o pass over their territory is jealously guarded by
European nations, and during the progress of the Great War the Dutch
repeatedly protested against the violation of their atmosphere by
German aviators. At the time of this mischance, however, France and
Germany were at peace--or as nearly so as racial and historic
antipathies would permit. Accordingly when officers of a brigade of
French cavalry engaged in manoeuvring near the great fortress of
Luneville saw a shadow moving across the field and looking up saw a
huge Zeppelin betwixt themselves and the sun they were astonished
and alarmed. Signs and faint shouts from the aeronauts appeared to
indicate that their errand was at least friendly, if not
involuntary. The soldiers stopped their drill; the townspeople
trooped out to the Champs de Mars where the phenomenon was exhibited
and began excitedly discussing this suspicious invasion. Word was
speedily sent to military headquarters asking whether to welcome or
to repel the foe.

[Illustration: (C) U. & U.

_British Aviators about to Ascend._

_Note position of gunner on lower seat._]

Meantime the great ship was drifting perilously near the housetops,
and the uniformed officers in the cars began making signals to the
soldiers below. Ropes were thrown out, seized by willing hands and
made fast. The crew of Germans descended to find themselves
prisoners. The international law was clear enough. The ship was a
military engine of the German army. Its officers, all in uniform,
had deliberately steered her into the very heart of a French
fortress. Though the countries were at peace the act was technically
one of war--an armed invasion by the enemy. Diplomacy of course
settled the issue peacefully but not before the French had made
careful drawings of all the essential features of the Zeppelin, and
taken copies of its log. As Germany had theretofore kept a rigid
secrecy about all the details of Zeppelin construction and operation
this angered the military authorities beyond measure. The unlucky
officers who had shared in the accident were savagely told that they
should have blown the ship up in mid-air and perished with it rather
than to have weakly submitted it to French inspection. They suffered
court-martial but escaped with severe reprimands.

The story of the dirigibles of France and Germany is practically the
whole story of the development to a reasonable degree of perfection
of the lighter-than-air machine. Other n