The instrument is much used in wireless telegraphy, as it is capable of showing the characteristics of currents of very high frequency.
Fig. 2,601.—General Electric moving coil oscillograph with case removed, showing interior construction and arrangement of parts. The oscillograph is furnished complete with a three element electro-magnet galvanometer, optical system, shutter and shutter operating mechanism, film driving motor and cone pulleys, photographic and tracing attachments, 6 film holders, and the following repair parts, for vibrators: 6 extra suspension strips; 6 vibrator mirrors; 1 box gold leaf fuses; 1 bottle mirror cement; 1 bottle damping liquid.
Fig. 2,602.—Oscillogram showing the direct current pressure of a 25 cycle rotary converter (below), and (above) the pressure wave taken between one collector ring and one commutator brush. The 12 ripples per cycles in the direct current voltage are due to a 13th harmonic in the alternating current supply.
Glow Light Oscillograph.—This device consists of two aluminum rods in a partially evacuated tube, their ends being about two millimeters apart. When an alternating current of any frequency passes between them a sheath of violet light forms on one of the electrodes, passing over to the other when the current reverses during each cycle. The phenomenon may be observed or photographed by means of a revolving mirror.
