AN IMPROVED DIRECTION INDICATOR TO BE USED AS A COMPASS AND OTHERWISE
Year: 1876

page_text: LETTERS PATENT to Leendert Janse, of Amsterdam, in the Kingdom of
Holland, but temporarily residing at Paris, in France, for the Invention of
"AN IMPROVED DIRECTION INDICATOR TO BE USED AS A COMPASS AND
OTHERWISE."
Sealed the 14th July 1876, and dated the 25th January 1876.
PROVISIONAL SPECIFICATION left by the said Leendert Janse at the Office
of the Commissioners of Patents on the 25th January 1876.
LEENDERT JANSE, of Amsterdam, in the Kingdom of Holland, but temporarily
residing at Paris, in France. "AN IMPROVED DIRECTION INDICATOR TO BE USED AS
A COMPASS AND OTHERWISE."
This Invention relates to an improved combination of parts forming a direction
indicator, and designed more especially to be used instead of the mariner's compass,
but also applicable for other purposes depending on the maintenance of a determined
direction.
In carrying out the Invention the indication of direction is obtained by means of
one or more rotating heavy rimmed wheels driven and mounted so as to be inde-
pendent, or as nearly so as possible, of any angular movement that the ship or
anything carrying the instrument may have in the horizontal or other plane in
which the indicator is set to work. The Invention also comprises a particular mode
(amongst others which might be adopted) of obtaining the desired indication from a
rotating wheel, by combining therewith a second wheel rotating in the opposite
direction, the two wheels being arranged to give motion, to indices or pointers
over a compass card or other indicating face or dial, which pointers, from their
reversed rotations, necessarily coincide with each other at two diametrically opposite
points of their revolutions. The direction to be observed is that of the reversely
rotating pointers at their coincidences, and certain corrections to be herein-after
referred to being assumed to be made, it will be obvious that if the two wheels
rotate in opposite directions with perfect uniformity, the coincidences of the pointers
must always take place in the same positions, and thus indicate the same direction,
notwithstanding angular movements of the ship or other support of the instrument.
The reversely rotating wheels may be arranged to yield a static indication of direc-
tion in other ways than by means of the two pointers.
In one modification of the instrument the paris are mounted in a casing sup-

page_text: ported like an ordinary compass bowl by a gimbal ring and springs, so as to be
as little affected as possible by rolling or pitching, or any abrupt movements of the
ship. The two rotating wheels are set with their spindles vertical and run in
jewelled holes; and every other possible precaution is taken to render them as
free from fiction as possible. The rotating wheels are driven by two equal but
separate clock movements, a modification of what is known as Earnshaw's chrono-
meter escapement being interposed in each movement in such a way that the
driving force is not communicated continuously but by successive impulses, each
of which occupies a very small proportion of the entire revolution of the wheel.
In consequence of this arrangement, any variation that angular movement of the
ship may at any moment cause in the action or effect of the impulses will corre-
spond to only a very small proportion of such angular movement, and its ratio
being once ascertained by suitable observations, subsequent observations can be easily
corrected for it. The effect of the friction of the pivots or bearings may be
corrected for in a similar way. It is desirable that the velocities of the wheels
should be as nearly uniform as possible, but inequalities in these velocities may
be ascertained by means of a special indicator and be also corrected for. Such
special indicator may consist of a graduated dial turned by means of one of the
wheels, and a pointer turned by the other wheel, but with a reversed motion
relatively to its wheel, so that its actual motion is in the same direction as that of
the dial. As long as the motions are uniform in their rates the pointer will keep
upon the same division of the dial, but will move relatively to the dial whenever
the rates are unequal. The observations of the instrument have to be corrected
for the rotation of the earth, excepting when the instrument is at the equator;
and this correction may be made by means of tables calculated for the purpose.
The two rotating wheels may be placed one above the other so as to have the
indicating pointers attached directly to their spindles, the spindle of the upper one
being made tubular so that the spindle of the lower one may pass through it; or
the wheels may be placed at the same level at different parts of the casing, and be
connected by suitable gearing to spindles placed centrally in the casing, and having
the pointers attached to them.
Instead of driving the rotating wheels by clockwork electro-magnetism may be
used for that purpose; or they may be driven by fluid pressure, acting as in a
turbine or Barker's mill.
The improved direction indicator may be used by itself or in combination with
a magnetic compass card, and it will show all deviations and errors of the latter,
whilst it is itself perfectly independent of all magnetic influences, and will yield
equally certain and accurate indications at whatever part of the globe it may be
used.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Leendert Janse in the Great Seal Patent Office on the 24th July 1876.
LEENDERT JANSE, of Amsterdam, in the Kingdom of Holland, but temporarily
residing at Paris, in France. "AN IMPROVED DIRECTION INDICATOR TO BE USED AS
A COMPASS AND OTHERWISE."
My said Invention relates to an improved combination of parts forming a direc-
tion indicator, and designed more especially to be used instead of the mariner's
compass, but also applicable for other purposes depending on the maintenance of
a determined direction.
In carrying out my Invention the indication of direction is obtained by means of
one or more rotating heavy rimmed wheels, mounted and driven so as to be inde-
pendent, or as nearly so as possible, of any angular movement that the ship or
anything carrying the instrument may have in the horizontal or other plane in

page_text: which the indicator is set to work. My Invention also comprises a particular mode
(amongst others which might be adopted) of obtaining the desired indication from
a rotating wheel by combining therewith a second wheel rotating in the opposite
direction, the two wheels being arranged to give motion to indices or pointers
over a compass card or other indicating face or dial, which pointers from their.
reversed rotations, necessarily coincide with each other at two diametrically opposite
points of their revolutions. The direction to be observed at any time is that of the
reversely rotating pointers at their coincidences, and certain corrections to be herein-
after referred to being assumed to be made, it will be obvious that if the two
heavy rimmed wheels rotate in opposito directions with perfect uniformity, the
coincidences of the pointers must always take place in the same positions, and thus
indicate the same direction, notwithstanding angular movements of the ship or.
other support of the instrument. The reversely rotating wheels may be arranged
to yield a static indication of direction in other ways than by means of the two
pointers.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append two Sheets of explanatory
Drawings and representing modifications of my improved instrument. In theso
Drawings the same reference letters are used to mark the same or like parts
wherever they are repeated.
Figures 1 and 2, on Sheet 1 of the Drawings, are a plan and a vertical section
showing one modification of the instrument, as contained in its box A, the lid
however of which is supposed to be removed; Figure 3, on Sheet 2, is a sectional
plan showing the arrangement of the clockwork. The parts are mounted in a
casing or bowl B supported like an ordinary compass bowl or chronometer by a
gimball ring C so as to be as little affected as possible by rolling or pitching, or any
abrupt movements of the ship, and if found desirable springs may be added to
secure greater steadiness. The external pivots of the gimball ring Care held by a
flat ring D carried by the box A, and this ring D is toothed on its outer edge and
has engaging with it a toothed wheel, which can be turned by a button E (Figure 1)
so as to shift round the instrument in its bowl B relatively to the box A. The two
rotating heavy rimmed wheels F, G, are set with their spindles f, g, vertical, and
run in jewelled footstep holes; and every other possible precaution is taken to
render them as free from friction as possible. The rotating wheels F, G, are
driven by two equal but separate clock movements, and the trains of toothed
wheels composing these movements will be quite easily understood from Figures 2
and 3 by those skilled in horology. Each movement comprises an escapement
slightly modified from what is well known as Earnshaw's chronometer escapement..
The heavy rimmed wheel F or G takes the place of the ordinary balance wheel, but
there is no spring to produce a backward-and-forward motion. The wheels F, G,
move continuously, each in one direction, but opposite to that of the other; the
driving force is however not communicated continuously but by successive impulses,
each of which occupies a very small proportion of the entire revolution of the
wheel. In consequence of this arrangement any variation that angular movement
of the ship may at any moment cause in the action or effect of the impulses will
correspond to only a very small proportion of such angular movement, and its
ratio having been once ascertained by suitable observations subsequent observations
can be easily corrected for it. The effect of the friction of the pivots or bearings
inay be corrected for in a similar way.
The rotating heavy rimmed wheels F, G, in this first modification are not placed
concentrically one over the other, but they act on concentrically placed spindles
h, i, the latter of which is tubular for the passage up through it of the former.
The motions are transmitted by toothed wheels j, k, fast on the wheel spindles f, g,
through intermediate wheels l, m, to wheels p, q, fast on the concentric spindles
h, i.
In all such arrangements it is absolutely indispensable for the concentric
spindles h, i, to revolve in the same directions and with the same speeds as the
wheels F, G, from which they derive their motion. The concentric spindles h, i,

page_text: have fixed at their upper ends two indices or pointers H, I, and these indices Daving
the same motions as the heavy rimmed wheels F, G, move round in opposite direc-
tions over the compass card or circle R marked with the usual compass points. It will
simplify explanations if we assume that in general the coincidences of the indices
H, I, occur on the true north-south diameter at the commencement of operations,
and then when a change of direction of the ship has taken place, the instrument
in its bowl B should be turned by means of the button E to bring the north-south
diameter into agreement again with the coincidences of the indices. If, however,
as will generally be the case, corrections have to be made, then a small slide s may
be adjusted in a groove in an outer graduated ring T fixed to the box A and
exhibit the algebraical sum of the corrections in such a manner as to be easily
applied.
Figures 4 and 5, on Sheet 2, are a plan and vertical section of a modification in
which the rotating heavy rimmed wheels F, G, are placed concentrically, the train
of clockwork being modified to suit, as will be easily understood from the Figures.
The lower wheel G is fixed on a spindle g, which is supported in a footstep bearing
at the bottom, and is extended up through tubular parts to a bearing at its top end
in a narrow diametrical bar U fixed over the top of the instrument. The upper
wheel is on a tubular spindle f, and the two spindles f, g, might have indices
(H, I) as in the first modification fixed directly on them, or they might have discs
fixed, as herein-after described with reference to Figures 6, 7; but an arrangement
is shewn yielding a static indication of direction in a convenient and simple
manner. A pointer V, which may extend quite across the instrument, is fixed on a
tube v extending down between the spindles f, g, to the space between the two
rotating heavy rimmed wheels F, G. At its bottom end the tube v has fixed to it
two or more arms w, having mounted loosely on their ends wheels W, which rest
With
on the rim of the lower wheel G, and support that of the upper one F.
this arrangement it is obvious that the pointer V must remain stationary as long
as the motions of the heavy rimmed wheels F, G, are exactly equal and opposite.
In the indicating arrangement, shown in Figures 6, 7, the concentric spindles
(,, or f, g,) have fixed on their upper ends discs, whose upper surfaces are made
black, excepting a white radial stripe on the lower disc, and a corresponding radial
slit on the upper one. Nothing will be seen through the upper slit excepting when
the white stripe below coincides with it, and if the motion is sufficiently rapid there
will appear a more or less permanent image which will constitute the indication of
direction required.
It is desirable that the velocities of the heavy rimmed wheels should be as nearly
uniform as possible, but inequality in these velocities may be ascertained by
keeping the instrument for a short time without angular motion, and observing
whether the coincidences of the indices or the pointer V keep stationary as they
ought to do. Very small differences of velocity may be corrected for, but larger
differences should be neutralised by adjusting the driving wheelwork.
The observations of the instrument have to be corrected for the rotation of the
earth, excepting when the instrument is at the equator (or in an equivalent
position), and this correction may be made by means of tables calculated for the
purpose.
Instead of driving the rotating heavy rimmed wheels by clockwork electro-
magnetism may be used for that purpose; or they may be driven by fluid pressure
acting as in a turbine or Barker's mill.
My improved direction indicator may be used by itself, or in combination with
a magnetic compass card, and it will show all deviations and errors of the latter,
whilst it is itself perfectly independent of all maguetic influences and will yield
equally certain and accurate indications at whatever part of the globe it may be
used.
Having thus particularly described my said Invention and the manner of per-
forming the same, I have to state that I do not restrict myself to the preciso details
herein described or delineated, but that what I believe to be novel and original, and

page_text: claim as the Invention secured to me by the herein-before in part recited Letters
Patent is,
1. An improved direction indicator, in which the desired indication is obtained
by means of one or more rotating heavy rimmed wheels, substantially in the manner
herein-before described.
2. The combination of two heavy rimmed wheels rotating at equal speeds, but
in opposite directions, for obtaining an indication of direction, substantially in the
manner herein-before described.
3. The combinations of parts constituting direction indicators, as herein-before
described and as shown on the accompanying Drawings.
In witness whereof, I, the said Leendert Janse, have hereunto set my hand
and seal, this Twenty-first day of July, in the year of our Lord One thousand
eight hundred and seventy-six.
L. JANSE, B.A. (L.S.)