Improvements relating to the Mariner's Compass.
Year: 1897

page_text: Date of Application, 25th Jan., 1897-Accepted, 17th Apr., 1897
COMPLETE SPECIFICATION.
Improvements relating to the Mariner's Compass.
I, ABRAM MITCHELL, residing at Shelter Island, in the County of Suffolk, and
State of New York, United States of America, Master Passenger Steamers, 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:
My invention relates to reflectors for use in compass-boxes, especially in such as
are employed on shipboard, and are required to be lighted or illuminated, so that the
compass-card may be distinctly seen at night.
The ordinary ship's compass-box is illuminated from the exterior and is provided
with a lid which may be raised upon occasion, as when it is required to take cross-
bearings, &c., a small aperture in the lid affording a slight view of the card, sufficient
to determine the course of the ship. The lid and the small aperture are used, because
the glare of the light in the box renders it impossible for the observer to discern
objects in the darkness for a few seconds after reading the compass, and this, while at
all times it is annoying and inconvenient, sometimes may lead to serious accident.
The object of my invention is to prevent the light within the box from affecting the
sight of the observer, and to accomplish this the invention involves the application of
a reflector within the compass-box, the same being calculated to direct all the light
from the lamps down upon the compass-card, so that it may be clearly seen, and allow
no light to pass to the eye of the observer except such as is reflected from the card
and therefore softened to such degree as to obviate all the disadvantageous effects
above alluded to, enabling one to dispense with the lid or cover entirely, if desired.
In the drawings, Figure 1 is a perspective view, and Fig. 2 a section and plan
view, of a compass-box having my improved reflector applied therein, this view being
taken on line X X of Fig. 3. Fig. 3 is a cross-section.
In all the figures like letters of reference, wherever they occur, indicate
corresponding parts.
A represents the compass-box, which in the most ordinary form has a hinged lid,
(represented at B,) the same being supplied with an aperture, as a, and this having a
suitable cover, as b.
C represents the compass-card. This is illuminated at night by lamps D D, one ou
each side of the box, the light from the lamps entering through openings through the
walls of the box, all the light being thrown therein.
Ordinarily the lid B remains closed, and the card is viewed through aperture d,
after opening the cover a very little, so as not to allow too much light to strike the
eye; and even with this precaution the observer finds it difficult to immediately
discern objects after the observation, and particularly upon a very dark night.
The hinged lid B is only opened when necessary to take cross-bearings on any
object, but this is frequently necessary, and at these times the full light from the
lamps strikes the eyes, with corresponding injurious or detrimental effects.
E is a reflector of any opaque substance which I employ to obviate the disadvantages
above referred to. It is located far enough above the card C and at one side of its
diameter so that the entire card may be viewed without difficulty from the exterior
of the box, and it extends from one side to the other between the openings which
admit the light to the box.
In the form shown in the drawings the reflector is in general tubular shape, the

page_text: lower portion being open, as indicated. This throws all the light from the lamps
down upon the card and screens the eyes, so that no light strikes the eyes, except
such as is first reflected by the card. This particular form of reflector breaks up
the light by numerous reflections within itself, and thus renders it less glaring upon
emerging through the opening in the lower part.
Of course the mere shape of the reflector might be changed, and its size and the
size of the opening in the bottom will depend upon the size of the box and the power
of the lamps.
With the improved reflector in place the lid may be kept entirely open all the
time, as in Fig. 3, or may be omitted from the box altogether.
The improved appliance has been found in practice to answer all the purposes of
the invention as previously set forth, and is, moreover, simple and cheap, and may be
easily applied to new boxes as well as to old ones.
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 :-
The compass-box having an opening at top, perforations in its side walls and
exterior side lamps applied on said walls, the tubular reflector open along its lower
portion, said reflector being mounted in the box, over the compass-card and at one
side thereof, and extending between the openings in the side walls of the box to
receive and direct the light from the lamps, the parts named being arranged,
constructed and combined, substantially as shown and for the purposes specified.
Dated this 25th day of January 1897.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents: