Improvements in Photo-printing and in the Apparatus Employed therefor.
Year: 1888

page_text: Date of Application, 17th Oct., 1888
Complete Specification Left, 27th June, 1889-Accepted, 27th July, 1889
PROVISIONAL SPECIFICATION,
Improvements in Photo-printing and in the Apparatus Employed
therefor.
I, EDWIN CHAMBERS JOHN DEVIS of the Athenæum, Glasgow in the County of
Lanark, North Britain, Engineer do hereby declare the nature of this invention to be
as follows:-
My Invention relates to apparatus for photo-printing.
The apparatus generally employed for making copies of tracings, documents &c.
on prepared paper by the action of light, consists of a glass plate set in a wooden
frame with a board pressed against it by means of crossbars with springs or wedges.
To keep the prepared paper close against the tracing considerable pressure is required;
the glass is therefore made thick and the frame is correspondingly strong and heavy
to give even support to the glass without liability to twist or warp. The whole
apparatus is consequently very heavy, expensive and cumbrous.
The primary object of my Invention is to provide an apparatus free from all these
objections and so render the photo-printing processes of wider utility to Engineers,
draughtsmen and others. A secondary object is to render such processes easily
applicable to the copying of subjects bound in books such as press copies of letters and
other documents.
The continuous and approximately uniform pressure of the tracing on the prepared
paper I obtain by stretching the former over any suitable curved surface the prepared
paper being between such surface and the tracing. For instance I take a sheet of
any suitable flexible material, such as cardboard next to this may be placed a soft
pad such as is generally used for such purposes (though it is not required as thick as
usual) next to the pad the prepared paper, and lastly the tracing to be copied. The
latter is secured along two sides to the cardboard or other sheet which is then slightly
bent by any convenient means and secured in the secured form. It will then be
found that if the apparatus has been properly constructed the tracing presses against
the prepared paper evenly over its whole surface and is ready to be exposed to the
light.
The flexible sheet may be curved first and the tracing then fixed to it with a
sufficient tension or the curved surface may be permanently formed on a solid block
of wood or other material, but I prefer the method first described.
In applying this method to printing from press copies contained in books, one
edge of the cardboard or other flexible sheet is butted against the binding of the book
between the page to be copied and the next, and the outer edge of the page is
secured to the outer edge edge of the cardboard which is then bent and fixed as
described.
The attachment of the edges of the tracing or document to those of the flexible
sheet may be by means of gum or other cement or preferably in most cases by means
of clips to which the cords or rods are attached which secure the card in its curved
form. In the latter case I design the clips so that the greater the tension in the
tracing, the greater the grip of the clips holding it in place and preventing
slipping.
Dated this 15th dot
inh 1000
JOHNSONS,
115, St. Vincent Street, Glasgow, Petitioner's Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in Photo-printing and in the Apparatus Employed
therefor.
I, EDWIN CHAMBERS JOHN DEVIS, of Laurel Cottage, School Road, Moseley, near
Birmingham in the County of Warwick, Engineer 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 following statement:-
This invention relates to the production of photographic prints of various subjects
such as drawings, tracings, documents &c. carried by flexible, translucent, materials
like paper, linen &c.
Its primary object is to provide an apparatus free from the chief objections of
thoso generally used, namely cumbersomeness, and costliness; and a secondary object
is to render the photo-printing processes applicable to purposes to which they cannot
easily be applied at present, for instance to the copying of matter bound in books,
such as press copies of letters, specifications &c.
The continuous and approximately uniform pressure of the subject to be copied on
the sensitised paper or other surface I obtain by the method of tension over a curved
surface in one of several different ways as hereafter described, this surface being
made as near an approach as practicable to the cylindrical form, but constituting
only a small portion of a cylinder, so that parallel light may fall on it with sufficient
uniformity.
In general construction the apparatus I prefer for office work consists of a flexible
sheet of any suitable material such as paper board, thin wood, vulcanite &c., of
appreciable thickness, with provision along two shorter edges for firmly attaching
either the subject itself or a translucent covering sheet of suitable material; also a
convenient provision for giving curvature to the Hexible sheet or board.
In this case
the sheet which, by its tension over the curved surface, gives the necessary pressure.
between the subject and the sensitised sheet is fixed firmly to the flexible board
before the latter is bent, and consequently acts as the outer layer of the board itself
and is subjected to a greater tension than can easily be obtained by other methods on
the same general principle.
Sometimes, however, I find it more convenient to stretch the subject or the
translucent cover over the curved surface after the latter has been formed; in which
cases the latter may be either made permanently to the desired curvature or temporarily
by bending a flexible sheet or board as before described and securing it before affixing
the subject. Sometimes, also, it is convenient to use a sheet or plate of glass as the
permanently curved surface, the subject being placed next to it and the pressure
produced by stretching over the sensitised paper an opaque covering of cloth or other
suitable material.
When using a temporarily curved board or sheet I obtain the curvature by means
of tension in cords, chains, bars, or other suitable appliances arranged at the back of
the said board or sheet and running from end to end, approximately in the direction
or directions of a chord or chords of the approximately circular curve formed by the
board when bent, or parallel to such directions, but some or all of such tensional
appliances may meet or cross each other diagonally to give increased rigidity to the
apparatus and without diverging sensibly from the plane or planes of the general
direction or directions just described.
I prefer, when possible, to produce the tension in the subject itself and not use an
auxiliary covering shect, but when the former is shorter than the flexible board, or
when protection from rain or dirt is required, it is often most convenient to use such
an auxiliary cover, though sometimes I either lengthen the subject by means of a
clip such as hereafter described, or I clamp it down to the flexible board at inter-
mediate points instead of at the ends of the latter. When protection from rain or
dirt is required,-unless the curved surface is of glass,-I use as an auxiliary covering
sheet some convenient translucent and waterproof material like waxed paper, or linen
or paper prepared with fine mastic varnish.

page_text: For copying subjects bound in books, such as press copies of letters, specifications
&c. I place the flexible board, which in this case may be a piece of cardboard, at the
back of and next to the page to be copied, with one edge butted against the binding of
the book. The sensitised paper having been placed on the flexible board, the outer
edge of the leaf is fixed firmly to the outer edge of the board by a suitable clip or
clamp, and the board is then slightly bent. A convenient way of bending and
securing, in this case, is to pass a small bar along the back, on the outside, or
between the back and the binding of the book, and pass tensional cords from
the clip or clamp to its ends, which should project from the binding for that
purpose.
This latter apparatus enables me to obtain copies of written matter from press
copies and more quickly than can be made by hand or in other ways, and at the same
time without risk of error, and this makes it very valuable in obtaining fuc similes as
evidence of the existence and exact nature of original documents which are either
lost or unavailable for reference from any cause.
The accompanying drawings show the construction of a few of the many forms
which my apparatus may take,-identical letters referring to the same or corresponding
parts in all the figures.
The single irregular line shown in Figs. 2, 4, 5 and 11 is to indicate the general
course which the subject or auxiliary cover follows, and its irregularity is purely for
the sake of distinctiveness, as it actually lies close and tight against the various
surfaces which it follows round, but if shown so would not be easily distinguishable
from such surfaces.
Referring to the accompanying drawings ;-Fig. 1 shows one of the simpler forms
of my apparatus as fixed up and being exposed to the light, and Figs. 2 and 3 show
parts of the same on larger scales. Thin wooden laths A are screwed to the battens B B B
to form the flexible board or sheet, which may be covered on its face (that is, the
side opposite to the said battens) with cloth or felt. Two strips of brass D are bent,
one over each end of the board, to protect the ends of the laths and to preserve a
straight edge, and are held in place by screws passing through the laths and
themselves into the end battens CC, which are so shaped as to leave grooves
between their outer edges and the brasses D D all along the ends of the board.
EE are clips formed of sheet brass bent to the section shown and of the same length
as the battens CC. To each of these clips are attached two cords or chains FF,
the opposite ends of which are attached to the shanks of hooks H H fixed near the
corners of a small board G. This apparatus is worked as follows:-The subject to be
copied, say a tracing, is turned face downwards on a table and the board A placed
on the top of it, also face downwards, the sensitised paper being between them, and
the tracing having been left larger than the board by about two inches at each end.-
One end of the tracing is turned back over the end of the board A and the edge of
one of the clips is pushed into the groove between the batten .C and the brass
strip D, taking the tracing with it and assuming the position shown in Fig. 2. The
second clip having been similarly adjusted at the opposite end of the board, the cords
or chains are shortened by turning over the small board G through half a revolution,
and each of them is hitched under its corresponding hook to secure the flexible board
in the curved form, the length of the cords having been previously adjusted to give
the right amount of curvature. In this pattern the board A is made thicker in the
middle than at the ends in order to give an approximately uniform curvature from end
to end, as it is evident that the bending moment of the tension in the cords is much
greater at the middle than at the ends of the board.
To partly equalise this bending moment and also to give a firmer hold on the
tracing I sometimes use the forms of clip and batten shown in Figs. 4 and 5, in
which the clips are formed of pieces of wood E with brass strips E of the forms
shown screwed on to one face, the battens C being of suitable section as shown also.
These clips are preferably so adjusted that, when the board is bent they stand out
about at right angles to the principal chord of the arc as shown by Fig. 8, so that the
line of tension, while parallel to that chord, is distant from it by about the width of

page_text: the clips, thus largely increasing the proportion of the bending moment at the ends of
the board to that at the middle.
To still further equalise the curvature, and also to make it sufficiently uniform with
a flexible board of uniform thickness I sometimes deflect the cords FF towards the
board at intermediate points, making them take the directions of two or more small
chords, instead of one large one. For short boards it is sufficient to attach the
tightening appliance to the central batten of the board at a distance from the latter
about equal to the width of the clips E E, as shown by Fig. 8, but for long boards it
is advisable to further subdivide the chords by passing the tensional cords F F through
rings attached to the intermediate battens of the flexible board, as shown by Fig. 9.
Attachment or deflecting cords are shown in Figs. 8, 9, and 12, and marked F¹.
Fig. 6 shows a second pattern of tightening appliance which may be used in place
of the tumbling board G before described, and consisting of four levers or bars K K K K
jointed together as shown, the cords F F F F being attached to them. M is a
spring tending to close the levers together and keeping a slight tension on the
cords while fixing the clips. L is a short cord to prevent the levers opening too far,
and N is a spring snap on one of the prolongations to catch the opposite prolongation
and thus keep the levers closed when the board is bent. This is the pattern of
tightener shown in Figs. 8 and 9. Fig. 7 shows a third pattern of tightener, with
which the two cords from each clip are joined into one and the single cord thus
formed passes through one joint of the levers and is attached to the opposite joint.
When the subject to be copied is shorter than the flexible board and no auxiliary
cover is used the former may be fixed to the board by any convenient clamps which
can be placed wherever desired in the length of the board, or it may be lengthened
by attaching a piece of paper or cloth to one or each end; either by cementing or by
means of a clip. One forin of such clip is shown in Fig. 13 where Q is the subject
and R the lengthening sheet, one end of each of which passes between the wood-
strip and the brass strip P, which fit each other tightly all along but are easily
separable.
When an auxiliary cover is used it takes the place of the tracing in the method of
operating as described in reference to Fig. 1.
To increase and render more uniforin the hold of the clip on the subject or
cover, strips of rubber, leather, cork, or other suitable material may be fixed to the
clip as shown at E' in Fig. 4, or to the end batten of the board if preferred.
To give a more rigid apparatus than any before described, and to give protection
to the subject and the working parts of the apparatus when exposed on wet ground,
I use a modification such as shown by Figs. 10 and 11 or an addition such as shown
by Figs. 9 and 12;-that is to say a frame in place of the clips and cords, or two
cross-bars in addition to them.
Fig. 10 shows a frame adapted for use with a flexible board having the end battens
shaped as in Figs. 1 and 2, and Fig. 11 is an enlarged view of a portion showing
one end of the board coming into engagement with it. The brass clips are replaced
by the flat strips S S, one of which is screwed along one end of the frame and the
other along a sliding piece U kept true by the guides X X and actuated by the
toggle hinges T T which work from one end of the frame (to which one of each set of
three hinges is screwed) and are connected together, so as to move simultaneously
and equally, by a piece of wood carrying a projecting piece 1. The strips S Š
overhang their seats by about a quarter of an inch all along on their inside edges, as
shown in Fig. 11, and towards the outside are clear above them by about an eighth of
an inch. The tracing or cover having been first stretched over these strips and fixed
by wedging the ends under them by means of the wood strips W, one end of the
flexible board is engaged with the left hand strip S, the overhang of the latter taking
the tracing or cover into the groove between the batten and the board; the right
hand end of the board is then dropped on to the sliding strip which is moved
forward into its groove, thus fixing the tracing or cover to the board.―The com-
pletion of the notion of the slide U, by pressing down the projecting piece 1, bends
the board, and the snap V catches the end of the frame and keeps the whole in

page_text: position. The frame may, of course, be modified to suit other patterns or
modifications.
•
As shown in Figs. 9 and 12 the clips are provided with one or more bolts Y,
projecting from each end and fitted with fly nuts which pass through slotted holes %,
in the cross-bars J, one of which is shown separate in Fig. 9. The bars are dropped
over these nuts which are then screwed up tight, making a rigid and easily portable
apparatus, and keeping the working parts off the ground. With long boards these
bars may be braced across diagonally by other bars, or may be replaced by a plain
frame without moving parts. When such cross bars or frames are used the curvature
of the board may be equalised by attaching its battens, by cords of the right lengths,
to the bars or the sides of the frame, as shown in Fig. 12, and the same may be
done when the curvature is produced by moving parts of the frame, as described with
reference to Fig. 10.
• I generally use the before described forms of apparatus in the manner described
with reference to Fig. 1, although they may be used without reversing the flexible
board that is to say, the subject and the sensitised paper may be arranged
first on the face of the board and the clips then adjusted from the front side,
but when I desire to work in such way, and in some other cases, I prefer a
modified form of the apparatus, in which the curved surface is formed first of all.-
This may be done conveniently by bending a flexible board and fitting it into a
light frame, to one end of which is fixed, by a suitable clip or clamp, the subject or
auxiliary cover, the opposite end of which is then brought down over the curved
surface and sensitised paper and fixed to the opposite end of the frame or board
and adjusted to the requisite tension by means of screws, cams, wedges, or other
suitable contrivances.
The method of and apparatus for making prints from press copies bound in books
I have already sufficiently described, and it does not require drawings to further
explain it.
In all forms of this apparatus it is important that the tension sheet should be very
firmly secured, that it may not slip, and that any edge round which it turns should
be straight, so that no creases may be produced in it.
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 :-
-
1. In an apparatus for photo-printing, the firm attachment of the subject to be
copied to a flexible board or sheet of appreciable thickness by means of easily
removable clips, and the bending of such board by force applied to such clips, as
described.
2. In an apparatus for photo-printing by means of a bent board or sheet, the
application of the force necessary to produce the curvature in the form of tension from
end to end of the board, or between points or lines near the ends but a little distance
back from them.
3. In such an apparatus, the equalising of the curvature of the board or sheet by
making the latter thicker at the middle than at the ends.
4. In such an apparatus, the equalising of the curvature by deflecting the line of
tension towards the board at one or more points, forming a broken line approximately
parallel to a series of subsidiary chords of the curve.
5. In such an apparatus, the use of additional cross bars or of a plain frame firmly
fixed to to it to give it rigidity and protection.
5. In such an apparatus, the use of a comparatively rigid frame for both bending
the board and giving it rigidity and protection, the bending tension being produced
in the frame itself, as before described.
7. In such an apparatus when used with additional cross bars or with a frame, the
equalising of the curvature by the tensional attachment of intermediate points of the
flexible board or sheet to the cross bars or the frame.

page_text: 8. In such an apparatus the use of an auxiliary translucent sheet to cover the
subject and give the necessary pressure on the sensitised sheet.
9. In such an apparatus the use of an auxiliary translucent and waterproof sheet
to protect the subject from wet, dirt, and grease.
10. In an apparatus for photo printing, the use of a previously formed curved
surface, forming, approximately, a small portion of a cylinder, on which the subject
and the sensitised sheet are afterwards stretched, with suitable fixing and tightening
appliances, and either with or without an auxiliary covering sheet.
11. The application of the various photo-printing processes to the copying of a
subject bound in a book, by stretching it over a curved surface for the purpose of
producing pressure between it and the sensitised sheet, as described.
12. Each and all of the forms of apparatus illustrated by the drawings appended
hereto or described herein before.
D
لريم
1
T
1000
EDWIN C. J. DEVIS.