Photographic Printing Meter or Actinometer.
Year: 1890

page_text: Date of Application, 15th Aug., 1890
Complete Specification Left, 15th May, 1891-Accepted, 20th June, 1891
PROVISIONAL SPECIFICATION.
Photographic Printing Meter or Actinometer.
I, HERBERT ALFRED LUCAS BARRY, of 17 East Parade in the City and
County of Newcastle-upon-Tyne, Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention has for its object the registering of the amount of exposure given
in printing platinum, opal or other prints.
The body of the meter is composed of wood or other suitable material, carrying
on the top a metal plate pierced with a number of holes of graduated sizes, counter-
sunk to allow free access of light without shadows.
Beneath the top plate is a piece of ground glass inserted and cemented into the
body of the meter to diffuse the light passing through the holes in the top plate.
The light then passes down through holes in the body of the meter, arranged con-
centrically with the holes in the top plate. Into the lower surface of the body a
second ground glass plate is inserted and cemented in position, thus preventing dust
entering the body of the meter. On this second glass plate, or preferably along
the edge of the base plate opposite the holes in the body, are figures corresponding
to the graduated sized holes in the top plate.
The whole of the body carrying the top plate and the two ground glass plates,
is hinged at one end to a metal base plate (which is fixed to the printing frame)
and is held down when closed by a spring catch. This base plate has provision
for holding a slip of sensitive paper, on which the body of the meter rests so that
the light passing through the holes in the top plate and down through the body of
the meter prints certain impressions on the sensitive paper according to the amount
of light allowed to pass and so registers the amount of exposure received by the
paper in the printing frame.
When a negative is being printed the progress of the printing process can be
ascertained, from time to time, by merely opening the meter upon its hinge and
examining the impressions, printed by the light passing through the various sized
holes, upon the sensitive paper the intensity of the impressions being graduated in
proportion to the sizes of the holes and thus, a test print having been obtained of
the required intensity, any number of others may be printed having the same
intensity, by observing the impressions made upon each new slip of sensitive paper
indicating the quantity of light which has passed through each hole.
Dated the 15th day of August 1890.
T. J. DANSON,
By L. W., per F. B.
COMPLETE SPECIFICATION.
Photographic Printing Meter or Actinometer.
I, HERBERT ALFRED LUCAS BARRY of 17 East Parade in the City and
County of Newcastle-upon-Tyne, Engineer, do hereby declare the nature of said
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:—
This invention has for its object the registering of the amount of exposure given
in printing platinum opal or other prints.
The body of the meter is composed of wood or other suitable material, carrying
on the top a metal plate pierced with a number of holes of graduated sizes, counter-
sunk to allow free access of light without shadows.

page_text: The accompanying drawings shew a printing meter drawn for clearness of twice
the intended size of the actual instrument.
Fig. 1 is a sectional side elevation.
Fig. 2 a plan partly on top plate and partly in section on line a-b of Fig. 1 and
Fig. 3 a cross section on line c-d of Fig. 1.
A is the metal bottom plate screwed or otherwise attached to the printing
frame so as to be readily removed and having in it a groove for the reception
of the sensitised test paper. The body of the instrument B (made. of wood,
vulcanite or other material) is attached to this plate by the hinge C and is secured,
when closed, by the sliding catch D or by some equivalent fastening. In the
body B. are holes concentric with those in the top plate and above these is a
recessed groove E to receive the ground, or opal, glass strip F.
10
The top plate G is shewn with its end edges turned back to slide in grooves
formed in B, but may, in an alternative form, be hinged or otherwise attached
thereto. The holes (shewn on drawing 6 in number, but may be more or less)
are graduated in size from 1 to 6 corresponding with similar numbers on the
bottom plate and are countersunk so as to permit the free passage of angular
rays of light without shadows. In the bottom part of the body B I may
introduce a strip of glass in a recess into which it may be cemented, as named
in my Provisional Specification, to prevent the entry of dist from the outside
but do not anticipate the necessity for this. Whilst the test printing is
proceeding the instrument is closed as shewn, and the required intensity of tone
having been obtained on the test print the instrument, is opened upon the hinge,
as shewn by the dotted lines, and the action of the light, passing through the
graduated holes in the top plate, upon the sensitised paper is noted. After this
the printing of any number of impressions may be proceeded with by simply noting
that the sensitised paper is just indicating the action of the light, passing through
the number of hole, previously noted in printing the test, print, and it is, thus
unnecessary to examine the progress of each print in the printing frame, as

page_text: each will be of the same tone as the test print the effects of the several exposures
being the same.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
<<
"
1st. A photographic printing meter or actinometer in which the required
intensity of tone is ascertained, from a test print, by the action of light passing
through holes of graduated areas-through some translucent medium onto a
sensitised surface upon which impressions of varied intensities, corresponding with
the areas of the holes, are produced the faintest of which impressions repeated upon
successive sensitised surfaces, regulates the exposure required for any number of
succeeding prints substantially as described, and, in one form, shewn by the
drawings.
2nd. The photographic printing meter or "actinometer" consisting of the
various parts in combination constructed and operating to effect the objects
hereinbefore set forth and in the manner shewn by the accompanying drawings and
description of same.
T. J. DANSON, F. Inst. P.A.,
2, St. Nicholas' Buildings, Newcastle-upon-Tyne, Agent for Applicant.