Double Frism Plates or Windows.
Year: 1897

page_text: Date of Application, 13th July, 1897-Accepted, 28th Aug., 1897
COMPLETE SPECIFICATION.
Double Frism Plates or Windows.
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:
which
My invention relates to prismatic lights, particularly such as are designed to be
used in lieu of window lights for the purpose of receiving, admitting and dis-
tributing in a proper manner the light on the outside of a building which it is
desired to use within. I have found in some extended investigations of prismatic
light that for certain purposes one angle of the prism will be most desirable,
while for other purposes some other angle may be better; but I also find that for
the most part the most desirable form of prism is that in
one edge is substantially at right angles to the surface of the glass, while the other
is considerably inclined thereto. In the use of prisms, and even in the use of the
prism I have last described, a considerable portion of the light which passes
through the same is diffused generally, so to speak, instead of being directed
forward as is desired. Such prismatic lights are commonly used for the purpose
of directing the light in lines parallel with the ceiling into and through the apart-
ment to be lighted. Now a single prism, such as that shown, will do this to a
considerable degree; but a considerable amount of light will also pass through
and as previously suggested be generally diffused or distributed and not to be
carried on the direct or forward line along with the greater portion of the light,
so to speak. This appears to be true with substantially all forms of prisms,
though perhaps some angles might be used in which this difficulty would not occur.
Some forms of prisms, however, are difficult to make and dithcult to preserve.
I find now that by placing in association with such prismatic light a second pris-
matic light, that the greater part of these rays of light diffused as suggested
are gathered up and directed into such parallel lines. In other words, two of these
prismatic lights under the ordinary conditions of use, when arranged as suggested,
will greatly increase the illumination of the interior of the room. These results
will follow to a greater or less degree from the use of many kinds of prisms, and
the prisms need not always perhaps be the same. But I find that very excellent
results flow from the use of double prisms where both have the perpendicular
edge; and that very excellent results flow from the use of double prismatic lights
where the inclined angle is about that shown in the drawing; and that very
excellent results flow from the use of double prismatic lights
where both are the same. The best form of my invention, therefore, appears to
be that in which I use two prismatic lights placed in substantial parallelism with
each other, each having a series of prisms thereon shaped substantially as shown
above and being practically the same in shape. These two sets of prismatic
lights may be placed in fixed and permanent relation to each other, or they may
be hinged together so that they may be used either double or single, as the case
may be, or as occasion may seem to require.

page_text: My invention is illustrated in the accompanying drawings, wherein
Figure 1 is a cross-section through two sheets made up each of a series of
sections of prismatic lights;
Figure 2 is a plan view of the same; and
:
Figure 3 is an end view of two sheets of prismatic lights hinged together.
Like letters indicate like parts in the several views.
The sections are indicated by the letters A A; the prisms by the letters B B
and the surrounding sash or frame by the letter C. D is the hinge.
These several sections of prismatic glass may be secured together in any
desired manner and framed up in any desired frame so as to constitute when
finished a filled window sash, so to speak. Two of these then are placed as indicated
and permanently associated in a surrounding fixed sash or frame; or they may
may be hinged together as shown, one being fixed in the window in any desired
manner and the other being hinged thereon.
The object of hinging the sections or lights together is in part to enable the
user to employ one window light and throw the light admitted therethrough
into a certain part of the room or diffuse it in a certain manner and thus as
varying conditions may require to superimpose the other window light and thus
change the character of distribution. These results of course will depend upon
the character of the prisms used. Moreover on some occasions and with windows
situated in a certain manner, it would be desirable to use but one set of prisms
on a very bright day, while on a dark or cloudy day the increased illuminating
effect due to the use of both sets of prisms might be desired.
I have shown in the prisms one and the same angles, but of course I might
use one angle in one of the glass and another angle in another glass, that is to say,
the first sheet of glass section might be a certain angle while the next sheet would
be a different angle and any desired angle can be used on either and each light
can be made up of several sections or not as the case may be.
The line E represents a light coming from about 51° from the horizontal and E¹
represents the direction which it takes in the body of the outside plate. E² re-
presents the direction which it takes in the second body or plate of glass, and Ea
the direction which it is desired to give such light in order that it may have the
useful effect of illuminating the room. If the plate or inner body of glass were
absent, the light in question would take the direction E and be practically use-
less. On the other hand, light coming from the direction F is refracted so as to
take the direction F in the outer plate, whence it passes in the direction F into
the room and needs no inner plates or prisms. This illustrates the fact that with
certain rism lights which are useful separately under conditions where the
light is received along the direction F, such prisms are wholly useless under other
conditions, as for example in a case where high buildings or obstructions are
located on the opposite side of the street. In such case, by a duplication of the
plates, they co-act in such way as to produce the desired result.
Having now 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:-
The combination of two layers of prismatic lights arranged substantially as
shown and described and for the purpose specified.
Dated this 15th day of July 1897.
Pattu
I day of July 1891.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.