VI 
CONTENTS. 
exhausting air, 59—Motion of the carriers, 64—Signals, 66—Derange¬ 
ments, 68—Mode of finding the position of an obstruction, 69— 
Various accidents, 71—Continuance of the service during derange¬ 
ments, 72—The system of lines in Paris, 73—The system in'Berlin* 
76—The compressed air telegraph, 77. 
PART II. 
THE ELECTRIC TELEGRAPH. 
-*- 
CHAPTER I. 
History .78 to 105 
First attempts, 78—Soemmering, 79—Schilling, 80—Ampere, 82— 
Cooke, 83—Wheatstone, 84—Morse, 88—The first electric telegraph 
in England, 90—In other countries, 91—In France, 92—In 1840, a 
submarine telegraph suggested by Wheatstone, 95—Walker’s experi¬ 
ments at Folkestone, 96—Brett’s submarine cables, 98—Cable laid 
between England and France, 101—A second cable laid, 103. 
CHAPTER II. 
Construction of Land Lines of Telegraph . 106 to 143 
The wires, 106—Joining the wires, 108—Posts, 109—Iron posts, 110— 
Insulating supports of various kinds, 114—Stretchers or strainers, 
123—Construction of the line, 127—Fixing the posts, 132—Placing 
the wires, 135—Aerial lines in English towns, 135—Subterranean 
lines, 137—Fixing the wires in tunnels and to walls, 142. 
CHAPTER III. 
Making and Laying Submarine Cables . . 144 to 193 
Progress of submarine telegraphy, 144—The electrical and mechanical 
conditions required in a cable, 146—Process of manufacture, 147— 
India-rubber and gutta-percha, 152—The core of the cable, 154—The 
protective covering, 155—The strength of cables, 156—The storage of 
cables, 158—Paying out the cable at sea, 160—The paying-out 
