49, 53, 55, 60, 75
differential, 79
polarised, 97
working speed of, 26, 75
Reproducing for newspapers, 60
Resistance of selenium, 109
of selenium cells, 110
regulating, 113
Retardation of current, 6
Retouching, 62
Rotary spark-gap, 28

Selenium, 99
cells, 8, 34, 55, 60, 64, 109, 110
machines, 45
Self-induction, 24, 78
Sensitiveness of selenium cells, 113
ratio of, 113
Silvered quartz threads, 44, 46
Spark-gap, 27
Speed regulator, 68
adjustments of, 69
Spring clutch, 71
Starting position of machines, 98
String galvanometer, 32
Stylus, 17, 18, 57, 61, 78, 95, 103
sparking at, 24
Stylus, angle of, 24, 78
defects of, 57
Submarine cable, 4
Synchronism, 11, 20, 36, 64, 69, 71

Telephograph, 74
advantages of, 76
method of working, 96
Telephone receiver, 83, 85
diaphragm, 48
improved, 51
Telephone relay, 48, 50, 52, 83, 85, 97
Telescope, 131, 136
Thermodetector, 32
Tow, 88
Transmission, distance of, 35, 72
speed of, 25, 35, 75

Vibration, natural period of, 39

Watkins, 105
power number, 105
Waves, damped, 30
undamped, 30, 31
Wheatstone bridge, 113
Wireless apparatus, 13
_Wireless World_, 31
Wynne, 105

Zirconia, 99

THE END

_Printed by_ R. & R. CLARK, LIMITED, _Edinburgh_.

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