IMPROVEMENTS IN BINOCULAR MICROSCOPES
Year: 1866

page_text: LETTERS PATENT to Peter Henry Lealand, of Euston Road, in the
County of Middlesex, Optician, for the Invention of "IMPROVEMENTS IN
BINOCULAR MICROSCOPES."
Sealed the 21st August 1866, and dated the 24th February 1866.
PROVISIONAL SPECIFICATION left by the said Peter Henry Lealand
at the Office of the Commissioners of Patents, with his Petition, on the
24th February 1866.
I, PETER HENRY LEALAND, of Euston Road, in the County of Middlesex,
Optician, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN BINOCULAR MICROSCOPES," to be as follows:-
By means of the improvements hereafter described both fields of view are
fully illuminated with the higher as well as with the lower powers, and
without curtailing the aperture of the object glasses.
The improvements consist in the employment instead of the prism now in
use of a parallel piece of glass, or other transparent medium of convenient
thickness and of a rectangular prism, or I employ two triangular prisms having
each two obtuse angles and one acute angle, and a rectangular prism. The
prisms or glass are placed so that the image is received by the direct body
after passing through them without suffering any material distortion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Peter Henry Lealand in the Great Seal Patent Office on
the 23rd August 1866.
1
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
HENRY LEALAND, of Euston' Road, in the County of Middlesex, Optician, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of February, in the year of our
Lord One thousand eight hundred and sixty-six, in the twenty-ninth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Peter Henry Lealand, Her special licence that I, the said
Peter Henry Lealand, my executors, administrators, and assigns, or such
others as I, the said Peter Henry Lealand, 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, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN BINOCULAR MICROSCOPES," upon the condition (amongst
others) that 1, the said Peter Henry Lealand, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their
hands and seals, 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 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 Peter Henry Lealand, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, reference being had to the Drawings hereunto annexed,
that is to say:-
By means of the improvements hereafter described both fields of view are
fully illuminated with the higher as well as with the lower powers, and
without curtailing the aperture of the object glasses.
The improvements consist in the employment instead of the prism now in

page_text: use of a parallel piece of glass or other transparent medium of convenient
thickness and of a rectangular prism, as represented in Figure 1 of the
accompanying Drawings, in which a is a piece of glass or other transparent
medium, the top and bottom surfaces d, e, of which are parallel, and ba
rectangular prism; or instead of the parallel piece a I employ in conjunction
with the rectangular prism 6 two triangular prisms as represented at c, c,
'Figure 2. Instead of the triangular prism 6 being rectangular it may be
formed with any desired angles. The cone of rays proceeding from an object
glass infringe upon the under surface e of the parallel glass a at an angle of
52°, more or less, the number of rays that are reflected depending upon the
inclination of this surface. The reflected rays enter the triangular prism b,
and the rest are refracted and emerge parallel with the incident rays, and are
transmitted into the direct tube of the binocular microscope. Those rays which
enter the prism pass to the inclined body after crossing the direct rays or the
rays which enter the prism may pass parallel to the direct rays by altering the
position of the prism b. In order to prevent the secondary image passing into
the triangular prism, and thereby causing a blurred image to be seen in the
slanting body, the parallel glass a must be of a given thickness, and for this
purpose the greater the inclination of this glass the thicker it must be.
And having now described the nature of my said Invention, and in what
manuer the same is to be performed, I declare that I claim,-
First, the employment in binocular microscopes of a parallel piece of glass
or other transparent medium (a), and of a triangular prism (6), substantially
as herein-before described and represented in Figure 1 of the accompanying
Drawings.
Second, the employment in binocular microscopes of two triangular prisms
(c, c,) and of a triangular prism (6), substantially as herein-before described
and represented in Figure 2 of the accompanying Drawings.
In witness whereof, I, the said Peter Henry Lealand, have hereunto set
my hand and seal, this Twenty-second day of August, One thousand
eight hundred and sixty-six.
P. H. LEALAND. (L.8.)