RECORDING THE DURATION AND INTENSITY of SUNSHINE
Year: 1884

page_text: I JAMES BROWN JORDAN of The Elms, Cherry Orchard, Staines, Middlesex;
Clerk of Mineral Statistics, Home Office, Whitehall, London, do hereby declare
the nature of my invention for RECORDING THE DURATION AND INTENSITY of
SUNSHINE to be as follows:―
The Instrument consists of a small cylindrical chamber of Metal or other
material impervious to light. It is fitted to a suitable stand with the incans of
aljusting its axis at right angles to the plane of the Sun's apparent motion at any
season of the year. This chamber is lined with paper prepared to indicate photo-
graphically the action of Sun light by change of colour. There are three small
apertures in the surface of the cylinder which admit rays of light into the chamber
at different hours of the day and these are masked by external screens, so adjusted
that a beam of light through one only can enter the chamber at the same time.
The two lateral or East and West apertures only come into use when the sun is
shining above the horizon for more than eight hours: [the aperture facing the East
admitting the rays before eight a.m. and that facing the West after 4 p.m.] The
third or central aperture which is in the plane of the meridian admits all Sunshine
which occurs between the hours of eight a.m. and four p.m. It is evident that a
ray of Sun light admitted through these openings will move over the opposite wall
of this otherwise dark chamber and will record its presence and the variations of
its intensity by acting on the sensitized paper, on which it leaves a distinct trace
whenever the Sunshine is sufficiently bright to cast a shadow. The recording
papers or diagrams are cut accurately to fit the cylinder and are ruled across in
vertical lines representing the hours and minutes of the day. The results are
rendered permanent by immersing the papers for a few moments in warm water,
which also renders the trace more distinct.

page_text: I JAMES BROWN JORDAN of the Elms, Cherry Orchard, Staines, Middlesex Clerk
of Mineral Statistics, Home Office, Whitehall, London do hereby declare the nature
of my invention for RECORDING THE DURATION AND INTENSITY OF SUNSHINE and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The Instrument consists of a dark cylindrical chamber of Metal or other material
impervious to light, with one or two moveable ends or covers which are necessary
for the insertion and removal of the recording diagrams or charts, to be afterwards
described.
This cylinder or chamber is mounted on a suitable stand provided with the
means of adjusting the axis of the cylinder at right angles to the plane of the Sun's
apparent motion, in any latitude, and at any season of the year.
On the inner circumference of the cylinder is placed a diagram or chart, printed
on paper or other material which has been prepared to receive photometrically the
action of Sunlight by change of colour-The diagrams thus employed are ruled
across in vertical lines representing the hours and minutes of the day and they are
accurately cut to fit into the cylinder.
There are three small apertures in the side of the cylinder, so arranged as to
admit the Sun's rays into the interior at successive hours of the day and each
aperture is so masked by external screens that a beam of light can enter into the
chamber through one of the apertures only at the same time.
Two of these apertures, one facing the east and the other facing the west (when
the instrument is in correct adjustment) come into use only at seasons when the
sun shines above the horizon for a longer period than eight hours--the easterly
aperture admitting the rays before eight o'clock in the forenoon and the westerly,
those after four o'clock in the afternoon-The third or central aperture, which
should face due South, in Northern Latitudes, admits the rays which occur between
the hours of Eight a.m. and Four p.m.
Rays of Sunlight thus admitted through these openings will, by virtue of the
Earth's daily rotation move over the opposite wall of the chamber and will record
their presence and the variations of their intensity by acting on the sensitized
surface of the chart leaving on it a distinct trace of chemical action, which is
rendered permanent by treatment according to, the nature of the chemical
preparation employed.
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
An Instrument constructed according to the foregoing description for Recording
the Duration and Intensity of Sunshine by means of a dark cylindrical chamber

page_text: into which the Sun's rays are admitted through one or more apertures in the
manner described, the cylinder or chamber being fixed to a suitable stand and lined
on the inside with a chart of paper, or other material, which has been rendered
sensitive to the action of Sunlight, and on which the sun's rays are directly received
and registered.