Improvements in or connected with Opera Glasses and Field Glasses to Adapt them for Telemetric Purposes.
Year: 1899

page_text: Improvements in or connected with Opera Glasses and Field Glasses
to Adapt them for Telemetric Purposes.
A communication by GUSTAVE HUMBERT, of 9, Rue Chevreul, & LÉON BLOCH,
of 1, Avenue de la République, both of Paris, in the Republic of France,
Colonel and Manufacturer respectively.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester,
both in the County of Lancaster, 118, New Street, Birmingham, in the County
of Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer,
do hereby declare the nature of this invention to be as follows:-
For a long time as shown by the numerous treatises on optics, learned men
and experts have deemed the use of a hair-cross in ordinary opera or field glasses
to be impossible.
It is in fact well known that if we attempt to adapt to these apparatuses, hair-
crosses (like those for instance in terrestrial or astronomical glasses) any lines,
strokes or divisions formed on or near the objective are absolutely invisible to
the eye of the operator.
Experiments have however enabled this problem to be very simply solved by
the present invention.
It divisions be formed with fine lines on the objective, the said lines become
absolutely invisible on looking through the eye glass, but if instead of looking
directly through the eye piece, the passage of the visual rays be limited and we
look either through a very small hole or through a narrow slit, the divisions are
then seen standing out very clearly and the most ordinary field glass becomes in
that way a telemetric field glass.
This is the substance of the present invention.
The hole or slit through which the visual rays are to pass may be obtained
in various ways, either by darkening the eye-glass or eye-glasses and reserving
a point or line thereon, or by stopping down the same by means of movable
shutters or a movable disc provided with a slit or a hole:
When we look through a slit the latter must be parallel to the lines of the
stadia, all other lines not parallel become invisible.
Various patterns of hair lines in the form of crosses, straight lines, and circles
may be used separately or in combination.
It is easy to understand all the combinations which may be obtained. With
a movable shutter a field glass becomes at will telemetric or otherwise.
With an apparatus such as described, a free side (for instance the left hand
side) allows of the object being easily looked for or found, then it is only
necessary to close the left eye and the right eye will see the same object in the
divisions of the stadia provided in the right hand portion.

page_text: Of course with this arrangement a large number of combinations variable
according to circumstances may be obtained at will.
In practice the divisions of the stadia will be traced on the objective or objec-
tives or on a glass which may be applied to the objective although a similar result
would be obtained with a hair cross placed in front of or behind the objective.
As regards the hole or slit herein before mentioned it is arranged on the ocular
or eye glass itself, or preferably formed in a shutter or disc, movable or fixed
placed near the eye glass either before or behind it.
It may even be formed in a disc, the distance of which from the eye glass is
variable.
Dated this 17th day of February 1900
Improvements in or connected with Opera Glasses and Field Glasses
to Adapt them for Telemetric Purposes,
A communication by GUSTAVE HUMBERT, of 9, Rue Chevreul, and LÉON BLOCH,
of 1, Avenue de la République, both of Paris, in the Republic of France,
Colonel and Manufacturer respectively.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester,
both in the County of Lancaster, 118, New Street, Birmingham, in the County
of Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer,
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;―
For a long time, as shown by the numerous treatises on optics, learned men
and experts have deemed the use of a hair-cross in ordinary opera or field glasses
to be impossible.
It is in fact well known that if we attempt to adapt to these apparatuses, hair-
crosses (like those for instance in terrestrial or astronomical glasses) any lines,
strokes or divisions formed on or near the objective are absolutely invisible to
the eye of the operator.
Experiments have however enabled this problem to be very simply solved by
the present invention.
If divisions be formed with fine lines on the objective a, the said lines b
become absolutely invisible on looking through the eye glass c, but if instead
of looking directly through the eye piece, the passage of the visual rays be limited
and we look either through a very small hole d' or through a narrow slit d, the
divisions are then seen standing out very clearly and the most ordinary field
glass becomes in that way a telemetric field glass.
This is the substance of the present invention.
The hole or slit & through which the visual rays are to pass may be obtained
in various ways, either by darkening the eye-glass or eye-glasses and reserving
a point or line thereon, or by stopping down the same by means of movable 4
shutters or a movable disc provided with a slit or a hole.
When we look through a slit the latter must be parallel to the lines of the
stadia, all other lines not parallel become invisible.
As a simple example we have shown in the accompanying drawings an ordinary
opera or field glass, converted into a telemetric glass."

page_text: Figure 1 is an elevation of the opera glass;
Figures 2 and 2 are end views looking through the eye glass;
Figure 3, a front view of the objectives; whilst
Figures 4, 5 and 6 show examples of the hair lines employed.
It is easy to understand all the combinations which may be obtained. With
a movable shutter a field glass becomes at will telemetric or otherwise.
When an apparatus such as described and shown in the drawings, a free side
(for instance the left hand side) allows of the object being easily looked for or
found, then it is only necessary to close the left eye and the right eye will see
the same object in the divisions of the stadia provided in the right hand portion,
(Figure 3).
Of course with this arrangement a large number of combinations variable
according to circumstances may be obtained at will.
In practice the divisions of the stadia will be traced on the objective or objec-
tives or on a glass which may be applied to the objective although a similar result
would be obtained with a hair cross placed in front of or behind the objective.
As regards the hole or slit herein before mentioned it is arranged on the ocular
or eye glass itself, or preferably formed in a shutter or disc, movable or fixed
placed near the eye glass either before or behind it.
It may even be formed in a disc the distance of which from the eye glass is
variable.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondents, I declare that what I claim is:-
:
The improvement in opera or field glasses which consists in arranging a hair
cross on the objective itself, or in proximity to the same, and in providing on or
near the eye-glass (in front or behind) a diaphragm or stop adapted to only
permit passage of the visual rays through a small hole or narrow slot, this being
the essential feature of the present invention, whereby, contrary to all known
theories, the divisions of the hair cross may be distinguished in an opera or field
glass, and it is rendered possible to convert any opera or field glasses into tele
metric glasses substantially as herein before set forth.
Dated this 17th day of November 1899.