CERTAIN IMPROVEMENTS IN CHRONOMETERS
Year: 1821

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
FERGUSON COLE, late of Hans Place, in the Parish of St. Luke's, Chelsea,
but now of Park Street, Grosvenor Square, in the Parish of St. George,
Hanover Square, being both in the County of Middlesex, Watch and Chro-
nometer Maker, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth did, by
His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-seventh day of
January, in the first year of His reign, give and grant unto me, the said
James Ferguson Cole, my exors, admors, and assigns, His especial licence,
full power, sole privilege and authority, that I, the said James Ferguson Cole,
my exors, adiñors, and assigns, during the term of years therein mentioned,
should and lawfully might make, use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, and also in all His Majesty's
Colonies and Plantations abroad, my Invention of "CERTAIN IMPROVEMENTS IN
CHRONOMETERS;" in which said Letters Patent, there is contained a proviso, that if
I, the said James Ferguson Cole, shall not particularly describe and ascertain
the nature of my said Invention, and in what manner the same is to be
performed, by an instrument in writing under my hand and seal, and cause
the same to be inrolled in His Majesty's High Court of Chancery within two
calendar months next and immediately after the date of the said Letters
Patent, that then the said Letters Patent, and all liberties and advantages
whatsoever thereby granted, shall utterly cease, determine, and become void,
as in and by the same, relation being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
James Ferguson Cole, do hereby declare that the nature of my said Inven-

page_text: tion, and the manner in which it is to be carried into effect, is fully and
faithfully described as follows, reference being had to the several Figures of
the Drawing which is annexed to such description, viz:-
The escapement of this chronometer is a detached one, the improvements in
which consist in the application of a safety pin to a detent with pivots, a lock-
ing plate to the balance axis, and the return or unlocking spring in a reversed
position. The detent is a light bar and in the middle of which at A (Fig. 1) is
an axis with pivots; on the upper surface of this bar at B projects a small
stud or pin; this stud or pin B is acted on by an angular notch C cut into the
edge of a circular plate D, D, attached by the screw F to the upper surface, or
fitted friction tight on the pipe or neck of the flanch or main pallet E, e,
which flanch or pallet is firmly fitted on the balance axis at G (Figures 1
and 4). The plate D, D, I term the locking plate, the outer edge of which
extends a little beyond the extreme acting part of the main pallet e at H in
the detent bar. The locking pallet which detains the. escape wheel during the
excursion of the ballance is fixed. When this pallet H is adjusted to its proper
depth in the escape wheel the position of the safety pin B may be determined,
as its place in the detent bar must be such as to allow freedom between itself,
the extreme passage of the escape-wheel teeth, and the edge of the locking
plate D, D, on the balance axis. On the under side and near the extreme end
of the detent bar projects a stud K (Figures 1 and 2), into which, the return
or locking spring L is pinned. The depth or hold which the lifting or, dis-
charging pallet I takes on the acting extremity of this, spring is determined
by 'the counter pin in its acting end at L, 'which pin rests against the..nose M
of the detent bar, and is shewn through the locking plate D; D,. and flanch E,
both which must be supposed transparent. The opposite side of the detent
bar in (Fig. 1) is represented by (Figure 3), in which Figure .the stud K. and
unlocking spring L is shewn upwards; a right line drawn from the root K of
the unlocking spring to its acting extremity. L forms an angle of about ninety
degrees to a right line drawn from the center of the balance axis to-the center
of the detent axis. The .end L of the unlocking spring is of a hooked
form, and has motion in nearly a right line between the balance axis and that
of the detent. The detent bar with its appendages must be accurately, poized
or balanced, so that when freely suspended on its pivots no part thereof shall
preponderate. The action of this escapement is as follows: When the deep
part of the angular notch C in the locking plate is in au position between the
balance center and safety pin B the locking pallet H will be withdrawn from the
repose tooth of the escape wheel by the lifting or discharging pallet I (Figures 1
and 4), and the impellant tooth of the escape wheel will be at liberty.to fall on

page_text: the acting part e of the flanch or main pallet, to which the locking plate D, D,
is attached.; both these are together advanced by the wheel's pressure, and
before the impelling tooth of the escape wheel has quitted the pallet e the
locking pallet I will be again replaced and secured by the locking plate.
This method of locking is applicable to a wheel of the duplex kind, as in
Figure 1, and is also applicable to a wheel of the kind generally used in
detached escapements, as in (Figure 2); but when the latter kind of escape
wheel is used the locking is performed with or without the plate D, D, as the
angle for throwing the safety pin B is in that case formed by the notch C
which is cut in the edge of the flanch E (Figure 2) to form the face or pallet
against which the escape wheel acts in giving impulse. The locking plate
when used with the kind of escape wheel represented in Figure 2 is of the
same effect whether fixed against the upper or under surface of the flanch
or main pallet.
The balance in this chronometer is constructed without arm, adjusting
weights, screw, cavity, or projection, which can displace or be resisted by
atmospheric air in its circular motion. This balance is in form a circular
plate, flat on one side, and turned hollow on the opposite side to such a
depth as will leave no more substance or thickness than is sufficient to firmly
support the rim. The principle of this balance is preserved, and the same
effects produced, whether it be made in one solid piece, or if the rim and
supporting plate be made in two and fixed together, such mode of construction
being shewn by the section (Fig. 4.)
The effect of heat and cold on this chronometer is compensated by a
curb, which curb is actuated by a compensator, the motion of which in one
direction increases and in the contrary direction diminishes the acting length
of the balance spring. The aforesaid curb and compensator is connected with
the balance cock and apparatus for adjustment in the manner hereafter
described, viz:
On the upper surface of the balance cock at A (Figure 5) is fixed a turned
collet, on the under-cut neck of which is fitted, with a spring clip, the moveable
time-regulating piece b, b, B. The surface or shoulder of the collet A, on
which the time-regulating piece bears, projects as much above the upper surface
of the balance cock as the thickness of the toothed rack, which is attached to
the under surface of the piece B, and acted on by the tangent screw C. This
screw is supported by two cocks D, D, which are secured by the screws e, e
to the foot of the balance cock. Through the piece b, b, B, is a long groove
or mortise, into which is fitted friction-tight the tenon of the sliding nut F, F.
This nut has on each side its tenon a shoulder bearing on the upper surface of

page_text: the piece b, b, B. G, G, G, is the expansion piece or compensator, of a circular
form, but is effectual if of an oval or angular form, and of which steel forms
the foot and outer part, and brass the inner part; or this arrangement of the
two metals may be reversed though not with equal effects. The foot of this
compensator is firmly attached by screws to the tenon of the sliding nut F, F,
the face of which tenon is flat and even with the under surface of the time-
regulating piece b, b, B. On the upper surface of the sliding nut projects a
piece H, through which, in a direction lengthwise with the slide, is a tapped
hole; into this hole is fitted the micrometer screw I, K. Near K on the axis
of this screw is a turned groove into which is fitted the head L of the guide
M, This guide, being firmly screwed to the upper surface of the time-
regulating piece, prevents the micrometer screw from moving longitudinally.
This micrometer screw admits of a revolving motion, by which the sliding
nut F, F, and compensator G, G, G, may be gradually moved from end to
end of the aforesaid groove or mortice, and the degree or
rate of com-
pensation for heat and cold be thereby adjusted. On the circular
edge of the time-regulating piece at b, b, project two ears, through each of
which is a tapped hole on the upper surface, and on those ears of the time-
regulating piece is firmly screwed the bridge or cock N by the screws o, 0.
Downwards through this bridge, in a position opposite or nearly opposite
to the center of motion and perpendicular to the plane of the time-regulating
piece b, b, B, is screwed a stud or axis, the slit head of which bears flat on the
upper surface of the bridge N and is shewn at P; on this stud or axis P,
which projects on the under side of the bridge N, is fitted a moveable socket q, q,
the length of which is nearly equal to the distance between the under surface
of the bridge N and upper surface of the balance cock, as also is the length
of the stud or axis P. To the socket q, q, is fixed the arm and curb R, S; the
inner edge of the arm R forms a right line to about the centre of the socket q, q.
In the acting end of the compensator and perpendicular to its upper plane is
screwed a stud V, which stud forms a connexion between the curb and com-
pensator by its action against the inner edge of the arm R. This arm is kept
in contact with the stud V by means of a spring which is fixed, as at W, on the
acting end of the compensator G, G, G, and carried by it. The contact of the
aforesaid arm and stud I also make by forming the piece R as a fork of two
prongs, one of which acts as a spring against the stud V, which in such case
is held between them. On the circular part of the arm R which surrounds
the socket 9, 9, projects the time-regulating curb S; on the under side of this
curb project two pins which check the balance spring that is held between
them; X shews that part of the balance spring which is so acted upon.

page_text: The action of the time regulator is as follows:-By turning with a key the
tangent screw C the time-regulating piece, compensator, curbs, index, and other
parts thereunto affixed will be set in motion, and the acting length of the
balance spring thereby increased or diminished, according to the direction in
which the tangent screw C is turned.
Above the upper plane surface of the arm R projects the socket head q, q,
on the outer under-cut edge of which is fitted with a spring clip the secondary
curb T; this curb is friction-tight, but moveable on the said socket. On the
step of the curb T is screwed two pieces z, 2, in each of which is a pin or
stud y, y; those studs and pieces seperately admit of being moved nearer to
or further from the curb center of motion by slackening the screws by which
they are confined. The pins or studs y, y, project on the under side of the
curb T and check the balance spring, in a manner similar to those in the time-
regulating curb S, and their effect when adjusted is that of compensating for
the effect produced by the difference of proportion which the escape wheel's
influence and continuity of action bears to the long and short vibrations of
the balance.
The curbs S and T move in a circle correspondent to the curvéd form of
the balance spring X, whether actuated by the compensator or expansion
piece G, G, G, or by the motion of the tangent screw C. To the extreme end
of the arm R is fixed a needle or index, which points to the divided scale 40,
50, 60, &c.
In witness whereof, I, the said James Ferguson Cole, have hereunto
set my hand and seal, this Twenty-sixth day of March, in the year of
our Lord One thousand eight hundred and twenty-one.
JAMES FERGUSON (L.8.) COLE.
AND BE IT REMEMBERED, that on the Twenty-sixth day of March,
in the roar of our Lord 1821. the aforesaid James Ferguson Cole came before