Pavement Lights having Forwardly Projecting Smooth Surfaced Prisms.
Year: 1897

page_text: Date of Application, 13th July, 1897-Accepted, 14th Aug., 1897
COMPLETE SPECIFICATION.
Pavement Lights having Forwardly Projecting Smooth Surfaced
Prisms.
I, JOHN MEIGGS EWEN, of No. 1129 The Rookery, Chicago, County of Cook,
State of Illinois, United States of America, Mechanical Engineer, do hereby
declare the nature of any invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
My Invention relates to vault lights or the like, and has for its object to pro-
vide a new and improved vault light, of which the following is a description,
reference being had to the accompanying drawings wherein,
Figure 1 is a view of a vault light embodying my invention;
Figure 2 shows a modified form of my invention;
Like letters refer to like parts throughout the several figures.
The ordinary vault light is so formed as to receive the light from a particular
direction, and direct it toward a given point, the light from all other directions
being directed towards some different point, and thereby being utilized to a little
or no extent.
It is a part of my invention to provide a vault light which will receive light
from at least two different directions, and direct it towards the same point, in
substantially parallel lines.
As shown in Figure 1 the vault light A is provided with the projecting prisms B,
each provided with the converging surfaces C and D the vault light is preferably
so positioned that the surface C is the rear surface and the surface I) the front or
forward surface. The surface C, is so formed as to receive light from a given
direction, as for example, the vertical light E is reflected towards the surface D
where it is refracted and takes the direction shown. The surface D is so formed
that light from another direction, as for example, the lowest ray F striking said
surface will be reflected towards the surface C; the ray striking the surface C,
after being reflected is at substantially the same angle as the ray E. The ray F is
then reflected by the surface C and refracted by the surface D so as to take the
direction substantially parallel to the ray E. It will, therefore, be seen that in
this construction both the surfaces C and D act as reflecting surfaces; the surface D
changing the direction of the oblique or angular rays of light F so that they will
strike surface C at the same angle as the rays E. By this construction I am
enabled to throw a greater amount of light towards any given point than is possible
with the ordinary vault light.
In Figure 2 I have shown a form of my invention to be used when the receiving
surface is at an angle instead of being horizontal as is shown in Figure 1. The
converging surfaces C and D in this event are so related as to produce the desired
result, that is to say: the surface D is so positioned as to reflect the light coming
from some definite direction, so that it will strike the reflecting surface C at the
sume angle as the light coming from some other definite given direction.

page_text: I have not attempted to show all the forms of my invention, as it is, of course,
evident, different forms may be used. It is also evident that the angular relation
of the surfaces C and I will depend upon the directions at which it is desired to
receive the two series of rays of light.
.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:
A prism tile comprising a body of glass one or more projecting ribs or prisms,
provided with converging front and rear surfaces, the angular relation of said
surfaces being such that all the rays of light coming from one direction strike one
of said surfaces and are reflected in a given direction, while all the rays of light
coming from a different direction strike the other surface and are reflected so as to
strike the first surface at the same angle as the first mentioned rays, whereby both
series of rays leave the vault light in substantially parallel directions.
JZASPAL
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.