IMPROVEMENTS IN THE MANUFACTURE OF FILES, RASPS, RUBBERS, TAPS FOR SCREWING, AND OTHER TOOLS REQUIRING HARDNESS AND DURABILITY
Year: 1872

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF FILES, RASPS, RUBBERS, TAPS
FOR SCREWING, AND OTHER TOOLS REQUIRING HARDNESS AND DURABILITY."—A
communication from abroad by Pierre Barrét and Claude Verdreau,
both of Paris, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 15th April 1872.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF FILES, RASPS,
RUBBERS, TAPS FOR SCREWING, AND OTHER TOOLS REQUIRING HARDNESS AND
DURABILITY," a communication to me from abroad by Pierre Barret
and Claude Verdreau, both of Paris, in the Republic of France, to be
as followÓ •

page_text: mixed steel, the core or centre part of the file or other tool being com-
posed of ordinary or any well-known kind of steel, such as Bessemer
for example, whilst the exterior portion is composed of cast steel. By
this means the tool combines within itself the stability of the steel
composing the centre or core and the hardness of the metal composing 5
the envelope or outer coating, hence files made in this manner arc less
liable to break under a sudden shock or blow, whilst at the same time
their hardness is such as to ensure their lasting a long period.
•
In carrying out this Invention the piece of steel intended for the core
is heated, say to a white heat, and whilst in this condition molten cast 1
steel is to be poured over or around it either whilst in a mould or other-
wise. The two metals become immediately welded together, and the file
(supposing such to be the tool to be manufactured) is then cut, tempered,
and finished in the usual manner.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 15th October 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of April, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF FILES, RASPS, RUBBERS, TAPS FOR
SCREWING, AND OTHER TOOLS REQUIRING HARDNESS AND DURABILITY," a commu-
"

page_text: nication to me from abroad by Pierre Barret and Claude Verdreau,
both of Paris, in the Republic of France, upon the condition (amongst
others) that I, the said John Henry Johnson, my executors or adminis-
trators, by an instrument in writing under my hand and scal, should
particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I; the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, that is to say:— .
It is well known that files are generally composed of cast steel.
tempered, or of what is known as German steel, and in all cases of one
and the same metal throughout, which is forged in order to impart to
them the desired form, after which the blank is cut and tempered to a
suitable degree. Whatever precautions may be taken in general, in
these various operations, and especially in the tempering and annealing,
it frequently occurs that files are broken by blows or their teeth become
stripped or wear out rapidly either on account of inferior steel improperly
made having been employed, or by reason of the steel having been
improperly worked or overheated, or of its having been tempered to an
excessive degree.
Now according to this Invention, in order to obviate these defects and
to obtain files of a uniform quality, durable and not liable to breakage,
as also taps for making screws, which should possess the same
qualities, a "mixed or combined steel" is formed, that is to say, the
natural steel, or any Bessemer, Rives, or other steel is sheathed in or
covered with cast steel. The steel thus combined or sheathed admits of
the desired degree of hardness and rigidity being obtained on the
outside, whilst a certain amount of flexibility, and at the same time
great strength are obtained in the interior, so that files thus made are
more durable, much less brittle, and capable of being used for a much
longer period than others.
In carrying out this Invention in the manufacture of files and similar
articles, a piece of steel of any suitable description, either natural steel
as herein-before stated, cemented iron, Bessemer steel, Rives' steel,

page_text: German steel, or the like, is heated to a suitable temperature (in general
to the most elevated temperature that it is capable of withstanding), and
around this bar, whilst heated almost to whiteness, cast steel is run,
which becomes welded thereto so as to form one piece with it. This
combined or sheathed steel when worked, tempered and annealed, offers, &
as before stated, this important advantage, that the whole of the external
portion becomes harder and more serviceable for use, whilst the centro
or interior portion or core, which is necessarily tempered to a much
lower degree, serves as an efficient support, and consequently the tool
is less liable to become fractured. By this process, therefore, files, taps 1
for screwing, and similar tools may be produced both cheaper and of
better quality than by the ordinary methods.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider to 1
be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
First. The peculiar manufacture of files, rasps, rubbers, taps for
scrowing, and other like tools as herein-before described.
Second. The use of files, rasps, rubbers, taps for screwing, and other 2
like tools manufactured in the manner herein-before described.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and seal, the Fifteenth day of
October One thousand eight hundred and seventy-two.