AN IMPROVEMENT IN SHIP COMPASSES AND THE METHOD OF FIXING, ARRANGING AND WORKING SUCH COMPASSES, TO INDICATE AND TO CORRECT THE LOCAL ATTRACTION IN IRON, STEEL AND OTHER SHIPS."
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Robert Evans at the Office of the
Commissioners of Patents on the 27th December 1881.
ROBERT EVANS of No. 1 Sandhill Quayside in the Borough and County of
Newcastle on Tyne. "AN IMPROVEMENT IN SHIP COMPASSES AND THE METHOD OF
FIXING, ARRANGING AND WORKING SUCH COMPASSES, TO INDICATE AND TO CORRECT
THE LOCAL ATTRACTION IN IRON, STEEL AND OTHER SHIPS."
My Invention relates to means of ascertaining and correcting the local attraction
in iron, steel and other ships, and consists in a steering compass, having in addition
to the usual lovers-line a movable lovers-line, and a compass reflected, elevated
and projected from the port, starboard, or both together, the stern or any other
part of the ship, but so that the reflected, elevated and projected compass is outside
the influence of local attraction, and the difference-shown by the respective cards―
between the reflected, elevated and projected compass free of local attraction and
the steering compass under the influence of local attraction, is plainly visible.
By the movable lovers-line the steering compass is made to have the same
bearing as the reflected, elevated and projected compass, and without interfering
with the changeable influence of the local attraction, a true or magnetic bearing
compass is at all times available.
To this end I gimbel a compass at the end of one or more rods, beams or poles,
which I project in a horizontal way by rack, gear or other means over the side or
sides of the ship, or in a circular way by pivoting the other end of the rod, beam
or pole, on the port, starboard or both together, the stern or any other part of the
ship, allways keeping the compass parallel with the ships-line.
The pivoted rod, beam or pole, on which the compass is gimbeled at the end, is
counterweighted, properly poised and worked near the steering compass, by lever,
gear or pulley, in order to bring the compass over the side or towards the centre of
the ship, where it falls on a raised post and is firmly fixed.
The length of the rod, beam or pole on which the compass is gimbeled, depends
on the construction of the ship, but is of sufficient length to bring the compass
outside the influence of local attraction.
The card of the reflected, elevated and projected compass, has a raised edge all
round, denoting the points; the compass-bowl is transparent and partly open on

page_text: the side facing the ship, so that in all positions the card is visible from near the
steering compass, supplemented by telescope and sights.
Where the fixed compass on the raised post before named, is found to be outside
the influence of local attraction in that position, I employ a series of reflecters to
show the bearing of the compass on a horizontal reflector near the steering
compass.
By these means I have available at all times the magnetic bearing of the
compass and the course of the ship, and however much the steering-compass is
affected by the influence of local attraction, I bring the steering-compass to a truo
or magnetic bearing, by the movable lovers-line.
The movable lovers-line is inside the steering compass and works east or west
by a tangent screw, either on the outerside or bottom of the compass-bowl.
The same may be effected by working a movable needle on the card in a similar
manner.
I may use seperately or together the means herein described.
I claim as new by this Invention, the bringing of a compass over the sides of
the ship, thereby having it outside the influence of local attraction; the ease and
promptitude by which the magnetic bearing of the compass, and the course of the
ship is found, and transferred by the movable lovers-line to the steering compass;
that instead of drawing the needle of the steering compass towards the lovers-line
I draw the lovers-line towards the needle without empoying counter magnets and
swinging of the ship, leaving the needle free in action, thereby establishing a true
or magnetic bearing compass; and the means of noting the changes in the local
attraction from day to day and at all times.