ting back."

In cases where deep pockets of hanging sand occur, which cannot be
held during lifting off and rolling over, machines are arranged to
roll the flask over in their operation and draw the patterns up under
the influence of the pneumatic vibrator, though, owing to the time
consumed in the rolling over process (and each operation counts in
seconds on a moulding machine) this style of machine is not usually as
rapid in its working as the simpler type, in which the flasks come off
in the same way they go on.

[Illustration: FIG. 6. SET OF PATTERNS FITTED TO PLATES.]

Fig. 6 shows a set of patterns as they are ordinarily fitted to plates
for this machine. Round holes will be noticed at places in the plate
surface. These are openings for the insertion of what are called
"stools."

When it is found necessary to support the sand surface at any point,
or generally, round holes are drilled through either plate or pattern
surface and loose cylindrical pieces are dropped into these holes,
their upper end surfaces being flush with the plate or pattern surface
and their lower ends resting on the plate called, from this use, a
stool plate. This plate appears in Fig. 7 at A and is hung solidly by
the brackets shown at B from the frame which carries the flasks, so
that it has the same upward motion as the flasks, and the upper ends
of the stools remain in contact with the sand of the mould until same
is lifted from machine. Fig. 7, showing a vertical section through a
machine, will make perfectly clear the position and action of these
stools.

[Illustration: FIG. 7. VERTICAL SECTIONS FITTED TO PLATES.]

As illustrating the importance of being able to work without stripping
plates on a line of work which is much more extended than that
possible with them, we may say that a machinist with a drill press
supplied with split patterns and planed pattern plates has matched and
fixed five sets of from four to eight pieces in a day: and wooden
patterns fitted for temporary use in the same way are of frequent
occurrence when it is not thought wise to go to the expense of metal
patterns on account of the relatively small number of castings to be
made from them.

It is not perhaps too much to say that pattern expense is not the
final evil of the costly and not durable stripping plate patterns.

* * * * *

ARTIFICIAL INDIA RUBBER.

One of the most recent important events in the history o