He went to his room very thoughtful, and the day following, being an "off" day, he spent between the machine-shop and the hangar where the B. I. 6 reposed. It must never be forgotten that Tam was a born mechanician. To him the machine had a body, a soul, a voice, and a temperament. Noises which engines made had a peculiar significance to Tam. He not only could tell you how they were behaving, but how they would be likely to behave after two hours' running. He knew all the symptoms of their mysterious diseases and he was versed in their dietary. He "fed" his own engines, explored his own tanks, greased and cleaned with his own hands every delicate part of the frail machinery. There was neither strut nor stay, bolt nor screw, that he did not know or had not studied, tested or replaced. He cleaned his own gun and examined, leather duster in hand, every round of ammunition he took up. He left little to chance and never went out to attack but with a "plan, an altairnitive plan an'--an open mind." And now since Müller must be settled with, Tam was more than careful. The difficulty about aeroplanes is that they look very much like one another. Tam fought indecisively three big white Albatross machines before a Fokker hawk darted down from the shelter of a cloud-wraith and revealed itself as the temporary preoccupation of Captain Müller. The encounter may be told in Tam's own words. "I' the ruthless pairsuit of his duty, Tam was patrollin' at a height o' twelve thoosand feet, his mind filled wi' beautifu' thochts aboot pay-day, when a cauld shiver passes doon the dauntless spine o' the wee hero. 'Tis a preemonition or warnin' o' peeril. He speers oop an' doon absint-mindedly fingerin' the mechanism of his seelver-plated Lewis gun. There was nawthing in sicht, nawthing to mar the glories of the morn. 'Can A' be mistaken?' asks Tam. 'Noo! A thoosand times noo!' an' wi' these fatefu' wairds, he began his peerilous climb. Maircifu' Heavens! What's yon? 'Tis the mad Muller! Sweeft as the eagle fa'ing upon his prey, fa's MacMuller, a licht o' joy in his een, his bullets twangin' like hairp-strings. But Tam the Tempest is no' bothered. Cal-lm an' a'most majeestic in his sang-frow--a French expression--he leps gaily to the fray--an' here A' am!" "But, Tam," protested Galbraith, "that's a rotten story. What happened after the lep--did you get up to him?" "A' didna lep oop," said Tam gravely; "A' lep doon--it wis no' the time to ficht--it wis the time to flee--an' A'm a fleein' mon." That he would deliberately shrink an issue with his enemy was unthinkable. And yet he rather avoided than sought Müller after this encounter. * * * * * One afternoon he came to Galbraith's quarters. Galbraith was rich and young and a great sportsman. "Can A' ha'e a waird wi' ye?" asked Tam mysteriously. "Surely," said the boy. "Come in--you want a cigar, Tam!" he accused.