Improvements in Prism Plates for Windows and the like.
Year: 1897

page_text: Date of Application, 7th Dec., 1897-Accepted, 2nd Apr., 1898
COMPLETE SPECIFICATION.
Improvements in Prism Plates for Windows and the like.
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 performed, to
be particularly described and ascertained in and by the following statement :-
My invention relates to prism lights and plates and has for its object to produce
new and useful improvements in prism lights and plates designed to produce an
increased illuminating effect when applied to the windows of apartments. The
prism lights as commonly used are molded, though of course they may be made in
other ways. They consist usually of a comparatively thin, substantially flat body
of glass a few inches square, (though of course they may be larger) and they have
commonly on one side a series of relatively small prisms systematically arranged to
produce an increased illuminating effect, and on the other side a relatively smooth
surface. In molding or forming these prism lights, it is found that this compara-
tively smooth surface will be somewhat irregular, owing in part to the peculiarities
of the glass and in part to the impossibility of always having an equal amount of
glass in the mold and in part to the contraction and expansion and to the cooling
and reheating of the glass in the process of molding and perhaps to other causes.
When the prism lights are assembled together to form a prism plate, the exterior
surface of such prism plate will be found to consist of a series of surfaces which are
slightly wavy and irregular and which have occasionally serious blemishes, and are
almost throughout their entire extent glazed, as it were. When therefore, you look
at such a plate from without, the effect is to a very great degree inartistic and
unsatisfactory. Moreover, in the formation of such prism lights very great difficul-
ties will be encountered owing to the irregularity of the contraction and expansion
of the glass, and thus there is always a considerable percentage of breakages. This
difficulty is particularly observed with reference to the sinooth surface as the prism
lights are commonly formed. The bottom of the mold usually contains the prism
forming grooves and the plunger which descends upon the glass in the mold tends
of course to cool its upper surface, and when this plunger is withdrawn, the upper
or smooth surface of the prism light becomes hot and runs or changes form and it
is perhaps to this action that the glaze or glare on the surface is due. The objects
of my invention, among other things, are to avoid this glared effect, to prevent or
at least obscure and render imperceptible the irregularities and imperfections other-
wise noticeable upon the receiving surface of the prism light, to prevent the
contraction and expansion in the prism light and thus to prevent breakages, to
secure an elegant exterior appearance of the prism light without materially detract-
ing from its illuminating effect, and secure a design in connection with the prism
light which shall be visible when seen from either side of the prism lights, to
provide lights and plates with suitable designs for artistic effects and to mount,
frame or support the complete plate in a proper and convenient manner. These
results among others I accomplish by the means illustrated in the accompanying
drawing.
Broadly speaking, I propose to form on the receiving side of the prism light
a design which shall preferably be characterized by the absence of extended

page_text: surface areas,
and the absence of broad or wide lines in the design, such design
to be either raised or sunken, or both and at varying levels, and its various
elements, if desired, of varying depths or altitudes as the case may be, and of
varying widths, if desired. Such a design formed on the receiving surface of the
prism light will lead to various results.
In the first place, the design raised or depressed when seen from the prism side
is varied or altered slightly, as you move from position to position while observing
such design. It is in a sense a variable design as seen through the prisms,.and
moreover its lines are softened so as to produce a very pleasing effect and relieve
the prism light of its more or less otherwise harsh appearance when seen from
within.
In the second place, such a design when seen from without as well as when seen
from within, has the appearance of a sort of texture formation, especially when
seen from a considerable distance, as is necessarily the case in ordinary practice.
The elements out of which the design are formed become thread-like and if the
design is properly made produce an effect like lace.
In the third place, the design having broken up the receiving surface into
several small divisions, areas or sections necessarily destroys the glazed effect
above referred to, for though these several areas or surfaces still individually have
the glazed effect, their areas are so small and the effect is so much interrupted by
the design proper that the glazed effect is not noticeable.
In the fourth place, the distortion of the receiving surface is almost entirely
prevented in the process of forming the prism light. This is properly brought
about in the following manner. When the plunger descends on the receiving
surface it chills and slightly cools such surface. When the plunger rises, the
depressed or lower surface of the receiving surfaces being nearer to the inner and
heated glass are remelted but the raised portions of the design being farther
therefrom and exposed on three sides are not remelted and they serve as a sort of
grid to hold the molten parts in position and keep them from running or changing
form and thus the imperfections of the receiving surface above referred to, and
which are so common in ordinary prism lights, are to a great extent obviated. If
any such imperfections nevertheless do exist in the finished product, they are
obliterated and their effects destroyed by the pressure of the raised lace-like
design.
In the fifth place, the upper or outer surface of the raised portions of the design,
since they do not appear to melt when the plunger is raised, do not become glazed,
and hence all that surface is free from the glazed effect.
In the sixth place, by distributing over the receiving surface of the prison light a
design, such as described, the contraction and expansion of the prisni lights, both
while being formed and when finished, is more uniformly distributed, and the
various strains within the glass are accommodated for in such way as to greatly
prevent or diminish the breakages.
In the seventh place, the shear marks which are almost invariably found on the
so-called receiving surface of the prism light and which result from the action of
the shears in clipping or cutting off the molten glass, as it runs into the mold, are,
if not obliterated, at least broken up and distributed in such a manner by the
design as to be imperceptible or at least not offensively present, which is the case
when they appear upon the extended smooth surface.
In the eighth place, the difficulties and disadvantages incident to the varying
quantity of glass in the mold are obviated. In forming devices of this kind, the
molten glass is put into the mold and the operator cuts off the running stream
when, in accordance with his trained judgment, a sufficient quantity of glass has
entered the mold, but obviously, he can never twice cut off exactly the same
amount, and irregularity in the size, shape or appearance of the finished product
must result from this variation in the amount of glass. This irregularity commonly
appears in the surface and distorts or disfigures it. Now, with this design as
suggested, the excess of glass in the mold is carried as an overflow into the figure

page_text: disfiguring manner. It is practically obliterated. In like manner if the glass is
less than the required amount, the irregularity is lost in the design.
In the ninth place, the lines of separation between the several prism lights which
form the plate, whatever their width, size or shape, are to a greater or less degree
obliterated or ininimized by the lines of the design which appear to cross the same,
or which are arranged with peculiar reference to the same, as for example in the
shape of borders for each light. For convenience, I have called these raised or
depressed lines figures or designs, a grid-like formation, though, as illustrated they
may assume forms quite unlike what would ordinarily be understood by the term
grid. They ought to be such as to hold the surface and keep it from changing
form in the process of manufacture, or to break up the finished surface into sinall
areas or both.
The side on which the lines are produced I call the receiving side,
though, of course, either side of the prism light or plate can be used as the
receiving side.
Figure 1 is an elevation of a prism light showing a design formed of raised
thread-like glass portions;
Figure 2 is a section therethrough on the line 2-2 of Figure 1;
Figure 3 is a section of a similar prism light where the design is formed by
sinking the grooves;
Figure 4 is a plan view of a prism light where the receiving surface has no design,
but is inore or less irregular ;
Figure 5 is a section therethrough;
Figure 6 is a view of a series of prism lights associated together and showing a
design so formed as to be carried over a series of such lights, the lights being
incorporated together by a frame so as to form a prism plate;
I have also shown a series of different designs or arrangements of the grid-like
form on the prism light.
Figure 7 illustrates a series of small designs on a prism light grouped together;
Figure 8 a series of small designs each independent; Figure 9 a series of geometric
forms not interlaced; Figure 10 a design in the form of a border about the prism
light; Figure 11 a form in which the center is ornamented and the outer portion
left as a smooth field; Figure 12 a somewhat similar form, with an ornamental
hollow square; Figure 13 the same, with an ornamental annulus; Figure 14 a form
in which the lines are not continuous, but have the appearance of dots, short lines,
etc.; Figure 15 a form in which a complex design is produced, there being various
surfaces of elevation whereby a sort of cut glass effect is produced.
I do not show the cross sections of these several forms, as it will be understood
that the cross sections would be somewhat similar to those shown in
Figures 2 and 3.
I have also illustrated a number of complete prism plates with ornamented parts
arranged so as to form designs.
Figure 16 illustrates a prism plate with ornamental bands across the top and
bottom; Figure 17 a prism plate with a field uniformly ornamented and a central
special ornament; Figure 18 a similar plate with a plain field; Figure 19 a plate
with an outer ornamented border and a uniformly ornamented central field;
Figure 20 a plain field with an ornamental hollow square; Figure 21 a similar plate,
in which the field is uniformly ornamented; Figure 22 a plate with a plain field and
an ornamental annulus; Figure 23 a plate with a plain field and an ornamental
border; Figure 24 a plate with a uniformly ornamented field and specially
ornamented bands; Figure 25 a similar plate with a plain field; Figure 26 a similar
plate with an ornamental annulus.
A, A, are prism lights. B, B, their body portions. C, C, prisms thereon
systematically arranged to produce an increased illuminating effect and relatively
small. D, D, are raised design elements or lines and E, E, are sunken design
elements or lines and F, F, indicate surfaces not ornamented. G, G, are depressions
or irregularities, such as referred to, in the surface of the light. A, H, are lines

page_text: which are directed towards, so as to appear to cross or intersect the framing
strips J, J. These framing strips divide the surface of the complete plate into a
series of surface areas, which are then ornamented so as to produce the effects
shown in the drawings.
The individual prism light may be ornamented in any of the various ways
shown, or other ways, and the prism lights having different ornamentation, or some
of them provided with one kind of ornamentation and others with another kind,
the whole being properly grouped, or some of them ornamented and others plain,
may be formed into prism plates, so as to produce the various effects set forth in
the drawings. When the design. is properly formed and the parts properly
formed all the objects above referred to will be attained. The glazed effect
will disappear, the receiving surface imperfections will either disappear or be
negligible, the top surface of the design will not be glazed, the design will
have a lace-like appearance, the glass of the lower surface when remelted
after the lifting of the plunger, will be held in place by the grid-like
elements of the design, and the design when viewed from the prism side will have
soft lines and be variable as the observer moves about, the excess or insufficient
amount of glass in the mold will produce no unsatisfactory appearance because it
will be lost in the design, the marks of the shears will not appear to disfigure the
receiving surface; the lines of separation between the several prism lights in the
plate will be minimized. The prism lights may be of any desired thickness, size
or shape, though comparatively small and thin lights, with small prisms, seem
best. The lines or elements of the design can be made in any desired manner and
of any cross section, though I prefer raised lines having sides upwardly converging
and formed by molding or pressing.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. A prism light comprising a substantially flat and thin body of transparent
material with a series of small prisms on one side thereof, systematically arranged
to produce an increased illuminating effect and distributed in a substantially
uniform manner over the prism side, and a grid-like design on a part of the
receiving side formed of lines produced in the transparent material and extending
. over a considerable portion of such receiving surface, so as to leave no relatively
large unbroken surfaces thereon.
2. A prism light comprising a substantially flat and thin body of transparent
material with a series of small prisms on one side thereof, systematically arranged
to produce an increased illuminating effect and distributed in a substantially
uniform manner over the prism side, and a grid-like design on a part of the
receiving side formed of lines produced in the transparent material and extending
over a considerable portion of such receiving surface, so as to leave no relatively
large unbroken surfaces thereon, said lines formed of the substance of the prism
light and slightly elevated above the general surface of the receiving side.
3. A prism light comprising a substantially flat and thin body of transparent
material with a series of small prisms on one side thereof, systematically arranged
to produce an increased illuminating effect and distributed in a substantially
uniform manner over the prism side, and a grid-like design on a part of the
receiving side formed of lines produced in the transparent material and extending
over a considerable portion of such receiving surface, so as to leave no relatively
large unbroken surfaces thereon, said lines provided with edges iu planes
substantially perpendicular to the receiving surface.
4. A prism light comprising a substantially flat and thin body of transparent
material with a series of small prisms on one side thereof, systematically arranged
to produce an increased illuminating effect and distributed in a substantially
uniform manner over the prism side, and a grid-like design on a part of the
receiving side formed of lines produced in the transparent material and extending

page_text: over a considerable portion of such receiving surface, so as to leave no relatively
large unbroken surfaces thereon, said lines of thin and of practically uniform cross
section.
5. A prism light comprising a substantially flat and thin body of transparent
material with a series of small prisms on one side thereof, systematically arranged
to produce an increased illuminating effect and distributed in a substantially
uniform manner over the prism side and a grid-like design on a part of the
receiving side formed of lines produced in the transparent material and extending
over a considerable portion of such receiving surface, so as to leave no relatively
large unbroken surfaces thereon, said lines produced in the transparent material
and slightly elevated upon the general surface of the receiving side and provided
with edges which are in planes substantially vertical to the receiving surface.
6. A prism light comprising a substantially flat and thin body of transparent
material with a series of small prisms on one side thereof, systematically arranged
to produce an increased illuminating effect and distributed in a substantially uniform
manner over the prism side and a grid-like design produced in the transparent
material on the receiving side, so as to have two planes of surface on the receiving
side, the surfaces in one plane glazed and the surfaces in the other plane unglazed,
as described.
7. A prism light comprising a substantially flat and thin body of transparent
material, with a series of small prisms systematically arranged on one side thereof
to produce an increased illumination and distributed in a substantially uniform
manner over the prism side and lines on the receiving side thereof arranged so as
to break the receiving surface into a series of relatively small surface sections,
substantially as described.
8. A prism plate comprising a series of small prism lights with interposed lines
of separation, a series of fragmentary designs produced on the receiving surface of
each prism light, said designs related, so that the fragmentary designs on a series
of prism lights when taken together, produce a complete design, some of the lines of
which appear to cross such lines of separation, substantially as described.
9. A prism light. substantially as shown and described and having any of the
designs herein shown formed thereon.
10. A prism plate substantially as shown and described and made up of prism
lights so as to have any of the designs herein shown formed upon such prism
plate.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.