respectively 3, 4 or 5 swings to one swing of the long pendulum,
they will not harmonize and a perfect harmonogram is not obtained.

A good stylus to contain the ink is easily made from a glass tube
1/4 in. in diameter. Heat the tube in an alcohol or Bunsen flame
and then, by drawing the two portions apart and twisting at the
same time, the tube may be drawn to a sharp point. An opening of
any desired size is made in the point by rubbing it on a
whetstone. Owing to the fact that the style of universal joint
described has so little friction, the stylus point must be very

[Illustration: Lines Made with the Harmonograph]

fine, or the lines will overlap and blur. A small weight, such as
a shoe buttoner, placed on the arm near the stylus will cause
enough friction to make the pendulum "die" faster and thus remedy
the trouble.
--Contributed by Wm. R. Ingham, Rosemont, Arizona.



** Cutting Circular Holes in Thin Sheet Metal [35]

In arts and crafts work, occasion often arises to cut a perfectly
circular hole in sheet copper or brass. To saw and file it out
takes time and skill. Holes up to 3 in. in diameter can be cut
quickly and accurately with an ordinary expansive bit.

Fasten the sheet metal to a block of wood with handscrews or a
vise. Punch a hole, with a nail set or punch, in the center of the