Window Prism Plates with Prisms Bent from the Straight Line.
Year: 1897

page_text: Date of Application, 13th July, 1897-Accepted, 28th Aug., 1897
COMPLETE SPECIFICATION.
Window Prism Plates with Prisms Bent from the Straight Line.
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 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 light diffusing devices, such, for example, as prismatic
windows and has for its object a new and improved device for this purpose of which
the following is a description, reference being had to the accompanying drawings,
wherein,
Figure 1 is a face view of a section of window glass embodying my invention;
Figure 2 is a section on line 2-2 Figure 1;
Figure 3 is a section on line 3-3, Figure 1;
Like letters refer to like parts throughout the several figures.
It has been the practice heretofore in forming prismatic glass or the like for
windows to form such glass so that the light is projected substantially straight
forward from the window. One of the objects of my present invention is to pro-
vide a glass for diffusing light which in the place of or in addition to projecting
the light straight forward, may throw the light to either side or in some other
direction than straight forward. It often happens that the light is only admitted
to the window through a small opening as in alleys and where there are obstruc-
tions in front of the window, and under such conditions the ordinary prismatic
glass cannot be satisfactorily used. It also often happens that a large room
inust be lighted by a window at one side thereof, hence it is necessary to throw
the light in some other direction than straight forward towards the rear of the
1000. Under such and like conditions the windows must be so formed as to
direct the light toward the place which it is desired to illuminate.
I have illustrated in the drawings several constructions showing the ordinary
prismatic glass modified in form so as to embody my invention.
In Figure 1 I have shown a face view of the ordinary section A of
prismatic glass provided with projecting ribs or prisms B. These prisms
in the ordinary prismatic glass extend straight across the face of the glass. As
shown in Figure 1 these prisms are displaced or bent out of line at some portion
along their length as at C so as to be forced out of their original line. I have
found that when the prisms are so formed, the light in addition to being thrown
straight forward is thrown in some other direction, as, for example, towards the
sides of the window. I have also found that the light can be directed toward
any given point by displacing these prisms to a given degree.
Figure 3 shows a section through the glass after the prisms have been displaced,
30 as to embody my invention. The displacement of the prisms in any given
case will depend of course upon the result desired and the conditions to be met,
as the direction in which the light is thrown will be controlled by the position
of these prisms.

page_text: I have spoken of prismatic glass, the trade name for the article to which I
refer, and the name which I prefer to employ is prism light. The prism lights
may, as illustrated, have some of their portions remaining in the original line
while the rest is bent out of that line, and carried forward in one or more right
lines.
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 light comprising a body of glass having a preferably smooth receiving
surface on one side with a series of prisms systemmatically arranged to produce
an increased illuminating effect on the other, some of said prisms extending across
the body of the plate in a broken straight line.