magic words, produces the card selected in one hand and the rest of the pack in the other.  This is accomplished by simply turning the deck end for end while the observer is looking at his card, thus bringing the wide end of the selected card at the narrow end of the pack when it is replaced.  The hands are placed behind the pack for a double purpose, as the feat then seems more marvelous and the observers are not allowed to see how it is done.

In prize games, players having the same score are frequently called upon to cut for low to determine which shall be the winner, but a fairer way is to cut for high as a person familiar with the trick shown in Fig. 2 can cut the cards at the ace, deuce, or three spot, nearly every time, especially if the deck is a new one.  This is done by simply pressing on the top of the deck as shown, before cutting, thus causing the increased ink surface of the high cards to adhere to the adjacent ones.  A little practice will soon enable one to cut low nearly every time, but the cards must be grasped lightly and the experiment should be performed with a new deck to obtain successful results.  —­Contributed by D.B.L., Chicago.

** A Constant-Pressure Hydrogen Generator [70]

By fitting three bottles, A, B, C, with rubber stoppers and connecting with glass tubes as shown in the sketch, hydrogen or other gases produced in a similar manner may be generated under constant pressure.  In making hydrogen, bottle B is partly filled with zinc nodules formed by slowly pouring melted zinc into water.  Hydrochloric acid is then poured in the small funnel, thus partly filling bottles A and C. When the acid rising from C comes in contact with the zinc, hydrogen gas is generated and fills bottle B. The gas continues to generate until the pressure is sufficient to force the acid back down the tube into bottle C, when the action ceases.  As fast as the gas is used the acid rises in the tube and generates more, thus keeping the pressure nearly constant, the pressure depending on the difference between the levels of the acid in bottle A and bottle B. As this device is easily upset, a ring-stand should be used to prevent its being broken, or if it is to be a permanent apparatus it may be mounted on a substantial wooden base.  This apparatus may also be used for preparing acetylene gas or almost any gas which requires a mixture of a solid and liquid in its preparation.  —­Contributed by C. S. J., Detroit.

** Restoring Tone to a Cracked Bell [71]

Many a bell with a deadened tone due to a cracked rim, can be given its original clear ringing sound by sawing out the crack with a common hacksaw.  Make the saw cut along the line of the crack.  The opening caused by the saw will allow the free vibration of the metal.  —­Contributed by F. W. Bently, Jr., Huron, S. Dak.

** How to Make a Paper Phonograph Horn [71]