Improvements in Apparatus for Copying Tracings by Means of Artificial Light.
Year: 1897

page_text: Date of Application, 20th Apr., 1897--Accepted, 22nd May, 1897
COMPLETE SPECIFICATION.
Improvements in Apparatus for Copying Tracings by Means of
Artificial Light.
1, BENJAMIN JAMES HALL, of 39 Victoria Street, in the County of Middlesex,
Iron and Steel Works 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 improvements in the apparatus for copying tracings by
means of artificial light described in the Specification of my Patent No. 569.
of 1896. The object of these improvements is to provide simple mechanism for
effecting the travel of the artificial light so as to provide for more equal distribution,
of the luminous rays, for varying the rate of travel of the light, and generally to.
simplify and increase the efficiency of the apparatus.
In the accompanying drawings
Figs. 1 and 2 are respectively front and side elevations of apparatus constructed
according to my present invention, and fitted with an electric arc lamp as the
source of artificial light;
Fig. 3 is a section taken on the line xx of Fig. 2, and Fig. 4 is a modification
thereof;
Figs. 5 and 6 are two forms of spring clips used for securing the ends of
covering; and
Figs. 7 and 8 are respectively elevation and plan drawn to an enlarged scale of
the clockwork mechanism for effecting the travel of the light.
The same letters of reference where they occur are used to denote the same or
corresponding parts in the several figures.
The lamp A is suspended from a cross bar A' to the extremities of which are
attached the two ends of a cord B which passes over the guide pulleys C C and
the pulley sheave D. By this method of suspension the lamp is prevented from
rotating on a vertical axis. To the frame of the pulley block D is secured one.
end of a cord B₁ which is passed over a guide pulley C¹ and its other end secured
to the winding drum E forming part of the raising and lowering mechanism. The
drum E may be a compound drum of two or more diameters and the cord B' is.
wound upon one or the other according to the required rate of travel of the lamp.
The drum E is fast on the spindle of a spur wheel F which gears with a pinion G
loose on a spindle H. Attached to the pinion G is a pawl K in gear with a
ratchet wheel L fast on the spindle H. An escapement wheel M is fast on the
spindle H and is controlled by an anchor pallet N on which is a pendulum rod O.
having an adjustable bob P all arranged in the well known manner.
The arrangement forms a simple clockwork mechanism of which the lamp forms.
the weight which operates the gear, the escapement being controlled by the pallet,
and the rate of travel being regulated by adjusting the bob P on the pendulum
rod, or by shifting the cord B' to a different diameter of the drum D, or by both.
A portion of the weight of the lamp may be compensated by a counterbalance
such as is shown in dotted lines at D', Fig. 2. To the spur wheel F is secured
a handle Q by the rotation of which in the opposite direction to the pull of the
weight of the lamp the cord B' is wound on the drum E and the lamp thus raised,.
the pawl K passing back over the teeth on the ratchet wheel L, the spindle H.
carrying the escapement being unaffected.

page_text: I have found that it is somewhat difficult to produce a straight sided cylinder
of glass of a sufficiently large size to be useful for the purpose of my invention
when applied to the production of copies of large dimensions. I therefore produce
two longitudinal half cylinders and secure these together by placing their edges in
rebates formed in longitudinal battens R, and around the top and bottom edges
of the cylinder so formed I fasten hoops or bands S of any suitable material.
In some cases I make the batten R separating the two half cylinders of such
a width that the cylinder takes a slightly elliptical form as shown in the enlarged
cross section Fig. 4. To the exterior of the battens R, I secure any suitable
number of spring clips T arranged transversely as shown in Fig. 2. For each
half cylinder I use a separate flexible covering U to the longitudinal edges of
which are secured metal or other rods which are sprung into position in the spring
clips T. The coverings are then secured together by straps V as shown in Fig. 2,
or if desired each cover may be strapped independently to a central rod W Figs. 3
and 4. Or the spring clips may have a series of hooks, teeth or serrations along
their surfaces as shown at Fig. 6, by springing the rods over which, the flexible
coverings can be tightened without the aid of straps.
The tracings to be copied are placed longitudinally of and on each half
cylinder instead of being rolled around the cylinder the two part cylinder
being made correspondingly larger for this purpose, and the cylinder is so
arranged that the shadows of the lamp rods are cast on the joints or battens R.
By this arrangement two originals, one on each half cylinder, may be copied at one
and the same time.
The cylinder may be made of more than two parts if found desirable, and
it may of course be made of any material which is transparent to photographic
rays.
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. Apparatus for copying tracings by means of artificial light, comprising a
cylinder of glass or other material transparent to photographic rays, made
up of two or more parts fitted, so as to form a straight sided cylinder, into
rebated battens and secured together by external hoops or bands, substantially as
described.
2. Apparatus for copying tracings by means of artificial light, comprising a
cylinder of glass or other material transparent to photographic rays made up of
two or more parts fitted, so as to form a straight sided cylinder, into rebated
battens carrying spring clips and secured together by external hoops or bands at
top and bottom, and a covering for each part of the cylinder with ends adapted
to engage with the spring clips on the battens and hold the tracings and sensitized
paper in proper position on the exterior of the cylinder, substantially as described
and illustrated in Figs. 1 to 6 of the accompanying drawings.
3. In apparatus for copying tracings by means of artificial light, the clockwork
arrangement for effecting the travel of the light and for varying the rate of
travel thereof substantially as herein described with reference to Figs. 7 and 8
of the accompanying drawings.
Dated this 20th day of April 1897.
F. W. GOLBY,
36 Chancery Lane, London, W.C., Patent Agent for the Applicant.