d by these silently moving, dinky sized, almost
imperceptible submarines which carry the ever-destroying torpedoes. And
the loss of lives will be more prodigious than ever.

SUBMARINE STRENGTH OF THE POWERS

Built Building.
Great Britain....................... 69
France.............................. 50
Russia.............................. 25
Germany............................. 24
Italy............................... 18
Austria............................. 6

SUBMERGED MINES--HOW THEY ARE LAID AND THEIR WORKING

The sinking of the light cruiser Pathfinder of the British navy by a
German mine in the North Sea early in the war called special attention
to the deadly character of the mines of the present day.

A modern mine-laying ship puts to sea with a row of contact mines on
rails along her side, ready for dropping into the sea. The rails project
over the stern. The essential parts of a special type of mine of recent
design consist of (1) the mine proper, comprising the explosive charge
and detonating apparatus in a spherical case; (2) a square-shaped
anchor chamber, connected with the mine by a length of cable; (3) a
plummet-weight used in placing the mine in position, connected with
the anchor chamber by a rope. Thus the mine appears on the deck of the
mine-laying ship before being lowered over the stern.

Before the mine goes over, a windlass inside the plummet-sinker is
revolved by hand until the length of cable between the plummet and the
anchor-chamber has been reeled off equivalent to the depth below the
surface at which the explosive mine is to float.

Then the entire apparatus is hove overboard. The plummet and
anchor-chamber sink, while the spherical mine proper is kept on the
surface for the moment by means of a buoyant air-chamber within. A
windlass in the anchor-chamber now pays out the cable between it and the
mine as the anchor-chamber sinks. On the plummet touching bottom, the
tension in the cable between it and the anchor-chamber is lessened, and
the windlass mentioned stops. The anchor-chamber thereupon sinks to the
bottom, dragging down the spherical mine until that is at the selected
depth ready for its deadly work.

CHAPTER XVII

AERO-MILITARY OPERATIONS

_Aerial Attacks on Cities--Some of the Achievements of the Airmen in
the Great War--Deeds of Heroism and Daring--Zeppelins in Action--Their
Construction and Operation._

During t