AN IMPROVED COMPENSATION APPARATUS FOR A HAIR SPRING BALANCE FOR A WATCH OR TIMEPIECE
Year: 1858

page_text: LETTERS PATENT to Edwin Bartholomew Horn, of the State of Massa-
chusetts, of the United States of America, for the Invention of "AN
IMPROVED COMPENSATION APPARATUS FOR A HAIR SPRING BALANCE FOR A
WATCH OR TIMEPIECE."
Sealed the 14th January 1859, and dated the 21st October 1858.
COMPLETE SPECIFICATION filed by the said Edwin Bartholomew Horn
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 21st October 1858, pursuant to the 9th Section of
the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, BE IT
KNOWN, that I, EDWIN BARTHOLOMEW HORN, of the State of Massachusetts,
of the United States of America, have invented "AN IMPROVED COMPENSATION
APPARATUS FOR A HAIR SPRING BALANCE FOR A WATCH OR TIMEPIECE," and do.
hereby declare that the nature of the said Invention, and the manner in which
the same is to be performed, or in other words, its construction and mode of
operation are fully described and represented in the following Specification
and the accompanying Drawings, of which Figure 1 exhibits a top view,
Figure 2 a side elevation, Figure 3 a front elevation, Figure 4 a vertical-
and longitudinal section of a hair spring and balance furnished with my
Invention.
In the Drawings A exhibits the balance, and B the hair spring of an
ordinary watch, the same being supported beneath a standard C.
It is well

page_text: known, that owing to the expansion of metals under any increase of
temperature, it is very difficult to keep the hair spring of a watch at a
uniform degree of tension. The purpose of what is termed the "chronometer
balance," is to compensate for the stretching of the hair spring, caused by
different degrees of temperature.
Instead of the chronometer balance, or any such contrivance making part
of a balance wheel of a watch, I employ what may be termed an expansible
or compensating spiral coil D, separate from the balance wheel, and formed of
two strips of metal a, b, laid side by side, and united together where they
touch one another; one of the strips, viz., a, being made of brass, while the
other or outer one b, is constructed of steel. The effect of heat on one of
these metals is to expand it much more than the other, that is to say, the
expansion of the brass will be about double that of the steel.
The con-
sequence will be that when the coil expands the extreme outer end of it will
be retracted instead of being advanced, and of course the movement will be
in the direction opposite to that of the adjacent or outer end of the hair spring,
the spiral coil being held stationary at its inner end, and having its outer end
connected to the outer end or part of the hair spring B, as shewn at c. The
hair spring at its inner end is attached in the usual manner to the balance,
and has its outer coil laying in a slit, formed as shown at d, in the rear bent
arm of an index lever, pointer, or regulator E, such as is well known and in
common use in most watches, its purpose being to so affect the action of the
spring, as to make the watch go either slower or faster, as circumstances may
require. The inner end of the spiral compensating scroll is fixed to a cylin-
drical projection e, extending upward from a plate F, which turns on a pivot f
extending upward from a standard G. Thus, when we turn the plate F
laterally on its pivot, the compensating scroll, the hair spring, and the balance
will be moved with it, consequently the pin or tripper g of the escapement
lever will be moved with such movement of the balance. Thus, it will be
seen, that the object or purpose of the movable plate F is to enable the said
pin or tripper to be properly adjusted to the escapement lever. The movable
plate F is furnished with a semicircular arch projecting from it, as shown in
the Drawings. This arc carries a slider i, which is notched to receive the
compensating scroll, which fits closely in the notch. This slider affords a
means of regulating the action of the compensating scroll, for the nearer the
slider is moved toward the outer end of the sroll, the less will be the amount
of movement of such outer end under any change of temperature. The slider
is therefore a regulator for the scroll with reference to its action on the hair
spring.

page_text: The advantage of my Invention over the well-known chronometer balance,
or that in which the rim of the balance wheel is made of two separate
concentric rings, one of which is composed of steel, and the other of brass, is
as follows:-First, the chronometer balance is very difficult of construction
and adjustment, and requires great care and skill in its manufacture and
adjustment; but mine can be made and applied to a watch at very much less
cost, and can be adjusted with far greater ease, and is not liable to get out of
order or adjustment. Besides, it has the advantage of the means of adjust-
ment of the beat or the pin or tripper g, of which the chronometer balance is
wanting.
I claim the application to the hair spring balance, and so as to operate
therewith, substantially as described, of a compensating scroll or coil D, com-
posed of two metals of variable expansive properties, and arranged together
substantially as described, or otherwise suitably constructed to effect the object
herein-before specified.
I also claim the method of applying a spring holder or stud, or a com-
pensating scroll to the hair spring and its stand, viz., by means of a movable
plate F, or its equivalent, supported so as to be capable of turning on a pivot
or its equivalent carried by the stand, the same being for the adjustment of the
beat, or the pin or tripper of the escapement lever, as specified.
I also claim the combination of the adjusting slider i, or its equivalent,
with the compensating scroll and the plate F, or its equivalent, the same being
for the purpose or to operate as specified.
In testimony whereof, I have hereunto set my signature and seal, this
Fourth day of October One thousand eight hundred and fifty-eight.
EDIZIN DARTHOLOMEW W HODN
EDWIN DIDTHOLOMEW HORNT
TOTOT
(Ms.)