AN IMPROVED APPARATUS AND MODE OF SIGNALLING TO PREVENT COLLISIONS AT SEA BY STEAMERS
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Robert Ediss Harris at the
Office of the Commissioners of Patents, with his Petition, on the
1st June 1875.
I, ROBERT EDISS HARRIS, of East Hackney, in the County of
Middlesex, Master Mariner, do hereby declare the nature of the said
Invention for "AN IMPROVED APPARATUS AND MODE OF SIGNALLING TO PREVENT
COLLISIONS AT SEA BY STEAMERS," to be as follows:―
This Invention consists of an improved apparatus and mode of
signalling from steamers by aid of a steam whistle, the special object of
the Invention being to communicate the quadrant of the compass which
the signalling steamer is steering in.
The apparatus consists of an eight-inch dial clock, but the hour and
minute hands are confined with their figures to a small circle on the
edge of the dial; the second hands, of which there are four at right
angles to each other, are set on a centre of the dial, and extend to about
three-fourths of the distance from the centre to the circumference.
A circle about five and a half inches diameter contains the division of
seconds, on the outside of which are five segments marked in black, one

page_text: of which measures ten seconds, the other four measure five seconds each,
the intervals between all being three seconds.
The dial is covered with glass, on which a flat or annular segment of
brass is arranged capable of adjustment to hide from view the black
segments not required, and thereby to prevent mistakes in signalling.
There is also arranged around the glass an external annular ring of
thin metal, about an inch and a half wide, with all the points of the
compass marked thereon; it represents an unmagnetised compass card,
and is capable of being shifted or moved round within its attachments
for the purpose hereafter explained.
The apparatus should be placed horizontally on a stand, with the
upper part of the dial (marked with a star) towards the ship's head; the
stand should resemble a binnacle protected with a cowl. Its position
should be on the bridge in close proximity to the steam whistle, or in
communication therewith, so that the apparatus being always under the
control of an officer may enable him to actuate the signal of the steam
whistle.
This being the construction of the apparatus it remains to explain the
operation and effect. Let us assume therefore, that one blast of steam
of ten seconds duration shall indicate a course from N. to E. N.; two
blasts of five seconds duration with an interval of three seconds between
them, a course from E. to S. E.; three blasts of five seconds duration
with similar intervals, a course from S. to W. S.; four blasts of five
seconds duration with similar intervals, a course from W. to N. W.
Now it will be seen that only forty-two seconds of the dial are as yet
used, thus leaving eighteen seconds for further indications; moreover,
although I have given the above examples, I reserve to myself the right
of changing or modifying them 'as experience may suggest.
The external ring with all the points of the compass marked thereon,
may be termed an adjustable "dumb card" or index; it is to be moved
round till the true point on which the steamer is proceeding is placed in
a line with the vessel's head; of course then all the true points of the
horizon will be indicated; hence it must follow that these points being
accurately known, all steamers in each other's vicinity (possessing the
apparatus) will have the true N.E., S.E., S.W., and N.W. quadrants of
the compass distinctly and concordantly represented,

page_text: When a signal whistle or whistles are heard reference must be made
to the "dumb card," and not to the steering compass or any other
compass, because they will only represent magnetic courses.
I may mention that the black divisions on the dial are for the purpose
of shewing exactly the traverse of the second hand, and the blank or
white divisions are for the accurate notation of the intervals. Four
second hands are used, so that the one just approaching the black
divisions may be immediately used instead of waiting perhaps for a
revolution of a single second hand, which might involve a minute's
delay.
By this Invention not only is an alarm made of an approaching vessel,
as is the ordinary custom with steam whistles and other means, but the
more important fact is made known of the actual course of the steamer or
steamers, by which means alone can absolute safety from collision in
dark or foggy weather be avoided.