away at him, and a fragment of shell had actually struck his fuselage. But he was not bothering about Archies. He did swerve toward a battery skilfully hidden behind a hayrick and drop two hopeful bombs, but he scarcely troubled to make an inspection of the result.

Then before him appeared his enemy. Tam had the sun at his back and secured a good view of the Müller machine. It was the great white dragon-fly he had seen two days before. Apparently Müller had other business on hand. He was passing across Tam's course diagonally—and he was climbing.

Tam grinned. He was also pushing upward, for he knew that his enemy, seemingly oblivious to his presence, had sighted him and was getting into position to attack. Tam's engine was running beautifully, he could feel a subtle resolution in the "pull" of it; it almost seemed that this thing of steel was possessed of a soul all its own. He was keeping level with the enemy, on a parallel course which enabled him to keep his eye upon the redoubtable fighter.

Then, without warning, the German banked over and headed straight for Tam, his machine-gun stuttering. Tam turned to meet him. They were less than half a mile from each other and were drawing together at the rate of two hundred miles an hour. There were, therefore, just ten seconds separating them. What maneuver Müller intended is not clear. He knew—and then he realized in a flash what Tam was after.

Round he went, rocking like a ship at sea. A bullet struck his wheel and sent the smashed wood flying. He nose-dived for his own lines and Tam glared down after him.

Müller reached his aerodrome and was laughing quietly when he descended.

"I met Tam," he said to his chief; "he tried to ram me at sixteen thousand feet—Oh, yes. I came down, but—ich habe das nicht gewollt!—I did not will it!"

Tam returned to his headquarters full of schemes and bright "thochts."

"You drove him down?" said the delighted Blackie. "Why, Tam, it's fine! Müller never goes down—you've broken one of his traditions."

"A' wisht it was ain of his heids," said Tam. "A' thocht for aboot three seconds he was acceptin' the challenge o' the Glasca' Ganymede—A'm no' so sure o' Ganymede; A' got him oot of the sairculatin' library an' he was verra dull except the bit wheer he went oop in the air on the back of an eagle an' dropped his whustle. But MacMuller wasn't so full o' ficht as a' that."

He walked away, but stopped and came back.

"A'm a Wee Kirker," he said. "A' remembered it when A' met MacMuller. Though A'm no particular hoo A'm buried, A'm entitled to a Wee Kirk meenister. Mony's the time A've put a penny i' the collection. It sair grievit me to waste guid money, but me auld mither watchit me like a cat, an' 'twere as much as ma life was worth to pit it in ma breeches pocket."

Tam spent the flying hours of the next day looking for his enemy, but without result. The next day he again drew blank, and on the third day took part in an organized raid upon enemy communications, fighting his way back from the interior of Belgium single-handed, for he had allowed himself to be "rounded out" and had to dispose of two enemy machines before he could go in pursuit of the bombing squadrons. In consequence, he had to meet and reject the attentions of every ruffled enemy that the bombers and their bullies had fought in passing.

At five o'clock in the evening he dropped from the heavens in one straight plummet dive which brought him three miles in a little under one minute.

"Did you meet Müller?" asked Captain Blackie; "he's about—he shot down Mr. Grey this morning whilst you were away."

"Mr. Gree? Weel, weel!" said Tam, shaking, "puir soul—he wis a verra guid gentleman—wit' a gay young hairt."

"I hope Tam will pronounce my epitaph," said Blackie to Bolt, the observer; "he doesn't know how to think unkindly of his pals."

"Tam will get Müller," said Bolt. "I saw the scrap the other day—Tam was prepared to kill himself if he could bring him down. He was out for a collision, I'll swear, and Müller knew it and lost his nerve for the fight. That means that Müller is hating himself and will go running for Tam at the first opportunity."

"Tam shall have his chance. The new B. I. 6 is ready and Tam shall have it."

Now every airman knows the character of the old B. I. 5. She was a fast machine, could rise quicker than any other aeroplane in the world. She could do things which no other machine could do, and could also behave as no self-respecting aeroplane would wish to behave. For example, she was an involuntary "looper." For no apparent reason at all she would suddenly buck like a lunatic mustang. In these frenzies she would answer no appliance and obey no other mechanical law than the law of gravitation.

Tam had tried B. I. 5, and had lived to tell the story. There is a legend that he reached earth flying backward and upside down, but that is probably without foundation. Then an ingenious American had taken B. I. 5 in hand and had done certain things to her wings, her tail, her fuselage and her engine and from the chaos of her remains was born B. I. 6, not unlike her erratic mother in appearance, but viceless.

Tam learned of his opportunity without any display of enthusiasm.

"A' doot she's na guid," he said. "Captain Blackie, sir-r, A've got ma ain idea what B. I. stands for. It's no complimentary to the inventor. If sax is better, than A'm goin' to believe in an auld sayin'."

"What is that, Tam?"

"'Theer's safety in numbers,'" said Tam, "an' the while A'm on the subject of leeterature A'd like yeer opinion on a vairse A' made aboot Mr. MacMuller."

He produced a folded sheet of paper, opened it, and read,