"I wish von Mahl had been under that bomb," grumbled his subordinate. "Can't we do something to get rid of him, Herr Captain?" Zeiglemann shook his head. "I have suggested it and had a rap over the knuckles for my pains. The fellow is getting us a very bad name." Five minutes later his orderly came to the group of which Zeiglemann was the center and handed him a small linen parachute and a weighted bag. The squadron-leader was cutting the string which bound the mouth of the bag when a shrill voice said: "Herr Captain, do be careful; there might be a bomb." There was a little chuckle of laughter from the group, and Zeiglemann glowered at the speaker, a tall, unprepossessing youth whose face was red with excitement. "Herr von Mahl," he snapped with true Prussian ferocity, "the air-services do not descend to such tricks nor do they shoot at burning machines." "Herr Captain," spluttered the youth, "I do what I think is my duty to my Kaiser and my Fatherland." He saluted religiously. To this there was no reply, as he well knew, and Captain Zeiglemann finished his work in silence. The bag was opened. He put in his hand and took out a letter. "I thought so," he said, looking at the address; "this is for you, von Mahl." He handed it to the youth, who tore open the envelope. They crowded about him and read it over his shoulder: "THIS IS THE FIRST WARNING OF THE AVENGER. SHAKE IN YEER SHOES. TREMBLE! Surround ye'sel' with guards and walls And hide behind the cannon balls, And dig ye'sel' into the earth. Ye'll yet regret yeer day of birth. For Tam the Scoot is on yeer track And soon yeer dome will start to crack!" It was signed with a skull and cross-bones. The young man looked bewildered from one to the other. Every face was straight. "What--what is this?" he stammered; "is it not absurd? Is it not frivolous, Herr Captain?" He laughed his high, shrill little laugh, but nobody uttered a sound. "This is serious, of course, von Mahl," said Zeiglemann soberly. "Although this is your private quarrel, the squadron will do its best to save you." "But, but this is stupid foolishness," said von Mahl as he savagely tore the note into little pieces and flung them down. "I will go after this fellow and kill him. I will deal with this Herr Tam." "You will do as you wish, Herr von Mahl, but first you shall pick up those pieces of paper, for it is my order that the aerodrome shall be kept clean." Tam swooped back to his headquarters in time for breakfast and made his report. "The next time you do tricks over Roulers they'll be waiting for you, Tam," said Blackie with a shake of his head. "I shouldn't strain that warning stunt of yours." "Sir-r," said Tam, "A've no intention of riskin' government property." "I'm not thinking of the machine, but of you."