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 circle to be cut, large enough to receive the spur of the expansive bit.  A few turns of the brace will cut out the circle and leave a smooth edge.  —­Contributed by James T. Gaffney, Chicago.

** Key Card for Writing Unreadable Post Cards [35]

A key card for use in correspondence on postals that makes the matter unreadable unless the recipient has a duplicate key card is made as follows:  Rule two cards the size of postal, one for the sender and one for the receiver, dividing them into quarters.  These quarters are subsequently divided into any convenient number of rectangular parts-six in this case.

These parts are numbered from one to six in each quarter beginning at the outside corners and following in the same order in each quarter.  Cut out one rectangle of each number with a sharp knife, distributing them over the whole card.  Then put a prominent figure 1 at the top of one side, 2 at the bottom and 3 and 4 on the other side.  The numbering and the cutouts are

[Illustration:  The Key Card]

shown in Fig. 1.  The two key cards are made alike.

The key card is used by placing it over a postal with the figure 1 at the top and writing in the spaces from left to right as usual, Fig. 3, then put 2 at the top, Fig. 4, and proceed as before, then 3 as in Fig. 5, and 4 as in Fig. 6.  The result will be a jumble of words as shown in Fig. 2, which cannot be read to make any sense except by use of a key card.  —­Contributed by W.J.  Morey, Chicago.

** Homemade Carpenter’s Vise [36]

The sketch shows an easily made, quick-working wood vise that has proved very satisfactory.  The usual screw is replaced by an open bar held on one end by a wedge-shaped block,