IMPROVEMENTS IN WATCHES AND CLOCKS
Year: 1854

page_text: LETTERS PATENT to Victor Athanase Pierret, of Paris, in the Empire of
France, and of Old Compton Street, Soho, in the County of Middlesex,
Sealed the 16th March 1855, and dated the 20th September 1854.
PROVISIONAL SPECIFICATION left by the said Victor Athanase Pierret
at the Office of the Commissioners of Patents, with his Petition, on the
20th September 1854.
I, VICTOR ATHANASE PIERRET, of Paris, in the Empire of France, and
of Old Compton Street, Soho, in the County of Middlesex, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN WATCHES AND CLOCKS"
to be as follows:-
These improvements relate to a novel arrangement of mechanism to be
applied to watches and clocks, for the purpose of indicating in a more simple
and efficient manner than heretofore the months of the year, days of week,
and dates of each day, in regular succession, as follows:-I effect the changing
movement of the characters employed to denote the several days of the week,
and present to view each day and date of the month in succession, by con-
necting together certain wheels which are separate and distinct from the
movement employed for indicating time, but which, for the purpose of this

page_text: Invention, I connect together, and thus render the ordinary movement of a
watch or clock available for indicating the days of the month and weck, as well
as for indicating time.
The nature of this Invention will, however, be better understood by the
following description of the mechanical arrangements which I employ for
effecting the same, that is to say:-
At the centre of the plate to which the dial of the watch or clock is to be
fixed, and upon the arbor which carries the hands, I place loosely a ratchet
wheel of 31 teeth, and to the upper side of this wheel I attach a division
plate with numeral figures engraved therein or painted thereon, from 1 to 31
inclusive, the whole of these numbers being employed to represent the number
of days contained in the longest months of the year; and on the right hand of
the before-mentioned wheel of 31 teeth I attach another ratchet wheel of 12
teeth, and to the upper side of this wheel I connect a plate, upon which are
painted or engraved at equal distances asunder the first syllable of the twelve
calendar months of the year, and on the left hand of the before-mentioned
whcel of 31 teeth I attach another ratchet wheel of seven teeth, and to the
upper side of this wheel I connect a plate upon which are painted or engraved
at equal distances asunder the first syllable of the seven days of the week.
To the left hand of the wheel of seven teeth I attach an ordinary toothed
wheel containing twice as many teeth as the hour wheel of the watch, and into
the pinion of the said hour wheel the before-mentioned wheel takes, and is
moved thereby, and such motion is transmitted to a detent from a small suail
or cam fixed as hereafter stated; said snail takes against a small roller con-
nected to the before-mentioned detent, and kept in contact therewith by
pressure from a spring. This detent is formed with two arms, one of which acts
against the diameter of the ratchet of 31 teeth, and the other against the
ratchet of seven teeth, and that arm of the detent which takes into the spaces
of the above ratchet I form bevil, and furnish with a spring, to prevent it
from penetrating further than is necessary between the teeth of the ratchet. I
also apply a small spring to the other arm of the detent; said spring being
formed bent, presses against the point of a triangular shaped piece of metal,
and thus prevents this spring from passing further between the teeth of the
ratchet than is actually necessary, and at the same time enables the spring to
be readily disengaged therefrom, and serves to prevent several teeth of the
ratchet of 31 teeth from escaping at one time; the same security is also
afforded to the ratchet of seven teeth, to prevent more than one tooth escaping
at a time. The detent is mounted upon a pivot, and receives movement from

page_text: the before-mentioned small snail or cam, which is fitted loosely on the pinion
of the wheel which takes into the hour wheel, as before mentioned, and at tho
same time it is kept back by a screw formed with a shoulder; the head of said
scrow is under the above-mentioned wheel, and the barrel of the screw passes
through a slot formed in the said wheel, so as to allow the snail to move on its
axis through a range of about 30 degrees; so that when the snail has moved
the detent to its full extent, the toothed wheel below it continues turning, and
thus brings the highest part of the snail into a line with the centre of the
roller against which it presses; and as the snail continues its movement, the
detent follows the snail quickly, by pressure from a spring against the edge of
said detent, and places the snail in a position for again acting upon the detent,
as above stated, and causes the springs of the detent to advance the wheels of
7 and 31 teeth one tooth each; and as the snail again presses the detent out-
wards, the arms thereof being flexible, pass over the teeth of the ratchet wheels
without imparting motion thereto.
And I would here remark, that the connecting of the above mechanism
with the ordinary watch movement does not in any way alter or affect the
going of the watch.
In conclusion, it should be observed that in adapting the above principle to
clocks I employ certain other parts, which, as they do not affect the principle
upon which this Invention is based, and as they may be varied in several
ways, I consider it unnecessary to enter now into any detailed description
thereof.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Victor Athanase Pierret in the Great Seal Patent Office on
the 20th March 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, VICTOR
ATHANASE PIERRET, of Paris, in the Empire of France, and of Old Compton
Street, Soho, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of September, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Victor Athanase Pierret, Her special licence that I, the said Victor Athanase
Pierret, my executors, administrators, and assigns, or such others as I, the said

page_text: Victor Athanase Pierret, my executors, administrators, and 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 "IMPROVE-
MENTS IN WATCHES AND CLOCKS," upon the condition (amongst others) that
I, the said Victor Athanase Pierret, by an instrument in writing under my
hand and seal, 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 Victor Athanase Pierret, do hereby
declare the nature of tho said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof (that is to say):-
My Invention of improvements in watches and clocks relates to certain
novel and peculiar arrangements of mechanism to be applied to watches and
clocks for the purpose of indicating in a more simple and efficient manner
than heretofore the months of the year, the days of the month, and the days
of the week, without in any way interfering with the ordinary mechanism for
indicating time.
The mechanical arrangements which I employ for effecting these objects
are as follows:--In the ordinary dial plate of the watch or clock I form three
openings, and at the back thereof, upon the arbor which carries the hour-
hand, I place loosely a division plate or dial with numeral figures engraved
therein or painted thereon from 1 to 31 inclusive, these said numbers being
employed to represent the number of days contained in the longest months of
the year. This dial or division plate is connected to a ratchet wheel having
thirty-one teeth, corresponding with the said numeral figures. Towards the
left hand also behind the ordinary dial is another dial plate, divided into seven,
and marked with the first syllables of the days of the week; and towards the
right hand is a third dial, divided into twelve, and marked with the first
syllables of the twelve calendar months of the year. These two dials are
respectively connected to ratchet wheels having seven and twelve teeth. In
gear with the pinion of the hour wheel I place an ordinary spur wheel, having
twice the number of teeth of the said hour wheel. Upon the arber of the
said hour wheel I place loosely a small cam or snail, which is driven by a pin
therein, taking into a slot in the wheel. This snail acts upon a friction roller

page_text: upon a catch or detent, which is kept in contact therewith by means of a
spring. This detent is formed with two arins, one of which acts against the
diameter of the ratchet wheel of thirty-one teeth, and the other against that
of the ratchet wheel of seven teeth. These wheels are respectively provided
with springs acting against the teeth, to prevent more than one tooth from
escaping at a time. Each time that the hour wheel makes two revolutions
(i.c., once in twenty-four hours.) the snail revolves once, and as the highest
point of the said snail passes the centre of the friction roller, the spring forces
the detent suddenly forwards, and causes the two arms thereof each to take
up one tooth of their respective wheels, and thus simultaneously alter the days
of the month and week. The dial which indicates the calendar month is
actuated each month by hand by means of a small lever. The method of
adapting my improvements to clocks is similar in principle, though slightly
differing in detail, as will hereafter be more fully explained with reference to
the Drawings hereunto annexed. The Drawings have similar figures and
letters of reference marked upon corresponding parts of the mechanism in the
several Figures, in so far as such parts appear or can be seen at each of
the Figures respectively, and will be readily understood from the following

page_text: than is necessary between the teeth of the ratchet wheel C. It should be
observed that the said shoulder is bevilled, so that the point of the spring can
readily leave it. Upon the lower arm is a spring, (also shewn in red lines), the
end of which is bent, and acts against a triangular-shaped piece of metal.
This spring acts in the same manner as the other, preventing the detent from
gearing further than is necessary with the teeth of the ratchet wheel A, and at
the same time retaining the facility of disengaging itself.
The small triangle serves a double purpose at the same time that it acts
upon the teeth of the wheel to turn the same; it enters between the teeth, and
prevents more than one tooth from escaping at a time. The same security is
also in like manner afforded to the wheel C, to prevent more than one tooth
thereof from escaping at a time. The detent F is mounted and vibrates upon
a pivot, and in its movement follows the form of the snail. The said snail is
mounted loosely upon the arbor of the wheel D; it is, however, retained by a
screw, the head of which is under the said wheel, and the pin thereof passes
through an opening a formed in the said wheel (see Figure 2), in such a
manner as to allow the said snail to move on its axis through an arc of about
30°, so that as soon as the snail by the movement of the wheel D has elevated
the detent upon its extreme point, the instant this point passes the centre of
the friction wheel, the pressure of the spring H causes the snail E to turn
quickly, until the said friction wheel rests upon the lowest part of the said snail,
and at the same time the small springs (shewn in red) each take up one tooth
of their respective wheels A and C. The continued movement of the wheel D
withdrawing the detent, the points thereof touch the back of the next teeth;
but as these ends are made flexible by the springs, they disengage without
producing the least movement of the ratchet wheels A and C. This com-
bination does not at all interfere with the ordinary movement of the watch, and
by its means as soon as a day has passed the following one is indicated. Under
the ratchet A is a piece of steel P (see Figure 3), through which the arbor of
wheel A moves. Within this piece P the cannon pinion and the arbor of the
hour wheel move freely; it also serves to receive the upper pivot of the minute
wheel. I would here remark that on the first day of each month the ratchet
wheel B will require to be moved one tooth by hand, which may readily be
done by means of the spring lever N. Also, as the ratchet wheel A is
calculated for the longest months in the year, it follows, that at the end of
those months that have less than thirty-one days the wheel A will require to
be moved one or more teeth by hand, which may readily be done by means of
the spring lever O. In some watches, for the sake of economy, I actuate the

page_text: wheel A and dial K, which indicates the days of the month, by more simple
means; but then the change, instead of taking place instantly, occupies about
two hours. In this case I dispense with the detent F and the snail E, and I
place two pins on the wheel D, one near the teeth, for turning the ratchet
wheel C, and the other nearer the axis, and a little longer, in order to gear
in passing with one tooth of the ratchet wheel A. The ratchet wheel A
also carries at the point of one of its teeth a small pin, which, every time it
passes the ratchet wheel B, causes it to turn one-twelfth of a revolution.
This arrangement is more particularly applicable to clocks without striking
movement.
Figure 4 represents a clock movement for the same purpose. The ratchet
wheels R and S are actuated by means of two small levers T and U. These
lovers are mounted at right angles to each other on the end of a rod which
passes through the movement. This rod carries at its other end a ratchet
wheel X of six teeth (see Figure 5). This ratchet wheel as well as the others
is provided with a retaining spring, for holding the teeth in proper position for
being acted upon, and to prevent more than one tooth being taken up at a
time. At the upper part of the striking wheel L, at the back thereof, are three
pins, projecting so as cach to take up one tooth of the wheel X at a time;
therefore, as the striking wheel I makes two revolutions in the twenty-four
hours, it follows that the wheel X, having six teeth, makes one revolution
in the same time; and consequently the small levers T and U, being fixed
upon the same axis, also make one revolution, and thus take up one tooth
cach of the wheels R and S. The pins in the striking wheel L are so placed
as to move the wheel S, and thus change the day of the month whilst the
clock is striking twelve at night. The ratchet of twelve teeth V for indicating
the month is actuated in the same manner as above described with reference
to the watch movement. Figure 6 shows the disposition of the several wheels,
&c. and the positions assigned to the barrels. Figure 7 shows the dials for
indicating the days and months as applied to a watch; and Figure 8 shows
the same as applied to a clock. Figure 9 shows the clock dial complete.
It will be evident that the date dials may easily be so arranged (if preferred)
as to form a curved line on the time dial.
Having thus described and set forth the nature and object of my said Inven-
tion of Improvements in Watches and Clocks, together with the best means
I am acquainted with for carrying the same into practical effect, I would
remark, in conclusion, that I claim as iny Invention, the novel and peculiar
arrangements of mechanism shewn in the annexed Drawing, and herein-before

page_text: more particularly described, as applied to watches and clocks for indicating
the day of the month, the day of the week, and also the calendar month
of the year.
In witness whereof, I, the said Victor Athanase Pierret, have hereunto
set my hand and seal, this Sixteenth day of March, in the year of
our Lord One thousand eight hundred and fifty-five.
VICTOR ATHANASE PIERRET. (L.S.)
Witness,
LAURENT BILLET,
33, Place du Caire, Paris.