Improvements in, Apparatus for Facilitating Nautical Calculations.
Year: 1889

page_text: Date of Application, 18th Sept., 1889
Complete Specification Left. 18th June, 1890-Accepted, 19th July, 189G
PROVISIONAL SPECIFICATION.
Improvements in, Apparatus for Facilitating Nautical Calculations.
I MICHAEL MICHELSEN of 10 Litherland Alley Liverpool in the County of Lancaster
Master Mariner, do hereby declare the nature of this invention to be as follows:-
The object is to provide apparatus whereby the deviation of a compass, the true
course at sea, and like problems may be solved without the intricate calculations at
present required.
Apparatus under my invention consists of "three graduated surfaces, two of which
are movable around a fixed centre and are capable of being secured in position as
required together with a pointer or indicator also movable about the said centre, and
capable of being clamped in position. The inner surface is graduated in the same way
as an ordinary compass card, the intermeiliate and outer surfaces are graduated
with degrees the outer surface having in addition the points of the compass marked
thoreon.
In a convenient construction the outer surface is on an annulus attached to or
formed with a frame which carries a fixed centre. The intermediate surface is on an
annulus fitting within the outer annulus and attached to or formed with a frame free
to rotate about the fixed centre whilst the inner surface consists of a disc fitting within
the intermediate annulus and free to rotate about the fixed centre above mentioned.
The pointer or indicator is of any suitable form. The clamping appliances.consist of
screws clips or other convenient devices.
Per pro J. T. KING,
J. Johnson,
Agent.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Facilitating Nautical Calculations.
1 MICHAEL MICHELSEN of 10 Litherland Alley, Liverpool in the County of Lancaster,
Master Mariner, 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 object is to provide apparatus whereby the deviation of a compass, the true
course at sea, and like problems may be solved without the intricate calculations at
present required.
Apparatus under my invention consists of three graduated surfaces, two of which
are movable around a fixed centre and are capable of being secured in position as
required, together with a pointer or indicator also movable about the said centre; and
capable of being clamped in position.
The inner surface is graduated in the same way as an ordinary compass card, the
intermediate and outer surfaces are graduated with degrees the outer surface having
in addition the points of the compass marked thereon.
In a convenient construction the outer surface is on an annulus attached to or
formed with a frame which carries a fixed centre. The intermediate surface is on
an annulus fitting within the outer annulus and attached to or formed with a frame
free to rotate about the fixed centre whilst the inner surface consists of a disc fitting
within the intermediate annulus and free to rotate about the fixed centre above
mentioned. The pointer or indicator is of any suitable form. The clamping appliances
consist of screws, clips or other convenient devices.

page_text: DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a plan and fig. 2. a transverse section of apparatus under my invention.
a is the outer surface in the form of an annulus secured to a base provided
with a centre C₁ the intermediate surface dis in the form of an annulus carried by
arms e provided with a bearing on the centre c.
The inner surface is in the form of a disc pivotted on the centre c. g is a
pointer also pivotted on the centre &, the whole being capable of being clamped
in any required position by the nut h. The outer surface a is worked with the
points of the compass and with degrees as shown, the intermediate surface is
graduated with degrees and the inner surface with the points of the compass all
as shown, other additional graduations may be made if desired.
In the position shown the apparatus has been used to find the true course.
i
The course required being south east the variation. 20° west and the deviation 11°
east. The pointer is placed opposite south east on the outer circle, the arrow-
head on the intermediate circle is placed opposite 20° west of north on the outer
circle, and the north pointer on the inner circle is placed 11° east of the arrow
head on the intermediate circle.
The pointer gas will be seen is then over south east by east on the inner circle..
This is the true course to steer. The deviation is found and like problems solved
by similar procedure to the above as will be evident to those versed in nautical
calculations.
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:
Apparatus consisting of a fixed circle and two movable circles graduated as herein-
before set forth in combination with a movable pointer substantially in the manner and
for the purpose set forth.
Per pro J. T. KING,
J. Johnson,
Agent.