Improvements relating to Lamps or Lanterns for Railway and other Purposes.
Year: 1888

page_text: Date of Application, 14th Jan., 1888
Complete Left, 19th June, 1888
Complete Accepted, 20th July, 1888
Improvements relating to Lamps or Lanterns for Railway and other
Purposes.
We JAMES THORNE, Merchant, and EBENEZER BANTON BURR, Engineer, both of
85 Gracechurch Street, in the City of London, do hereby declare the nature of this
invention to be as follows:-
The object of our invention is to provide for projecting the available rays emanating
from a source of light in one parallel beam.
Heretofore spherical lenses have usually been employed for concentrating the rays
from a source of light; for example in signal lamps for railway and other purposes.
In some instances, a parabolic reflector has been used for this purpose, generally without
a lens as in the well-known projectors or "search lights," and sometimes with a lens of
spherical form, or with a parabolic lens as set forth in the specifications accompanying
our applications for Letters Patent dated respectively 12th February A.D. 1887,
No. 2262, and 13th May A.D. 1887 No. 7046.
Now we have discovered that, by employing a lens of parabolic, or approximately
parabolic contour arranged in the proper position relatively to the source of light, we
can, without the use of a reflector, attain results in respect of the concentration of the
rays and the intensity of the projected beam which far exceed the results heretofore
attained with the ordinary spherical lenses and reflectors.
We have, moreover, ascertained that, when a parabolic lens and a parabolic reflector
are used together, as described in our said former specifications, some of the rays
concentrated by the reflector are deflected by the lens in such a manner that they
radiate therefrom, that is to say, the lens and reflector counteract each other, and,
although this is advantageous for some purposes, yet, by reason of such deflection and
radiation, the beam from a lamp provided with such lens and reflector will not be so
intense as that projected from our improved lamp herein described.
In our improved lamp we use a single lens of such form or configuration that it will,
without a reflector, utilize all, or nearly all the available rays emanating from the
source of light, that is to say, will convert these rays into a parallel beam. The said
lens is placed at a greater or less distance from the light according to the dimensions
of the said lens.
1
1
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HASELTINE, LAKE & Co., .
45, Southampton Buildings, London,
Agents for the Applicants.

page_text: We, JAMES THORNE, Merchant, and EBENEZER BANTON BURR, Engineer, both of
85 Gracechurch Street, in the City of London, 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 :-
.
The object of our invention is to provide for projecting in one parallel beam the
available rays emanating from a source of light, by means of a lens such as is herein-
after described, without a reflector.
Heretofore spherical lenses have usually been employed with reflectors for the
purpose of concentrating the rays from a source of light; for example in signal-lamps
for railway and other purposes. In some instances, parabolic reflectors have been used,
generally without a lens as in the well-known projectors or "search lights," though
sometimes with a lens of spherical form or with a parabolic lens as set forth in the
specifications accompanying our applications for Letters Patent dated respectively
12th February A.D. 1887, No. 2262, and 13th May A.D. 1887, No. 7046.
Moreover it has heretofore always been considered necessary that, in order to
increase the illuminating power of a lamp, a reflector should be used in combination
with a lens.
Now we have discovered that, by employing a lens of which the interior surface is
plane and the exterior surface is so curved in one sweep as to give a parallel, or nearly
parallel beam from a point, we can, without a reflector, attain results in respect of the
concentration of the rays and the intensity of the projected beam which exceed the
results heretofore attained in these respects with the ordinary spherical lenses and
reflectors as used in combination, and we are thus enabled to construct an improved
lamp in a simplified form. The curvature of the exterior surface of the lens should,
for this purpose, be what is known as parabolic, or approximately parabolic or elliptic
or approximately elliptic.
In our improved lamp, therefore, we dispense with a reflector and we use a single
lens of which the interior surface is plane and the exterior surface is curved as above
described so that the said lens will utilize all, or nearly all, the available rays emanating
from the source of light, that is to say, will convert these rays into a parallel, or
nearly parallel beam. The said lens is placed at a greater or less distance from the
light according to the effect desired to be produced and found capable of being produced
by the lens.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we wish it understood that we
claim :-
Our improved lamp constructed without a reflector and provided with a lens such
as is hereinbefore described, being so shaped as to convert the rays of light passing
through it into a parallel, or nearly parallel beam.
Dated this 18th day of June 1888.
JAMES THORNE.
EBENEZER BANTON BURR.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.