Improvements in and connected with Reflectors for Lamps or the like.
Year: 1898

page_text: Date of Application, 4th Apr., 1898
Improvements in and connected with Reflectors for Lamps
or the like.
I, FREDERICK RICHARD BOARDMAN, of 223, Pentonville Road, King's Cross, in
the County of London, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
My invention relates to improvements in reflectors for electric, gas or oil lamps
or the like and is specially applicable for the public lighting of streets or the
like, and is a further development of a Patent No. 5318 of 1891, granted to me
relating to reflectors more particularly for use in electric arc lamps.
It is the ordinary practice in street lighting to place the reflector above the
lamp or source of light and the said reflector is usually in the form of the surface
of a cone with its base lowest and horizontal. The effect of this arrangement
is to throw the greater part of the light from the lamp or source of light on to
the ground around and near the foot of the lamp post. This, therefore, leaves
the greater part of the ground between two or more lamp posts almost destitute
of light. This is all the more noticeable the lower the ordinary conical reflector
is placed over the lamp or source of light and, therefore, the reflector cannot be
placed in its most effective position; namely, as near the source of light as
possible without creating the above mentioned effect:
In carrying my invention into effect and in order to obviate the above men-
tioned defect and throw the reflected rays of light out nearly horizontal and
parallel to the pavement or ground, I place above the source of light and as near
as possible thereto an inverted conical or inverted truncated conical reflector.
Around the upper edge of the said reflector I place a second truncated conical
reflector with its base lowest and the edge of the truncation resting on and coin-
ciding with the upper edge of the above mentioned inverted conical or inverted
truncated conical reflector. To still further increase the amount of light thrown
horizontally I may place underneath the source of light and as near as possible
thereto a conical or truncated conical reflector with its apex or truncation, as the
case may be, nearest to the source of light.
The effect of this arrangement is as follows: The rays of light coming from
the source of light and striking the inverted conical or inverted truncated conical
reflector are reflected outwards and very nearly horizontal or parallel to the
ground or pavement, or at a very slight angle therewith, thus illuminating a
very large area which with the ordinary conical reflector would be almost desti-
tute of light. The rays of light striking the second truncated conical reflector
are reflected downwards and almost vertical thus illuminating the ground around
the foot of the lamp post. The rays of light striking the third or conical or trun-
cated conical reflector placed underneath the source of light and which would
without the reflector merely illuminate the ground around the foot of the lamp
post, are reflected outwards and very nearly parallel to the ground or pavement

page_text: thus greatly increasing the amount of light over a larger area where it is most
required, instead of concentrating the light in a smaller area as is the case with
the old type of reflector previously mentioned.
The reflectors which I use may be of any suitable material and construction,
and of more or less slightly modified shapes from those above mentioned. I may,
of course, use any of the above mentioned reflectors separately or I may use
them in combination as the circumstances may require. The reflectors may also
be used with any source of light such as electric, gas, oil lamps or the like.
Dated this Fourth day of April 1898.
Improvements in and connected with Reflectors for Lamps
or the like.
I, FREDERICK RICHARD BOARDMAN, of 10, Union Court, Old Broad Street, in
the County of London, Electrical Engineer (late of 17, Leopold Street, Burdett
Road, London, E., and of 223, Pentonville Road, King's Cross, 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 follow-
ing statement:-
My invention relates to improvements in reflectors for electric, gas or oil lamps
or the like and is specially applicable for the public lighting of streets or the
like and is a further development of a Patent No. 5318 of 1891, granted to me
relating to reflectors more particularly for use in electric arc lamps.
It is the ordinary practice in street lighting to place the reflector above the
lamp or source of light and the said reflector is usually in the form of the surface
of a cone with its base lowest and horizontal. The effect of this arrangement
is to throw the greatest part of the light from the lamp or source of light on to
the ground around and near the foot of the lamp-post. This therefore leaves
the greater part of the ground between two or more lamp-posts almost destitute
of light. This is all the more noticeable the lower the ordinary conical reflector
is placed over the lamp or source of light and therefore the reflector cannot be
placed in its most effective position, namely as near the source of light as
possible without creating the above mentioned defect.
In carrying my invention into effect and in order to obviate the above men-
tioned defect and throw the reflected rays of light out nearly horizontal and
parallel to the pavement or ground, I place above the source of light and as near
as possible thereto an inverted conical or inverted truncated conical reflector.
Around the upper edge of the said reflector I place a second truncated conical
reflector with its base lowest and the edge of the truncation resting on and coin-
ciding with the upper edge of the above mentioned inverted conical or inverted
truncated conical reflector. To still further increase the amount of light thrown
out horizontally I may place underneath the source of light and as near as possible
thereto a conical or truncated conical reflector with its apex or truncation as the
case may be nearest to the source of light. The effect of this arrangement is as
follows: The rays of light coming from the source of light and striking the
inverted or inverted truncated conical reflector are reflected outwards and very
nearly horizontal or parallel to the ground or pavement, or at a very slight angle
therewith, thus illuminating a very large area which with the ordinary conical
reflector would be almost destitute of light. The rays of light striking the

page_text: second truncated conical reflector are reflected downwards and almost vertical,
thus illuminating the ground around the foot of the lamp post. The rays of
light striking the third or conical or truncated conical reflector placed under-
neath the source of light and which would without the reflector merely illumi-
nate the ground at the foot of the lamp post are reflected outwards and very
nearly parallel to the ground or pavement, thus greatly increasing the amount
of light over a larger area where it is most required, instead of concentrating the
light in a smaller area as is the case with the old type of reflector previously
mentioned.
The reflectors which I use may be of any suitable material and construction,
are of more or less slightly modified shapes from those above mentioned. I may-
of course use any of the above mentioned reflectors separately or I may use
them in combination as the circumstances may require. The reflectors may also
be used with any source of light such as electric, gas, oil lamps or the like.
In order to make the nature of my invention more readily understood, I have
appended hereto the accompanying sheet of drawings.
In the said drawings
A represents in section the above mentioned inverted conical or inverted trun-
cated conical reflector.
B represents in section the above mentioned second truncated conical reflector
with its base lowest and the edge of the truncation resting on and coinciding
with the upper edge of the above mentioned inverted conical or inverted truncated
conical reflector.
C represents in section the conical or truncated conical reflector with its apex
or truncation as the case may be nearest to the source of light which in this case
is an electric glow lamp.
D represents an arrangement for carrying the two first mentioned reflectors
from the ordinary shade ring attachment on the electric glow lamp holder.
X represents a point from which issue diverging rays R, R, R, which are
reflected as shown on the drawing, and as is hereafter described by way of a
type or example.
The ray of light R, proceeds upwards from the source of light and strikes
against reflector A. It is then reflected outwards almost horizontally as shewn.
The ray R proceeds upwards from the source of light and strikes against
reflector A is reflected therefrom and strikes against reflector B. It is then
reflected therefrom as shewn, in a downward direction and would illuminate the
ground round the foot of the lamp post.
The ray Ra proceeds downwards, strikes against the reflector C and is reflected
outwards and almost horizontally as shewn. It will then be seen that the
majority of the rays of reflected light are thrown out almost horizontally instead
of being concentrated round the foot of the lamp post, thus illuminating a much
larger area and very much more effectually than with the ordinary reflector.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The arrangement of reflector or reflectors adjacent to the source of light
in such a manner as to diffuse the rays.
2. The use of an inverted conical reflector as near to the source of light as
possible, which has the effect of throwing the rays in a nearly horizontally
direction.
3. The combination of the before mentioned conical reflector with a second
truncated conical reflector so arranged as to intercept the direct light which
would otherwise be thrown upwards, this second reflector being preferably
arranged that the plane of truncation coincides with the plane of the outer edge
of the first mentioned conical reflector.

page_text: 4. In order to still further increase the amount of light thrown out horizon-
tally, a third conical reflector may be placed below the source of light and as
near to the same as possible in order to distribute the direct rays which are other-
wise thrown vertically downwards. By this means the light, instead of being
very intense over a small area directly below its source is more equally diffused
over a much larger area.
Doted this 2nd law of Ton 1800