IMPROVEMENTS IN MEANS AND APPLIANCES FOR PRODUCING POWERFUL ARTIFICIAL LIGHTS FOR PHOTOGRAPHIC AND OTHER PURPOSES
Year: 1878

page_text: LETTERS PATENT to George Edward Alder and John Archer Clarke, both of
Croydon, in the County of Surrey, for the Invention of "IMPROVEMENTS IN
MEANS AND APPLIANCES FOR PRODUCING POWERFUL ARTIFICIAL LIGHTS FOR
PHOTOGRAPHIC AND OTHER PURPOSES."
Sealed the 8th October 1878, and dated the 11th April 1878.
PROVISIONAL SPECIFICATION left by the said George Edward Alder and
John Archer Clarke at the Office of the Commissioners of Patents on the 11th
April 1878.
GEORGE EDWARD ALDER and JOHN ARCHER CLARKE, both of Croydon, in the
County of Surrey. "IMPROVEMENTS IN MEANS AND APPLIANCES FOR PRODUCING
POWERFUL ARTIFICIAL LIGHTS FOR PHOTOGRAPHIC AND OTHER PURPOSES."
The improvements relate to illuminating purposes generally, and also to the
practice of photography by means of artificial light. They consist in the use of
one or more powerful lights of any convenient kind, such as the electric, magnesium,
lime, gas, or a pyrotechnic light in combination with one or more reflectors capable
of being fixed at any angle, but arranged so as to receive and reflect the concen-
trated rays of light in any desired direction, together with the use of a semi-
transparent medium, tinted, or otherwise placed between the reflected light and the
object or matters to be lighted, in such manner that the reflected rays of light shall
be dispersed or diffused equally, and thus all strong shadows on the illuminated
objects done away with, and by so reflecting and dispersing the light economise it,
and also render it more suitable for photographic purposes than the present concen-
trated rays of artificial light reflected or otherwise at present in use.
The improvements can be performed by making the reflectors conveniently of
silvered glass built up of small pieces and fixed in a curved or other convenient
shaped, metal or otherwise, constructed frame in front of the reflector; and in its
centre of focus is placed the light, and in front of the light is placed a screen of

page_text: opal or ground glass, or of papier mineral, tinted or otherwise, or other semi-
transparent medium of sufficient size to prevent the passage of any rays of light,
save through its medium, and thus all rays are dispersed.
The light is supplied with air and the products of combustion carried off by
suitable inlet and outlet tubes.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Edward Alder and John Archer Clarke in the Great Seal
Patent Office on the 10th October 1878.
GEORGE EDWARD ALDER and JOHN ARCHER CLARKE, both of Croydon, in the
County of Surrey. "IMPROVEMENTS IN MEANS AND APPLIANCES FOR PRODUCING
POWERFUL ARTIFICIAL LIGHTS FOR PHOTOGRAPHIC AND OTHER PURPOSES."
Our Invention has for its object the production of photographs without the aid of
daylight, and at times and in places where it would ordinarily be impossible to
produce them.
We use any of the well-known actinic artificial lights, such as the electric,
magnesium, or pyrotechnic compounds, by preference the pyrotechnic, on account of
its not requiring expensive apparatus and machinery. It is well known, however,
that unaided artificial light is useless for the production of satisfactory pictures, as
rays of light coming from a point are quito unsuitable for the purpose. Our
Invention enables the operator to produce pictures equal to those taken by ordinary
daylight. For this purpose we employ a reflector of suitable size, by preference one
about 4 or 5 feet in diameter, in conjunction with the said light, and with the
reflecting surfaces placed at suitable angles; we prefer to render the rays of light
parallel or convergent to a focus. In conjunction with the reflector or otherwise we
employ one or more semi-transparent screens placed between the source of light and
the object to be photographed, by which means the rays of light are dispersed or
diffused equally, and a soft and suitable light obtained for photographic purposes.
The improvements are to be performed by making the reflectors of silvered glass
or other reflecting surfaces built up of small pieces, or otherwise formed, and fixed
in a curved or other convenient shaped metal or otherwise constructed frame. In
front of the reflector and in its centre of focus is placed the light, and in front of
the light is placed one or more screens of opal or ground glass, or of papier mineral,
tinted or otherwise, or other semi-transparent media of sufficient size to prevent
the passage of any rays of light, save through its medium, and thus all rays are
dispersed.
In practice we often find it desirable to subdue the principal light by placing a
violet or blue-tinted glass in front of it.
When either a pyrotechnic composition or magnesium is employed to produce the
light a lantern of glass must be used with a chimney to carry off the fumes arising
from the burning of the light, and the light supplied with air by suitable inlet.

page_text: Having thus declared the nature of our said Invention, and the manner in which
it is performed, we claim,―
Firstly. One or more screens in conjunction with artificial light for diffusing the
rays of said light.
Secondly. One or inore suitable reflectors for multiplying rays of artificial light
and reflecting them at proper angles, in combination with one or more semi-
transparent media for diffusing said rays, all for the purpose of illuminating objects
for photographic purposes, all substantially as described and set forth.
In witness whereof, we, the said George Edward Alder and John Archer
Clarke, have hereunto set our hands and seals, this Tenth day of October,
AD 1978
GEORGE EDWARD ALDER. (LS.)
JOHN ARCHER CLARKE.
(L.S.)