Year: 1887

page_text: I, JOHN CLARK DOBBIE of 24 Clyde Place, in the City of Glasgow, Nautical
Instrument Maker, do hereby declare the nature of this Invention to be as follows:-
My invention relates to improvements in the mariner's compass and it comprises
improved means for suspending the compass cord and compass box or bowl for
carrying and adjusting the quadrantal correctors and for taking azimuthal bearings.
In the improved compass the compass card is carried upon a cross bar which also
serves to carry the needles and to the centre of which the cap may be attached either
directly or as is preferred by light chains links or cords which by permitting of the
movement of the cap independently of the card serve to lessen the oscillation of the
latter on the movement of the compass box. The compass box or bowl is carried in
the usual gimbal rings and the outer ring is suspended by links or chains from spring
brackets secured to the binnacle case the said brackets being composed of helical
springs or of wires intertwined or of spring blades or the like fitted in sockets on the
inside of the binnacle case to project upwards and inwards therefrom the suspension
chains being attached at the upper ends of the springs; or the compass when
provided only with a single gimbal ring may be carried upon laminated or similar
springs fitted to the inside of the binnacle case the bearers of the gimbal ring resting
on or being secured to the said springs. The quadrantal correctors of deviation which
are preferably in the form of iron globes are carried on a circular frame within the
binnacle case which is or may be bulged out to make room for the same; and the
globes are adjustable on said frame both radially and circumferentially. For taking
azimuthal bearings 1 fit upon the glass cover of the compass box or bowl a reflecting
mirror made in two parts which are hinged or jointed together so that their reflecting
surfaces may be brought to lie at any angle to each other. One of the parts of the
D

page_text: mirror serves to reflect the object whose bearing is to be taken and the other reflects
the reading of the compass card; and in using the azimuth instrument the mirrors
are moved by hand until the reflection of the object and the scale are in the centres of
the respective mirrors. Either or both of the mirrors may be made of V shape or in
the form of reflecting surfaces inclined to each other the more readily to ensure the
bringing of the object to the centre.

page_text: I JOHN CLARK DOBBIE of 24 Clyde Place, in the City of Glasgow, Nautical
Instrument Maker, 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 :-
This Invention relates to improvements in the mariner's compass and it comprises
improved means for suspending the compass bowl and for taking azimuth bearings.
Under the Invention the compass bowl a is as seen in vertical section at figure 1
and in plan at figure 2 of the annexed drawings carried in the gimbal rings b, c and
the outer ring is suspended by links or chains d, from the upper ends of spring
catches e, which are secured at or near their lower ends to the interior of the binnacle
or case f
The spring brackets e may be composed of wires intertwined or plaited or of spring
blades or of helical springs or the like fitted in or passed through sockets or
fasteners secured on the inside of the binnacle case the brackets projecting upwards
and inwards therefrom as shown.
When the compass bowl is carried in only one gimbal ring as at b, figure 3 the said
ring is or may be supported on springs fitted horizontally to the inside of the
binnacle case the bearers of the gimbal ring resting on or in sockets or eyes h³ made
centrally in the length of each spring. The springs are or may be supported in
position by passing the ends of them loosely through straps i bolted or secured to the
interior of the binnacle case the springs being loose to provide for their elongation and
the steadying of the compass bowl in the rolling or heaving of the ship in rough
weather.
l
For taking azimuth bearings I fit upon the glass cover of the compass bowl a a
reflecting mirror made in two parts k, hinged or jointed together so that their
reflecting surfaces may be brought to lie at any desired angle relatively with each
other. The mirror & serves to reflect the object whose bearing is to be taken and the
mirror reflects the reading of the compass card. In using the instrument the
mirror k, is moved by hand around its bearings until the object to be observed is
reflected upon it as is also the mirror 1, and the frame or slide m, carrying the
apparatus is then turned round in azimuth until the reflections of the scale of the
compass card and of the object observed are exactly in the centres of the respective
mirrors the bearing of the object being then read from the reflection of the compass
card.
To facilitate the getting of the reflection exactly in the centre of the mirrors either
or both of them may be made V shaped as indicated at figure 4, or the surface of the
nirrors may be made concave.

page_text: Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed Ì declare that what I
claim is
1. In a mariners compass suspending the compass bowl from spring brackets
secured to the interior of the binnacle substantially as described with reference to
figures 1 and 2 of the annexed drawings.
2. In a mariners compass supporting the compass bowl on horizontal springs
substantially as described with reference to figure 3 of the annexed drawings.
3. The combination of azimuth mirrors as described with reference to figures 1, 2
and 4 of the annexed drawings.