IMPROVEMENTS IN STEREO- SCOPES.
Year: 1879

page_text: LETTERS PATENT to Howard Grubb, of Leinster Road, Rathmines, in the
County of Dublin, Ireland, for the Invention of "IMPROVEMENTS IN STEREO-
SCOPES.
"
Sealed the 1st July 1879, and dated the 15th January 1879.
PROVISIONAL SPECIFICATION left by the said Howard Grubb at the Office
of the Commissioners of Patents on the 15th January 1879.
HOWARD GRUBB, of Leinster Road, Rathmines, in the County of Dublin,
Ireland. "IMPROVEMENTS IN STEREOSCOPES."
My Invention relates to a construction of stereoscopes and an arrangement of
the lenses and other optical parts thereof in such a manner as to render the instru-
ments more convenient for use than those of ordinary construction, and to facilitate
their adjustment to suit various sizes of pictures and different visions. According
to one niтangement for this purpose I place the two pictures side by side in the
usual way, but place them horizontally with their faces downwards when they are
transparent, illuminated from above, or opaque, illuminated from below, or with their
faces upwards when they are opaque and illuminated from above.
The optical
arrangeinent in either case is the same, except that the object lenses have simply to
be inverted. These object lenses are conveniently made in a composite form, one
face of each being made convex to operate as a lens and the other faces of prism
form, so that the rays passing through the lens face are reflected at right angles or
nearly so, and both being so set as to converge the reflected rays on a concave
mirror. From these the rays aro reflected to the eyes of the observer, the right cyc
receiving the image of the left picture and the left eye receiving the image of the
right picture. The lenses may be separate from the prism reflectors, and mirrors
may be substituted for the latter. In another arrangement the two pictures instead
of being as usual placed on their mount, side by side, right and left, are placed the one
above or beyond the other, being most conveniently laid horizontally or nearly so with
their faces upwards. Above them are placed two mirrors which may most advan-
tageously be prism reflectors, so adjusted that each reflects one of the pictures into
one of the observer's eyes, and the other reflects the other picture into the other eye.
Obviously the pictures may be placed vertically or inclined, the mirrors or prisms
being adjusted to reflect the rays in the desired directions to the eyes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Howard Grubb in the Great Seal Patent Office on the 11th July
1879.
HOWARD GRUBB, of Leinster Road, Rathmines, in the County of Dublin,
Ireland. "IMPROVEMENTS IN STEREOSCOPES."
My Invention relates to a construction of stereoscopes and an arrangement of
the lenses and other optical parts thereof in such a manner as to render the instru-
ments more convenient for use than those of ordinary construction, and to facilitate
their adjustment to suit various sizes of pictures and different visions. According
to one arrangement for this purpose I place the two pictures side by side in the
usual way, but place them horizontally with their faces downwards, when they are
transparent, illuminated from above, or opaque, illuminated from below, or with their
faces upwards when they are opaque and illuminated from above. The optical
arrangement in either case is the same, except that the object lenses have simply to
be inverted. These object lenses are conveniently made in a composite form, ono
face of each being made convex to operate as a lens, and the other face of prism
form, so that the rays passing through the lens face are reflected at right angles or
nearly so, and both being so set as to converge the reflected rays on a concave
mirror. From these the rays are reflected to the eyes of the observer, the right cyc
receiving the image of the left picture and the left eye receiving the image of the
right picture. The lenses may be separate from the prism reflectors, and mirrors
may be substituted for the Intter. In another arrangement the two pictures instead
of being as usual placed on their mount side by side, right and left, are placed the
one above or beyond the other, being most conveniently laid horizontally or nearly
so, with their faces upwards. Above them are placed two mirrors, which may
most advantageously be prism reflectors, so adjusted that the one reflects one
of the pictures into one of the observer's eyes, and the other reflects the other
picture into the other eye. Obviously the pictures may be placed vertically or
inclined, the mirrors or prisms being adjusted to reflect the rays in the desired

page_text: at Fig. 40; instead of reflecting prisma, refracting prisms may be employed, as shewn
at Fig. 5, the prisms being relatively inverted. For the reflecting prisms various
forms may be employed. They may be simple right angled prisms, as in Fig. 6,
made either of flint glass or of crown glass, the latter being silvered on the reflecting
side, or instead of being right angled they may be made for angles differing from
90°. If desired to magnify the pictures one surface may be made convex, as in
Fig. 7, or a separate convex lens may be combined with the prism, ns in Fig. 8.
The combination of lenses and prisms inay be made achromatic by making the prism
of flint glass and the lens of crown glass in suitable proportions and combining
them, as shewn at Fig. 9. When the prisms are used for refracting without
reflecting they may be made either as single prisms, preferably of crown glass, as in
Fig. 10, or with a convex surface, as in Fig. 11, or it may be rendered achromatic
by combining flint and crown glass, as shewn at Fig. 12, or both achromatic and
magnifying, as shown at Fig. 13.
Having thus described the nature of my said Invention, and in what manner the
same is to be performed, I claim in respect of stereoscopes,-
First. The combination of two magnifying prisms or reflectors and lenses with a
concave mirror, whereby rays from two pictures reflected at right angles, or nearly
so, reach the eyes of an observer in such manner as to give the effect of a single
picture, substantially as herein described with reference to Fig. 1 of the accom-
panying Drawings.
Second. The arrangement of two reflecting prisms or reflectors so that two
pictures placed horizontally, or nearly so, ono above or beyond the other, are seen
by an observer looking with both eyes into the prisms, as one picture, substantially
as herein described with reference to Fig. 3 of the accompanying Drawings.
In witness whereof, I, the said Howard Grubb, have hereunto set my hand
and seal, this Second day of July, in the year of our Lord One thousand
eight hundred and seventy nine.
HOWARD GRUBB. (L.8.)