MAKING PORTABLE MACHINES OR INSTRUMENTS TO BE PLACED UPON A DESK OR TABLE, AND so CONTRIVED AS TO FOLD OR NOT INTO A SMALL COMPASS, MADE OF WOOD; BRASS, OR OTHER METAL, TO SUPPORT Á SILKEN SHADE, MADE FOR THE PURPOSE OF PRO- TECTING THE EYES FROM A STRONG LIGHT, ADDED TO WHICH IS A GEEEN,BLUE, OR OTHER COLOURED GLASS; IN A FRAME; AND IN SUCH A POSITION TITE A WINDOW, LAMP, OR CANDLE, DEPENDANT UPON THE COLOUR OF THE GLASS REFLECTOR, UPON THE BOOK OR PAPER PLACED WITHIN THE BOUNDS OF IT'S SHADOW,
Year: 1820

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERIC
MIGHELLS VAN HEYTHUYSEN; of Sidmouth Street, in the Párish of St: Pañeras,
and County of Middlesex; send greeting.
WHEREAS His most Excellent Majesty King George the Fourth, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Eighteenth day of March, in the first year of His reign, did, for
Himself; His heirs and successors, give and grant unto me; the said Frederic
Mighells Van Heythuysen; His especial licence that I; the said Frederick
Mighells Van Heythuysen, or my éxecutors, administrators, and assigns; or
such others as I, the said Frederic Mighells Van Heythuysen, my executors;
administrators, 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, my Invention of "MAKING
PORTABLE MACHINES OR INSTRUMENTS TO BE PLACED UPON A DESK OR TABLE, AND
so CONTRIVED AS TO FOLD OR NOT INTO A SMALL COMPASS, MADE OF WOOD; BRASS,
OR OTHER METAL, TO SUPPORT Á SILKEN SHADE, MADE FOR THE PURPOSE OF PRO-
TECTING THE EYES FROM A STRONG LIGHT, ADDED TO WHICH IS A GEEEN, BLUE, OR
OTHER COLOURED GLASS; IN A FRAME; AND IN SUCH A POSITION THAT WHEN PLACED
OPPOSITE A WINDOW, LAMP, OR CANDLE, IT WILL TAKE OF THE GLARE OF WÉITÉ
PAPER BY SHEDING A GREEN OR BLUE; OR ANY OTHER TINGE, DEPENDANT UPON THE
COLOUR OF THE GLASS REFLECTOR, UPON THE BOOK OR PAPER PLACED WITHIN THE
BOUNDS OF IT'S SHADOW, SO THAT PRINT HOWEVER SMALL, OR WRITING, IS RENDERED
MORE PLAIN OR LEGIBLE BY REASON OF THE GLARE BEING THUS TAKEN OFF THE
WHITE PAPER BY DAY, AND PARTICULARLY BY CANDLELIGHT;" in which said

page_text: Letters Patent there is contained a proviso obliging me, the said Frederic
Mighells Van Heythuysen, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of my said Invention, and
in what manner the same is to be performed, and to 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 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
Frederic Mighells Van Heythuysen, do hereby declare that the nature of my
said Invention or apparatus for supporting a green or other coloured glass
in such a position so that the rays of light, either from a window, or candle,
or lamp, shall be made to shed a tinge of green or other colour upon a book
or paper placed within it's influence, whereby the glare of light shall be
taken off white paper, and the rays of light softened and cooled, which
machine I call a sight preserver, and which said machine or instrument may
be affixed to a candlestick or lamp, containing ignited oil or gas, or any other
inflamable article. The manner of using and making the same is described in
the following explanation thereof (that is to say):-
When not attached to a lamp or candlestick (although in that case it must
be used with a candle or lamp, or light from a window), the coloured glass is
fixed in a frame, manufactured of metal or wood,-which frame is fixed upon a
joint to a taliscope slide, rising out of a pedestal, so that the glass screen can
be raised as may be found necessary to keep it in a proper level with the
light, and the joint by which the taliscope slide is fixed to the frame is
supplied with a double nob or thumb screw to tighten the said joint when it
becomes too easy or slack by friction, to support steadily the glass, either in
an oblique or horizontal position as may be required, to cast the tinge upon
the place desired, to which may be added another joint to act in a contrary
direction to the last, so that the glass may be placed so as to cast a tinge
of green or other colour, according to the colour of the glass, upon a book,
whilst the person using it reclines back in his chair and reads. This may
also be accomplished by what is termed a ball and socket joint, or by what
is also called a universal joint. On the top of this frame, for the purpose
further guarding the eyes from the bad effects of a strong light, I fix a ball
(but the sight preserver may be made without, or so that it may be taken off,
which in some cases is desirable, as some people may prefer the having the
green or other coloured glass supported horizontally over their book, that they
may read a book, or write under the coloured glass by daylight, which is
preferable to green spectacles, for the coloured glass, being kept at a proper
of

page_text: distance from the eyes, do not strain or irritate them, as coloured spectacles
invariably do). Through this ball a hole is perforated to pass a wire to form
a frame, into which is sown silk or other stuff, for a screen; another hole is
also made partly through the said ball, into which a thumb screw is introduced,
to press or gripe the wire silk screen, to keep it perpendicularly even, if the
glass should be in an oblique or horizontal position. Of course this screen may
be made of any other material, but that which I have described I prefer, it
being the most light and elegant. This machine is very portable, as the glass
screen can be folded back, and the wire silk screen taken off, so that it can
be packed in a small case and sent to any part of the world. When this
glass screen or sight preserver is fixed to a candlestick, the sconce or sconces
to contain the candle or candles must project from the shaft of the candle-
stick by the means of branches, either permanently fixed, or so as to be taken
off at the will of the owner, and the frames with the joints above described,
containing the glass screen, &c., made to rise out of the shaft of the candle-
stick, either by the assistance of a talicope slide or rod, to draw out of the
shaft, which can be tightened by a screw when it is as high or as low as may
be found necessary to keep it in a proper level with the light, as the candles
burn down or are replaced by others. When fixed to a lamp or gas pipe
there will be no need of the taliscope slide or rod with a screw, but the screen,
together with the joints above described, may be fixed to the lamp upon a
small branch, which may be so contrived as to take off or put on at the desire
of the person using it.
In witness whereof, I, the said Frederick Mighells Van Heythuysen,
have hereunto set my hand and seal, this Sixteenth day of May,
in the year of our Lord One thousand eight hundred and twenty.