IMPROVEMENTS IN MICROSCOPES
Year: 1876

page_text: LETTERS PATENT to Robert Kemp, of the Firm of R. and J. Beck, of Lister
Works, Holloway, in the County of Middlessex, and of Cornhill, in the City of
London, for the Invention of "IMPROVEMENTS IN MICROSCOPES."
PROVISIONAL SPECIFICATION left by the said Robert Kemp at the Office
of the Commissioners of Patents on the 13th October 1876.
ROBERT KEMP, of the Firm of R. and J. Beck, of Lister Works, Holloway, in the
County of Middlesex, and of Cornhill, in the City of London. "IMPROVEMENTS IN
MICROSCOPES."
The Invention relates to improvements in means employed in illuminating objects
under the microscope. For this purpose, instead of employing a diaphragm intersect-
ing the tube of the illuminator or condenser, and employing a number of different
illuminating lenses to screw on according to the power required, I fix around the
ordinary "illuminator or " condenser
tube an eccentric tube which serves as
"
an axis for another tube provided with a milled flange and acting in combination
with a spring catch and indents to regulate the motion thereof. This last mentioned
tube has a pin, stud, or screw projecting from the side thereof, and a tube having a
slot therein to fit the pin, stud, or screw is passed over such tube and is thus
compelled to rotate with it. For the low-power lens this outer tube has the end
thereof provided with a diaphragm which is perforated with circular and other
shaped apertures, as is well understood, which diaphragm works close up to the
outer surface of the lens, and by turning it any of the apertures may be placed
central with the illuminating lens. When however a number of different lenses are
required, instead of forming the end of the outer tube with a diaphragm as above
described, I mount in such end a number of different lenses, each of which may be
brought central with the axis of the "illuminator' or "condenser" by simply
turning the tube carrying the same, and when it is desired that a lens should allow
only the passage of a hollow cone of light to illuminate the object I grind off the
back of the lens flat and blacken such flat surface so as to leave only an annular
surface of the lens for the transmission of the illuminating pencil of light.
"

page_text: be brought central with the axis of the "illuminator" or "condenser" by simply
turning the tube g; and when it is desired that a lens should allow only the passage
of a hollow cone of light to illuminate the object, I grind off the back of the lens
flat, as shewn by Figure 7 (which is an edge view to an enlarged scale of one of
such lenses), and blacken such flat surface. I thus leave only an annular surface of
the lens of any required width for the transmission of the illuminating pencil of
light.
"
By my Invention I am enabled to produce a much more convenient and efficient
form of "illuminator or "condenser" than those heretofore in use, as when using
the low power lens the diaphragm is brought close up to the lens and is therefore
more efficient in use; and when using a number of lenses of different powers several
of such lenses are mounted in the end of a single tube capable of being rotated so
as to bring any one of such lenses into use as may be required, whilst by grinding
off the back of a lens flat and blacking such flat surface I am enabled to dispenso
with a diaphragm for stopping out the centre of such lens for producing a hollow
cone of light.
Having thus described the nature of my said Invention, and the mode in which I
carry the same into effect, I would have it understood that what I claim is,-
First. The employment of a diaphragm mounted in front of and close to the lens b,
and provided with a number of circular and other shaped apertures, each of which
is capable of being brought into position for use as may be required, in manner sub-
stantially as herein shown and described.
And, Secondly. I claim mounting in front of the lens a number of different
lenses each of which is capable of being brought into position for use, as may be
required, in manner substantially as herein shown and described.
In witness whereof, I, the said Robert Kemp, have hereunto set my hand and
seal, this Tenth day of April, in the year of our Lord One thousand eight
hundred and seventy-seven.
ROBERT KEMP. (LS.)