Improvements in the Manufacture of Prismatic Windows, Glazed Gratings, and the like.
Year: 1897

page_text: Date of Application, 13th July, 1897-Accepted, 30th Oct., 1897
COMPLETE SPECIFICATION
Improvements in the Manufacture of Prismatic Windows, Glazed
Gratings, 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 per-
formed, to be particularly described and ascertained in and by the following
statement:—
My invention consists in Prism Lights and Prism Plates made from such
lights, and has for its object to produce prism lights having smooth, unbroken
surfaces on the plane side, and prism plates having smooth, unbroken surfaces
on the plane sides as more fully hereinafter explained and described.
Figure 1 is a plan view of the plane side of the prism light.
Figure 2 is a cross-section through the same.
Figure 3 is a plan view of a prism light.
Figure 4 a cross-section through the same.
Figure 5 is an edge view, and
Figure 6
plan view of my finished and improved prism light.
Figure 7 is a plan view of a finished prism plate.
Figure 8 a plan view of the same before the plate has been finished.
Figure 9 a cross-section of Figure 8.
Figures 7, 8 and 9 are on a smaller scale than the others, and
Figures 8 and 9 illustrate the prism plate when to be subjected to a different
treatment.
Like parts are indicated by the same letter in all the figures.
A is the edge rim or border of a prism light and it should be of uniform
thickness. B is the central depressed surface of the light and C is the raised
surface of such light. D is the line of separation between the edge or border and
the central surface and it is frequently in the form of a sort of groove, not
easily shown in the drawings, but very noticeable in the product. The object of
the prism lights is to introduce light into rooms and properly direct or control
it, and therefore, of course, such prisms are to be used in high grade buildings and
as fronts in expensive shops and on great thoroughfares. Smooth and perfect
finish is therefore of the greatest importance, since the prism plates are intended
practically to take the place of plate glass.
In the prism lights heretofore formed the prisms did not ordinarily extend
to the outer margin of the plate, but a rim was left and then the prism lights were
assembled to form a prism plate, being united by the lead mountings such as
are commonly employed in stained glass and ornamental work. In forming these
prism lights, the molds were constructed so that the bounding line of the prism
area coincided with the groove or indentation D, and therefore such groove was
unnoticed and negligible. Now, however, the prisms extend to the outer edge
of the body of the prism light in every direction, so far as that may be possible,
and hence if the groove be suffered to remain, it appears as a line or lines running

page_text: across the prisms and disfiguring the product, rendering it, to a degree,
undesirable for the work for which it is intended. In the ordinary process of
moulding, however, it is impossible to avoid this groove-like appearance, or at
least to avoid an irregular and unsatisfactory surface, as indicated in the drawings.
In ordinary practice, the central surface is sometimes elevated above and some-
times depressed below the surface of the surrounding rim or border. The sur-
rounding rim or border is kept of uniform thickness so as to make the application
of the prism light to its frame easy and satisfactory, and this uniformity is
particularly desirable when the prism lights are to be mounted into prism plates
by my electro-glazing method.
EE are the prisms and F the smooth uniform finished surface of the body G
of the prism light. In applying my method and producing my product, I arrange
the molds so that every, prism light formed will have a central surface C-projecting
above the surface of the border A instead of being in any instance depressed
below as is the surface B. In other words, I make the departure from the surface
uniformity desired, always positively in the direction of an excess of material
or an elevation of surface on that part of the prism light surface which does not
coincide with the surface of the border or edge. These prism lights are then
subjected to a grinding or polishing treatment which removes the excess, reduces
the surface to uniformity with the surface of the border and obliterates the
groove of line D. The product thus formed is illustrated in Figures 5 and 6. It
only remains, now to unite these prism lights together into the prism plate, as for
example the prism plate illustrated in Figure 7, and this is done by connecting
them in a net or grid having the warps H H, the ties J J and the surrounding
frame K. At least this is one way of uniting or mounting them so that they are
ready for the sash. The important feature of this method of mounting is that
the several prism lights must be united by an intervening substance which adheres
so closely to the edges of the lights that it holds them by its contact or engage-
ment with such edges and does not therefore require to be extended or projected
beyond the surfaces of the prism lights.
If the surfaces of the connecting net elements are thus flush with the surfaces
of the prism lights, it is obvious that the product will be a complete prism plate
composed of prism lights and a securing net and frame, the whole presenting
a continuous plane and uniform and finished surface, to which a high polish
may easily be given, so as to make it closely approximate the finished effect of
plate glass and to make it suitable for buildings of the highest class and grade.
The difference between the product thus produced and that heretofore produced
by the best application of my electro-glazing method of mountings is illustrated
in Figures 8 and 9, where in the finished product are shown the depressed as well
as the elevated surfaces of the prism lights and also the roughened or irregular
surface L.
In mounting the prism lights by my electro-glazing process, and this is true
also of other processes of mounting, the keys J1 J1 project beyond and overhang
the corners of the lights usually on both surfaces, and these keys may be extended
laterally so as to form beads, so to speak, along the warps or the ties. In the
final finishing of the plate, these keys on the plane side of the plate may be
entirely removed so as to produce the uniform and smooth surface above referred
to. This can perhaps be most safely done in cases where the prism lights are
mounted by my electro-glazing process, and if need be, either with that or other
processes, the edges of the lights may be shaped or treated so as to make it safe
thus to remove the overhanging keys or beads. Of course, all these improvements
are applicable where the prisms, as shown in Figure 8, do not extend entirely
across the prism surface of the lights, but in such cases improvements are not
quite so necessary. In some instances it may be found desirable to mount the
lights first and then by polishing and grinding to remove the projecting and
irregular surfaces, keys, beads, and the like, and bring the whole to a finished
uniform surface. And it is possible also to accomplish the results sought to be

page_text: obtained by this invention by grinding to a uniform surface, either before or
after mounting, even when the edge or rim A is not formed in the first instance
of uniform thickness.
My preferred process, however, is to first produce the prism lights with a uniform
edge and an elevated surface, Second, to grind away the excess of material and
obliterate the line or groove by bringing the whole to a surface uniform with
the surface of such edge, Third, to mount the lights into a prism plate by my
electro-glazing process. Fourth, to grind the finished product so as to make the
whole surface of metal and glass perfectly uniform and to remove the projecting
keys, beads, or the like.
As previously suggested, there may evidently be great modifications from what
is above shown and described without departing from the spirit of my invention,
and I do not wish to be limited to the particular things shown and described.
I have shown and described my invention as applied to prism lights and prism
plates, but it is equally applicable in many other cases, as for example, to a degree
at least in connection with ornamental glass, stained glass, tiles, and the like.
In forming glass articles, it is the practice to estimate in each operation the
amount of material necessary to produce the article and in forming in the old
way these prism lights, it is the object of the molder to get exactly the proper
quantity of molten glass, but this he never succeeds in doing, but always has a
little too much or not quite enough to give the smooth surface. In the formation
of many glass articles, as for example pitchers, this is a matter of no consequence,
as the excess of glass can be suffered to remain in the bottom or some other part
of the pitcher where its presence is unnoticed, though in fact such articles are
never fac similes of each other. To produce the result herein sought for, however,
the prism lights must be fac similes of one another.
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. The process of producing prism lights which consists in putting in the
mold an excess of molten glass and thus forming two surfaces, one the established
surface, the other an excessively elevated surface on the plane side of the prism
light, then grinding such excessively elevated surface to a uniformity with the
established surface.
2. The process of producing prism plates which consists in putting into the
mold for each prism light an excess of molten glass and thus forming two surfaces,
one the established surface, the other the excessively elevated surface on the
plane side of the prism light, then grinding said excessively elevated surfaces
to a uniformity with the established surface, then uniting the series of said
prism lights in a prism plate with intermediate metallic portions, then bringing
the surface of said metallic portions to a uniformity with the established surface
of the prism lights and thus producing a prism plate having a smooth unbroken
surface on its plane side of glass and metal.
3. A complete prism plate composed of series of prism lights joined together
by an inner light metallic net, frame or grid and by an exterior strong frame,
the whole brought to an even smooth receiving surface composed partly of the
plane surfaces of the prism lights and partly of the metallic edges of the net or
frame, substantially as described.