufacture
of billiard balls superior to those of ivory and much cheaper, all as hereafter
described.
The trials heretofore made by others with india-rubber have failed chiefly
because they could not vulcanize to a greater diameter than from about 2 to
32 inches without causing the core to crack and the ball becoming porous. It is
also well known that the rubber expands considerably in the vulcanizing, and by
a size of 2 to 23/4 inches this expansion is so considerable that moulds of tin are
bulged and even burst. I therefore make my moulds of cast iron.
The inner half spheres of the mould are tinned. The two parts are held together
by means of and between discs and tic bolts.
The vulcanizing has heretofore usually been done in about 1/2 to 2 hours, and
by a temperature of 315 degrees Fahrenheit and more. As however the aforesaid
cast-iron moulds even are unable to withstand the aforesaid quick expansion, I
according to this Invention take about ten hours for the vulcanizing and employ
a gradually increasing heat. After the vulcanizing I turn the ball accurately. In
order to make the balls of the same specific gravity as ivory, I add about 50 per
cent. of heavy spar (Schwerspath) to the rubber. I color the balls if required
before vulcanizing, and the color may thus penetrate an eighth of an inch or more.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Gustav Magnus in the Great Seal Patent Office on the 11th August
1876.
GUSTAV MAGNUS, of Berlin, Prussia. "A NEW OR IMPROVED MANUFACTURE
OP BILLIARD BALLS AND SIMILAR OBJECTS."
The object of this Invention is to produce a new material which shall be cheaper
than ivory and at the same time quite as suitable for billiard balls and similar
articles. Various materials have been proposed but none have hitherto proved
suitable; efforts have more especially been directed towards the production of a
material having india-rubber for base. After three years of constant and expensive
trials I have at last succeeded in inventing a material for and mode of manu-
facture of billiard balls superior to those of ivory and much cheaper, all as hereafter
described.
Ivory is not homogeneous, the core or inner parts are heavier than the outer,
hence the centre of gravity is rarely in the very centre of the ball, and thus the
accuracy of their action is impaired. My new material however is perfectly homo-
geneous; take a billiard ball made therowith and one made of ivory, put them in
a bath of mercury, and it will be found that the ivory ball will oscillate while the
other at once gets into a state of rest. Ivory balls will only take a small quantity
of colouring matter without the material becoming impared, and henco recoloring
is necessary after a while. Balls made with my material are dyed before being
vulcanized, and have an outer dyed scale of about an eighth of an inch thickness.
The outside of ivory balls often soon splits and cracks, and they have then to be
turned up again causing inequality in the sizes of a set of balls; this is impossible
with balls made of my material. The latter have moreover a much greater elasticity,
which has been proved by throwing one with full force against a stone when it re-
bounded about eighty feet in height and was quite unhurt. The bone of mammoth
and other extinct animals which has a smaller elasticity than ivory is sometimes
used for billiard balls. But balls made of my material are at least as elastic as the
best ivory and considerably cheaper, and ivory is gradually getting dearer.
The trials heretofore made by others with india-rubber have failed chiefly
because they could not vulcanize to a diameter of from about two to three and a
half inches without causing the core to crack and the ball becoming porous. I
therefore first tried to harden a ball about one and a half inch diameter, I then
surrounded it with a layer of soft rubber to a diameter of two inches and vul-
canized it afresh; I then surrounded it with a layer of soft rubber to a diameter of
two and three-eighths to two and three-quarter inches and vulcanized it again.
Balls so produced nevertheless had several faults, thus, the layers had no mutual
cohesion, the durability was impared, the sound produced in the use of them was
hollow, and the centre of gravity was not in the centre of the ball. There remained
then only the difficult problem of making the balls of the full size at once and to
vulcanize them without producing the aforesaid faults, and I invented a mode of
moulding and vulcanizing. It is also well known that the rubber expands con-
siderably in the vulcanizing, and by a size of two to two and three-quarters inches,
this expansion is so considerable that moulds of tin are bulged and even burst, I
therefore make my moulds of cast iron.
Figure 1 of the annexed Drawing shews such a mould. The inner half spheres
of the mould are tinned. The two parts are held together by means of and between
discs and tie bolts, as shewn at Figure 2.
The vulcanizing has heretofore usually been done in about one and a half to two
hours, and by a temperature of 315 degrees Fahrenheit and more. As however the
aforesaid cast-iron moulds even are unable to withstand the aforesaid quick ex-
pansion, I according to this Invention take about ten hours for the vulcanizing, and
employ a gradually increasing heat. After the vulcanizing I turn the ball accurately.
In order to make the balls of the same specific gravity as ivory I add about fifty

page_text: per cent. of heavy spar (Schwerspath) to the rubber. I color the balls if required
before vulcanizing, and the colour may thus penetrate an eighth of an inch or more.
And having thus fully described the nature of this Invention, I declare that I
claim the hercin-before described mode of manufacture of billiard balls and similar
objects, substantially as set forth.
In witness whereof, I, the said Gustav Magnus, have hereunto set my hand
and seal, this First day of August, in the year of our Lord One thousand
eight hundred and seventy-six.
GUSTAV MAGNUS. (L.S.)