thereby detonated.

Another proposed mining method differs materially in its application. In
this instance it is suggested that the mines should be sent aloft, but
should not be of the contact type, and should not be fired by impact
detonators, but that dependence should be placed rather upon the
disturbing forces of a severe concussion in the air. The mines would
be floating aloft, and the advance of the airship would be detected. The
elevation of the mines in the vicinity of the invading craft would be
known, while the altitude of the airship in relation thereto could be
calculated. Then, it is proposed that a mine within d certain radius
of the approaching craft, and, of course, below it, should be fired
electrically from the ground. It is maintained that if the charge were
sufficiently heavy and an adequate sheet of flame were produced as a
result of the ignition, an airship within a hundred yards thereof would
be imperilled seriously, while the other mines would also be fired,
communicating ignition from one to the other. The equilibrium of the
airship is so delicate that it can be readily upset, and taking into
account the facts that gas is always exuding from the bag, and that
hydrogen has a tendency to spread somewhat in the manner of oil upon
water, it is argued that the gas would be ignited, and would bring about
the explosion of the airship.

Another method has even been advocated. It is averred in authoritative
circles that when the aerial invasion in force of Great Britain is
attempted, the Zeppelins will advance under the cover of clouds. Also
that the craft will make for one objective--London. Doubtless advantage
will be taken of clouds, inasmuch as they will extend a measure of
protection to the craft, and will probably enable the invading fleet
to elude the vigilance of the aeroplane scouts and patrols. Under these
circumstances it is suggested that balloon-mines should be sent aloft
and be concealed in the clouds. It would be impossible to detect the
wires holding them captive, so that the precise location of the lurking
danger would not be divined by the invader. Of course, the chances are
that the invading airship would unconsciously miss the mines; on the
other hand the possibilities are equally great that it would blunder
into one of these traps and be blown to atoms.

An English airman has recently suggested a means of mining invading
Zeppelins which differs completely from the foregoing propos