AN IMPROVEMENT OF THE BALANCE SPRINGS AND THEIR ADJUSTMENTS OF CHRONOMETERS AND OTHER TIME- KEEPERS
Year: 1836

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
JOHN DENT, of the Strand, in the County of Middlesex, Chronometer Maker,
send greeting.
WHEREAS His present most Excellent Majesty King William the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-third day of April, in the sixth year of His reign,
did, for Himself, His heirs and successors, give and grant unto me, the said
Edward John Dent, His especial licence, full power, sole privilege and
authority, that I, the said Edward John Dent, my exors, admors, and assigns,
or such others as I, the said Edward John Dent, my exors, adññors, or assigns,
should at any time agree with, and no others, from time to time and at all
times hereafter during the term of years therein expressed, should and law-
fully might make, use, exercise, and vend, within England, Wales, and the
Town of Berwick-upon-Tweed, my Invention of "AN IMPROVEMENT OF THE
BALANCE SPRINGS AND THEIR ADJUSTMENTS OF CHRONOMETERS AND OTHER TIME-
KEEPERS;" in which said Letters Patent is contained a proviso, that I, the said
Edward John Dent, shall 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 said Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, T, the said
Edward John Dent, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, are particularly
described and ascertained as follows, that is to say:-
It is well known that the delicate spiral balance springs of chronometers
and other timekeepers, and their adjustments, are exceedingly liable to injury,
from oxidation or rust, both during the progress of their manufacture and
when in use, and whereby they are not only subject to decay, but their rates
of-going-or-accuracy of performance is very considerably varied from time to
time. Now, this said oxidation or rust may either be caused by the moisture-
ordinarily contained in the atmosphere, especially in the sea air in voyages, or
in countries particularly exposed to its action. Nor are chronometers only
liable to suffer from these causes, but also from the perspired matter and the
breath of the workman during the progress of their manufacture.
Now, it is the chief object of my Invention to prevent as far as possible the
said oxidation or rust, by coating or defending those delicate parts of chrono-
meters with a coating or varnish sufficiently flexible to allow the perfect free
action of the balance springs, and yet capable of preventing the action of
moisture, or saline and other vapours, to which they are liable to be.exposed;"
and I hereby claim as my Invention, and the object of this Patent, the use and
application of any fit and proper flexible, defensive coating or varnish to the
more effectual prevention of oxidation or rust in the balance springs, and
adjustments of chronometers and other timekeepers. In order however to
afford an example of the best means I am acquainted with for carrying my
said Invention into effect, I will describe the composition of such a varnish or
coating as I have found to answer the purpose completely. I take half an
ounce by measure of pure spirit of turpentine, and put to it forty grains of
camphor, and also add ten grains of bruised gum copal to the said mixture, I
then heat it nearly to its boiling point, and keep it in that state for two hours;
I then filter the mixture through cotton or other proper substance. This
varnish should be kept in an air-tight bottle closed by a glass stopper, the
mouth of it being sufficiently large to admit the balance spring and its adjust-
ment, which are to be put into the bottle in a dry state, and free from oil or
grease; and after being completely immerged in the varnish, are to be carefully
drained before they are removed from the bottle. The balance spring and its
adjustment must then be placed into a temperature from two hundred to three
hundred degrees of Fahrenheit's thermometer, and be kept therein from six
to eight hours.
I would remark, that in place of using pure spirit of turpen-
tine and camphor. I prefer to use half an ounce of an oil found in portable

page_text: gas reservoirs when that oil can be obtained, but as portable gas is now but
little employed and is going out of use, the materials I have above described
will be found to answer well, and may be readily obtained from chemists, care
being observed in obtaining pure spirits of turpentine.
Having thus described my Invention, and the best means I am acquainted
with for carrying it into effect, I would wish it to be understood I do not
claim a right to any mixture or processes for varnish making, but only to
the application of any fit and proper and sufficiently flexible coating or
varnish to the balance springs and adjustments of chronometers and other
timekeepers, and thus effectually protect the said balance springs whilst
under the different exposures of temperature during their manufacture when
moisture is likely to be deposited thereon, and also to resist atmospheric
attacks, as well as the many damps and impregnated vapours to which the
chronometers and other timekeepers are frequently subjected on shipboard, and
particularly tropical climates.
In witness whereof, I, the said Edward John Dent, have hereunto set
my hand seal, this Twenty-first day of October, in the year of our