rtened to suit the scale of reproduction. One is attached by a fixed
pivot at a to the board on which the drawing is done. At b and e are
removable pivots, used for adjusting the rods; at c is a pivot which
projects an inch or so below the rods. The pointer is inserted at d for
enlargement, or at f for reduction, the pencil being in the unoccupied hole
at d or f.

If a same-sized copy is desired, the fixed pivot is transferred to d, and
the pencil and pointer placed at a and f respectively.

Construction of an Enlarging and Reducing Pantograph.--Cut out of
1/8-inch oak, walnut, or beech four rods 5/8 inch wide and 19 inches long.
Smooth them well all over, and make marks near the ends of each, exactly 18
inches apart. The graduation of the rods for the adjustment pivot holes is
carried out in accordance with the measurements given in Fig. 187. It is
advisable to mark out and bore each rod separately if you do not possess a
machine which will drill holes quite perpendicularly; if you do, all four
rods can be drilled at one operation.

In Fig. 187 the lower row of numerals indicates the number of times (in
diameters) the original is enlarged when all four holes similarly figured
are used; the upper row, the size of the copy as compared with the original
in case of reduction.

If proportions other than those given are required, a very little
calculation will locate the necessary holes.

Pivots.--All the pivots must fit their holes accurately, as any looseness
at the joints detracts from the truth of reproduction. For pivots band b
and e may use brass screws and small pieces of hard wood as nuts to hold
them in position. The nuts should screw on rather stiffly, and not be
forced hard against the rods, as free motion with little friction at all
joints is essential for good work.

[Illustration: FIG. 187.--Diagram showing how to mark off pantograph
rods. The dotted lines above rod give distances of holes from ends.]

The fixed pivot at a may be merely the shank of a wire nail of the proper
size driven into the board, a cork collar being slipped over it to keep the
rod the proper distance from the board. For c use a screw to the head of
which has been soldered half an inch of a round-headed brass nail, which
will move easily over the paper. At d is needed a hollow pivot, fashioned
out of a quarter of an inch of pencil-point protector or some other thin
tube, burred over slightly at the ends so as not to fall out. The end