AN IMPROVED INSTRUMENT FOR ASCERTAINING THE VARIATION OF THE COMPASS;
Year: 1884

page_text: I, HANS HARILD of 81 Clive Street North Shields, Seaman passed ordinary
master, do hereby declare the nature of my said invention for "AN IMPROVED
INSTRUMENT FOR ASCERTAINING THE VARIATION OF THE COMPASS;" to be as
follows:-
My invention relates to an improved instrument by means of which the true
pole can be determined and the variation of the compass ascertained in any latitude
without the aid of time.
I provide a compass card a, Figure 1, divided in the ordinary manner and
swinging freely in gimbals. A balance-rod b is attached to the underside of the
compass card a the said balance-rod being provided with four weighted adjusting
screws c.
•
Figures 2 and 3 are a side elevation and plan of the instrument. The centre
pin or rod d is fitted into a hole in the compass card a The said pin or rod is
secured to the underside of the platform e which is pointed at each end and is
provided with a reflector f and a spirit level g. In the centre of the platform e is
a standard h carrying on its upper end an annular dial i. The said dial is fixed
perpendicularly to the side of the said standard h facing the side of the platform e.
Within this dial i another dial j is arranged, the dial j turning on a central pin or
pivot in the standard h and attached to and operated by an arm or lever k. The
said dials are marked with suitable scales by which the arm or lever k may be set
to the suu's declination and to the degree of latitude. Attached to the said arm
or lever k and projecting in a line therewith towards the end of the platform e and
over the reflector f is a screw rod l. This screw rod represents the axis of the
earth and passes through a ball m representing the centre of the earth and also.
through a suitable frame or support carrying a circle n the said circle representing
a degree of latitude, both the ball m and circle 'n being adjustable upon the said
rod . When the declination is North the ball m must be between the circle n
and the dials but when the declination is South the circle must be between the
ball m and the dials. These positions are for North latitude when the latitude is
south the positions must be reversed. These alterations of position are effected by
reversing the rod in the arm k. The circle n (which I call the shadow circle) is
shown in plan in figure 4 and the reflector fin figure 5.
2

page_text: The operation of the instrument is as follows. The rod d is fitted into the
centre of the compass card and the reflector fis placed upon the platform e at right
angles to the standard h. That point of the platform e which is under the screw-
rod must point to the pole nearest to the observer it being set to the north point
when the observation is taken in north latitude and to the south point when in
south latitude. The arm or lever k is then raised until the dials mark the sun's
declination: Then look from above into the reflector fin such a manner as to
bring the upper part of the shadow-circle n in a line with the reflection of that
part of the circle.---Then-adjust the ball m until its centre is in a line with the
circle n and its reflection The arm or leverk is then raised until the dials i and j
show the latitude the said arm being then secured by the clamp-screw k¹. If the
spirit level g indicates that the compass card a is not horizontal it must be adjusted
by the adjusting screws c until it swings horizontally. The compass card a is then
turned, until the shadow from the shadow-circle n falls on the ball m when the
north point of the compass card will indicate the true pole.
Two shadow-circles n may be used one, smaller than the other.and the shadows
of both should coincide on the ball'm."
When the sun is not shining with sufficient power to throw a shadow I use the
sight-vane shown in figure 6. The rod o is inserted into the arm or lever k in
place of the rod . p is a tube pivotted to the end of the rod o and q is a guide
for fixing the tube at an angle to the rod o by means of a screw. One end of the
tube p is closed with the exception of a small central aperture through which the
observation is taken. At the other end of the tube. four, wires are arranged two
of which cross the other two at right angles so as to form a small central space or
aperture where the said, wires. cross each other. This sight-vane. is set to the
declination in the manner, previously described the length, of the tube p when set
. to the declination being in a line with its reflection. When the lever k is raised
so that the dinis indicate the latitude the rod o is turned in the arm or lever h
until the tube p points to an altitude equal to the altitude of the sun. The
compass card a is then turned until, when the observer is looking through the
aperture in the closed end of the tube p, the sun appears in the central space formed
by the crossing of the wires at the other end of the said tube. The north point of
the compass card will then indicate the true pole. When both the declination and
latitude are north or south the closed end- of the tube p must incline towards the
dials but when the declination is opposite to the latitude the other end of the tube
having the crossed wires must incline towards the dials.
i

page_text: "
I HANS HARILD of 81 Clive Street, North Shields in the County of North-
uinberland do hereby declare the nature of my said invention for "AN IMPROVED
INSTRUMENT FOR ASCERTAINING THE VARIATION OF THE COMPASS' and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accompanying
drawings forming a part of this specification :-
4
:
'
My invention relates to an improved instrument by means of which the truè
pole can be determined and the variation of the compass ascertained in any latitude
without the aid of time.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is an elevation of my improved instrument.
Figure 2 is a plan of the compass card and gimbals.
Figure 3 is a plan of the inner gimbal.
Figure 4 is an elevation of the balance rod.
Figure 5 is a plan view of the same.
,
Figure 6 is a plan of a portion of my improved instrument without the compass
card and gimbals.
Figure 7 is a plan of the shadow circle..
Figure 8 is a sectional view of the same.
Figure 9 is a side elevation of the "sight-vane."
Figure 9 is a view of one end of the tube of the "sight-vane."
S
Figure 10 is a side elevation of a portion of my improved instrument showing a
modification thereof.
Like letters indicate like parts in all the figures.
In figure 1 I have shown an elevation of my improved instrument complete,
when all its parts are fitted together. a is the shadow circle (shown in plan and
section in figures 7 and 8) which represents a parallel of latitude and consists of a
rim a carried by the arms a radiating. from a central boss a³. The periphery of
the said rim al inclines, one edge of the rim being of a greater circumference than
the other and that edge which is of the greatest circumference terminates in a
blunt knife-edge a' as shown in figure 8. This edge a* forms the circle from which
the shadow is cast and is on the inner side when the shadow circle is in the position
shown in figure 1. The boss a³ of the shadow circle is tapped to screw upon the
screw rod c which represents the axis of the earth. The screw rod c also carries a
truncated cone 6 having concave sides as shown in figure 1. The apex end of the
said cone is in contact with and may be secured to the inner side of the boss a³ of
the shadow circle in which. position the upper and lower surfaces of the said cone will
form arcs of circles struck from the upper and lower extremities of the edge at of
the shadow circle. The said cone is provided with a scale of twenty four degrees
numbered from 0° to 24°. The first degree line marked 0° is in line with the plane

page_text: of the edge a of the shadow circle and that marked 24° is at an angle of twenty
four degrees from the plane of the edge at of the shadow circle. The degree marks
are drawn around the cone parallel to its base. The cone 6 is solid towards its
apex, but, for convenience hollow towards its base and is tapped so that the screw
rod c passes longitudinally through its centre as also through the boss a³ of the
shadow circle, so that the positions of the shadow circle and cone upon the said
screw rod c can be adjusted as described above.
The screw rod c is secured at its inner end, in a socket in the lever or arm d by
the set screw e or by other suitable means. The lever or arm d is pivotted and
turns freely in the upper extremity of the standard and attached to the pin or
pivot of the said lever so as to turn freely therewith is a circular dial y the said
dial being arranged perpendicularly to the standard f. Fixed to the said standard
and surrounding the dial g is an annular dial the said dials being so arranged
that the inner dial g (or "Vernier ") can revolve freely inside the annular dial h. The
dial h bears a scale dividing it into 120 equal parts, each part or mark on the scale
being equal to 3° (three degrees) or 360° (three hundred and sixty degrees) for the
'entire scale, or circumference of the dial The zero or 0 is in line with the screw
rod c when the same is parallel to the base or platform of the instrument. The
inner dial ("or Vernier ") g has a scale of sixty equal parts, the said scale
extending around only 18ths (one hundred and nineteen, one hundred and
twentieths) of the circumference of the dial, that is to say when the zero of the
"Vernier" is opposite the zero of the outer dial the sixtieth division on the
"Vernier dial is opposite the 119th division on the outer dial. Each of the
divisions of the "Vernier" dial represents three minutes (3) of a degree.
The lower end of the standard f is fixed in the centre of a platforin i pointed at
both ends as shown in the drawings. One end of the platform i carries a spirit-
level k. A pin or stud on the underside of the platform fits into the hole or
socket in balance rod l. "
The balance rod l consists of a straight stem with a cross-head or horizontal
piece formed on or secured thereto. Above and below the cross-head are
central bosses or enlargements 13 and 18. The underside of the latter forms a
shoulder upon the said balance rod. The said balance rod is carried by gimbal
rings. In figure 2 I have shown three gimbal rings m, n and o. The balance
rod slips into a socket m¹ of a disc m² carried in the centre of the inner gimbal m
(shown in Figure 3) the underside of the boss 13 resting upon the central disc m².
The lower end of the balance rod carries the weighted adjusting screws n' and
the axes of the gimbal rings are knife-edged as shown at n' figure 1.
A compass
card P is arranged within the inner gimbal m and secured upon the cross-head ¹ of
the balance rod. The said card can be revolved around the upper circular boss (*
of the balance rod, and is provided with two slots q through which pass two clamp
screws r which screw into the cross-head of the balance rod. By means of the
said slots the position of the said card can be adjusted, the card being held in the
desired position by turning down the clamp screws r. Two studs or buttons 8 are
provided to facilitate the turning and adjustment of the card. In figure 1 I have
shown the outer gimbal ring o carrying a bowl t to prevent the wind from getting
under the compass card p and vibrating it, but my improved instrument may be
used with or without the outer gimbal ring o and bowl t. The inner gimbal m is
marked with a point indicating the ship's head.
Instead of using the cone b as previously described;. I may use a ball z (Figure 10)
which screws upon the rod c and is readily adjusted thereon: The said ball
represents the centre of the earth and is marked with a central circumferential' line
or equator u¹
The operation of my-improved instrument, when the cone b is used, is as
follows-The compass card p is set to the variation by moving its north point-so
many degrees to the right or left of' one of the points' of the platform i, and the
Baid con pass card is then secured by the clamp screws r. The arm or lever' d' (and
with it the screw rod c shadow circle a, and cone 6)' is then raised until the diala

page_text: mark the latitude. Thus if it be required to set it to latitude 45° 30' the arm or
lever d must be raised until the zero of the "Vernier" or inner dial g is in line
with the fifteenth division of the outer dial h which is 45°. The arm or lever d
is then still further raised until the mark 30' on the "Vernier" g coincides with
the next mark above it on the outer dial h. The required angle of 45° 30' will
then be given and the arm or lever d is clamped in position to the outer dial h by
the clamp and screw h¹. The compass card p should then be adjusted to a level
by means of the weighted screws n¹ on the balance rod, and spirit-level k and the
balance rod, compass card, and standard turned until the shadow of the edge a* of
the shadow-circle a falls on the division on the cone which marks the declination
for the day, when the point at the ship's head will indicate the magnetic course,
the difference between this and the ship's head by compass is the deviation of the
compass, or if the instrument is not set to the variation the difference will be the
variation of the compass In North latitude the arm or lever d must point to
the North and in South latitude to the South. When the declination is North the
cone b must be between the shadow circle a and the dials, but when the declination.
is South the shadow circle a must be between the "cone band the dials. These:
positions are for North latitude, for South latitude the positions must be reversed
and these alterations of position are effected by reversing the rod o in the arm or
lever d.
•
Instead of the cone 6 I may use a ball u (as shown in figure 10). I then
arrange on the platform i under the rod c and at right angles to the standard fa
reflector j sliding in a frame so as to be moved from or towards the standard f.
The cone b only marks every whole degree of declination but the ball may be set
to mark 3 minutes of a degree. The operation of my improved instrument with
the ball u.will be as follows:-The arm or lever 'dis. raised until the dials show
the declination. For example, to set to declination. 20° the arm or lever d must be
raised until the zero of the "Vernier" or inner dial g is opposite the sixth mark on
the outer dial h. This gives 18%. The arm d is then still further raised until the
mark 2° on the "Vernier" coincides with the next mark above it on the dial /
when the arm will be set to the declination of 20°. The screw rod c is then
secured in the arm or lever d so that the shadow circle a is next to the dials, and
the said shadow circle is adjusted in position until the lower edge of the said circle
is in line with its reflection and the equator on the reflected part of the ball in the
reflector j.. The shadow circle is then secured in this position on the rod c by
means of a screw nut on the said rod, which nut is screwed up tightly against the
boss as of the shadow circle. The circle and ball are now set to the declination
and the rod c may be reversed according as the declination is North or South. The
arm or lever d is then raised until the dials denote the latitude, the balance rod,
compass card and standard are then turned until the shadow of the edge at of the
shadow circle falls on to the line drawn around the centre of the ball, when the
point at the ship's head will indicate the true or magnetic course as the case may
be. The screw rod c must always point to the pole nearest to the observer and the
relative positions of the ball and shadow circle must be varied according to the
declination and latitude as above described for the use of the cone.
When the sun is not shining with sufficient power to throw a shadow I use the
'sight-vane". shown in figure 9. The end v' of the rod vis inserted into the arm
or lever & in place of the screw rod c. To the other end of the rod v is pivotted a
tube w provided with a guide x of semi-circular form secured to the underside of
said tube w for the purpose of setting the tube to any desired angle after which it
is secured by a screw y. The said guide is marked with a scale, the zero of which
is at the lowest point of the guide when the tube w is at right angles to the rod v
and the scale extends from each side of the zero mark to 90° (ninety degrees). One
end of the tube w is closed with the exception of a small central aperture through
which the observation is taken. At the other end of the tube four wires w¹ are
arranged two of which cross the other two at right angles, thus forming a small
central aperture w³ where the said wires cross each other (as shown in figure 9*),

page_text: This "sight-vane" is set to the declination by inclining the tube w to rod v until
the division on the guide which is the declination is on line with the centre of
rod vand it is then secured by the screw y. When the lever d is raised so that
The
the dials g and h'indicate the latitude the rod vis turned in its socket in the arm
or lever d'until the tube points to an altitude equal to the altitude of the sun.
compass card p is then turned until, when the observer is looking through the aperture
in the closed end of the tube w the sun appears in the central space w formed by the
crossing of the wires w¹ at the end of the said tube. The point at the ship's head
will then indicate the true or magnetic course. When both the declination and
latitude are North or South the closed end of the tube w must incline-towards the
dials but when the declination is opposite to the latitude the other end of the tube
having the crossed wires w³ must incline towards the dials.
I do not limit myself to the precise details herein set forth as the same may be
varied without departing from my invention, but,
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
"
.J
10
First In an instrument for ascertaining the variation of_the_compass, the
shadow circle a substantially as and for the purpose herein set forth.
..Second In an instrument for ascertaining the variation of the compass, the
cone b, substantially as and for the purpose herein set forth.
Third-In an instrument for ascertaining the variation of the compass, the
u, substantially as and for the purpose herein set forth.
ball
. Fourth In an instrument for ascertaining the variation of the compass, the
screw rod c (representing the axis of the earth) substantially as set forth.
Fifth-In an instrument for ascertaining the variation of the compass, the
combination of the shadow circle a and the screw rod c, with either the cone 6 or
ball u, substantially as set forth.
Sixth-In an instrument for ascertaining the variation of the compass, the
combination of the shadow circle a the screw rod c, arm or lever d, and dials g
and h, with either the cone b, or ball u, substantially as set forth.
Seventh-In an instrument for ascertaining the variation of the compass, the
combination of the shadow circle a, the cone b, the screw rod c, the arm or lever d,.
dials g and h, standard f, and platform i substantially as herein set forth.
Eighth-In an instrument for ascertaining the variation of the compass, the
combination of the shadow circle a, ball u, screw rod c, arm or lever d, dials g
and h, standard f, platform i, and reflector j, substantially as herein set forth.
Ninth In an instrument for ascertaining the variation of the compass, the.
'sight-vane" substantially as and for the purpose herein set forth and illustrated
in figures 9 and 9*.
Tenth-The general combination and arrangement of parts of my improved
instrument, substantially as herein set forth.