"Adieu!" he called gently. "Watch for a flare amongst the buildings to-morrow night. If you do not see one, then return again the following night. If still there is no sign, sail on and leave me. Adieu!" The motor above hummed a low-pitched song, the sling at the end of the rope bearing this gallant officer upon it dropped from the platform and went shooting down under the airship. "Good luck!" whispered Andrew. "Ah! There goes a very gallant fellow. Now, gently with that tackle. The barometer places us five hundred feet above the city. We shall have to lower very carefully when we have let out four hundred feet of the line." In the inky darkness of the night the ship had slowly descended till she was suspended at the height mentioned above this besieged city. And now those aboard her slowly paid the rope out over the motor, letting it go foot by foot once they guessed that the burden they were lowering was nearing the ground. Perhaps ten minutes had passed before they found that the line hung slack. A pull upon it disclosed the fact that the Major must have left it. "Haul in!" commanded Andrew. "Now, we will rise again, and sail right away from the city. Let us hope that our plucky friend will be successful." The following morning found the ship hovering at a great height over a deserted stretch of country, where she lay inert in the air, as if resting after her long trip from England. But that night the motors hummed again, and presently she was back over Adrianople. "Now, all hands set to work to watch for a flare," Andrew commanded. "We'll divide the city into various portions, and so make sure by giving a different part to each one of us that the Major's signal cannot go undetected." But though the eyes turned upon the dark surroundings of the beleaguered city never left their object, there was no flare to attract their attention, and presently the first signs of dawn warned Andrew and his comrades that the time had come to depart. A loud detonation in the far distance, and a streaming flame of fire, hastened their decision, and they rose at once and headed away from the city followed by the noise of artillery in action. In fact, a fierce attack had begun upon Adrianople, and though the huge airship put many miles between her and the contending armies, the dull muffled roar of guns still reached them on occasion. But towards evening the battle slackened, and that night, when once more over the city, there was not a sound to disturb the silence; not a note came to the ears of the listeners above to tell them of the armies beneath them. "Fine and clear, but dark enough for our purpose," said Joe, straining his head over the rail of the observation platform of the vessel. "Let us hope that we shall see the signal this evening, for I confess that I shall be glad to get away from those guns. Did you see the shells bursting as we left in the morning?"