IMPROVEMENTS IN MICROSCOPES.
Year: 1881

page_text: LETTERS PATENT to Francis Herbert Wenham, of No. 164, New Bond Street, in
the County of Middlesex, Engineer, for an Invention of "IMPROVEMENTS IN
MICROSCOPES.'
"
PROVISIONAL SPECIFICATION left by the said Francis Herbert Wenham
at the Office of the Commissioners of Patents on the 12th January
1881.
FRANCIS HERBERT WENHAM, of No. 164, New Bond Street, in the County of
Middlesex, Engineer. "IMPROVEMENTS IN MICROSCOPES."
The first improvement relates to the stand for carrying the limb body of the
microscope. The stand consists of a segment of a circle or sector extending behind
the limb and beneath the stage. The centre is from a point in the axial line of the
microscope body, slightly above the stage, and in the plane occupied by an ordinary
object slide thereon, so that when the microscope is inclined by a rack or pinion
movement, or otherwise to or from the observer, the object in focus is at the centre
of rotation. The sector passes between guides or jaws upon a base with an
arrangement for fixing the instrument at any inclination. The microscope is
attached to the sector by an axis, so that it can be inclined on either side; the
centre line of this axis also intersects that of the body in the plane of the object on
the stage. The base turns on a foot plate, the axis of which is also in a
perdendicular line intersecting the object. The edge of this foot plate may be
divided into degrees for measuring apertures, and indicating angles of illumination.
When the miscroscope is inclined backwards by the sector movement or turned
sideways on the back axis, or rotated on the base foot plate, these movements used
either separately or combined in all directions admit a ray of light from a fixed
source to reach the object, as all the movements radiate from this as a centre.
The second improvement is for an application of anti-friction rollers for the fine
focussing movement of microscopes. Two rollers as far asunder as convenient are
passed transversely between the adjacent edges of the limb and body. The rollers
are kept in position by end flanges, and are let into transverse grooves sufficiently
wide for the range of the fine focusing movement. The rollers are held in position
77

page_text: by a swing bar or adjusting screw with end socket joints passing through the
limb of the microscope and a spring plate to give elastic pressure.
The third improvement is for a simplified form of thin mechanical stage, having
two superposed milled heads for traversing placed above its plane so that no part
projects to interfere with the entire rotation if it is constructed with a circular
movement. This stage has only one traversing plate which is moved by two racks
crossing each other, the two pinions actuating cross sliding strips. The spindle of
one pinion passes through the other, which is tubular, or one milled head may be
above the stage and the other or both directly beneath.
As described in my former Patent (A. D. 1877, No. 496), stages have been made
with only one top moving plate actuated by superposed milled heads, projecting
sideways (commonly known as the Tyrrel movement), but the stage herein
described differs from my previous Patent by the superposed milled heads being
placed in the position described, and also in having two racks crossing each other
instead, and a screw and rack.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order by the Lord Chancellor, filed by the said Francis Herbert Wenham
in the Great Seal Patent Office on the 22nd July 1881.
FRANCIS HERBERT WENHAM, of No. 164, New Bond Street, in the County of
Middlesex, Engineer. "IMPROVEMENTS IN MICROSCOPES."
This Invention has for its object improvements in microscopes. The first
improvement relates to the stand for carrying the limb and body of the microscope.
The stand consists of a segment of a circle or sector A, A, extending behind the
limb B and beneath the stage C, Fig. 1. The centre is from a point in the axial
line of the microscope body, slightly above the stage, and in the plane occupied by
an ordinary object slide thereon, so that when the microscope is inclined (by a rack
or pinion movement or otherwise) to or from the observer, the object in focus is at
the centre of rotation, the sector passes between guides or jaws D upon a base with
an arrangement or clampscrew E for fixing the instrument at any inclination. The
microscope is attached to the sector by an axis F, so that it can be inclined on
either side, the centre line of this axis also intersects that of the body in the
plane of the object on the stage. The base turns on a foot plate G, the axis of
which is also in a perpendicular line intersecting the object. The edge of this foot
plate may be divided into degrees for measuring apertures and indicating angles of
illumination. When the microscope is inclined backwards by the sector movement,
or turned sideways on the back axis F, or rotated on the base foot plate G, these
movements, used either separately or combined in all directions, admit a ray of
light from a fixed source to reach the object, as all the movements radiate from the
object as a centre.
The second improvement is for an application of anti-friction rollers for the fine
focusing movement of microscopes. Two rollers H, H, Fig. 1, as far asunder as
convenient are placed transversely between the adjacent edges of the fine movement
slide I between the limb and body. The rollers are kept in position by end flanges
and are let into transverse grooves sufficiently wide for the range of the fine
focusing movement. The rollers are held in position against the slide by a swing
bar or adjusting screw J, with end socket joints passing through the limb of the
microscope and a spring plate to give elastic pressure.
The third improvement (shewn in side view Fig. 1, and in plan Fig. 2) is for a
simplified form of thin mechanical stage having two superposed milled heads A¹, A¹,
for traversing placed above its plane, so that no part projects to interfere with the
entire rotation if it is constructed with a circular movement. This stage has only
one traversing plate which is moving by two racks crossing each other, as shown
at B, Fig. 2, the two pinions actuating cross sliding strips C¹, C'. The spindle
of one pinion passes through the other which is tubular, or one milled head may
be above the stage and the other or both directly beneath.
As described in my former Patent (A.D. 1877, No. 496), stages have been made
with only one top moving plate actuated by superposed milled heads projecting
side-ways (commonly known as the Tyrrell movement), but the stage herein
described differs from my previous Patent by the superposed milled heads being
placed in the position described, and also in having two racks crossing each other
instead of a screw and rack.
Having described the nature of the said improvements, I claim their use and

page_text: FRANCIS HERBERT WENHAM. (L.S.)
Signed, sealed, and delivered by
the above named Francis Herbert
Wenham, in the presence of
A. W. BARNARD,
Clerk to Messrs. Ford, Lloyd, & Bartlett,
Solicitors,
4, Bloomsbury Square,
W.C.