Improvements in Glass Globes for the Diffusion and Distribution of Light.
Year: 1896

page_text: Date of Application, 10th Nov., 1896-Accepted, 19th Dec., 1896
COMPLETE SPECIFICATION.
Improvements in Glass Globes for the Diffusion and Distribution
of Light.
We, GEORGE WILLIAM BALLOU, of 10 Wall Street, in the City of New
York, County and State of New York, U.S.A., Gentleman, and AUGUSTUS
SEAVER, of Needham, in the County of Norfolk, State of Massachusetts, U.S.A.,
Manufacturer, do hereby declare the nature of our invention, and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
Our invention relates to glass globes for enveloping, diffusing and distributing
electric-, gas-, and other lights used for illuminating streets, dwellings, churches,
theatres, etc.
The object of our invention is to diffuse and distribute the rays of such light,
and particularly electric and other lights of high candle power, by means of glass
globes having a surface made up of reflecting and refracting prisms of such
smoothness and perfection of polish that the globes will not detract from, but
virtually increase the normal or general illuminating power of the light.
Another object of our invention is to devise a process or method of making
prismatic globes whereby we are enabled to produce such globes of spherical or
spheroidal form in one entire piece of glass with perfect and polished interior
prisms, the outer surface of the globe being plane and smooth.
By our new process or method of manufacture, we are enabled to produce the
globes and prisms under conditions which preserve the fullest transparency of that
portion of the glass which forms the exterior, or main sbell of the globe, and at
the same time augment the smoothness and transparency of the side surfaces of the
prisms, and also make the prisms very close together, very distinct and uniform in
outline, and with smooth and brilliant surfaces and with the edges drawn sharp so
that the globe approximates cut glass in appearance. This said brilliant appearance
of the globe results from the drawing of the glass (by blowing) along, or away
from, the edges of the prisms, which said edges have been previously formed or
chilled in the first step of the process, so that sharp-edged prisms are ensured, and
so that in completing the globe by blowing all superficial mold-marks are obliterated
from the surfaces of the globe and prisms. The globe, therefore, presents the
least possible resistance to the passage through it of the rays of light, and the
prisms, or lens-formations of the globe, by reflection and refraction, increase
the apparent size of the flame or light within the globe, and diffuse the light
without loss of illuminating power, and particularly with the electric, and other
very strong lights, the globe acts to increase the effective general illuminating
power, while at the same time it tempers and softens it to the eyes.
We will now describe our invention in detail in connection with the accompanying
drawings which form a part of this specification and in which:
Fig. 1 is a sectional elevation of the mold and plunger employed in the first step
of our process for forming the bloom or blauk of glass from which the globe is
formed.
Fig. 2 is a sectional view of the plunger.
.
Fig. 3 is a side elevation of the blank with the punty or blowing tube attached.
Fig. 4 is a sectional elevation of the forming mold, showing in dotted lines the
globe. waste glass and blowing tube

page_text: Fig. 5 is an elevation in reduced size of the globe, with a portion broken away.
Fig. 6 is a sectional plan view of the globe shown in Fig. 5; and
Fig. 7 is a sectional perspective view of a portion of the body of the globe.
A represents a mold which may be made in two parts a, a, each formed with a
semi-cylindrical cavity b, b rounded and closed at the bottom, and B represents a
substantially cylindrical plunger less in diameter than the cavity of the mold,
tapered and rounded at its lower end and formed with longitudinal ribs c, c, around
its circumference. These ribs are close together and the grooves or recesses cc
aré by preference brought to sharp poiuts, but in some cases they may be rounded
! as shown at the right of Fig. 2 at c, which formation will slightly round out the
opposite inclined surfaces of each rib. CCC is a guide structure for centering
the plunger to the cavity of the mold A and said structure in connection with a
stop C on the handle of the plunger serves to limit the inward thrust of the
plunger into the mold, so that a sufficient body of glass will remain un listurbel in
the body of the mold after the plunger has been inserted the proper depth.
In practice the two sections of the mold A will be closed and a proper quantity of
molten glass will be poured therein, then the plunger B will be forced down into the
nold and into the molten glass and left to remain until the whole body of glass has
become sufficiently cooled, or set, to be removed for blowing, and then the plunger will
be carefully withdrawn. In the interval of time the plunger remains in the glass the
prisms being partially isolated thin strips of glass, will have become chilled at
their edges from contact with the plunger and of lower temperature, than the
remainder of the glass. On being removed from the mold the operator applies
a cap and tube H H', usually termed a "punty," to the open end of the blank and
lifts the latter from the mold A and by twirling forms the flange h in that portion
of the blank which previously surrounded the plane portion of the plunger above
the grooves and ribs. The blank is then placed in the shaping mold or form D
and is blown to proper size, the same being reheated in the blowing process as
often as required. The forming mold D may be made in two sections adapted to
be opened and closed, and at its open end is formed or provided with the annular
and beveled template i which perfects the flange . In blowing, the surplus of
glass forms a waste bulb H2 which is to be broken away at the angle from the
permanent flange, which latter is subsequently cut or ground true. The reheating
of the blank is external to the partially formed globe so that at all times the
edges of the prisms remain in a chilled or comparatively cool condition, and in the
process of blowing and enlargement of the blank to the proper size, the glass
becomes thin between the prisms and very smooth and transparent, and at the
same time the prisms are distended and the opposite inclined surfaces thereof are
depleted of glass and the prisms become slender, very regular and smooth, while
the thin edges of the prisms become sharp and regular and conform perfectly to the
curved outline of the completed globe. All surfaces of the completed globe thus
become highly polished, clear and transparent to the extent of being nearly, if not
quite, as brilliant as cut glass.
While we design to enlarge the spaces in the plunger as shown at Fig. 2, and
thus make the opposite sloping surfaces of the V-shaped prisms more concaved
than they would be if the surface were plane, we do not wish to be limited to
this, or any specific form of the grooves in the plunger, for the degree of
refraction and reflection of the prisms and intermediate concave lenses may in
this manner be varied according to the size of the globe to be made and
according to the particular kind of light with which the globes may be designed
to be used.
The globe constructed as described comprises the outer smooth spherical
surface, the curved interior prisms or lenses f', and the intermediate thinner
lenses alternating the curved prismatic lenses f', which are (in vertical section
of the globe) periscopic convex lenses as shown in Fig. 5, while the opposite
inclined side surfaces of the prisms are either plane or concave and merge into
the thin lenses, so that each lens f becomes substantially a plano-concave lens

page_text: as shown at 1, 2, 3, Fig. 7. The reflecting and refracting results are such that in
looking through the globe at the light the lines of vision cross at a point about mid way
between the source of light and the edges of the prisms so that the flame or source
of light is greatly magnified and also softened to the eyes, and, reversely, the light
is correspondingly outwardly diffused. The rays of light which strike the apex of
each prism are focused at a point away from the globe corresponding to the extent
of surface exposed to the direct rays of light, and each sloping side surface of the
prisms reflects the light to its neighbouring inclined surface, and then is refracted
out into the room, while the lenses 2 (1, 2, 3) between the prisms diverge the rays
of light horizontally, and also vertically, the latter owing to the general curved or
spherical formation of the body of the globe.
We do not limit ourselves. to any specific proportions, but for ordinary
incandescent electric lamps we find that for a globe five inches in transverse
diameter, and five and one-half inches long, the blank shoald be four inches in
diameter, and five inches long, and the glass three-sixteenths of an inch thick to
the base of the prisms.
Having now particularly described and ascertained the nature of our said inveu-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The manufacture of glass globes for enveloping electric and other artificial
lights by the process or method of pressing contracted prisms in the interior of a
hollow blank of glass, and then, while in a plastic state, enlarging said prisms and
drawing their surfaces to a polished condition with or without a forming mold;
substantially as herein set forth.
2. The reduction of the absorption of artificial light by refraction of the rays
through pressed meridional prisms in a glass globe whose surfaces have been
distended and drawn to a polished condition while in a plastic state; substantially
as hercin set forth.
3. The method, or process, herein described of making glass prismatic globes,
which consists in first forming chilled prisms upon the inner surface of a hollow
blank of glass, and then drawing the glass between the prisms by blowing the blank
to finished form; substantially as and for the purposes set forth.
4. The method, or process, herein described of making glass prismatic globes,
which consists in first forming a blank of glass having a substantially smooth exterior
surface and a central cylindrical cavity formed with a series of longitudinal prisms
chilled at their edges from contact with a plunger, and then by successively
blowing and externally rebeating the blank, drawing the glass between the prisms
and enlarging and fashioning the same to finished form; substantially as set
forth.
5. As a new article of manufacture a prismatic spherical globe, made in one
piece of glass, and having a smooth exterior surface and having interior alternate
prisms and concave lenses, which prisms and lenses are also periscopic convex
lenses from base to apex of the globe; substantially as described.
6. As a new article of manufacture a prismatic spherical globe, open at one end
only, and made in one piece of glass, and having a smooth exterior surface and
baving interior alternate prisms and concave lenses, which prisins and lenses are
also periscopic convex lenses from base to apex of the globe; substantially as
described.
Dated this 10th Jan of November 1900
S. S. BROMHEAD,
97 Newgate Street, London, Agent for Applicants.