IMPROVE- MENTS IN MECHANICAL SLIDES FOR MAGIC LANTERNS
Year: 1871

page_text: LETTERS PATENT to John Holmes Wrench, of No. 39, Gray's Inn
Road, in the County of Middlesex, for the Invention of "IMPROVE-
MENTS IN MECHANICAL SLIDES FOR MAGIC LANTERNS."
PROVISIONAL SPECIFICATION left by the said John Holmes Wrenchi
at the Office of the Commissioners of Patents, with his Petition, on
the 7th March 1871.
I, JOHN HOLMES WRENCH, of No. 39, Gray's Inn Road, in the County
of Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MECHANICAL SLIDES FOR MAGIC LANTERNS," to be as
follows:-
Mechanical slides for magic lanterns in which the object or a part of
the object is required to rotate have the glass containing such object
or part object applied to a metal frame formed with teeth as a rack

page_text: to be operated by the teeth of a pinion, but the formation of such rack
teeth is troublesome and expensive. The teeth are also very liable to
become broken and are troublesome and expensive to repair.
The object of my improvements is to remedy these evils by employing
a series of recesses or holes around the ring of metal carrying the object
glass to be moved, such recesses or holes being taken into by the points
or teeth of a small wheel of corresponding gauge. When desired two
of such rings may be simultaneously operated one on each side of the
pin wheel to cause the respective rings to move with their object glasses
in opposite directions.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Holmes Wrench in the Great Seal Patent
Office on the 5th September 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HOLMES WRENCH, of No. 39, Gray's Inn Road, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of March, in the year of
our Lord One thousand eight hundred and seventy-one, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Holmes Wrench, Her special
licence that I, tho said John Holmes Wrench, my executors, ad-
ministrators, and assigns, or such others as I, the said John Holmes
Wrench, 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,
usc, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN MECHANICAL SLIDES FOR MAGIC LANTERNS," upon the
condition (amongst others) that I, the said John Holmes Wrench, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and scals, 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

page_text: 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 John Holmes Wrench, do hereby
declare the nature of the 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:—
Mechanical slides for magic lanterns in which the object or a part of
the object is required to rotate, have the glass containing such object or
part object applied to a metal frame, which as now constructed is formed
with teeth as a rack to be taken into and operated by the teeth of a
pinion, but the formation of such rack teeth is troublesome and ex-
pensive. The teeth. are also very liable to become broken and are
troublesome and expensive to repair.
The object of my improvements is to remedy these evils by employing
a series of recesses or holes around the ring of metal carrying the object
glass to be moved, such recesses or holes being taken into by the points
or teeth of a small wheel of corresponding gauge. When desired two of
such rings may be simultaneously operated one on each side of the pin
wheel, to cause the respective rings to move with their object glasses in
opposite directions.
Figures 1 and 2 show sections of part of a mechanical slide of a magic
lantern with my improvements applied to it, and Figure 3 represents a
portion of one of the revolving rings separately. In each of these views
the same letters indicate corresponding parts.
a, a, are the revolving rings of which I have shewn the slide to have
two, though only one may be employed if desired, as is well understood;
a' are the holes therein, or in place of holes there may be simply recesses
to receive points or teeth of corresponding guage from the wheel b, such
wheel being applied to an axis b¹ worked by a small winch handle, as is
usual.

page_text: Having thus described my Invention and means which I adopt in
carrying the same into effect, I would have it understood that what I
claim is, the improvements in mechanical slides of magic lanterns,
substantially as described.
In witness whereof, I, the said John Holmes Wrench, have here-
unto set my hand and scal, this First day of September, in the
year of our Lord One thousand eight hundred and seventy-one.