A NEW OR IMPROVED ACTINOMETER
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
We, CLEVELAND GREEN, of The Woodlands, Alveston, Stratford-on-Avon,
Warwickshire, Gentleman, and LOUIS VARLEY FUIDGE, of Ivy Cottage, Stratford-
on-Avon, aforesaid, Artist, do hereby declare the nature of our invention for
"A NEW OR IMPROVED ACTINOMETER" to be as follows:-
Our Invention relates to a new or improved actinometer and has for its object
to provide a simple pocket instrument particularly for use by photographers for
ascertaining the proper time for exposing a plate in the camera or a sensitized
paper in the printing frame.
In carrying our Invention into practice we provide a flat box preferably of
metal and of circular shape and of suitable size for the pocket. The said box is
provided with a lid or cover on the face of which is shewn a graduated scale of
permanent tints of colour arranged radially and numbered from 1 upwards. We
prefer to arrange the said tints on a glass or porcelain plate fixed to the inside of
the lid so as to shew on the face through radial perforations therein.
The said box holds a supply of sensitive paper the top one of which is partly
exposed through one of the said perforations which is left clear for that purpose.
When it has been exposed for a given time it shews, by comparison with the said
graduated scale of tints, the light's exact actinic power.
Several readings can be taken on the same piece of paper by simply turning the
lid round for a short space to expose a fresh part.
Between the said top piece of paper and the supply we use an opaque plate so
that the supply will remain unaffected by the light.
Instead of a circular box as above described a rectangular or other shaped box
may be used and the tints may be arranged in rows or in any other manner
instead of radially for the purpose above described as will be readily understood.
We have found our Actinometer of great service when working with dry plates
as by it we are able to very readily obtain the time of exposure for plates of
different makers and thereby effect a great saving in plates.
Dated this 29th day of October 1884

page_text: COMPLETE SPECIFICATION.
We, CLEVELAND GREEN, of The Woodlands, Alveston, Stratford-on-Avon,
Warwickshire, Gentleman, and LOUIS VARLEY FUIDGE, of Ivy Cottage, Stratford-
on-Avon, aforesaid, Artist, do hereby declare the nature of our invention for
"A NEW OR IMPROVED ACTINOMETER "and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying drawings and to the letters
and Figures marked thereon, that is to say :-
Our Invention relates to a new or improved actinometer and has for its object
to provide a simple pocket instrument particularly for use by photographers for
ascertaining the proper time for exposing a plate in the camera or a sensitized
paper in the printing frame.
We proceed with reference to the accompanying drawings to fully describe our
Invention.
Similar letters refer to similar parts throughout the several Figures.
Fig. 1 is a plan, Fig 2 a side elevation and Fig. 3 a sectional elevation of an
actinometer made according to our Invention; Fig. 4 shews the porcelain or glass
plate forming part thereof removed; Fig. 5 shews the opaque plate of the same;
Fig. 6 is a plan and Fig. 7 a sectional elevation of the box part of the actinometer
separately; Fig. 8 shews a piece of sensitized paper after exposure in the
actinometer. Fig. 9 is a plan and Fig. 10 a sectional elevation of a modified form
of actinometer made according to our Invention and Fig. 11 shews a further
modification of our Invention.
We will first describe our Invention with reference more particularly to
Figs 1 to 8, both inclusive,
For the purposes of our Invention we provide a flat box A preferably of metal
and of circular shape and of suitable size for the pocket. The said box is provided
with a lid or cover B on the face of which is shewn a graduated scale of permanent
tints of colour arranged radially and numbered from one upwards (say from 1 to 7
as shown on the drawings). We prefer to arrange the said tints on a glass or
porcelain plate C (shewn separately in Fig 4) or an enamelled or other plate may
be used, fixed to the inside of the lid B so as to shew on the face through radial
perforations a¹ therein. The said porcelain plate C has a perforation c¹ corre-
sponding with one of the perforations a³ in the lid B.
b
The said box A holds a supply of sensitive paper, as D, the top one D² of which
is partly exposed through one of the said perforations a3 which is left clear for
that purpose and which we call the "recorder." When the paper has been exposed
for a given time through the "recorder" a² it shews, by comparison with the said
graduated scale of tints 1, 2, 3, 4, 5, 6, 7, the light's exact actinic power and the
correct length of exposure required at that time to obtain that depth of tint.
Fig. 8 shews the piece of paper D¹ removed after being exposed until the part &
has acquired a depth of tint equal to 4.
Several readings can be taken on the same piece of paper by simply turning the
lid round for a short space to expose a fresh part of the paper through the

page_text: Between the said top piece of paper D¹ and the supply D we use an opaque
plate E (shewn separately in Fig. 5) so that the supply D will remain unaffected
by the light.
Instead of using a glass or other plate as above described we sometimes for
cheaper articles arrange the tints directly on the lid of the box, as shown in Fig. 9
either by painting, enamelling or by other suitable means or process.
Instead of a circular box as above described a rectangular or other shaped box
may be used and the tints may be arranged in rows or in any other manner instead
of radially for the purpose above described as will be readily understood. Fig. 11
shews an actinometer of rectangular shape constructed in accordance with our
Invention to operate as above described, the tints 1, 2, 3, 4, 5, 6, 7, 8, being
arranged in a row and the "recorder" a alongside thereof.
We have found our actinometer of great service when working with dry plates
as by it we are able to very readily obtain the time of exposure for plates of
different makers and thereby effect a great saving in plates.
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we declare that what
we claim is
1. A new or improved actinometer as hereinbefore described, that is to say, a
box or case for holding a piece or pieces of sensitized paper and having arranged on
or to shew through its face or lid a scale of tints and a space through which the
within contained piece of sensitized paper can be seen for the purpose hereinbefore
described with reference to our drawings.
2. The new or improved actinometer as herein before described and illustrated,
that is to say, a box or case of circular or other shape having arranged on or to
show through its face or lid a scale of permanent tints and a perforation a²
substantially as and for the purpose hereinbefore described and illustrated.