Chapter VI.--THE ELECTRIC TELEGRAPH.
Needle instruments--Influence of current on the magnetic needle--Method of reversing the current--Sounding instruments--Telegraphic relays--Recording telegraphs--High-speed telegraphy 127
Chapter VII.--WIRELESS TELEGRAPHY.
The transmitting apparatus--The receiving apparatus--Syntonic transmission--The advance of wireless telegraphy 137
Chapter VIII.--THE TELEPHONE.
The Bell telephone--The Edison transmitter--The granular carbon transmitter--General arrangement of a telephone circuit--Double-line circuits--Telephone exchanges--Submarine telephony 147
Chapter IX.--DYNAMOS AND ELECTRIC MOTORS.
A simple dynamo--Continuous-current dynamos--Multipolar dynamos--Exciting the field magnets--Alternating current dynamos--The transmission of power--The electric motor--Electric lighting--The incandescent lamp--Arc lamps--"Series" and "parallel" arrangement of lamps--Current for electric lamps--Electroplating 159
Chapter X.--RAILWAY BRAKES.
The Vacuum Automatic brake--The Westinghouse air-brake 187
Chapter XI.--RAILWAY SIGNALLING.
The block system--Position of signals--Interlocking the signals--Locking gear--Points--Points and signals in combination--Working the block system--Series of signalling operations--Single line signals--The train staff--Train staff and ticket--Electric train staff system--Interlocking--Signalling operations--Power signalling--Pneumatic signalling--Automatic signalling 200
Chapter XII.--OPTICS.
Lenses--The image cast by a convex lens--Focus--Relative position of object and lens--Correction of lenses for colour--Spherical aberration--Distortion of image--The human eye--The use of spectacles--The blind spot 230