^278 



Popular Science Monthly 



Music by Wireless 



UNITED STATKS Patent 1,166,582, 

 issued in 1916 to G. Desilels, shows 

 an interesting "Wireless Apparatus for 

 Producing and Transmitting Musical 

 Sounds." By the use of this method, 

 which is here shown diagrammatically, 

 it is possible to play tunes the same as on 

 a piano, and to have the nuisic thus 

 played transmitted by wireless to a 

 distant station and there reproduced. It 

 is seen that alternating current power 

 lines are led to the primary of trans- 

 former 43 by way of the special piano- 

 keyboard switches shown at 22. All of 

 these are connected in parallel, and 

 closing any of them serves to apply 

 power to the transformer. The secon- 

 dary charges condenser 47, which dis- 

 charges with oscillations tlirough the 

 primary portion of helix 46 and which- 

 ever of the rotary spark gaps 3 to 10 is 

 connected by the high-voltage switches 

 of keyboard 22. It may be noted that 

 in the drawing of the patent itself the 

 condenser and spark gap are incorrectly 

 connected to the helix and transformer; 

 from the specification it is obvious, how- 

 ever, that the wiring siiow^n was intended. 

 The novel points of the system are in 

 the rotary gaps 3 to lo and in the key- 

 board 22. Each of the gaps has a 

 different number of spokes, and the 

 numbers are chosen so that the spark 

 frequencies correspond to the notes of an 

 octave in the musical scale. Thus if 

 key 23 is pressed, disc 3 is connected; if 

 this disc has 10 spokes and if the shaft 

 revolves about 1500 r.p.m., 250 sparks 

 per second will be produced. Since tin- 

 spokes are evenly spaced, the sjiarks will 

 occur regularly, and a musical note of 

 about middle C on the musical scale will 

 be produced. If key 30 were pressed, 

 double the number of sparks would 

 occur per second, and the musical tone 

 would be one octave higher. Similarly 

 the other keys connect the other gaps, 

 wliich have their spark freciuencies 

 pro])erly (-hosen so as to give the various 

 notes of the scale. When more than one 

 jjctave is desired additional gaps are 

 made use of; instead of increasing the 

 number of spokes indefinitely the in- 

 ventor prefers to duiilicate the ocla\e of 

 gaps but to rotate the next higher group 

 at (Iciuble speed. This of course (l(nii)les 



the spark frequency and therefore 

 doubles the pitch. By supi^lying suf- 

 ficient power it is feasible to play chords 

 by pressing several of the keys at the 

 .same time. The loudness of the musical 

 tone can be regulated by rheostats 

 operated by pedals and connected so as 

 to vary the intensity of the sparks. It 

 is easily seen that the radiation from a 

 transmitter of this sort would produce 

 musical tone effects in any recei\er, 

 using a telephone in comliination with 

 any of the usual rectifying detectors. 



Music may be transmitted by means of 

 this wireless apparatus 



Lighting Audion Bulbs Cheaply 



AMATEIRS who are not fortunate 

 ^ enough to possess a storage battery 

 often light their audions by the current 

 from dr\- cells. When the detector is 

 used for any length of time, howe\er, the 

 expense of this method is almost pro- 

 hil)iti^'e. Tiie following is suggested as 

 an exceedingly inexpensive substitute, 

 which ma>' be used by those who can 

 secure worn-out dry cells: 



Cut the tops from fi\e one-quart jars 

 or bottles, and fill tlieni one-third to one- 

 half full with a saturated solution of sal- 

 ammoniac. Next .scrape all the shellac 

 from the zinc of five okl dry cells, and 

 punch 1-8 inch holes about an inch apart 

 all over the shell. W'hen these cells are 

 placed in the prei^ared solution the\' 

 will light till' bulb nearly as long as a 

 new l)atter\', and at an expense of possi- 

 bh' two cents for the (-hemical. 



