AN IMPROVED HELIOTYPIC OR PHOTOLITHOGRAPHIC PROCESS AND. APPARATUS TO BE USED THEREIN
Year: 1885

page_text: I, HENRY HARRIS LAKE of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings in the County of Middlesex do hereby declare the nature
of my invention for AN IMPROVED HELIOTYPIC OR PHOTOLITHOGRAPHIC PROCESS
AND. APPARATUS TO BE USED THEREIN" 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 an improved heliotypic or photo-lithographic process and
apparatus to be used therein.
The heliotypic process could formerly only be used for the reproduction of
drawings or the like executed in dots and lines. The reproduction of drawings
shaded in Indian ink, of water-color drawings, oil paintings or photographs offered
great difficulties because it was necessary that the primary condition should be
fulfilled, viz that the different shades of the picture should appear as lines or dots.
Various means, partly chemical and partly mechanical were tried to effect this
change of the tints of the picture or photograph, with however only imperfect
results.
In the accompanying drawing
Figures 1, 2 and 3 illustrate in a general manner a known process of producing a
picture with points or dots.
Figure 4 illustrates the new process.
Figures 5, 6, 7, 8 9 and 10 shew apparatus for carrying the improved process
into practice.
Heretofore a photographic negative B was first produced from the original A as
shewn in Figure 1, then a diaphanous positive D was produced from the negative B
as shewn in Figure 2 and finally before the transparent positive D was placed a
transparent sheet L Figure 3 provided with dots or lines, in order to produce
therefrom the dotted and lined negative E.

page_text: According to the improved process, the finished negative E is, as shewn in
Figure 4, produced directly from the original A, the sheet L being placed in front
in the camera.
For this purpose a specially constructed frame A, Figure 5 is provided which can
be arranged in any ordinary camera for reproduction.
Figure 5 shews the general arrangement of the said frame.
Figure 6 shows the journal support.
Figure 7 the locking bar.
Figure 8 a view of the locking device from above and
Figure 9 a lateral view of a hook.
The accurate and absolutely reliable fastening of the said frame to the camera is
of considerable importance for the whole process to succeed, and is accomplished in
the following manner, that is to say :-The camera has on the lower edge a broad
ledge or flange a with which are connected two taper steel studs 6 b' fastened by
bolts. These two studs b 6¹ fit two small perforated steel plates c c¹ fixed to the
frame A and carry the latter.
In order to press the frame closely against the camera and to prevent even the
very slightest displacement by accidental shaking, on the upper right and left hand
sides of the frame, are arranged the locking devices V which effect a perfectly safe
fastening of the frame.
These locking devices, the details of which are represented in Figures 6 and 10,
consist of the hooks d fastened to the frame, and of the locking bars R screwed to
the camera the said bars carrying, as shown in Figures 5, 7 and 8, pins S. When
the locking bars R. which turn upon the bolts Z are moved in the direction of the
arrow, Figure 8, the said bars R slide over the curved surface Figure 9 of the
hooks d and thereby press the frame still more firmly upon the studs 6 61, whilst
the pins S on the locking bars bear against the other curved surfaces in Figure 10
of the hooks d and thereby press the frame with suitable power against the
camera.
In the interior of this frame which is arranged in a similar manner to the so
called reversing frames, is placed the prepared glass plate with the picture surface
upwards, and the wedges K K¹, on the upper and left hand sides of the frame are
tightened, in order to hold the plate. Narrow strips of thin card-board e, Figure 5,
are then put upon the said plate near the edges so that a diapositive which is
provided with shade lines or dots can be placed upon the same without injuring
the sensitive layer of the first plate.
The four spring clamps f which hold the diapositive are then closed, and the
frame is fixed in the camera. After accurate adjustment has been effected, the
plate is exposed to the light, but only for the third part of the entire duration of
exposure which is deemed necessary. After this the slide of the frame is closed
and the latter is placed in a dark chamber, the four spring clamps fare opened, the
diapositive is removed and replaced by a second the lining of which differs from
that of the first diapositive and is fastened again by the spring clamps f; the frame
is then closed and again put in the camera; The plate is now exposed for the
remaining two thirds of the necessary exposure.
The means described of fastening the frame in the camera are of great importance
for this reason, that they enable the repeated removal and insertion of the frame
without the least difference becoming peceptible in the negative. The entire
process is now terminated and by reason of the exchanges of the diapositives
occupies only a few minutes longer time than that necessary for an ordinary
photograph. The transfer upon stone or metal is performed in the manner
heretofore adopted.
The advantages of the improved process are a much more accurate reproduction
'than heretofore, the latter being effected by only a single exposure, and transfers
are dispensed with, thereby rendering the process very reliable and simple, so that
it costs less than the so called "auto-type" process.

page_text: 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
The above described process for the reproduction by the heliotypic or photolitho-
graphic process, of drawings or the like by means of the frame A, provided with
the locking devices V, and the supporting studs, which enable negatives to be
produced with point and line shading.
HASELTINE, LAKE & Co.,
.
For the Applicant.