[Illustration:  Flowers]

** How to Preserve Egg Shells [288]

Many naturalists experience difficulty in preserving valuable egg shells.  One of the most effective ways of preserving them is as follows:  After the egg is blown, melt common beeswax and force it into the shell with a discarded fountain pen filler.  Set in a cool place until the wax hardens.  The most delicate shells treated in this manner can be handled without fear of breaking, and the transparency of the wax will not alter the color, shading, or delicate tints of the egg.  —­Contributed by L. L. Shabino, Millstown, South Dakota.

** Homemade Phonograph [289]

Make a box large enough to hold four dry cells and use it as a base to mount the motor on and to support the revolving cylinder.  Anyone of the various battery motors may be used to supply the power.  The support for the cylinder is first made and located on the cover of the box in such a position that it will give ample room for the motor.  The motor base and the support are fastened by screws turned up through the cover or top of the box.  The location of these parts is shown in Fig. 1.

The core for holding the cylindrical wax records is 4-1/2 in. long and made of wood, turned a little tapering, the diameter at the small or outer end being 1-5/8 in., and at the larger end, 1-7/8 in.  A wood wheel with a V-shaped groove on its edge is nailed to the larger end of the cylinder.  The hole in the core is fitted with a brass tube, driven in tightly to serve as a bearing.  A rod that will fit the brass tube, not too tightly, but which will not wobble loose, is threaded and turned into the upper end of the support.  The core with its attached driving wheel is shown in Fig. 3.  The dotted lines show the brass bearing and rod axle.  The end of the axle should be provided with a thread over which a washer and nut are placed, to keep the core from coming off in turning.

The sound box, Fig. 2, is about 2-1/2 in. in diameter and 1 in. thick, made of heavy tin.  The diaphragm, which should be of thin ferrotype tin, should be soldered to the box.  The needle is made of a piece of sewing needle, about 1/8s in. long, and soldered to the center of the diaphragm.  The first point should be ground blunt, as shown in the sketch.  When soldering these parts together, take care to have the diaphragm lie perfectly flat and not made warping by any pressure applied while the solder is cooling.

The tin horn can be easily made, attached to the sound box with a piece of rubber hose and held so it will swing the length of the record by a rod attached to the top of the box, as shown.

The motor can be controlled by a small three or four-point battery rheostat.

[Illustration:  Phonograph and Construction of Parts]

—­Contributed by Herbert Hahn, Chicago, Ill.

** A Substitute for a Compass [289]

An easy way to make a pencil compass when one is not at hand, is to take a knife with two blades at one end, open one to the full extent and the other only halfway.  Stick the point end of the fully open blade into the side of a lead pencil and use the half-open blade as the center leg of the compass.  Turn with the knife handle to make the circle.  —­Contributed by E. E. Gold.  Jr.  Victor, Colo.