ted on what is called the
delayed-action principle. Such bombs explode after penetrating the fort
or object which they strike, instead of going off by contact. Germany is
said to have developed some of these that were of such size and power as
to penetrate an armored ship. As much as 50 pounds of explosives or
chemicals is declared to have been carried in some of the larger ones.

The big dirigibles mount machine guns of superior range. Some of them
have been armored to an extent, and to make them less easily detected
they have been painted tints and colors to harmonize with the clouds and
sky. Special kinds of gas have been used to fill the envelopes or bags,
and instead of one large bag they consist of a series of bags enclosed
in an envelope or casing, so that if a bullet would penetrate the
envelope it would only destroy one of the gas bags, and not cause the
whole thing to collapse.

Besides having proved of great value in the land campaigns, the aircraft
has shown itself to be one of the most effective devices of warfare for
use against the submarine, and all manner of naval craft. From the
heavens they can see the submarine under the water, and as either the
dirigible or the aeroplane can develop a speed greater than that of any
battleship or cruiser, it is not difficult for it to soar over the
vessel and drop bombs upon it. Even gas bombs have been used in the
raids by the aircraft.

ACCURACY THE GREAT DIFFICULTY.

The difficulty in the use of bombs has been in accurately directing the
death-dealing devices when the airship or aeroplane is in motion. To
assist in this work aerial range finders have been devised. These are
constructed on the principle of the finder on a camera, with graded
scale markings to indicate the allowance that must be made for speed and
motion. Complete apparatus has been built up for launching the
projectiles from the large dirigibles, and to insure the missiles
traveling properly vanes have been attached to some of them.

In a test made under the auspices of the French Government and the
Aerial Club of France, a few years ago, one of the bomb-launching
machines on an aeroplane scored eleven bull's-eye shots in a target ten
yards in diameter, from an altitude of more than 2000 feet, while the
aeroplane was going at a speed of more than 65 miles an hour.

Though there has not been any widespread use of the plan the air has
been "mined" in an experimental way to protect certain sec