Improvements in Magnetic Compasses.
Year: 1892

page_text: Date of Application, 18th Mar., 1892
Complete Specification Left, 17th Dec., 1892-Accepted, 11th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in Magnetic Compasses.
JAMES HENRY STEWARD 406 Strand London Optician do hereby declare the
nature of this invention to be as follows:
The improvements relate more particularly to magnetic compasses for military
and other purposes where a pocket or portable compass will be useful at night for
marching on a definite position or for travellers & surveyors.
It consists of the
following-
1. The application of a divided ring with reversed degrees or points or both
reversed degrees & points to be used in connection with a moveable direction bar &
a fixed luminous line or definite marks in lid of case so that when the magnetic
north of compass card is under the north end of direction bar the luminous line in
lid shall indicate as a luminous finger the line of march or direction of objective
point: This divided ring is attached to the inside of the box, preferably parallel
to the bottom, but it could be fixed at right angles to the bottom of compass box
or engraved or marked on the inside of compass box in any suitable position to
allow of the direction bar being set to any particular degree.
2. The application of a jewel or centre to the moveable direction bar so that it
forms the centre for the top of pivot of magnetic needle to swing in, & thus take
the place of the usual centre as fitted (in horseback compasses) into a fixed bar or
into the top glass. By this means the steadiness of the magnetic needle is ensured
& the advantage of a setting direction bår for use with luminous painted compass
card maintained.
3. The form of setting bar by which greater accuracy of setting is ensured, for the
slotted end permits of the reversed divisions on ring being clearly seen.
4. The application of a hinged mirror to the inside of the lid of case, or one fixed
at a suitable angle so that the observer may see when the compass card or dial is
quite steady before removing from his eye. The check & lock stops as ordinarily
fitted permitting of the card being fixed at settled bearing.
5. The application of vulcanite to the base of the compass box scored with
concentric rings or other cuts that would produce a certain amount of friction or
hold when placed on paper & so prevent it slipping; concentric rings cut in metal,
box or other wood would answer for producing friction but preference is given to
vulcanite.
6. The application of a line to the cover glass of compass in such a position that
it is in true line with the line in lid or marks or notches. This line on the glass
will then form what is called the "lubbers line" & so secure a closer or clearer
reading under certain conditions & if necessary or desired a magnifying lens can
be fixed by transparent cement above this line for enlarging the degrees &c. on
compass card or reversed circle of degrees.
7. The improved combination of a dead stop, locking or check, or both, with the
compass centre fitted in the moveable direction bar, so that said card does not
move after taking a bearing.
8: The application of horizontal lines drawn on a glass or tube let into the top
of hinged cover in such a way that on looking through slotted or V sights on
opposite side of compass box the said horizontal lines denote approximately the
angle included by any object observed, the lines being proportionate to degrees.
9. An improved magnetic compass substantially as described with all or any of
the improvements described.
L

page_text: COMPLETE SPECIFICATION.
Improvements in Magnetic Compasses.
JAMES HENRY STEWARD 406 Strand London Optician 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 :-
The improvements relate more particularly to magnetic compasses for military
and other purposes where a pocket or portable compass will be useful at night
for marching on a definite position, or for travellers and surveyors.
The accompanying illustrations will facilitate description of improvements which
are as follows:-
The application to the inside of the compass box of a divided ring with reversed
degrees or points, or both reversed degrees and points to be used in connection
with a moveable direction bar and fixed luminous line or definite marks in lid of
case so that when the magnetic north of compass card is under the north end of
direction bar the luminous line in lid shall indicate as a luminous finger the line
of march or direction of objective point. This divided ring of reversed degrees
or points or both reversed degrees and points is for preference fixed to the inside of
box in a horizontal position, i.e. parallel to the bottom but it could be fixed at
right angles to the bottom or the degrees &c. could be engraved or marked on
the inside of the compass box itself in any suitable position to permit of the
moveable direction bar being set to any particular degree.
In Figure 1. A A' in the compass box of ordinary kind of any convenient size
& shape, B the hinged cover to protect the glass fitted in the usual bezel while
D is the direction bar that can be rotated by the milled ring D' D" in which the
two ends are fixed at E E. F is the divided ring referred to by which to set the
direction bar and G is the luminous line in lid that points to the required direction
when north end of compass card H is under the north end or cross end of direction
bar D.
•
By the application of a jewel or centre I of hard material such as agate to the
moveable direction bar D so that it forms a centre for the top of the pivot of
magnetic needle of compass card to swing in, as shewn in Fig. 3, it takes the place
of the usual centre as fitted in compasses known as the horse back pattern, where
the centre is fixed into a fixed bar or into the top glass or crystal lens as is some-
times employed. By this means the steadiness of the magnetic needle is ensured
and the advantage of a setting bar maintained for use with the luminous painted
card without the drawback of having any other bar appearing against the luminous
paint as would be the case if the jewel or agate was in the ordinary fixed bar and
a setting bar was fitted in addition. By slotting the end of the direction bar D
or bringing it to a finer end as shewn respectively in Fig. 2. D* D, exact directions
can be arranged for or definite magnetic bearings registered by day or night. In
order to see when the magnetic card is at rest a mirror K is fastened inside the lid
and hinged at L so that the observer can conveniently see by the reflection of the
card the exact moment to apply the stop. By this means considerable time
in observations. The stops are similar to those usually supplied to compasses, but
in the improved combination of the same with the special centre fitted in direction
bar previously described it is possible to stop the compass card dead true at its
right bearing by either the check stop Q or lock stop P & note the bearing after
taking the compass from the eye & holding it in any convenient way to see the
divisions on the card. The reason the card stops true is that there is no room for
any play in the centres or caps laterally when the card is pressed on its edge by
the check stop or lifted up by the lock stop, while in ordinary compasses fitted with
check & lock stops & one centre & cap only to the magnetic card it is possible &
thus often a different bearing is shewn before the stop is applied to that recorded
when card is stopped. The sights consist of a slotted plate M for the one next
saved

page_text: the eye which folds up and down, while a line N on glass or other transparent
medium in the cover forms the other sight and enables the object to be intersected
by the observer.
When the magnetic card is at rest the bearing is shown by the lubbers line O
which in order to be seen readily is a white line on a black ground or black line on
a white, and in order to be near the edge of the card is continued on the inside of
ring of setting bar at such a position that it is true when the north or crossed
end of direction bar is opposite the zero.
To the bottom of the compass box is attached or inserted a piece of vulcanite
or wood scored with concentric rings or other cuts that will produce a certain
amount of friction or hold on drawing paper attached to a sketching board or pad,
for it is found that flat bottom compasses of metal are apt to shift after being
placed in the right position for sketch, on slightly tilting the board. Metal, wood,
asbestos, or papier mache so scored will answer but preference is given to
vulcanite.
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 I
claim is
1. The application of a divided ring or painted, engraved, or impressed circle
of divisions with reversed degrees or points or both reversed degrees & points to
the inside of a magnetic compass box in conjunction with a moveable direction bar
& luminous line in lid of case for the purpose herebefore stated substantially as
figured and described.
2. The combination of a jewelled or stone centre with a moveable direction bar
for the compass pivot to work in together with the check and lock stops, or either
check or lock stop for stopping the compass dead true substantially as figured
and described.
3. The combination of the jewelled or stone centre for compass pivot with a
moveable direction har substantially as described.
4. The application of a reflecting mirror hinged to the lid of case in such a way
that the observer may see (when lid is vertical) the moment the dial or magnetic
card is steady, substantially as described and figured.
5. The application of a piece of vulcanite, asbestos, papier mache, wood or
metal scored with concentric rings or other cuts, to the bottom of the compass box
to produce a certain amount of friction and so remain in position on the sketch or
table or cavalry sketching board when slightly tilted.
6. An improved magnetic and sight compass substantially as figured and described
with any or all the improvements specified in above claims.
Dated this Sixteenth day of December 1892.
J. H. STEWARD.