of B
at f has a slotted hole to grip the pencil or pointer, as the case may
be.

A Same-size Pantograph.--For making a same-size copy, tracing may be
preferred to the use of a pantograph; but if a pantograph is adopted, a
special apparatus may be constructed for the purpose. The arrangement is
exactly the same as that already described, excepting that the only holes
needed are those at a, c, d, f, at the middle points of the four rods, the
parallelogram formed by the rods being equal-sided. The fixed pivot is
situated at d, and pencil and pointer holes are made at a and f.

Using the Pantograph.--When adjusting the instrument for reduction or
enlargement, make sure that the adjustment pivots are in the holes
corresponding with the scale. The fixed pivot, pointer, and pencil must be
rigid, and, with pivot c, be of such a length that the pantograph as a
whole moves parallel to the paper. A little sliding weight to place on the
rod near the pencil will be found useful for keeping the pencil point in
constant contact with the paper.

If the apparatus works stiffly, ease the holes a trifle and lead-pencil
the wood at all points where two surfaces rub. It is absolutely impossible
to make a good reproduction with a stiff, jerky pantograph.

To decide the positions of original and the paper for the copy, get the
pointer centred on the original and adjust the paper till its centre is
under the pencil.

XXXVII. A SILHOUETTE DRAWING MACHINE.

With this very simple apparatus you will be able to give good entertainment
to such of your friends as may wish to have black paper records of their
faces in profile.

The machine is merely a long rod, with a sliding pencil attached to one end
and a metal pointer stuck into the other, supported near the pencil end on
a pivot which permits free movement in all directions.

For heads and busts only, the rod and pointer combined need not be more
than 4 feet 6 inches long. The rod is a 1/2-inch blind rod, the pointer a
stout knitting-needle driven axially into one end of the rod. This pointer,
being of small diameter, follows the minor curves and angles of the
features much more closely than would be possible with the rod.

The support is a piece of wood, 1-1/2 inches square and 12 to 15 inches
long, screwed on to a large foot, which should be fairly heavy, as any
tilting or slipping will, of course, spoil the silhouette. The universal
joint for the rod is made by soldering a sm