IMPROVEMENTS IN OPTICAL INSTRUMENTS, BY THE REVOLUTION OF WHICH VARIOUS DESIGNS OR PATTERNS MAY BE PRODUCED TO THE EYE
Year: 1858

page_text: LETTERS PATENT to John Gorham, of Tunbridge, in the County of Kent,
Surgeon, for the Invention of "IMPROVEMENTS IN OPTICAL INSTRUMENTS, BY
THE REVOLUTION OF WHICH VARIOUS DESIGNS OR PATTERNS MAY BE PRODUCED
TO THE EYE."
Sealed the 12th October 1858, and dated the 14th April 1858.
PROVISIONAL SPECIFICATION left by the said John Gorham at the Office
of the Commissioners of Patents, with his Petition, on the 14th April
1858.
I, JOHN GORHAM, of Tunbridge, in the County of Kent, Surgeon, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN OPTICAL IN-
STRUMENTS, BY THE REVOLUTION OF WHICH VARIOUS DESIGNS OR PATTERNS MAY BE
PRODUCED TO THE EYE," to be as follows:-
It is well known that colors may be made to appear as mixed in various
proportions by their being suitably distributed on the surface of a disc which is
made to revolve rapidly, and instruments for producing this effect to the eye
are called colour tops. Now, my Invention consists in combining with such
instruments the use of a disc, with a hole in the centre sufficiently large to

page_text: cause it to fit loosely on to the spindle of the top, but only so large as to admit
of its vibrating to a small extent, such disc having appended at or near its
circumference a light weight for the purpose of slightly retarding its motion
with the top and causing it to vibrate, as required, on the spindle of the same,
on which it is placed during the revolution of the top. This moveable disc is
blackened on its upper surface, and has a pattern or device cut completely
through its substance, so as to admit of colours on the surface of the ordinary
disc of the revolving top below being seen through the spaces cut out of the
moveable disc when viewed from above. By this arrangement both the
colours and the pattern appear multiplied many times during rotation, thus
producing the designs. The proportion of the diameter of the hole in the
centre of the moveable disc to that of the spindle of the top may be varied,
but I prefer that it should be about as 4 to 3; that is to say, that if the
diameter of the spindle is three-tenths of an inch, that of the hole should be
four-tenths.
The slight weight appended at or near the circumference of the moveable
disc is a small piece of string or silk, but this may be varied so long as the
appendage, be it what it may, is properly adjusted in order to be capable of
producing the required successive vibrations of the moveable disc on the
spindle of the revolving top.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Gorham in the Great Seal Patent Office on the
13th October 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
GORHAM, of Tunbridge, in the County of Kent, Surgeon, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of April, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Gorham, Her special license that I, the said John Gorham, my
executors, administrators, and assigns, or such others as I, the said John
Gorham, 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

page_text: Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN OPTICAL
INSTRUMENTS, BY THE REVOLUTION OF WHICH VARIOUS DESIGNS OR PATTERNS MAY
BE PRODUCED TO THE EYE," upon the condition (amongst others) that I, the said
John Gorham, 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Gorham, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement (that is to say) :-
My Invention of "Improvements in Optical Instruments, by the Revolution
of which various Designs or Patterns may be produced to 'the Eye," has for
its object the production to the eye of multiplied or kaleidoscopic patterns or
designs, in the manner herein-after described. It is well known that the
colours of surfaces arranged in various proportions and in different colours may
be made to appear as mixed by their being suitably distributed on the surface
of a disc which is made to revolve rapidly, and the instruments for producing
this effect to the eye are called colour tops or wheels.
Now, my Invention consists in combining with such instruments the use of
a disc with a hole in the centre sufficiently large to cause it to fit loosely on
to the spindle of the top or wheel, but only so large as to admit of its vibrating
to a small extent, such disc having appended at or near its circumference a
light weight for the purpose of slightly retarding its motion with the top or
wheel, and causing it to vibrate as required on the spindle of the same, on
which it is placed during the revolution of the top or wheel. Thus the disc
when placed on the spindle is made to revolve about the same axis and in
the same direction as the wheel, and in a plane parallel therewith, but at a
short distance from it, and with a motion retarded as to its velocity; while as
to its direction, the motion is broken up or converted into a series of rapid
jerks or isochronous vibrations. This moveable disc is blackened on its upper
surface, and has a pattern or device cut completely through and out of its
substance, so as to admit of the colours on the surface of the ordinary colour
top or wheel below being seen through such pattern or device when viewed
from above. It results from this arrangement, that if the colour top or
wheel rotates vertically, then the vibrating disc occupies a position in front
of the wheel that is between it and the eye in all cases.

page_text: I have not thought it necessary to shew any particular pattern or device,
because my Invention does not relate thereto. The disc may be made of any
suitable light material, such as paper or cardboard, and the pattern or device
may be cut or punched by mechanism or by hand. I have found it convenient
to cut by hand the pattern or device on a disc of paper (of about the thickness
of writing paper), which will admit of folding such disc when cut as required
in a folded state, and opened out to form the pattern or device, being
strengthened or stiffened by means of a light frame of card; but the mode
of manufacturing and cutting the disc may be varied. Now, if both the
ordinary colour top or wheel and the disc with the pattern or device cut in it
were set in motion and made to travel with equal velocity, the colours on the
wheel below would appear mixed, while the pattern on the disc would appear
to be effaced; but by retarding the motion of the disc, and causing it to
move in a series of isochronous vibrations as above stated, each pattern is
retained for an instant of time before the eye, sufficiently long, however, to
form a distinct image, and from the rapidity of the vibrations a whole circle
of images is thus portrayed on the retina before that image produced at the
first vibration is withdrawn or effaced. By this process both the colours and
the pattern appear multiplied many times, thus producing the designs to
the eye.
I would remark that various plans might be contrived for retarding the
motion of the vibrating disc, and producing the required vibrations, but that
which is stated above is that which I have found best for the purpose. It is
effected by making the aperture in the centre of the vibrating disc sufficiently
large to admit of free motion on the spindle, and then by appending at or
near its circumference a light weight, such as a piece of string or silk, which
by the resistance it receives from the atmosphere, and by its impulses thereon
during the rotation of the disc, both retards the motion of the latter, and
produces its required vibrations.
The proportion of the diameter of the aperture in the centre of the moveable
disc to that of the spindle of the top or wheel is about as four to three. Hence,
with a central aperture in the disc of four-tenths of an inch in diameter
adapted to a spindle of three-tenths of an inch in diameter, I have been
enabled to construct many beautiful designs.
Having thus described the nature of my Invention, and in what manner the
same is to be performed, I would have it understood that I do not claim as
of my Invention the mode of manufacturing the moveable disc above described,
but I do claim the use of the moveable disc with a pattern or device cut or

page_text: pierced in it, and made to revolve with a retarded and vibrating motion, in
combination with the ordinary colour top or wheel, so as to produce designs
to the eye, in the manner described.
In witness whereof, I, the said John Gorham, have hereunto set my
hand and seal, the Eleventh day of October, in the year of our Lord
One thousand eight hundred and fifty-eight.
Witness,
WILLIAM SPENCE,
50, Chancery Lane, London,
Patent Agent.
JOHN GORHAM. (L.S.)