A CERTAIN METHOD OP TEMPERING ALL INSTRUMENTS AND MANUFACTURES OF STEEL
Year: 1789

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
HARTLEY, of Golden Square, in the City of Westminster, Esquire, send
greeting.
WHEREAS His most: Excellent Majesty King George the Third; by His
Royal Letters Patent under the Great Seal of. Great Britain, bearing date 'the
Ninth day of June, in the Twenty-ninth. year of His reign, did give and 'grant
unto me, the said David Hartley, my executors, administrators, and assigns,
His especial licence, full power, sole privilege and authority, that I, the
said David Hartley, my executors, administrators, and assigns, and every! of
them, by myself and themselves, or by my and their deputy or deputies,
servants or agents, or such. others as I, the said. David Hartley, my 'exécutors'
administrators, or assigns, should at any time agree with, and no others, from
time to time and at all times.thereafter, during the term of years therein
expressed, should and lawfully.mightimake, use, 'exercise, and vend, within that
part of Great Britain, called England, His Dominion of: Wales, and Town of
Berwick-upon-Tweed; my said Invention of "A CERTAIN METHOD OP TEMPERING
ALL INSTRUMENTS AND MANUFACTURES OF STEEL," in such manner as to me,
the said David Hartley, my éxecutors, admors, and assigns, or any of them,
should. in my or their discretion. seem, meet; and that I, the said David
Hartley, my executors, administrators,. and assigns, should and lawfully, might
have and enjoy the whole profit, benefit, commodity; and advantage, from time to
time coming, growing, accruing, andiarising by reason of the said Invention,
for and during the term of years therein.. mentioned; to have; hold; 'exercise,

page_text: and enjoy the said licence, powers, privileges, and advantages therein-before
granted, or mentioned to be granted, unto me, the said David Hartley, my
executors, administrators, and assigns, for and during and unto the full end and
term of fourteen years from the date of the said Letters Patent next and
immediately ensuing, and fully to be compleat and ended, according to the
Statute in such case made and provided; in which said Letters Patent there is
contained a proviso, obliging me, the said David Hartley, by an instrument in
writing under my hand and seal, to cause a particular description of the nature
of my said Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within one calendar month
next and immediately after the date of the said Letters Patent, as in and by
the same (relation being thereunto had), may more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
David Hartley, do hereby declare that the said Invention consists, and is made
and performed, in the following manner, viz*:-
A new and scientific principle of tempering all edged instruments and other
manufactures of steel, independant of the mode hitherto accustomed of temper-
ing them by colour, viz, by the application and use of any pyrometer, or
thermometer, or any other precise or regulated mode of measuring heat, in the
hardening and tempering of steel, according to the respective degrees of heat
which the respective sorts of steel, or the respective sorts of edges, or other
instruments of steel, may require. The principle which constitutes the Inven-
tion is, the application of the above mentioned mode of measuring heat, as
the certain and infallible test and means of communicating the respective
degrees of heat which may be required uniformly and without the least variation
through the whole substance and every part of any edged or other instrument
of steel, of what shape, or size, or description soever. The tempering beats are
various, according to the various sorts of steel and the different instruments to
be tempered. In general, they lye between the points of four hundred degrees
and six hundred degrees. upon Fahrenheit's scale of heat. The principle
of tempering by thermometrical test being established, the precise points of
heat are to be adapted to the respective sorts of steel and the respective in-
struments to be tempered. It is not possible to enumerate all the various
ways which may be devised for indicating precise points of heat by thermo-
metrical test. The most accurate and comprehensive description that I can give
of the general principle and manner of applying this test to the tempering of
steel is, by putting the thermometrical test, whatever it may be, close and con-
tiguous in the same place or vessel, or immerged in and surrounded by the
same medium, of what nature or kind soever that medium may be, or of what-

page_text: ever substance or materials it may consist, for receiving and communicating
heat, together with the instruments to be tempered, in such manner that what-
ever degree of heat shall be applied so as to effect the instruments of steel, the
same degree of heat shall be indicated by the thermometrical test, and thereby
afford certain and precise means of administering and regulating such proper
degrees of heat in tempering of steel, as the case may require.
This is a particular description of the nature of my said Invention, and of
the manner in which I do use and perform the same.
In witness whereof, I have hereunto set my hand and seal, this Third day
of July, in the Twenty-ninth year of the reign of our Sovereign Lord
George the Third, by the grace of God, of Great Britain, France, and
Ireland, King, Defender of the Faith, and so forth, and in the year of
our Lord One thousand seven hundred and eighty-nine.