mp--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

Chapter XIII.--THE MICROSCOPE, THE TELESCOPE,
AND THE MAGIC-LANTERN.

The simple microscope--Use of the simple microscope in the telescope--The
terrestrial telescope--The Galilean telescope--The
prismatic telescope--The reflecting telescope--The parabolic
mirror--The compound microscope--The magic-lantern--The
bioscope--The plane mirror 253

Chapter XIV.--SOUND AND MUSICAL INSTRUMENTS.

Nature of sound--The ear--Musical instruments--The vibration of
strings--The sounding-board and the frame of a piano--The
strings--The striking mechanism--The quality of a note 270

Chapter XV.--WIND INSTRUMENTS.

Longitudinal vibration--Columns of air--Resonance of columns of
air--Length and tone--The open pipe--The overtones of an
open pipe--Where overtones are used--The arrangement of the
pipes and pedals--Separate sound-boards--Varieties of stops--Tuning
pipes and reeds--The bellows--Electric and pneumatic
actions--The largest organ in the world--Human reeds 287

Chapter XVI.--TALKING-MACHINES.

The phonograph--The recorder--The reproducer--The gramophone--The
making of records--Cylinder records--Gramophone
records 310

Chapter XVII.--WHY THE WIND BLOWS.

Why the wind blows--Land and sea breezes--Light air and moisture--The
barometer--The column barometer--The wheel barometer--A
very simple barometer--The aneroid barometer--Barometers
and weather--The diving-bell--The diving-dress--Air-pumps--Pneumatic
tyres--The air-gun--The self-closing door-stop--The
action of wind on oblique surfaces--The balloon--The
flying-machine