Improvements in Illuminating Glasses for Deck Lights, Gratings, and the like.
Year: 1891

page_text: Date of Application, 16th Mar., 1891-Accepted, 25th Apr., 1891
COMPLETE SPECIFICATION.
Improvements in Illuminating Glasses for Deck Lights, Gratings, and
the like.
I, THADDEUS HYATT, of 9, Farringdon Road, in the City of London, Pave-
ment Light Manufacturer, 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 illuminating glasses such as ships' deck lights pavement
lights and the like it being an improvement upon what is known as the " prism
form of light.
The prism lights in use at present are of two kinds the "prism" which is that
principally used for decks and the semi prism" so called which is used in metal
gratings mainly for side walks for lighting basements.
The defect of the "prism "deck light is that a considerable percentage of light
is lost by the reflection back into the air of its perpendicular rays while the defect
of the semi prism "light is the irregular distribution of light around and beneath
same, this defect being principally caused by the corners left by the sharp angles
of the lines on which it is made.
To clearly explain the nature of my invention I will describe it in connection
with the accompanying drawings.
"
As now constructed the ordinary "prism in deck light consists as shown in
Figures 1, 2, and 3, of a glass plate or walking surface a. and a depending prism or
pendant b. of the triangular shape shown. As will be seen in Figure 3, the vertical
rays of light (indicated by the arrows) falling through same on to one of the
angular faces of the pendant b. are projected across to the other face and thrown
from thence vertically upward. In the semi-prism this particular defect does not
exist as there is but one reflecting side as shown in Figure 13, which is an end
elevation of the form at present in use.
To remedy this I propose to form these prism lights as shown in Figures 4, 5,
and 6, where the pendant portion is "hollow" and consists of two sloping reflecting
faces c. c. back to back and two vertical faces d. d. forming two long
prisms" the light falling in which is reflected from the faces c. c. as shown by the
arrows.
« semi-
In place of using two long plain "semi-prisms "however I may form the pendant
as represented in Figures 7, 8, and 9, where four glass cylindrical pendants (which
may be joined together or not) are shown. These pendants which are cylindrical
or approximately cylindrical or oval at their root or base are cut away or formed
with the sloping reflecting faces c. c. and the vertical or approximately vertical
faces d. d. which are rounded or curved. In this way the inside of the "prism" is
composed of the eight reflecting faces c. c. back to back and so much of the vertical
inside half of the cylinders as are not cut away by these sloping faces.
The light
distributing portion of the pendant therefore (apart from the reflecting faces c. c.)
is composed of a number of curved vertical faces which while allowing the light to
be projected forward out of same also distribute it evenly and thoroughly through-
out the body of the glass which thus presents a light and brilliant appearance with
a minimum amount of shadows. In Figures 10, 11, and 12, 1, show a further
modification in which in place of making the pendant of a single row of cylinders
side by side with the triangular hollow cut or formed through them longitudinally
which means that the reflecting faces c. c. occupy each but one half of the diameter
of the cylinder I make them of two rows of cylinders in which case the hollow is
composed of a series of sloping sides c. c. each of which receives the whole of the
perpendicular rays that fall upon the top face of each cylinder. In this form of

page_text: pendant a considerably greater amount of curved light distributing surfaces d. d.
are left in the inside hollow portion of the pendant.
"
The "semi-prism pavement light formed according to my invention consists of
an upper walking face a and as shown in Figures 14, 15, and 16, two of the
cylindrical or oval or as shown somewhat flattened oval pendants before described
having the sloping reflecting faces c. In a semi-prism" constructed as above
there are no sharp angles forming corners which throw shadows into the pendant as
in Figure 13, but rounded faces which while throwing the greater part of the light
forward as is required in basements and the like where such are used yet distribute
a certain amount around the same, a grating composed of a number of such
improved lights" presenting an evenly lighter and brilliant appearance from
whatever point it is viewed. In Figures 17, 18, and 19, I show a further modi-
fication in which I form a hollow or groove from the top to the bottom of the
reflecting faces c. for the purpose of further distributing the light through the
pendant which grooving may as will be evident be applied to the sloping faces of
the other cylindrical pendant. Or in place of grooving the same or of employing
a plane surface c. I may slightly curve or outwardly bulge the same to assist in
distributing the light.
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 :-
1. An illuminating glass having a flat external surface and a pendant composed
of two "semi-prisms the reflecting faces of which are placed back to back
substantially as described.
2. An illuminating glass having a flat external surface and a pendant comprised of
a number of depending portions of cylindrical or approximately cylindrical form
arranged in a row or rows and having sloping reflecting faces either Hat or slightly
curved arranged back to back substantially as described.
3. An illuminating glass having a flat external surface and a "semi-prism" or
pendant composed of depending pieces of cylindrical or approximately cylindrical
form placed side by side having sloping reflecting faces either flat or slightly
curved substantially as described.
4. An illuminating glass having the cylindrical or approximately cylindrical
pendants above described with their reflecting faces longitudinally grooved or
hollowed.
Dated this 16th day of March 1891.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Applicant's Agent.