As the crow flies, St. Petersburg is thirty degrees of latitude, or eighteen hundred geographical miles, north of Alexandria, and this distance the _Ithuriel_ and her consorts, flying at a speed of a hundred and twenty miles an hour, traversed in fifteen hours, reaching the Russian capital a few minutes after seven on the evening of the 27th. The Rome of the North, basking in the soft evening sunlight of the incomparable Russian summer, lay vast and white and beautiful on the islands formed by the Neva and its 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.