"Tell his nobs to see if the automobile has arrived," softly urged Billy.
Henri sent the flunky ahead to investigate. He guessed now, and correctly, that his chum did not intend that they should leave by the front door.
Like ghosts they flitted through the dimly lighted corridors of the palace, into the unknown backstairs regions, hoping to find an easy outlet at the rear.
An open window coming handy, the boys essayed a jump therefrom, landing on all fours in the walk leading to the tradesman's gate. Darting out into a side street, the fugitives relapsed into a brisk walk, fearing to here excite suspicion by undue haste.
Alone in a great and strange city, as ignorant of locality as of the language spoken by the average inhabitant, Billy and Henri, as the former would have put it, "were up against it, good and strong."
Yet they won out, and meeting the wildly searching special messengers in the gray dawn, without ado climbed into the pilots' places of the waiting biplanes and sent the powerful machines in whirring flight toward the distant towers of Warsaw.
To follow them beyond this fixed destination is to turn the leaves of the next record, under the title of "Our Young Aëroplane Scouts in Russia; or, Lost on the Frozen Steppes."
Transcriber's Notes: