of torpedoes and miles of cable that the Egyptians did not understand
how to use. The French war with China was equally unsatisfactory from
a military point of view. The Chinese at Foochow were annihilated
because the French opened fire first, and the only shell that
penetrated a French ironclad was filled with lamp black instead of
powder. The national riots that we are accustomed to hear of in South
America are likewise of little instructive value; they buy their
weapons of more civilized people, but there is always something
fatally defective about the tactics pursued in using them. It may be
said in general terms that in these days of extreme power in fighting
machines, the greater the efficiency the less the simplicity and the
more knowledge required in the care of the weapons. When powder was
merely powder the advice of the old adage to "trust in God and keep
your powder dry" was ample to maintain the efficiency of the powder
for all purposes; but nowadays if you keep your powder dry you will
burst your gun, and if you keep your gun-cotton dry you are liable to
blow up your ship.

It is rather difficult to-day to define what high explosives are, in
contradistinction to gunpowder. Thirty years ago we could say that
powder was a mechanical mixture and the others were chemical
compounds; but of late years this difference has disappeared.

The dynamical difference, however, still remains. Gunpowder in its
most efficient form is a slow-burning composition, which exerts a
relatively low pressure and continues it for a long time and to a
great distance. High explosives, on the contrary, in their most
efficient form, are extremely quick-burning substances, which exert an
enormous pressure within a limited radius. Ordinary black gunpowder
consists of a mechanical mixture of seventy-five per cent. of