An Improved Optical Magnifying Instrument.
Year: 1889

page_text: Date of Application, 9th Jan., 1889
Complete Specification Left, 1st Oct., 1889-Accepted, 2nd Nov., 1889
PROVISIONAL SPECIFICATION.
An Improved Optical Magnifying Instrument.
A communication from abroad by THÉODORE SIMON, of Paris, in the Republic of
France.
1, GEORGE CECIL DYMOND M. Inst. M.E. of the Agency for Foreign Patent
Solicitors 6 Lord Street, Liverpool and 6, Bank Street, Manchester, both in the
County of Lancaster, and 323 High Holborn in the County of Middlesex, Patent
Agent, do hereby declare the nature of this invention to be as follows:-
The optical instrument forming the object of this application may, in many cases,
replace with advantage the ordinary magnifying glass formed of a lens, which is used.
for magnifying very small objects, signs or characters.
It is for this reason that my correspondent proposes to give the name "magnifying
glass" to the instrument, although, as will be explained, it is constructed with
mirrors.
Magnifying glasses made of a glass lens, magnify by forming an image of the object
looked at, the luminous rays of which only reach the eye after passing through a
certain thickness of glass, whereby they are considerably weakened. Again, the range
of action of these magnifying glasses is limited. The magnifying glass, the object to
be looked at, and the eye of the observer, must occupy relative positions and distances
which cannot vary to any great extent, and especially for reading very small text it is
very inconvenient that the eye should be constrained to keep at so slightly variable a
distance. It is, therefore, proposed to replace the lens by reflecting mirrors,
chosen and arranged in a suitable manner to greatly magnify the object, and
to form an image, the rays of which will reach the eye without being appreciably
weakened.
The following arrangement has been adopted, which forms a simple and convenient
instrument for attaining the object in view.
Among other advantages, it does not prevent the light from illuminating the object
to be observed, and it enables the observer to read very fine text without being
obliged to move the instrument laterally and without being constrained to keep his
eyes at any fixed distance.
The apparatus is composed of a curved mirror, and a plane mirror placed one above
the other, and at such an angle that, if the object to be viewed is placed, say, for
example, in a suitable position on the plane on which the apparatus rests, its image
reflected and magnified by the curved speculum will be reflected by the plane mirror
to the eye of the observer.
The degree of magnifying power depends, (according to the laws of optics), on the
curvature of the mirror.
By a curvature suitably chosen it, is easy to include within the range of the concave
speculum, the whole width of the object to be microscopically examined, such, for
example, as printed characters, so that it will never be necessary to move the
apparatus laterally and it will therefore be sufficient to move it only backwards and
forwards.
It is easily understood that, if written or printed paper is placed in front of the
observer in the aforesaid plane, all that be need do is to place upon it the reflecting
microscope or magnifying glass a little beyond the part to be magnified, and to look
into the plane mirror taking up any suitable position at any suitable distance which
suits his own convenience.
The apparatus being open at both ends the part at which the observer looks is
illuminated on nearly all sides, a circumstance which further facilitates the

page_text: If the instrument is constructed with mirrors of a small curvature, it may be used
for examining an object of small dimensions with greater magnifying power.
The plane mirror may also be replaced by a curved mirror which will itself alter the
dimensions.of the reflected image.
The two mirrors are each fixed in a frame, and the two frames are fixed in a suitable
position by means of two-side plates, each furnished with a stud or thumbpiece, by
which the apparatus can be held.
The mirrors may be of glass or other substance in ordinary use, with a coating of
quicksilver or entirely of metal with a plate or coating of silver, if desired.
The frame may be furnished with handles, rings or other appendages according to
the use that is to be made of the apparatus.
Datad this 8th day of Jonna 1980
WM. P. THOMPSON & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Optical Magnifying Instrument.
A communication from abroad by THÉODORE SIMON, of Paris, in the Republic of
France.
I, GEORGE CECIL DYMOND M. Inst. M.E., of the Agency for Foreign Patent
Solicitors, 6, Lord Street, Liverpool and 6, Bank Street, Manchester, both in the
County of Lancaster, and 323, High Holborn in the County of Middlesex, Patent
Agent, do hereby declare the nature of this invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the following
statement
This optical instrument forming the object of this invention can be applied with
advantage in a good many cases in the place of the ordinary magnifying glass which
is formed of one lens, and which is used for the examination of objects, signs, or very
small letters, and has a strong magnifying power.
For this reason this optical instrument is called a magnifying glass notwithstanding
it is made of mirrors as will be hereafter explained.
The magnifying glasses made of a glass lens produce a magnifying effect by
forming a virtual image of the examined object, the luminary rays of which only reach
the eye after having crossed the glass, which weakens then considerably.
On the
other hand the field of view is rather limited. The glass, the object which is to be
examined, and the eye of the examiner must assume relative positions and distances
which cannot be changed to any great extent, and for reading very small text
particularly, it is very inconvenient, that the eye should 'he compelled to keep within
such a slight variable distance.
For these reasons it is proposed to substitute for the lens, reflecting mirrors, selected
and arranged in such a manner as to produce a strong magnifying effect and without
any perceptible weakening of the luminary rays.
By the following arrangement, there is formed a plain and convenient instrument
for the purpose stated.
Among other advantages, the instrument does not prevent the 'light from falling on
the object which is to be examined, and it enables the examiner to read a very small
text without the necessity of moving it in a lateral direction and without compelling
the eye to remain at a certain distance.
In the accompanying drawing, which forms a part of this description, and in which
like parts are indicated by like letters of reference :-
Figure 1 shows a front elevation of the instrument, and
Figure 2 a transverse section of the same.
The apparatus is composed of a curved mirror B and of a flat mirror A, arranged one
above the other and forming a suitable angle, so that, the object which is to be
examined, being placed at C on the plane CD, its image is reflected and magnified.

page_text: by the curved mirror B, and reflected and transmitted by the flat mirror A, to the eye o
of the observer. This travel of the luminary rays is indicated by the lines C BA O.
According to the laws of optics, the magnifying of the object depends upon the
curving of the mirror. With a suitable curving, it will be easy to embrace in the
field of view of the concave mirror, a latitude of text sufficient to render a motion of
the instrument in a lateral direction superfluous, so that it will be sufficient to move it
only forward and backward.
It is evident that, when the written or printed page is placed before the observer,
on the plane DC, it will be sufficient to place the mirror magnifying glass a little
higher and to look in the flat mirror, taking at the same time a convenient position
and distance.
As the apparatus is open at the back H, the object which is read is lighted from
nearly all sides, which makes the reading still easier.
Provided with slightly curved mirrors, this instrument can be used for examination
on a field of view of little extent. The flat mirror can also be replaced by a curved
one, which will also change the dimensions of the reflected image.
The two mirrors, are, as shown in the drawing, arranged on their frame, and the
two frames are kept in a suitable position by two lateral plates, each provided with a
knob or ear P.
The mirrors can be made of foliated glass or any other substance ordinarily used
for such purposes, or be entirely metallic, silvered or silver-plated.
The frame can be provided with handles, rings or other appendages, according to
the use that is to be made of the instrument.
Having now particularly described and ascertained the nature of the sai...
invention, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what claim is :-
1. A magnifying glass, formed of two mirrors, one curved and one flat, or both
curved, arranged so as to form with each other and with the object, such angles, that
the image reflected by the one will be returned by the other mirror to the eye of the
observer, more or less magnified, substantially as set forth.
2. The construction of the above described mirror magnifying glass of all kinds of
materials, in all forms or dimensions, and with extent of field of view and of
magnifying capacity applicable for all uses, substantially as set forth.
Dated this 30th day of September 1889.
WM. P. THOMPSON & Co.,
Agents for the Applicant.