IMPROVED APPARATUS FOR CORRECTING DEVIATIONS OF SHIPS' COMPASSES
Year: 1884

page_text: I, WILLIAM SPINK, of 32 Seagate, Arbroath, in the county of Forfar, Teacher of
Navigation, do hereby declare the nature of my said Invention for "IMPROVED
APPARATUS FOR CORRECTING DEVIATIONS OF SHIPS' COMPASSES," to be as follows:-
The object of this invention is to provide means for correcting the deviations of
ships' compasses, and enabling the correct magnetic course of a vessel to be
ascertained.
The improved apparatus comprises an upright stand or pillar which may be
secured to the ship's deck in any convenient situation, and which carries a vertical
spindle capable of rotating on the stand. On the pillar is fitted a dumb compass
card which is loose and capable of being turned by hand in setting the apparatus,
and on the spindle above is a pointer and a vane, or smoke funnel, or other device
capable of indicating the direction of the wind. The dumb card is fitted so that it
may be turned by hand while on the pillar to set it to any position, or to ascertain
the direction of the wind by the position of the pointer over it, and it can be
removed and fitted on the revolving spindle to rotute with it.
In using the apparatus, the ship is turned with its head say to "east" by com-
pass, the dumb card is set to the same point, and the pointer is turned to the
direction of the wind. The indication on the dumb card is noted. Then the ship's
head is turned "west" by compass and a like indication is taken, and the mean of
the two bearings gives the correct magnetic direction of the wind. The dumb card
is then raised and fixed to the spindle in a position in which the pointer shows the
mean of the bearings taken. By placing the ship's head at any point of the compass
by the dumb card the correct magnetic course to steer by the aid of the compass is
indicated, while the smoke travels in the line of the pointer.
When the apparatus is used in sailing ships, the upright pillar is or may be
jointed and fitted with a quadrant and spirit level or plummet, so that the upper
part carrying the dumb card and pointer may be set vertically when the ship
heels over. The quadrant in this case may also sorve to indicate the angle of
heeling.
The means of indicating the direction of the wind is by preference a smoke
funnel attached to the vertical spindle, tho smoke being taken from a burning lamp
attached to the funnel, or from any other source.
Dated this Eleventh day of November 1884.

page_text: Compasses.
T, WILLIAM SPINK, of 32 Seagate, Arbroath, in the county of Forfar, Teacher
of Navigation, do hereby declare the nature of my invention for "IMPROVED
APPARATUS FOR CORRECTING DEVIATIONS OF SHIPS' COMPASSES," and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
The object of this invention is to provide means for correcting the deviations of
ships' compasses and enabling the correct magnetic course of a vessel to be
ascertained.
In the accompanying Drawings figure 1 is an elevation and figure 2 is a plan of
the improved apparatus I employ for this purpose. Figure 3 is a vertical section
on a large scale showing details of construction, and figure 4 is a plan of figure 3.
The improved apparatus comprises an upright stand, pillar, or frame A, which
may be secured to the ships' deck in any convenient situation, and on which is
hung on gimbals a box case B carrying a vertical hollow spindle C capable of
rotating and of being fixed relatively to the stand. Within the box B on the pillar
or stand A is fitted a dumb compass card D, which is fitted on a loose sleeve E, and
is capable of being turned by hand in setting the apparatus; and on the spindle C
above is a pointer F and a lamp case G provided with a vane or smoke funnel H
or other device capable of indicating the direction of the wind. The dumb card D
is fitted on the sleeve E, so that it may be turned by hand to set it to any position
or to ascertain the direction of the wind by the position of the pointer F over it,
and it is arranged to turn with the spindle C by using a pinching screw e to fix the
sleeve E to the spindle C the spindle itself being in like manner fixed when set by
using a screw c to secure it to the rod J which is fixed in the frame B' of the
gimballed case B.
In using the apparatus the ship is turned with its head say to "east" by com-
pass, the dumb card D is disengaged from the spindle C and is set to the same
point and the pointer is turned to the direction of the wind, the vane or smoke
funnel being turned with it and set by fixing the pinching screw e. The indication
on the dumb card is then noted. Then the ship's head is turned "west" by com-
pass and a like indication is taken and noted. The mean of the two bearings gives
the correct magnetic direction of the wind. The dumb card is then fixed to the
spindle C by means of the pinching screw e in a position in which the pointer F,
shows the mean of the bearings taken. Then by placing the ship's head at any
point of the compass by the dumb card when fixed to the spindle C, the correct
magnetic course to steer by the aid of the compass is indicated, whilo the smoke
travels in the line of the pointer.
•
When the apparatus is used in sailing ships the upright plumb rod J is or may
be jointed and fitted with a quadrant or clinometer I and a spirit level or plummet,
so that the upper part may be set vertically when the ship heels over. The
quadrant in this case may also serve to indicate the angle of heeling. In the
example shown in the drawings, a long rod J is secured to the spindle C and is

page_text: fitted with a weight J serving to maintain the spindle in a vertical position.
A spring K fitted between the frame B' and the plate L' serves to prevent undue
oscillation of the weighted rod J, and a rubber cushion L is fitted on said rod
to bear against the plate I secured adjustably to the frame A; may serve as a
corrective against undue influence of the spring.
The means of indicating the direction of the wind is by preference a smoke
funnel H attached to the vertical spindle C, the smoke being taken from a burning
lamp sot in the case G to which the funnel is attached; but any other suitable
means of facilitating the setting of the pointer to the direction of the wind may be
employed.
The following directions for using the instrument may be found suitable for
nautical men.
Rules for working the instrument for finding the magnetic direction of the ship's
head by the wind:-Place the instrument so that the feet of it are straight with
the fore and aft line of the ships deck, the lubber line forward. Before putting
the ship off her course, slow her down or stop her a little to windward of her
course, make her pay off gently by a turn of the propeller, or by hauling up one of
the head sails, if she does not pay-off without. The instant the ship comes to her
course straighten the smoke which issues from the funnel pointer and tighten the
upper screw in the lamp tube, turn the dumb card till the same point is at the
lubber line of the instrument as the ship is at by compass, the hand on the top of
the dumb card will then show the compass direction of the wind with the ship's
head at that point which is to be used as a check against the wind shifting during
the operation. Then place the ships head at "east" or "west" by compass, say
"east" stop the ship as above, straighten the smoke, and turn the dumb card to
have "cast" at the lubber line of the instrument; this will give the compass
direction of the wind as indicated by the hand, with the ship's head.at cast, which
note down. Turn the ship slowly round; and place her head at west by compaяs
and dumb card, repeating the operation as above, and note the direction of the
wind, the mean of the two directions at the east and west points, will be the
magnetic direction of the wind, to which clamp the hand with the lower screw in
the lamp tube, the instrument will then show the magnetic direction of the ship's
head, as the ship falls round slowly at any course if the smoke is kept leaving the
funnel pointer in a straight line by the person working the instrument and the
wind does not shift its direction during the operation, to prove which the compass
direction of the wind can be proven by repeating the first part of the rules laid
down, or even the whole operation can be repeated if any doubt exists.
The same precaution is not necessary as to stopping the ship at the east and
west points as at the ship's course if the deviations are not very large, by taking
the mean of the two bearings at these points the aberration of the smoke is
corrected and will therefore bring the magnetic direction of the wind practically
the same.
Rules for working the instrument to find the magnetic direction of a ship's head
by sun, moon, planets, or stars, without azimuth tables, time, latitude, or declination
of the object: Place the instrument so that the feet of it are straight with the fore
and aft line of the ship's deck, the lubber line forward. Before putting the ship
off her course by compass, place the same point of the dumb card to the lubber line
of the instrument by turning it from underneath the dumb card table, the screws
in the lamp being slackened, direct the azimuth tube M, which is fitted on the
vertical spindle, to the object selected, and note the time by watch to the nearest
minute. The hand on the top of the dumb card will then show the compass
azimuth of the object with the ship's head at that point, which note down alongside
of the time, wait till ten minutes elapse, and repeat the operation, note the time
and compass azimuth. The difference of the two azimuths will be the change of
bearing in ten minutes. Placo the ship's head at "east" by compass and the east
of the dumb card at the lubber line of the instrument, direct the azimuth tube to
the object and note the time and azimuth, turn the ship slowly round to west,

page_text: giving the compass sufficient time to steady and repeat the operation, noting the
time and azimuth with the ships head at "west" by compass and instrument, the
mean of the two times and azimuths will give the object magnetic azimuth at
the middle time; now having the azimuth at the middle time and the change of
azimuth in ten minutes, the instrument can be clamped to the magnetic bearing
of the object, with perfect safety as far as practical purposes are concerned for the
next twenty minutes which will give plenty of time to get the course set, after
the instrument is clamped to the magnetic bearing of the object. The ship's head
correct magnetic will be indicated by dumb card at the lubber line if the azimuth
tube is kept in a direct line to the object, turn the ship slowly round to give the
compass time to follow, steam for a short time at the course before fixing it, so that
the compass may have time to lose any deviation of other courses.
The instrument can also be used for the ordinary method of azimuths or time
azimuths of celestial objects, or for taking bearings correctly for cross bearings of
two objects or for double bearings while sailing along any coast or the magnetic
bearing of one object can be found by the rules laid down for the wind, the ship
being stationary at the time, or the magnetic bearing of two objects in a line can
be found on the same principle and deviations of the compasses found or a steering
table made.
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
The combination of parts forming the improved instrument or apparatus for
taking magnetic bearings at sea and correcting deviations of ships compasses
substantially as herein set forth.