The pilot turned in his seat and grinned over his shoulder at the observer. The grin was the only visible portion of his face: the rest was hidden by flying-helmet and goggles and worsted muffler. The grin said: “It’s a fine morning and the old bus is running like a witch. What’s the odds on sighting a Fritz?” The observer laughed and shouted an inaudible reply against the roar of the wind. He pulled a slip of chewing gum out of his pocket, bit off a piece, and passed the rest to the pilot. Then he adjusted the focus of the high-power glasses and began methodically quartering out the immense circular expanse of sea beneath them. Half an hour had passed when the wireless operator in the rear leaned forward and tapped him on the shoulder. His listeners were to his ears, and he was scribbling something on a slate. “S.O.S.--S.O.S.”--a bearing from a distant headland--“fourteen miles--S.O.S.--S.O.S.--come quickly--I am being shelled--S.O.S.--Subma----” The operator paused with his pencil above the slate, waited a moment, and handed the slate forward. The message, soundless, appealing, that had reached them out of the blue immensity had ceased abruptly. The pilot glanced from the compass to a small square of chart clamped before him, and slowly turned the wheel. Then he looked back over his shoulder and grinned again. A quarter of an hour later the pilot extended a gauntletted hand and pointed to the rim of the horizon. A faint smudge of smoke darkened into a trailing cloud, and presently they saw ahead of it the forepart of a ship, driving through the water at a speed which clove a white, irregular furrow across the surface of the sea. She was swerving from side to side like a hunted buck, and as the dirigible dipped her nose and the hum of the wind redoubled to a roar in the ears of the crew, they saw away to the west a tiny cigar-shaped object. At intervals a spurt of flame shot from it, and a little pale mushroom-shaped cloud appeared above the steamer as the shrapnel burst. The _Blimp_ swooped at eighty miles an hour upon that cigar-shaped object. The observer braced his feet and grasped the bomb release lever, his jaws still moving about the piece of chewing-gum. The sea, flecked with little waves, rushed up to greet them. They had a glimpse of the submarine’s crew tumbling pell-mell for the conning-tower hatchway, of the wicked gun abandoned forward still trained on the fleeing merchantman. The next instant the quarry had shot beneath them. A sharp concussion of the air beat upon the fragile car and body of the airship as her nose was flung up and round. The dirigible’s bomb had burst right forward on the pointed bows, and the submarine was diving in a confused circle of broken water and spray. The _Blimp_ turned to drop another bomb ahead of the rapidly vanishing wake, and then marked the spot with a calcium flare, while the wireless operator jiggled a far-flung “Tally ho!” on the sending-key of his apparatus.