As it was, they swept upwards and westward at such a speed that they had gained the cover of the thunder-cloud, and placed a considerable area of it between themselves and the town, long before the storm broke over Aberdeen, and so they were provided with ample shelter under, or rather over, which they were to make their attack on the _Lucifer_.
They waited until the clouds coming up from the westward joined those which had begun to gather thick and black and threatening over the Russian fleet soon after the tremendous cannonade had begun. The shock of the meeting of the two cloud-squadrons formed a fitting counterpart to the drama of death and destruction that was being played on land and sea.
The brilliant sunshine of the midsummer afternoon was suddenly obscured by a darkness born of smoke and cloud like that of a midwinter night. The smoke of the cannonade rose heavily and mingled with the clouds, and the atmospheric concussions produced by the discharge of hundreds of heavy guns, brought down the rain in torrents. Almost continuous streams of lightning flashed from cloud to cloud, and from heaven to earth, eclipsing the spouting fire of the guns, while to the roar of the bombardment was added an almost unbroken roll of thunder.
Above all this hideous turmoil of human and elemental strife, the three air-ships floated for awhile in a serene and sunlit atmosphere. But this was only for a time. Arnold had taken the position and altitude of the _Lucifer_ very carefully by means of his sextant and compass before he rose into the air, and as soon as his preparations were complete he made another observation of the angle of the sun's elevation, allowing, of course, for his own, and placed his three ships as nearly perpendicular as he could over the _Lucifer_, floating on the under side of the storm-cloud.
His preparations had been simple in the extreme. Four light strong grappling-irons hung downwards from the _Ithuriel_, two at the bow and two at the stern, by thin steel-wire rope; two similar ones hung from the starboard side of the _Orion_, which was on his left hand, and two from the port side of the _Ariel_, which was on his right hand. As they gained the desired position, a man was stationed at each of the ropes, with instructions how to act when the word was given. Then the fan-wheels were slowed down, and the three vessels sank swiftly through the cloud.