Some heavy wire bent in the shape of a U and fastened to the under side of the trough at the can end will furnish supports to keep that end of the trough the highest and place the opening in the can close beneath the water faucet.  A common pin stuck through one end of the film and then in the trough close to the can will hold it in position for washing.  Five minutes’ washing with this device is sufficient to remove all traces of the hypo from the film.  —­Contributed by M. M. Hunting, Dayton, O.

** Wood Burning [331]

[Illustration:  Burnt Wood]

Burnt wood work done with an ordinary reading glass and the sun’s rays.

** The Diving Bottle [331]

This is a very interesting and easily performed experiment illustrating the transmission of pressure by liquids.  Take a wide-mouthed bottle and fill almost full of water; then into this bottle place, mouth downward, a small vial or bottle having just enough air in the bottle to keep it barely afloat.  Put a sheet of rubber over the mouth of the large bottle, draw the edge down over the neck and wrap securely with a piece of string thus forming a tightly stretched diaphragm over the top.  When a finger is pressed on the rubber the small bottle will slowly descend until the pressure is released when the

[Illustration:  Pressure Experiments]

small bottle wilt ascend.  The moving of the small bottle is caused by the pressure transmitted through the water, thus causing the volume of air in the small tube to decrease and the bottle to descend and ascend when released as the air increases to the original volume.

This experiment can be performed with a narrow-necked bottle, provided the bottle is wide, but not very thick.  Place the small bottle in as before, taking care not to have too much air in the bottom.  If the cork is adjusted properly, the bottle may be held in the hand and the sides pressed with the fingers, thus causing the small bottle to descend and ascend at will.  If the small bottle used is opaque, or an opaque tube such as the cap of a fountain pen, many puzzling effects may be obtained. —­Contributed by John Shahan, Auburn, Ala.

** How to Make an Inexpensive Wooden Fan [332]

Select a nice straight-grained piece of white pine about 1/4 in. thick, 3/4 in. wide and 4 in. long.  Lay out the design desired and cut as shown in Fig. 1, and then soak the wood in hot water to make it soft and easy to split.  Cut the divisions very thin with a sharp knife down to the point A, as shown in the sketch, taking care not to split the wood through the part left for the handle.  The fan is then finished by placing each piece over the other as in Fig. 2.  This will make a very pretty ornament.  —­Contributed by Fred W. Whitehouse, Upper Troy, N.Y.

[Illustration:  Cutting the Wood and Complete Fan]

** Combination Telegraph and Telephone Line [332]

The accompanying diagrams show connections for a short line system