An Improved Process of Pneumatic Drawing, and Apparatus therefor.
Year: 1891

page_text: Date of Application, 15th Dec., 1891-Accepted, 16th Jan., 1892
COMPLETE SPECIFICATION.
An Improved Process of Pneumatic Drawing, and Apparatus
therefor.
We, NORMAN ALONZO CHATFIELD, Portrait Artist, and ABSALOM ESTY
HOOVER, Photographer, both of 269 Dearborn Street, Chicago, in the County of
Cook and State of Illinois, United States of America, 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 :-
We have discovered by continued experiment that if crayon, dry paint, black-
lead, or other coloring-matter or similar substance be pneumatically forced while in
a powdered or finely-divided state against the surface of the paper or other material
used in drawing the particles of the substance will become attached thereto or be
forced under or between the fibres of the paper, or, in other words, become partially
incorporated therewith, producing a mark of greater or less size according to the
size of the current of compressed air, or according as the apparatus is moved
toward or from the paper. By moving the apparatus through which the current
passes in one direction or another, lines of any form or dimensions may be formed.
This process may be employed in drawing and finishing portraits, landscapes,
designs, &c., and to carry out such process we have devised a machine whereby
the current of compressed air may be directed as desired, and whereby the crayon
or other substance used may be powdered or ground and introduced into the current
of air; and our invention consists in the process and apparatus for carrying out
the same, as hereinafter described.
In the drawings,
Figure 1 is a central vertical longitudinal section of the pneumatic pencil used
in carrying out the process;
Fig. 2, a similar section of the grinding-machine;
Fig. 3, a section on line 3 3 of Fig. 2, looking in the direction of the arrow;
Fig. 4, a perspective view of a cradle or frame used to support the substance
being ground, and
Fig. 5 similar views of parts of the apparatus.
The pencil A is made of any suitable dimensions, and, as shown, is hollow
throughout its length and provided with a tip a, adjustably connected to the body
of the pencil by screw-threads or in any other suitable manner. The size of the
opening in this tip determines the size of the blast, and when it is desired to
increase or diminish the size thereof the tip may be taken off and replaced by a
larger or smaller one. The tube A', which forms the inner lining of this pencil,
extends, as shown, out of the rear end thereof, and is adapted to be inserted into
the end of a flexible tube, which is connected, as hereinafter described, with the
grinding-machine. This grinding-machine consists of a case or sheath made in
two parts B B', the part B consisting of a case or sheath of suitable dimensions
to receive the parts hereinafter to be described, and made of any suitable material
and preferably in the form shown in Figs. 2 and 3 of the drawings, and provided
with clamps I, whereby it is attached to the ordinary maul-stick. The part B
consists of a tube attached by means of screw-threads or in any other suitable
manner to the case B', as shown. To the left-hand end of this tube B is attached
a taper thimble b, adapted to be connected with any suitable source of compressed
A similar thimble b¹
air and supply-as, for instance, an air pump or reservoir.
is attached to the right-hand end of the sheath B' and is connected, preferably by
means of a flexible tube, (not shown,) with the rear end of the tube A. To prevent

page_text: clogging of the tube, we prefer to place over the inner end of the thimble &' a piece
ef wire-gauze b".
In the tube B, is secured a frame or cradle C, preferably made in the form
shown in Fig. 4, wherein it is circular at one end and semicircular at the other, of
a proper size to fit the interior of the tube, the two end pieces being connected by
side bars or rods. The circular end is open, as shown, to afford a free passage for
the air. This cradle is provided with cross-bars c, on which is placed the material
to be ground, and a set-screw c', whereby the sides of the cradle are adjusted to
bind against such material and hold it in place. The cradle when inserted into
the tube B may be held in place by means of the end of the sheath B and the
taper thimble b, though any other means may be used, as desired. Immediately
above the cradle is placed a bow D, preferably of the form shown more particu-
larly in Fig. 5, and a piece of emery-cloth or similar substance E is attached to
the downwardly-projecting ends of the bow D by means of clamp-plates dd,
which are screwed to the end of the bow. A loop F is attached to the forward
end of the bow, and to this is fastened one end of an elastic-band G, the other
end of which is attached to a cross-rod, engaging with notches in the rearward
side of the circular end of the cradle C, by means whereof the elastic band and
bow may be adjusted at different distances from the cradle C. The clamp-plate d
is provided with a loop, as shown, through which the elastic band passes, and
which serves as a guide for such band and support for the bow. We next construct
a segmental lever H, which is pivoted in the sheath B. To one end of this lever
is attached a strap h, the other end of which is attached to a loop in the clamp-
plate . The shaft or spindle of the lever H passes, as shown in Fig. 3, out
through the case, and a lever H' is secured thereto, the opening where the shaft
passes through the case being covered by an elastic tube / to prevent the escape
of air. From this construction it will be seen that as the lever H is pressed
toward the right, Fig. 2, the lever I will be moved in the same direction, carrying
along with it the bow and the emery-cloth attached thereto, drawing such cloth
across the surface of the material to be ground and grinding a portion thereof, and
that as the pressure on the lever H' is released the elastic band G will draw the
bow and paper toward the left, Fig. 2, bringing the lever H into the position
shown in the dotted lines and again drawing the emery-cloth across the surface of
the material to be ground. In this way by alternately pressing the lever Hand
releasing such pressure a reciprocating motion is imparted to the bow and cloth,
which pass back and forth upon the surface of the material, grinding off particles
from the same.
The parts being constructed and put together as shown, the thimble being
connected with a suitable source of compressed air, and the thimble with the
pneumatic pencil, the device is operated as follows: The case inclosing the grinding
mechanism is preferably held in the left hand and the pneumatic pencil in the
right. The air is admitted under pressure to the case B B₁, and a reciprocating
motion being imparted to the bow and emery-cloth, as hereinbefore described, the
material supported in the cradle is ground with greater or less rapidity, as desired.
As the particles are ground off they immediately enter the blast, which becomes
charged therewith and by which they are carried through the pencil and forced
against the paper to which they attach themselves or with which they become
partially incorporated. By moving the pencil as necessary any portrait, landscape,
design, &c., may be drawn upon the paper or other material used. By varying
the intensity of the blast the size of the nozzle a and the rapidity of the
grinding the intensity and size of the line drawn may be varied easily, as occasion
may demand.
In using this apparatus lines of the utmost fineness and delicacy may be drawn,
and drawings of any sort and in any color can be executed with great rapidity and
precision. As great force is exerted by the blast, the finely-divided particles are
not only deposited upon the surface of the material used, but, as shown by a

page_text: microscopical examination, they are forced between or partially under the fibres
thereof, becoming to a greater or less extent incorporated with a part of the material
itself. This adds greatly to the durability of the drawings, the lines, if made by
a current or stream of air under pressure, being almost indelible.
As will be evident, the apparatus is exceedingly simple, consisting, as it does, of
but few parts, which are easily adjusted or replaced. It should be understood that
we do not intend to limit ourselves to the exact forms herein given to the several
parts, since form not being essential to the successful operation of the device the
parts may be varied in many ways, as desired-as, for example, a coiled spring
may be used in place of the elastic band G, or the tube may be attached to the
pencil in other ways than that herein shown, and any such changes we regard as
coming within the spirit and gist of our invention, which consists, as regards the
process in drawing pictures, &c., by pneumatically forcing powdered or finely-
divided material against the surface upon which the picture is to be drawn and
as regards the apparatus in providing a suitable device for carrying out the
process.
In order to carry out the process, it is not necessary to use the exact form of
mechanism herein shown, since the material may be governed in any other way
desired and then forced against the surface on which the drawing is to be made by
the air-pressure. The machine herein shown is therefore intended but as an illus-
tration of one form of apparatus by means whereof the process may be carried
out, and as a limitation to that form alone.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
1. The process of drawing, which consists in pneumatically forcing finely-divided
crayon, dry paint, or similar material against a dry surface upon which the drawing
is to be made, whereby the particles of such material become attached to such
surface, substantially as described.
2. The process of drawing, which consists in reducing crayon, dry paint, or
similar material to a finely-divided state while exposed to an air-blast, whereby as
the particles of such material are ground off they are carried along by the blast
and forced against the surface upon which the drawing is to be made, becoming
thereby incorporated with such surface, substantially as described.
3. The combination of a hollow pencil, a grinding mechanism connected there-
with, and means for forcing air through the pencil and grinding mechanism,
whereby the substance ground is blown out through the pencil, substantially as
described.
4. The combination of a case B B', a cradle C, a bow D, grinding material
secured by means of suitable clamps, and means for imparting a reciprocating
motion to such bow, substantially as described.
5. The combination of a case B B', a cradle C, a grinding-bow D, an elastic
band G, attached to the bow and cradle, a lever H, connected to the bow, a
lever H, rigidly attached to the lever H, whereby the bow is moved in one direction
by the lever Hand in the other by means of the band G when the lever is released,
substantially as described.
6. A cradle C, provided with cross-bars c to support the material to be ground,
and a set-screw c', substantially as described. .
7. The combination of a case B B, a cradle C, a bow D, grinding material
secured thereto, a lever H and band G, attached to the bow, a lever H¹, rigidly
connected to the lever H, a pencil A, connected to the case B B', and means for
forcing air through the case and pencil, whereby as the material upon the cradle
is ground by means of the bow it is blown by the air through the pencil, substan-
tially as described.
8. The combination of a cradle, a grinding-bow, and an elastic band attached to

page_text: the bow and adjustably connected with the cradle, whereby the bow is adjusted at
different distances from the cradle, substantially as described.
Dated this 15th day of December 1891.
F. W. BARKER,
Applicants' Agent.