AN ELECTRIC TELL-TALE COMPASS
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by Fleeming Jenkin at the Office
of the Commissioners of Patents, with his Petition, on the 20th
June 1863.
I, FLEEMING JENKIN, of Duke Street, Adelphi, in the County of Middlesex,
do hereby declare the nature of the Invention for "AN ELECTRIC TELL-TALE
COMPASS," to be as follows::-
The object of the Invention is to obtain from a compass placed in one part
of a vessel (which compass is herein-after called the sending compass) indi-
cations of the direction of that compass at a distant part of the vessel, on an
apparatus or instrument (herein-after called the receiving. instrument), by
means of electric currents transmitted along insulated wires.
The purposes to which this Invention may be applied are obvious; some of
them are the following:-The sending compass may be placed as a standard
compass in a part of the vessel at which the deviation is small, while the
receiving instrument is placed in any convenient position, and without regard.to.
the deviation, may be used as a tell-tale for the guidance of the steersman or
for the use of the officer on deck, or to convey to the officer's cabin or else-
where indications from the sending compass of the course actually steered, or to
give an alarm when the prescribed course is deviated from by a certain amount
and for similar purposes.
The manner of effecting this is as follows:-From one pole of a battery.org

page_text: :
ether rheomotor an insulated wire (herein-after called the single wire)
proceeds to and is in metallic connection with a contact piece attached to and
moving with the needle of the sending compass. From the other pole of the
battery a hundred other insulated wires (more or fewer, but for distinction I
call them "the hundred wires,") proceed first to the receiving instrument and
thence to the sending compass, where they are connected with terminals,
which terminals are arranged at equal intervals round the sending compass.
The contact piece there touches either one terminal or two adjacent terminals,
and completes the circuit through the single wire and the one or two (as the
case may be) of the hundred wires. The currents so sent give 200 different
signals at the receiving instrument and indicate the position of the sending
compass within 10th of its actual direction. The contact between the
contact piece and one or more terminals may be either continual and produced
by a light spring made by torsion or otherwise, pressing the contact piece
against the terminal or terminals or by mercurial contact or other similar
means; or in order to avoid the effect of friction and cohesion on the direction
of the sending compass, the contact may be made intermittent. This inter-
mittance may be the result of an automatic make and break piece such as is
used in connection with a Rhumkorff's coil, so that the current itself from time
to time breaks the contact and allows the needle of the sending compass to
take up its proper position, or the intermittence of contact may be the result
of a succession of intermittent. currents in tone! direction sent, by a magneto-
electric rheomotor. The intermittence of contact may be conveniently.pro-
duced by currents sent through a separate pair of wires. The signals may, be
either automatic and continual or they may be temporarily, produced at the
will of the operator at the receiving instrument, in which case the sending
compass will only give signals in answer to a demand by the operator; at other
times the needle of the sending instrument is absolutely free. At the receiving
instrument the requisite indication is given by the one or two of the hundred
wires for the time being in contact with the contact piece. Among other
ways in which this indication may be given it may be done by coiling a portion
of each of the hundred wires' round 'aiseparate soft-iron core, and arranging the
hundred wires radially round a receiving needle or compass made astatic if
required, the order of succession of the cores round the receiving compass
being the same as the order of the terminals round the sending compass. One
pole of the receiving needle will then take up the direction of the core of the
one of the hundred wires or a direction half way between' the direction of the
cores of the two of the hundred wires which is or are for the time being in
contact with the contact piece at the sending compass, and will then show the

page_text: same course as the sending compass. By breaking the circuit of such of
the hundred wires as are within a given angle of the course which is required
to be steered the receiving instrument may be made to ring a bell or give
an alarm whenever the ship's course deviates from the given course by that
angle.