IMPROVEMENTS IN ILLUMI- NATING THE DIALS OF CLOOKS AND OTHER INSTRUMENTS IN WHICH DIALS ARE EMPLOYED
Year: 1851

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULES
FRANÇOIS DOREY, of Havre, in the Republic of France, Gentleman, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Fourth day of
November, One thousand eight hundred and fifty-one, in the fifteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant uato
me, the said Jules François Dorey, my exors, admors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Jules François.
Dorey, my exors, adiñors, and assigns, or such others as I, the said Julės
François Dorey, my exors, admors, or assigns, should at any time agree with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, in the Islands
of Jersey, Guernsey, Alderney, Sark, and Man, and in all Her Majesty's
Colonies and Plantations abroad, my Invention of "IMPROVEMENTS IN ILLUMI-
NATING THE DIALS OF CLOOKS AND OTHER INSTRUMENTS IN WHICH DIALS ARE
EMPLOYED;" in which said Letters Patent is contained a proviso that I; the
said Jules François Dorey, shall cause a particular description of 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, to be enrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately

page_text: 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Jules François Dorey, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had to
the Drawing hereunto annexed, and to the figures and letters marked thereon,
that is to say:-
My Invention consists in illuminating the dials of clocks and other instru-
ments in which dials are employed by means of a light placed behind a disc
of plate glass or other transparent substance carrying semi-transparent figures,
letters, graduations, or marks, and in proximity to which is the index or hand
or indices or hands also of a semi-transparent substance. The light is placed in
such a position that its rays in passing through the dial may not reach the eyes
of the observer, which is in most cases effected by placing the light below the
centre of the dial on which it is concentrated by means of reflectors. The
effect of this arrangement is that the light freely traverses the transparent disc
without rendering it luminous, while the semi-transparent figures or marks are
rendered luminous and appear bright on a dark ground, at the same time the
semi-transparent index or hand or indices or hands is or are rendered luminous
by the rays which traverse the disc, and thus the hands and the figures or
marks on the disc appear bright while the rest of the dial forms a dark ground.
In order to render this as dark as possible a chamber of black cloth or other
dark coloured material is constructed behind the dial. When the dial is
illuminated from the exterior by daylight, or otherwise, the semi-transparent
hands and figures appear bright, while the light passes through the rest of the
dial without illuminating it, and the observer only sees the black chamber
through the transparent part of the dial. The effect is thus similar to that
already mentioned, that is to say, the hands and figures appear bright on a
dark ground. This effect is just the reverse of that produced by the ordinary
method of employing a semi-transparent disc with opaque letters and hands.
Figure 1 of the Drawings hereunto annexed is a vertical section, and
Figure 2 is a sectional plan of an illuminated dial for a clock constructed and
arranged according to my Invention. Figure 3 is a front view of the same
drawn to a smaller scale. The same letters refer to similar parts in all the
Figures.
A is a disc of plate glass on which the numbers of the hours from I to XII.
are depicted and rendered semi-transparent by grinding the surface of the
glass, or by painting the numbers upon it. or otherwise; B is the dark chamber

page_text: formed of black cloth; C, C, C, C, are a series of gas lamps supplied by the
branches C from the pipe C, the end of which is represented as broken off* in
the Drawing, as it may be conducted in any direction which may be found most
convenient; in lieu of gas lamps, oil or other lamps may be employed. They
are furnished with reflectors D, D, D, D, by which their light is diffused over
the dial. These reflectors should be arranged as to diffuse the light as equally
as possible upon the dial. E, E', are the hands of the clock which are made
of ground glass, or painted glass, or other semi-transparent material surrounded
by a metallic beading. The hour hand E is perforated in the centre and
mounted upon the spindle F, which is made hollow and traversed by the
spindle which carries the minute hand E'; F' is the spindle which com-
municates the motion from the clock to the hands, which are connected with
each other by wheelwork and provided with balance weights in the usual
manner. The spindle F receives and intercepts a portion of the light
of the lamps, and might therefore be seen from the exterior if this defect
were not provided against; it is therefore covered with a piece of black
or dark coloured chenille wound round it in a spiral form, which I find
to answer the intended purpose. The spindle casts a shadow on the dial,
which, however, is rendered almost or quite imperceptible by employing four
lamps, and causing the four faint shadows to fall between the five upper figures
on the disc. The spindle turns in a metallic bearing fixed in the centre of the
disc A, and this bearing therefore intercepts and prevents the light from falling
upon the hands at that part. To render the effect more agreeable a circle or
rosette is painted or ground upon the dise A round the bearing, and the hands.
thus appear to spring from this rosette with a dark spot in its centre. A similar
effect may be produced by making the centre of the hands larger in diameter
than the metallic bearing in the disc A.
To prevent any of the light of the lamps from falling upon the top or sides
of the dark chamber B a series of narrow screens H, H, are suspended from
the top and sides so as to intercept this light.
The whole apparatus is so arranged that the products of combustion from
the lamps pass away without affecting either the dial or the works of the
clock.
If it be required to protect the hands by an external covering a second disc
of glass may be fixed on the exterior, and the whole dial will be visible through
it, or the hands may be placed behind the disc A instead of in front of it, and
then such additional disc of glass will not be required.
In applying the Invention to other instruments than clocks, the arrangement
is similar to that above described, but in lieu of the clock spin lle F, a spin lle

page_text: set in motion by the required instrument is introduced, and the figures, letters,
graduations or marks upon the disc A are adapted to it. The dials of weather-
cocks, pressure guages, barometers, and other instruments in which dials are
employed may be thus illuminated. When the motion of the index is recti-
linear or other than circular, the form of the disc A is adapted to it.
I have mentioned glass as the material employed for the disc A and for tlie
hands or indices, but other transparent materials, such as gelatine or tale, may
be employed.. When very large discs are required several plates of glass may
be fixed in a frame, but such frame should be made as narrow as is consistent
with the strength required in order to prevent it from unnecessarily inter-
cepting the light.
Having now described the nature of my Invention, and the manner in which
the same is to be performed, I wish it to be understood that I do not confine
myself to the precise forms and materials herein-before described, as the same
may be modified while retaining the peculiar character of my Invention;
but I claim as my Invention of improvements in illuminating the dials of
clocks and other instruments in which dials are employed, the application of a
transparent disc having semi-transparent figures, letters, graduations or marks
in combination with a semi-transparent hand or index or semi-transparent
hands or indices, as herein-before described.
In witness whereof, I, the said Jules François Dorey, have hereunto
set my hand and seal, this Thirtieth day of April, One thousand eight
hundred and fifty-two.
JULES FRANÇOIS (L.s.) DOREY.
Taken and acknowledged by Jules
François Dorey (party hereto) at
.Havre, in the Republic of France,
this 30th day of April, 1852, before
ma
This is the Specification referred to in the affidavit of Benedict Gobey.
Sworn before me, this 3rd day of May, 1852,
J. JEFFERSON.
BENEDICT GOBEY, of No. 12, Cursitor Street, Chancery Lane, Law Stationer,
maketh oath and saith that he hath been informed and believes that the
.signature "G. W. Featherstonhaugh," Her Britannic Majesty's Consul at

page_text: Havre, set, subscribed or written in the margin of the Specification bereunto
annexed and marked with the letter A, and dated the Thirtieth day of April,
One thousand eight hundred and fifty-two, and purporting to be executed and
acknowledged by Jules François Dorey, of Havre, in the Republic of France,
Gentleman, before the said George William Featherstonhaugh, on the said
Thirtieth day of April, is of the proper handwriting of the said George William
Featherstonhaugh.
Enrolled the Third day of May, in the year of our Lord One thousand
eight hundred and fifty-two.