The extraordinary steps made within five years in the arts of
destruction were illustrated by the twelve-inch Armstrong rifles of
England and the Essen gun, throwing a 1212-pound shot. In 1862 the
heaviest projectile shown did not exceed one hundred pounds. For
field-service the limit of practice in weight seems long ago to have
been reached: for forts and ships it cannot be far off. Armor and
projectiles must soon bring each other to a standstill; as when, in
the Italian wars of the fifteenth century, offence and defence reached
the _reductio ad absurdum_ of the incapacity of men-at-arms to inflict
serious injury upon each other, or even to pick themselves up when
the weight of their armor, with some aid from the clumsy blows of
an antagonist, had overthrown them. Assailant and assailed were _in
equilibrio_, and personal equilibrium could not be restored. Some such
inane result may be witnessed when a pair of hostile iron-clads, out
of sight of their nursing convoys, shall meet alone upon the deep;
with the disagreeable difference that they will, if they go down, have
a great deal farther to fall than the cuirassiers of the land.

[Illustration: VIENNA EXPOSITION BUILDING AND GROUNDS, 1873.]

Since 1851 a new commercial cement had come into operation in the
adoption by neighboring powers of the French metrical system. England
and America still hold out against the mètre and the gramme; and the
press of both occasionally levels at it the old jokes of making the
spheres weigh a pound of butter and the polar axis measure a yard
of calico. With the innovation, however, our merchants have become
perforce familiar, a large share of their imported commodities
being invoiced in accordance with it. Its immense superiority to our
complicated and arbitrary weights and measures, in the tables whereof
the same word often has half a dozen meanings, is beyond argument.