Improvements in the Manufacture of Colored Lenses for Signal and other Lamps.
Year: 1889

page_text: Date of Application, 16th Feb., 1889
Complete Specification Left, 16th Nov., 1889-Accepted, 21st Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Colored Lenses for Signal and
other Lamps.
I, JAMES THORNE, of 85 Gracechurch Street, in the City of London, Merchant
do hereby declare the nature of this invention to be as follows:-
My invention relates to the manufacture of colored lenses for signal and other
lamps.
:
Heretofore such lenses have been made either by applying colored glass to the
curved surface of a plano-convex lens formed of colorless or clear white glass or
crystal or by placing in a recess or cavity in the plane surface or flat side of a lens
of this kind a disc of colored glass or by placing a disc of colored glass behind the
colorless lens and securing it in the socket ordinarily provided for holding such lens,
or in a separate metal rim or socket provided for the purpose..
These methods of providing for the coloring of the rays of light passing through
the lens are objectionable for various reasons. In applying colored glass to the
curved surface of a lens, great difficulty is experienced in obtaining uniformity in
the thickness of the colored glass: the result is that a beam of light projected by
means of a lens so made, is seldom of uniform color, the rays of light which pass
through the centre portion or apex of the lens usually being of a much darker shade
than those which pass through the surrounding parts of the lens. When a disc of
colored glass is placed in a recess or cavity in the plane surface or flat side of the
lens, the said disc is necessarily of smaller diameter than the lens: a ring of colorless
glass or crystal is therefore left around the colored glass, and consequently the beam
of colored light is surrounded by rays of light to which no color has been imparted,
and which, by combining or mingling with the colored rays, diminish the efficiency
of the lamp for signalling purposes. In cases where a disc of colored glass is
placed behind the lens as above mentioned, oil, dust and other substances are liable to
enter between the said disc and the lens and thus obscure the light.
Now the object of my invention is to provide a colored lens which will be free
from the defects hereinbefore mentioned, and which will be less costly than a lens
made according to either the first or the second of the well-known methods above
referred to.
For this purpose, I take a lens of colorless glass or crystal made in the usual or
other suitable manner with a plane surface, and I combine therewith a disc of
colored glass of the same, or approximately the same diameter as the said lens, but
of sufficiently large diameter to ensure the coloring of all the rays of light which
pass through the lens and I unite the said disc and lens around the edges thereof
in such a manner as to form a fluid-tight joint between the same.
I find it advantageous to manufacture my improved colored lens in the following
manner, viz. -The colorless lens and the disc of colored glass are first heated, in an
oven or otherwise, to a temperature of say from one hundred and fifty to two
hundred degrees Fahrenheit, to prevent fracture of the same during the operation of
uniting them as hereinafter specified. The lens is then placed, with its curved surface
downward, in a recessed bed of cork or other material which is a slow conductor or
non-conductor of heat, so that the plane surface of the said lens is level with or
slightly higher than the top of the said bed. The disc of colored glass is then placed
upon the plane surface of the lens so that it is concentric therewith, care being taken
that the contiguous surfaces of the lens and disc are previously thoroughly cleaned
and that no dust or other matter is allowed to enter between the said leus and disc.
The edges of the lens and disc are then united by blowing with an ordinary blow-
pipe, using a flux of glass-powder or other suitable material. A-fluid-tight joint is

page_text: thus formed which will effectually prevent the entrance of oil or other matter between
the said lens and disc.
The said disc may be cut from colored sheet glass, which, as is well known, can
be easily and cheaply made of uniform color throughout.
By my invention, therefore, I can make a very efficient and serviceable colored
lens at a low cost.
Dated this 16th day of February 1889
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Colored Lenses for Signal and
other Lamps.
I, JAMES THORNE, of 85, Gracechurch Street in the City of London, Merchant,
do hereby declare the nature of this 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 the manufacture of colored lenses for signal and other
lamps.
Heretofore such lenses have been made either by applying colored glass to the
curved surface of a plano-convex lens formed of colorless or clear white glass or
crystal or by placing in a recess or cavity in the plane surface or flat side of a lens
of this kind a disc of colored glass; or by placing a disc of colored glass behind the
colorless or clear white lens and securing it in the socket ordinarily provided for
holding such lens, or in a separate metal rim or socket provided for the purpose.
These methods of providing for the coloring of the rays of light passing through
the lens are objectionable for various reasons. In applying colored glass to the curved
surface of a lens, great difficulty is experienced in obtaining uniformity in the
thickness of the said colored glass; the result is that a beam of light projected by
means of a lens so made, is seldom of uniform color, the rays of light which pass
through the centre portion or apex of the lens usually being of a much darker shade
than those which pass through the surrounding parts of the lens. When a disc of
colored glass is placed in a recess or cavity in the plane surface or flat side of the
lens, the said disc is necessarily of smaller diameter than the lens; a ring of colorless
or clear white glass or crystal is, therefore, left around the colored glass, and
consequently the beam of colored light is surrounded by rays of light to which no
color has been imparted, and which, by combining or mingling with the colored rays,
diminish the efficiency of the lamp for signalling purposes. In cases where a disc of
colored glass is placed behind the lens as above mentioned, oil, dust and other
substances are liable to enter between the said disc and the lens and thus obscure the
light.
Now the object of my invention is to provide a colored lens which will be free
from the defects hereinbefore mentioned, and which will be less costly than a lens
made according to either the first or the second of the well-known methods above
referred to.
For this purpose, I take a lens of colorless or clear white glass or crystal, made in
the usual or other suitable manner with a plane surface or flat side, and 1 combine
therewith a disc of colored glass of the same diameter as the said lens, or it may be
of slightly smaller diameter than the lens providing that it is large enough to ensure
the coloring of all the rays of light which pass through the lens; and I unite the
said disc and lens around the edges thereof in such a manner as to form a fluid-tight
joint between the same.
:-
I find it advantageous to manufacture my improved colored lens in the following
manner, viz. The colorless or clear white lens and the disc of colored glass are first
heated in an oven or otherwise, to a temperature of say from one hundred and fifty

page_text: to two hundred degrees Fahrenheit, to prevent fracture of the same during the
operation of uniting them as hereinafter specified. The lens is then placed, with its
curved surface downward, in a recessed bed of cork or other material which is a
slow conductor or non-conductor of heat, so that the plane surface of the said lens
is level with, or slightly higher than the top of the said bed. The disc of colored
glass is then placed upon the plane surface or flat side of the lens so that it is
concentric therewith, care being taken that the contiguous surfaces of the lens and
disc are previously thoroughly cleaned and that no dust or other matter is allowed to
enter between the said lens and disc.
The edges of the lens and disc are then united by blowing with an ordinary blow-
pipe, using a flux. of glass-powder or other suitable material. A fluid-tight joint is
thus formed which will effectually prevent the entrance of oil or other matter between
the said lens and disc.
The said disc may be cut from colored sheet glass, which, as is well known, can be
easily and cheaply made of uniform color throughout.
By my invention, therefore, I can make a very efficient and serviceable colored
lens at a low cost.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed 1 wish it understood
that I claim:—
First. The manufacture of a colored lens by securing to the plane surface or flat
side of a colorless or clear white lens, by means of a fluid-tight joint, a disc of
colored glass of the same or approximately the same diameter as the said lens.
Second. A colored lens consisting of a disc of colored glass placed against the flat
sile of a colorless or clear white lens and united thereto at the edges by blowing,
substantially as hereinbefore described.
Dated this 15th day of November 1889
JAMES THORNE.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.