Page:Popular Science Monthly Volume 88.djvu/968

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��Popular Science Monthly

��A Musical Electric Door- Bell

AN unusual door-bell, differing from the noisy regular electric bell, is here described. This apparatus may- look unpractical and clumsy, but it can be covered up in a neat wooden case, if desired. Procure a small instrument commonly known as the "tubaphone."

��drilled in the upper end of the strip serves to admit a screw holding a wooden hammer-head. A small strip of felt is glued to each striking side of the block. These proceedings, as de- scribed, are carried out for the other strips, hammers, etc., along the appara-. tus. Another piece of brass is fastened to

��A tubaphone consists of a wooden rack each of the long hammers to act as a trip.

��on which are mounted several pieces of brass tubing cut into different lengths, and properly tuned to give forth the various notes of the scale, when set in vibra- tion. Such instruments are usually sold at fifty cents, the price depend- ing upon the size, etc. Several strips of pine about 2 ins. wide, and 7/8 in. thick are pro- cured to be used in the framework. It is simple to make, and is readily understood by examin- ing the diagram.

The tubes are sus- pended, as shown, on rings or rubber bands. The distance between the tubes should be at least one inch ; the first and last tubes must also be about one inch from the edge of the frame- work, for placing a support on each side. The base luay be of any size desired, but these dimensions can only be determined by calculation, and upon the number of brass tubes used, etc. A roller should be turned out from a piece of pine, long enough, of course, to be within the range of every hammer striking the brass tubes. A shafting attachment on the roller is also to be provided for.

Lastly, the hammers are made of sheet brass, having a length that will reach from the base of the apparatus, to a point slightly above the bottom of the suspended tubes. A hole is drilled in the bottom end of each strip, which is firmly fastened to the base by a round-headed wooden screw. The hole

��I^OOOEM FRAMEWORK

��It is riveted to the ham- mer so that its upper end will come in touch every now and then with the wooden pegs, fastened on the revolving-roller. The setting of the pegs in the roller requires some pa- tience; one mistake will be of more value than an hour's description. The pegs, which are obtained from a shoemaker, must be set so that the music will sound cor- rect, care being taken that the higher tubes vi- brate in sym- pathy with the lower notes. With an ordi- nary motor and push-button, with the con- nections de- picted, the ar- rangement will be found com- plete. As soon as the button is pressed, the motor will revolve, and, being shafted on to the roller, will rotate it. The pegs will actuate the hammers, and the hammers will in turn vibrate the brass tubes, producing the musical strains, which show that someone is at the door. Such melodies as "Home Sweet Home," may be made and if the folks tire of the same tunes, several rollers may be on hand and changed as often as desired.

Antenna Wire Strength

PHOSPHOR bronze antenna wire is practically as strong, for the same cross-section, as the best iron. This is nearly twice the strength of copper and over four times that of aluminum.

���The mere pushing of a button at the door causes this apparatus to play a tune

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