IMPROVEMENTS IN LAMPS OR TAR METH SARA
Year: 1882

page_text: LETTERS PATENT to Arnold Wright Kershaw of Lancaster in the County of
Lancaster Architect for an Invention of "IMPROVEMENTS IN LAMPS OR
TAR
METH
SARA
An
a
PROVISIONAL SPECIFICATION left by the said Arnold Wright Kershaw at
the Office of the Commissioners of Patents on the 20th October 1882.
ARNOLD WRIGHT KERSHAW of Lancaster in the County of Lancaster, Architect
IMPROVEMENTS IN LAMPS OR LANTERNS FOR THE BETTER AND MORE EQUABLE
DIFFUSION OR DISTRIBUTION OF ARTIFICIAL LIGHT
My improvements in the more equable distribution of artificial light is
accomplished by constructing the lamp surrounding the light partly as a reflector,
and partly as a refractor. The upper part of the lamp I construct as a hollow
hemisphere the inner surface of which is a reflector; the lower part is made of
flint or other glass having transparent refractive properties.
The light is by means of the reflector above thrown down upon the bottom,
which is so constructed as to refract the light and diffuse it more evenly than
hitherto between, as in the case of street lighting, the posts upon which the lights,
are raised,

page_text: .
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arnold Wright Kershaw in the Great Seal Patent Office on the
18th April 1883.
ARNOLD WRIGHT KERSHAW of Lancaster in the County of Lancaster Architect
IMPROVEMENTS IN LAMPS OR LANTERNS FOR THE BETTER AND MORE EQUABLE.
DIFFUSION OR DISTRIBUTION OF ARTIFICIAL LIGHT
My object in the more equable distribution of artificial light is accomplished by
constructing the lamp surrounding the light partly as a reflector and partly as a
refractor: the upper part of the lamp is constructed hollow as a hemisphere, the
inner surface of which acts as a reflector, and the lower part of the lamp I make of
flint or other glass having transparent refractive properties. The light by means of
the reflector above is thrown down upon the refractor which diffuses the light
more evenly than hitherto.
Such being the object and nature of my invention I will now proceed to describe
the same more fully aided by the accompanying drawings in which Figures 1 and 2
are respectively the vertical section and horizontal sectional plan of one of my
arrangements for a lamp or lantern in which the upper part C is a hemispherical or
hemispheroidal reflector of silvered glass, highly polished metal, or other material,
which reflects all the light from the upper hemisphere O back through the point of
light A, or from a point adjacent on to the lower hemisphere B, which is a refractor
or lens of flint glass or other suitable material, which has the effect of so
distributing the light, that on any horizontal plane within certain.limits, the light
will be of equal intensity.
To illustrate my meaning a lamp or lantern as here shewn and described would
approximately if illuminated by a powerful electric light, placed say ten yards
above the ground level, equally illumine the ground assuming it to be level within
a radius of seventy-five yards, or thereabouts: these effects can be varied more or
less by altering the form of the refractor or lens.
It will be manifest from the above description that this arrangement utilises the
whole of the light emanating from a certain point and that too exactly where it is
required.
Lamps made according to my invention have the further advantage of being
almost if not entirely free from parts casting shadows, perforations can be made in
any portion of the reflector or the refractor for pipes in the case of gas or for such
things as the wires or carbons in the case of the electric light.
->
By varying the form of the refractor or lens somewhat in the manner as shown
on plan by Figure 3, the vertical section remaining the same, the light may be
distributed over a square area instead of circular, and in fact by thus varying the
plan of the refractor or lens, the light may be distributed over almost any form of
-area desired.
A modified form of my improved lamp is shown by Figure 4, in which the
reflector is parobolic or approaching to that curve, in which case the light striking
the reflector is thrown on the outside edges of the area to be illuminated: the upper
edge of the refractor or lens B is carried above the point of light A equally
distributing in level planes the light passing through it.
Figure 5 is a view of a wall bracket shewing a combination of Figures 1 and 4,
the direct rays of the angle E. F. and the reflected rays of the angle EF all pass
through the refractive lens Bª and are thus distributed, the rays of the angle G. H.
and also of the refracted rays G H₁ both being reflected downwards from the
parabolic upper reflector C. The reflector and refractor in this case are both

page_text: capable of variation on plan to suit circular, square, rectangular, or other form of
area to be illuminated.
As before stated the reflector and refractor may be made of various forms, a
few of the forms which the refractor may take are shewn in Figures 6. 7. 8..and 9,
Figure 9 being in two pieces instead of one.
The weight of the lenses or refractors may be reduced by being made as shewn
in Figures 6 and 7 which are both variations on the refractors in Figure 1: the
other modified forms of refractors being capable of similar variation, the effect
being practically the same as with the original ones from which they are varied.
These lamps may be fixed on brackets supported or suspended by any ordinary
mechanical contrivance they may also be enclosed in obscured or coloured glass
shades if desired.
Having thus described my said invention and the manner in which the same is
to be carried into effect, I have to state that I do not confine myself to the precise
details herein described and delineated as the same may be varied without altering
the characteristic nature of my invention, but that what I believe to be novel and
desire to be secured to me by the herein before in part recited Letters Patent is:
The construction of lamps or lanterns with the reflector or refractor as before
described and delineated in Figures 1 and 2.
The modified forms of such reflectors and refractors as in part shewn in
Figures 3. 4. 6. 7. 8. and 9.
The combination forming wall lamps as before described and shewn by Figure 5.
In Witness whereof.I the said Arnold Wright Kershaw have hereunto set
my hand and seal this sixteenth day of April in the year of our Lord One
thousand eight hundred and eighty-three.
בז זDNA
DIAM TERCIT
ARNOLD WRIGHT KE
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