s ten tributaries; its innumerable
palaces, churches, and theatres, and long straight streets of stately
houses, its parks and gardens, and its green shady suburbs, making up
a picture which forced an exclamation of wonder from Arnold's lips as
the air-ships slowed down and he left the conning-tower of the
_Ithuriel_ to admire the magnificent view from the bows. They passed
over the city at a height of four thousand feet, and so were quite
near enough to see and enjoy the excitement and consternation which
their sudden appearance instantly caused among the inhabitants. The
streets and squares filled in an inconceivably short space of time
with crowds of people, who ran about like tiny ants upon the ground,
gesticulating and pointing upwards, evidently in terror lest the fate
of Kronstadt was about to fall upon St. Petersburg.

The experimental department of the Arsenal had within the last two or
three years been rebuilt on a large space of waste ground outside the
northern suburbs, and to this the three air-ships directed their
course after passing over the city. It was a massive three-storey
building, built in the form of a quadrangle. The three air-ships
stopped within a mile of it at an elevation of two thousand feet. It
had been decided that, before proceeding to extremities, which, after
all, might still leave them in doubt as to whether or not they had
really destroyed all means of analysing the explosives, they should
make an effort to discover whether Professor Volnow had received them
for experiment, and, if so, what success he had had.

Mazanoff had undertaken this delicate and dangerous task, and so, as
soon as the _Ithuriel_ and the _Orion_ came to a standstill, and hung
motionless in the air, with all their guns ready trained on different
parts of the building, the _Ariel_ sank suddenly and swiftly down,
and stopped within forty feet of the heads of a crowd of soldiers and
mechanics, who had rushed pell-mell out of the building, under the
impression that it was about to be destroyed.

The bold manoeuvre of the _Ariel_ took officers and men completely by
surprise. So intense was the terror in which these mysterious
air-ships were held, and so absolute was the belief that they were
armed with perfectly irresistible means of destruction, that the
sight of one of them at such close quarters paralysed all thought and
action for the time being. The first shock over, the majority of the
crowd took to their heel