A New Combination of Camera and Compass, so Designed and Arranged as to Record Photographically the Magnetic Bearings of Objects Photographed.
Year: 1894

page_text: Date of Application, 20th June, 1894
Complete Specification Left, 13th Dec., 1894-Accepted, 19th Jan., 1895
-
PROVISIONAL SPECIFICATION.
A New Combination of Camera and Compass, so Designed and
Arranged as to Record Photographically the Magnetic Bearings
of Objects Photographed.
JOHN BRIDGES LEE M.A. Barrister-at-Law of the Inner Temple, present
address, Constitutional Club Northumberland Avenue London do hereby declare
the nature of this invention to be as follows:-
This invention consists essentially in the combination of a photographic camera
with a magnetic compass so designed and adjusted that when an ordinary latent
photographic image is impressed upon a sensitive plate or film in the camera there
shall be impressed at the same time a latent photographic image of a portion of a
graduated are which indicates the magnetic bearings of objects in the field of view
of the camera.
One method by which I carry the principle of my invention into effect is by
fitting inside a photographic camera a magnetic compass with a cylindrical trans-
parent rim which is graduated on the outside and revolves with the magnetic needle.
The graduations should correspond to the graduations of an ordinary prismatic
compass. The compass may be covered by a dead-black cover but there must be
apertures in the top of the lid and on the side where the rim is closest to the back
of the camera so as to admit of the free passage of a pencil of rays from the lens
through those apertures and through a small area of the transparent graduated rim
to the sensitive plate when it is in place for receiving a latent photographic image.
The adjustments must be such as to secure that the graduated transparent
cylindrical rim of the compass may in its revolution pass near to the sensitive
film.
The axis of revolution of the compass and the optical axis of the lens should be
in the same plane. A fixed vertical hair or wire also in the same plane and in
close contact with the sensitive surface of the prepared photographic plate when in
place marks the optical median plane of the image. The image of that hair or
wire will serve also as an index to mark the magnetic bearing of any object in the
median plane of the field of view. The top of the camera should be fitted outside
with spirit levels and also with sights of any ordinary approved pattern or if
preferred with a telescope. The line of sight should be in the same plane as the
optical axis of the lens-the axis of revolution of the magnet and the index hair
or wire before referred to.
Ordinarily a box camera of fixed focus will be the most convenient form of
camera to employ.
When the apparatus has been accurately constructed and adjusted and carefully
used each photograph taken will bear on its face a record of the magnetic bearing
of objects in line with the centre of the field of view and the angular bearings of
other objects in the field can be afterwards computed from measurements which
can be made in office or elsewhere.
Dated this 20th day of June 1894.

page_text: A New Combination of Camera and Compass, so Designed and
Arranged as to Record Photographically the Magnetic Bearings
of Objects Photographed.
1, Joux BRIDGES LEE, M.A., Barrister-at-Law of the Inner Temple, present
address, Constitutional Club, Northumberland Avenue, London, 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 invention consists essentially in the combination of a photographic camera
with a magnetic compass so designed and adjusted that when an ordinary Intent
photographic image is impressed upon a sensitive plate or film in the camera, there
shall be impressed at the same time a latent photographic image of a portion of n
graduated are, which indicates the magnetic bearing of objects in the field of view
of the camera.
One method by which I carry the principle of my invention into effect is by
fitting inside a photographic camera, a magnetic compass with a cylindrical trans-
parent rin, which is graduated on the outside and revolves with the magnetic
needle. The graduations should correspond to the graduations of an ordinary
prismatic compass. The compass inny be covered by a dead-black cover, but there
must in such ense be apertures in the top of the lid and on the side where the rim
is closest to the back of the camera, so as to admit of the free passage of a pencil
of rays from the lens through those apertures and through a small area of the trans
parent graduated rim to the sensitive plate when it is in place for receiving a latent
photographic image, but an extensive top cover to the compass is not necessary and
it may be almost entirely dispensed with provided sufficient be retained to afford a
firm stop against which the cap of the compass needle pivot socket can be held
when the compass needle is raised off the pivot by the mechanism hereinafter
described. The adjustments must be such as to secure that the graduated trans-
parent cylindrical rim of the compass may in its revolution pass near to the
sensitive film.
The axis of revolution of the compass and the optical axis of the lens should be
in the same plane. A fixed vertical hair, fibre or wire, also in the same plane and
in close contact with the sensitive surface of the prepared photographic plate
when in place, marks the median vertical plane of the image. The image of that
hair, fibre or wire will serve also as an index to mark the magnetic bearing of any
object in the median plane of the field of view.
The top of the camera should be fitted outside with spirit levels and also with
sights of any ordinary approved pattern, or, if preferred, with a telescope. The
line of sight should be in the same plane as the optical axis of the lens, the axis of
revolution of the magnet and the index hair, fibre or wire before referred to.
Ordinarily a box camera will be the most convenient form of camera to employ.
When the apparatus has been accurately constructed and adjusted and carefully
used, each photograph taken will bear on its face a record of the magnetic bearing,
of objects in line with the centre of the field of view, and the angular bearings of
ther objects in the field can be afterwards computed from measurements which
can be made in office or elsewhere.
And in order that my said invention may be more clearly understood and readily
carried into effect, I will proceed aided by the accompanying drawings, more fully
to describe the same.

page_text: Fig. 1 is a side view, Fig. 2 is a front view, Fig. 3 is a longitudinal section,
Fig. 4 is a plan, Fig. 5 is a cross section and Fig. 6 is a back view, of a camera
provided with my improvements.
Fig. 7 is a side view, Fig. 8 is a front view, Fig. 9 is a plan, Fig. 10 is an
underside view and Fig. 11 is a cross section, of the compass and its fittings.
Fig. 12 is a cross section of the compass and its graduated cylindrical rim
separately, and
Figs. 13, 14 and 15 are separate views of a clip for adjustably fixing the vertical
wire, fibre or hair in position on its carrying frame.
In carrying my invention into effect I prefer to use a box camera a provided
with a good rectilinear photographic doublet lens preferably fitted with an iris
diaphragm.
The body a of this camera is preferably made of aluminium, thereby securing
lightness combined with strength and rigidity.
In combination with such camera and lens, I use a compass needle e in connection
with a vertically divided scale marked preferably on the outer surface of a
cylindrical rim c', which rim should be composed of some material transparent to
photographically active rays of light and the divisions and figures should be quite
opaque or vice versa. In the manufacture of the cylindrical scale have used thin
strips of mica and celluloid, both of which I have found eflicient. This cylindrical
scale is mounted on a framework e² supported and carried by the compass
needle c.
Such framework should be as light as possible, preferably form it of
aluminium the pivoting should be accurate and as non-frictional as possible.
Ordinarily the south seeking pole of the needle is set to 0° of the vertical trans-
parent scale e', so that the magnetic reading may be 0° when the camera faces towards
magnetic north and all bearings photographically recorded will then be magnetic
bearings, but the needle is adjustable and can be set to any degree on the scale, so
that whenever the magnetic declination of a place is known, the needle may be set
and clamped in such position with reference to the vertical scale that the bearings
photographically recorded will be true geographical bearings.
The pivot rises from the surface of a copper tray to which it is rigidly
fixed. This copper tray c is fitted underneath with guides c to enable it to slide
backwards and forwards on correspondingly shaped guides formed on or fixed to a
raised table d fixed to the bottom of the camera; the said tray is preferably
provided with two similar symmetrically placed toothed racks operated by the
same pinion e, which traverses the space below the tray c and is parallel to the
front and back of the camera. This arrangement of two side racks, one pinion and
central raised table with guides, secures that the compass structure shall move
accurately backwards and forwards in the camera without any side twist. The
pinion is worked by knobs cs on the outside of the camera, and these knobs are
provided with short arms or pointers by which the operator can see what is the
position of the compass and vertical frame structure. The parts shown at
Figs. 7 to 12 can all be racked entirely out of the instrument by means of the
pinion a'.
e is a double dark slide of any suitable or well known construction, it is however
so arranged as to slide into the back of the camera sideways from the right side of
the camera, and the partition which separates the plates when the slide is charged
is of blackened aluminium, and I prefer that the double dark slide should be of a
type which admits of the plates being placed and held with their long axes either
horizontal or vertical as may be desired.
The shape of the copper tray is immaterial but it should be sufficiently firm
and rigid to obviate risk of its being bent or distorted by any minor accidents or
careless handling, and it must not extend so far backwards as to interfere with the
near approach of the divided rim or compass scale to a prepared photographic plate
when in place.
When the copper tray c and the structures which it carries and supports are
racked back as far as they will go, the double dark slide e being in position and the

page_text: front shutter drawn out, the hindermost portion of the compass scale should be
well inside the slide e and separated from the sensitive surface of the photographic
plate or film by the smallest possible interval consistent with there being no danger
of actual contact.
Between the compass scale c' and the sensitive surface is a fixed index f, which
may consist of a very fine vertical wire, hair, or a fibre of unspun silk, and it may
come in actual contact with the sensitive photographic surface. This index I
prefer to continue as a vertical line across the whole depth of the sensitive plate or
film, and the ends of such vertical index I preferably adjustably attach by simple
clips to a rectangular frame rigidly attached to the compass tray c and held
securely in position by sloping back stays. The frame with its index can
enter the dark slide e and be pressed close against the sensitive surface of the dry
plate or film when the tray c is racked fully back after opening the slide shutter,
and the frame effectually safeguards the compass scale from any risk of being
injured by the shutter.
The front of the tray c has fixed thereto the extended portion of a plate or
arm, whose smaller free end extends over the axis of the compass neelle to
afford a firm stop or support against which the cap of the needle socket or axis is
pressed when the compass needle is raised from its pivot as hereinafter described.
This plate or arm c" is covered with dead-black velvet.
The focussing screen has a small arena of clear transparent glass opposite
the rearmost part of the cylindrical scale to enable the latter to be easily
read.
The pivot point the vertical index
and the principal optic axis of the
photographic lens must be all in the same vertical plane.
When not in use the tray e, which carries the compass needle e with its vertical
transparent rim or scale e and supporting frame, can be racked well forward so
as to be out of the way, and at the same time that the tray is racked forward, the
compass needle is raised from its pivot and the top of the pivoting cap or
socket held against the flat top support formed by the plate or arm
The mechanism for raising the magnetic neelle e off its pivot consists of a flat
dise of copper with a hole in the centre through which the pivotting axis passes,
n small projecting ring being preferably formel around said hole to pass into the
pivoting socket of the compass structure when the disc is raised. This disc g is
provided with two legs g of brass or copper symmetrically placed right and left
of the centre and passing through holes in the tray Attached to the bottom of
the inside of the camera are two inclined surfaces a', so arranged that when the
tray is racked forward the legs g must travel up these inclined surfaces a',
thereby raising the disc y which in its turn lifts the needle with its superstructure
off the pivot and presses the top flat surface of the pivoting cap or socket against the
stop or support; when the tray is racked back the legs slide down the inclined
surfaces a and ultimately become quite free thereof; the disc descends with the
legs until it rests on the tray and the magnetic structure is lowered on to its
pivot and left quite free. Small spiral springs beneath the tray e may be
used to pull down the copper dise g and to hold it down when the tray c is racked
back.
?
The top of the camera is fitted outside with spirit levels and also with sights
of any ordinary approved pattern, or, if preferred, with a telescope i ns shown in the
drawings. The line of sight should be in the safe plane as the optical axis of the
leus, the axis of revolution of the magnet, and the vertical index hair or wire before
referred to. Except the magnetic needle and the steel pivot on which it is pivotted,
there should be no iron or steel used in the construction of any part of the
instrument.
The construction and arrangement of parts herein described are such as I have
found to answer in carrying my invention into effect, but various modifications of
detail may be adopted without departing from the peculiar character of my
invention.

page_text: Having now particularly described and ascertained the nature of my said inven
tion, and in what manner the same is to be performed, I declare that what 1
claim is :-
1. The combination of a camera and internal compass so designed and arranged
as to record photographically the magnetic bearings of objects photographed
substantially as herein shown and described.
2. The use of a magnetic compass inside a photographic camera in such a way
that the magnetic bearings of objects outside the camera can be photographically
recorded.
3. The combination with a photographic camera, of a compass inside the camera,
the needle of which is attached to a frame carrying a hollow cylinder of thin
celluloid, mica, glass, or other equivalent transparent material, which is divided on
its surface and which passes in its revolution quite close to, but not touching, the
surface of a sensitive photographic plate or film when exposed in a photographic
camera, so as to admit of images of the divisions being directly impressed upon the
sensitive plate or film by the direct agency of rays coming through the photographic
lens, substantially as herein shown and described.
4. The combination with a combined photographic camera and internal compass,
of a vertical wire, hair or fibre between the compass scale and a prepared sensitive
plate or film, in such manner that the wire, hair or fibre shall serve at the same
time as an index for reading and recording the bearings and also to mark on the
photograph the median vertical plane of the instrument and image, substantially as
herein shown and described.
5. The combination with a photographic camera, of an internal compass, a
meridional index wire, hair or fibre, a vertically divided cylindrical scale rotating
with the compass needle, mechanism substantially as herein shown and described
for carrying the compass structure and the rectilinear frame supporting the
meridional index inside a dark slide (after the shutter is withdrawn) and for
lowering the magnet upon its pivot at the same time, and means for lifting the
magnet or compass structure off its pivot when the whole compass structure is
carried forward in the camera so as to be out of the way.
PEALS
12
J. BRIDGES LEE,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.