Improved Apparatus for Use in Signalling between Navigable Vessels in a Fog.
Year: 1889

page_text: Date of Application, 16th July, 1889-Accepted, 31st Aug., 1889
COMPLETE SPECIFICATION.
Improved Apparatus for Use in Signalling between Navigable
Vessels in a Fog.
1, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of 53,
Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent Agents,
do hereby declare the nature of this invention (a communication to me from abroad
by Nicholas Aermann Borgfeldt, of 221, Rodney Street, Brooklyn, King's County,
State of New York, and Benjamin Lichtenstein, of 12, West 72nd Street, City,
County and State of New York, United States of America, Manufacturers) and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
The object of this Invention is to enable the masters of steam and other vessels on
the high seas and other waterways, to ascertain definitely the direction in which other
vessels hidden by fog, are moving with respect to the motion of their own craft and
the distance between the vessels.
It is exceedingly difficult, by the mere sense of hearing to know from what direction
a sound emanates. The master of a vessel in a fog hearing the signal of another
vessel cannot definitely know whether that other vessel approaches him or recedes
from him from either the port or starboard side.
By this invention, this difficulty is sought to be overcome; and it consists principally
in a clock having a movable hand and having a dial which is divided in a particular
manner hereinafter described, so as to indicate distance instead of merely indicating
time; that is to say, it indicates distance by reckoning the time consumed for the
sound to travel. The Invention consists in the arrangement of the clock dial and its
appurtenances, as hereinafter more fully described.
Reference is to be had to the accompanying drawing forming part of this
Specification; in which figure 1 is a plan view; figure 2 a vertical section, on line cc
figure 1, of the improved fog signal indicator; and figuró 3 is a detail of the
index hand.
In the drawing, the letter A represents a clockwork of ordinary or suitable con-
struction adapted to revolve an arbor a once around its axis in, say, one minute or
other subdivision of time. On this arbor is frictionally held a hand or pointor B
which, when the clock-work is in action, revolves with the arbor once in every minuto
or other subdivision of time. The hand B can however, be turned freely on the
arbor a to which it is frictionally united in suitable manner and, for the purpose of
turning it conveniently by hand, it is provided with a handle b, as shown. The frame C
of the clock-work carries a dial D which is divided from its zero point d in peculiar
nanner, viz. starting from the zero point in the direction of the arrow shewn in
figure 1, which is the direction in which the hand or pointer B is moved by the clock-
work, the dial first shews a section e, which in the drawing is marked with the
numerals 1, 2, 3, and is of a length which corresponds with the motion of the hand B
during the time consumed by the giving of a signal on board the vessel that
carries this clock. The next section of the dial f, adjoining the section e, is as
long as the section e and corresponds with the motion of the hand B during the
time consumed by the giving of a signal by the distant vessel. From the end of the
section to the zero point d, regarding the dial in the direction of the arrow, said dial
is divided into spaces indicating twice the distance travelled by sound; that is to say,
sound travelling, as has been ascertained, 1120 feet per second, or a little more than a
mile of 5280 feet in five seconds, the dial is divided at double that rate into sections
:: 1," "2," "3,"
indicating miles and parts thereof; thus, the marks """"""
"4," "5," etc., on the dial indicate double the distance in miles travelled by sound
during the period of time consumed by the pointer B in travelling from one of said
3

page_text: marks to the other. In other words, the pointer B will travel from the end of the
section to the mark "," in a space of time equal to that consumed by sound in
travelling twice one-quarter of a mile, etc. Adjoining the dial, there is a movable
index hand E placed on a rail y for convenient adjustment so that said index
hand E may be set over any desired part of the dial. The index hand E as
shewn in figure 3, consists of two fingers e² et which are at a distance apart
corresponding to the width of the section e. In order that the pointer B may he
brought to the zero point d quickly and accurately, we provide a stop i which may
come in the path of the pointer so as to stop it at zero. The stop consists of a finger
that is carried by a spring arm secured to the frame of the clock. The spring arm j
at one part is normally held above the handle (see dotted lines figure 2) and is
provided with an opening to permit the arm j to pass over the handle 7. When the
spring-arm is in its normal raised position, the stop finger i will be held out of the
path of the pointer B (see dotted lines figure 2). When desiring to bring the pointer
to the zero point, the arm is depressed which permits the handle to project through
and above the arm j in position to be grasped. The stop finger is thus carried down
into the path of the pointer B, as in full lines figure 2, and when the pointer is now
turned to the zero point the stop finger i will arrest it at that point.
When the arm j
is now released, the finger i will be raised and permit the pointer to travel over
the dial.
This being the construction of the clock, its operation is as follows; Supposing the
vessel having this clock to be in a fog, and supposing the instructions to all vessels in
a fog to be that immediately upon one hearing the signal of another he shall respond
by a certain number of blasts, say three; now if the captain of the vessel having this
clock hears the signal of another vessel he is expected to immediately turn the hand B
to zero and then to give his three blasts. During the giving of these three blasts,
the hand B by the clock-work will be moved along the section of the dial. By the
time the responding signal of the distant vessel is heard the pointer B will have
traversed the section f of the dial plus so much of the dial as corresponds to the time
consumed by sound in travelling doublo the distance between the two vessels. Thus,
if the vessels are one-quarter of a mile apart and if the signal is given by the one
vessel whilst the hand B passes the section e of the dial, the captain of such vessel will
hear the opposite signal after the sound of his own signal has travelled to the distant
vessel, the distant vessel having given its signal in reply (which consumes time
corresponding to the length of the section f of the dial) and after finally the sound of
the last mentioned signal has reached the first vessel. By that time the pointer B
will be opposite the mark "" of the dial indicating therefore that the vessels are one
quarter of a mile apart from one another. Immediately upon hearing the return
signal, the captain of the first vessel again puts the hand of his clock to zero, again
gives a reply signal, and will know, when he receives the return signal, whether the
vessels are nearer to one another than before or further apart. In order to facilitate
these observations, the movable index hand E can be used to advantage it being placed
by the captain in line with the position of the pointer B occupied by the same at the
time the distant signal was heard. Thus, when the first signal from a distant vessel is
heard, the short finger of the index hand E is placed opposite the position on the
dial occupied by the pointer B when the signal is heard. The pointer B is then
immediately moved to the zero point again and permitted to travel over the dial when
the finger of the index hand is again placed opposite the pointer when the next
signal is heard, and so on as each signal is heard. The distance between the short and
long fingers e and e¹ of the hand E allows for the time consumed by the distant
vessel in sounding its first signal.
Regulations connected with the use of this clock could be readily arranged, so that
the captains, when ascertaining that the vessels approach one another and when they
find that they are, say, one mile apart from one another only, shall both stop, with
liberty to exchange such signals as will permit the one or the other of these vessels to
proceed without risk of collision; in fact the word " Stop" may be put on the one
mile mark of the dial the words "Half Speed on the one and a half mile mark etc.
23

page_text: We are satisfied that, by an intelligent use of this clock, collisions of sailing vessels
and of steam vessels especially can readily be avoided.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed, We declare that what we
claim is;
1. A clock having a pointer B and means for automatically moving the same and a
dial D divided into sections indicating lineal measurement at the rate of double the
distance travelled by sound during the motion of the pointer B.
2. In a clock having a pointer B and means for automatically moving the same,
the dial D having independent sections ef and having its remaining portion divided
into sections indicative of double the distance travelled by sound during the motion
of the pointer B, substantially as described.
3. In a clock having a pointer B and means for automatically moving the same,
the dial D, having independent sections ef and having its remaining portion divided
into sections indicative of double the distance travelled by sound during the motion of
the pointer B, in combination with the movable index hand E, substantially as
described.
4. The combination, with the pointer B, of the stop finger i adapted to come in the
path of the pointer to stop it at the zero point, substantially as described.
5. The combination, with the pointer 13, of the stop finger i and a spring arm j
carrying the same; the finger i being adapted to come in the path of the pointer to
stop it at the zero point, substantially as described.
6. In a clock having a pointer B and means for moving the same, the dial D having
independent section e. in combination with the movable index hand E consisting of
the two fingers e² et that are at distances apart corresponding to the width of section e,
substantially as described.
Dated this 16th day of July 1890.
TU
A. MELVILLE CLARK.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.