Window and Pavement Prism Lights having Inscribed Circular Prism Surfaces.
Year: 1897

page_text: Date of Application, 13th July, 1897-Accepted; 4th Sept., 1897
COMPLETE SPECIFICATION.
Window and Pavement Prism Lights having Inscribed Circular Prism
Surfaces.
71
I, JOHN MEIGGS EWEN, of No. 1129 The Rcokery, Chicago, County of Cook,
State of Illinois, United States of America, Mechanical Engineer, do hereby
declare the nature of my 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 lights and prism plates made therefrom.
Illustrated in the accompanying drawing, wherein
It is
Figure 1 is a plan view of a prism light hexagonal in shape with a circular prism
surface;
Figure 2 is a similar view of a square light;
Figure 3 is a view of a prism plate composed of such prism lights.
Like parts are indicated by the same letter in all the figures.
A A are the bodies of the prism lights, preferably smooth on one side and having
each a set of prisms B B, which prisms are arranged in a substantially circular
body. Care non-prismatic corner portions of such lights. In the plate, it will
be observed that the angle of the prisms varies in the different lights. The
lights B B having the prisms greatly inclined; the lights B2 B3 having them
less inclined and the lights B3 B3 having the prisms horizontal. The value of this
invention can be better understood when it is taken in connection with the method
or means by which such prism lights and plates are made. In prism plates for
ordinary use, it is very desirable to have variously arranged angles.
In my
drawings, I have not attempted to show any particular arrangement of angles
or to indicate an arrangement of angles suitable for any particular purpose, but I
have endeavoured simply to illustrate as it were diagrammatically the manner
in which my invention can be made use of.
Now it is evident that if we desire to have a considerable number of angles in
a given plate, it would be necessary to have a separate mould for each variation
in the angles of the prism. In speaking of angles of the prisms, I do not refer to
the angular cross-section of the prism, but to the angular arrangement of the
prism on its light or plate, particularly with reference to the horizontal. By
having a series of prism lights all of them the same shape in their body portions,
and by having a central circular prismatic body on each, I can by the use of my
mould, for which I have made application for letters patent of even date herewith,
secure any desired angle by simply turning the bottom of the mould slightly. In
putting these prism lights together, it is very evident that the greatest uniformity
in their shapes, thickness, etc. is desirable and there is a positive disadvantage
in working from different moulds. My invention permits me to use the same
mould and therefore to get prism lights which are all as nearly as possible perfectly
uniform in every respect, except that there may be a great variety when considered
with reference to the angular relation of the prisms.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. A prism light having a body shaped as indicated with an inscribed prism
surface as indicated, substantially as described and for the purpose set forth.
2. A prism plate composed of a series of prism lights arranged, shaped and
formed substantially as described and for the purpose set forth.
Dated this 13th day of July 1897.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.