Improvements in Lamp Signals for Vessels.
Year: 1890

page_text: Date of Application, 12th Aug., 1890-Accepted, 1st Nov., 1890
COMI DELD
Improvements in Lamp Signals for Vessels.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me from abroad by Charles Herschel Koyl of Easton Pennsylvania
and Frank Arthur Douglas Hancock of Savannah Georgia both in the United
States of America) and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
נ,
"
Under the ordinary code of signal lights now in vogue for vessels under way the
observer in approaching a vessel "bow on or within say about one point of "bow on
would see the two ordinary round coloured lights at present in use-green upon
starboard, red upon port and knowing by this that a vessel is approaching him on a
course directly opposite to the one he is steering, would govern his vessel accordingly.
But in approaching a vessel on either bow, when only a single light (red or green as
the case may be) is seen, then the observer would know that the course of the
approaching vessel was at an angle to his own.
But while he would know this much
in a general way, he would be wholly unable on a dark night to determine the angle
of approach, and thus to take timely precaution to avoid collision.
For the purpose of enabling the observer to more accurately determine the angle
of approach, various plans have been from time to time suggested; all contemplating
the use of some auxiliary light or lights, in conjunction with the ordinary red and green
lights required by law. One of the more recent plans is to provide in conjunction
with the usual port and starboard lights, auxiliary lights of the same colour as the main
lights, to which they respectively pertain, these lights being separated by screens
which shut off the rays from ahead, but allow the lights to be seen from the side-the
arrangement being such that as the vessels turns in her course a greater or less number
of these lights will be exposed, thus affording an indication of the direction of angle
of approach.
According to this invention it is proposed also to use auxiliary lights in conjunction
with those now required by law. The auxiliary lights employed according to this
invention however do not resemble and are in no seuse the same as the ordinary red
and green lights; uor for the results obtained is dependence placed upon variations
in the number of lights visible at any one time.
The auxiliary light used according to this invention as a direction indicator is
furnished by a reflector the surface of which has the contour, or approximately the
contour of the longitudinal segment of a paraboloid-the light or lamp whose flame is
to be reflected being located at a point corresponding to the focus of the paraboloid of
which the said reflector is a segment.
A reflecting surface of the form specified has the property of making parallel all
rays reflected by it, the consequence being that thereby can be obtained a solid band
of light of definite dimensions. This band should be of such dimensions as to be seen
by the observer within any conventional or agreed upon number of points-say for
example, four points, or about 45°. For this purpose the curvature of the paraboloidal
section should be slightly modified so that there will be sufficient divergence of the
reflected rays to permit the band of light to be seen within this range, on each side
of the vessel specified.
By placing one of these reflectors so that it will give a vertical band of light, and
then another so that it will give a horizontal band of light, the lamps for these reflectors
being red or green, according to the colour of the ordinary signal lights in conjunction
with which they are used; then by so locating the vertical reflector and regulating
its divergence that it can be seen as a vertical band of light only from one point to
five points from "bow on "-that is to say, when approaching the vessel at an angle

page_text: OI from II to with her keel, and by so locating the horizontal reflector and
regulating its divergence that it can be seen as a horizontal band of light only from
five to nine points from "bow on "-then, by thus locating these reflectors one hand of
light only would be seen at a time, and according as this is vertical or horizontal, the
observer can determine the angle of approach with sufficient accuracy to enable him
to intelligently take such
measures as may be necessary in order to avoid
collision.
By arranging the two paraboloidal segments on each side in the form of a cross,
one lamp will serve for the pair, whose axes are so located as to make with each
other the requisite angle-the lamp of course being placed in the focus common to
the paraboloids.
This same lamp indeed may also serve in addition as the ordinary conventional
light required by law.
Such lamp would be constructed as usual on the side from the vessel, and on the
other side would present to the paraboloidal reflectors, segments of Fresnel lenses
adapted to each reflector, and therefore running at right angles to each other in the
lamp.
The invention is not confined to any particular number of these paraboloidal
reflecting segments, nor to their special arrangement with relation to each other, but
the arrangement preferred is that which is above outlined, and which is illustrated
in the accompanying drawings to which reference will now be made.
Figure 1 is a diagrammatic view indicating the ranges within which it is supposed
that the several lights are respectively distinctively visible.
Figures 2 and 3 are views indicating the positions assumed by the bands of light
when visible.
Figure 4 is a perspective view of a signal in which the two paraboloidal segments
are crossed and so placed that the lamp by which they are illuminated will be in a focus
common to the two paraboloids of which they are segments.
The vertical paraboloidal reflecting segment is indicated at A, and the horizontal
segment at B. The lamp is shown at C. Each reflector consists of a reflecting
surface enclosed like a looking glass, in a strong frame which may be of metal or other
suitable material.
When the two segments are placed as in Figure 4, with the lamp located at their
common focus, the horizontal segment will form in effect the box or frame by which
the lamp so far as its functions as a signal is concerned will be shielded on the side
and back, as usual in the case of coloured signal side lights.
I have herein before indicated that cach segment should be visible through a certain
range or number of points and that, for this purpose it will be desirable to somewhat
modify its shape from that of a mathematically exact paraboloidal segment. This can
readily be done by slightly modifying the longitudinal curvature of the horizontal
segment and the transverse curvature of the vertical segment so that at the requisite
distance there will be sufficient divergence of the rays to produce a beam or band of
light which will be visible through the predetermined range of points. And to increase
the vertical range in which the segments will be visible as bands of lights, the transverse
curvature of the horizontal segment and the longitudinal curvature of the vertical band
can also be modified.
To accomplish this result in both cases however the modification in the form of the
reflector need be very slight, and it remains to all intents and purposes of the contour
of the segment of a paraboloid.
Having described this invention and the manner in which the same is or may be
carried into effect, I state in conclusion that the invention is not restricted to the
details herein set forth, for manifestly it can be very considerably varied in a number
of particulars without departure from the nature of the invention; but what I claim as
new and of this invention is as follows:-
1. In signal lights for vessels, the combination with the usual coloured port and
starboard lights, of coloured supplementary side lights visible only through a range

page_text: including a predetermined number of points to port or starboard respectively, and
consisting of reflectors having the contour or approximately the contour of the segment
of a paraboloid, fixed in the positions in which they will be visible throughout the
range prescribed, and lamps situated at points corresponding to the foci of the
paraboloids of which the said reflectors are segments, substantially as and for
the purposes hereinbefore set forth.
2. In signal lights for vessels, two or more reflectors formed as paraboloidal segments,
placed on the side of the vessel at an angle to each other so that the band of light
reflected by one shall be at an angle to the band of light reflected by the other, and
situated and formed so that each shall be visible through a range of points different
from that through which the other is visible, in combination with a lamp or lamps
situated at focal distance from said reflectors, substantially as and for the purposes
hereinbefore set forth.
3. In signal lights for vessels, the combination of crossed or intersecting paraboloidal
reflecting segments formed and situated on the vessel so that each shall be visible
through a range of points different from that through which the other is visible,
with a lamp situated in the common focus of the paraboloids of which said reflectors
are segments.
4. The combination with the two crossed or intersecting paraboloidal reflecting
segments, of a lamp situated in their common focus, serving at once both to illuminate
the said reflecting sections, and also as the ordinary conventional port or starboard
coloured signal light, as the case may be, substantially as and for the purposes herein-
before set forth.
5. In signal lights for vessels a direction indicator consisting of a paraboloidal
reflecting segment formed and situated or fixed on the vessel as described, so as to
be visible from the side as a band of light, through a range including a predetermined
number of points only, and a lamp situated at a point corresponding to the focus of
the paraboloid of which the reflector is a segment, substantially as and for the purposes
herein before set forth.
Dated this 12th day of August 1890.
J. H. JOHNSON & Co.,
Agents.