applications to engineering purposes on shore in time of war, and in
most cases they are better than powder. They received the serious
attention of French engineers during the siege of Paris, and were
employed in the various sorties which were made from the city, in
throwing down walls, bursting guns, etc. An explosive for such
purposes, and indeed for most military uses, should satisfy the
following conditions:

(1) Very shattering in its effects.

(2) Insensible to shocks of projectiles.

(3) Plastic.

(4) Easy and safe to manipulate.

(5) Easy to insert a fuse.

(6) Great stability at all natural temperatures and when used
in wet localities.

Neither blasting gelatine, dynamite nor gun-cotton fulfills all these
conditions; but they satisfy many of them and are more powerful than
other substances. For the destruction of walls, trees, rails, bridges,
etc., it is simply necessary to attach to them small bags of
explosive, which are ignited by means of blasters' fuse and a cap of
fulminate of mercury, or by an electric fuse.

We now come to the application of high explosives to warfare in the
shape of bursting charges for shells. This is the latest phase of the