Both officers riveted their gaze upon the nebulous object which, as the destroyer overhauled it, assumed the shape and appearance of a large steamer, while their ears caught the steady throb of engines. "I'll give her a hail," said Lawless, picking up the megaphone. But before he had time to raise it to his mouth the fog was split by a yellow streak of fire and a shell came whizzing over the _Knat's_ bows. "By the Lord, an enemy ship!" ejaculated the Lieutenant, and passed the word to open fire with the machine guns. The quick-firer just below the bridge led off, but before the other guns had a chance to follow suit a heavy bank of fog rolled up and obliterated the steamer as completely as though a curtain had been lowered. Although invisible, the vessel's engines could still be heard and, guided by the sound, the _Knat_ was kept on her trail, Lawless waiting only for the fog to lift in order to open fire again. While he was still expecting this to happen there came the notes of a bugle and at the sound the Lieutenant nearly tumbled down the bridge ladder in astonishment. For it was the dinner call as given on British ships: "Officers' wives eat puddings and pies, But soldiers' wives eat skilly." "What the dickens does it mean?" he murmured, and then, raising his voice, hailed the mysterious steamer. "Ahoy there, ahoy! Where away?" came the answer. "On your port quarter." "What ship is that?" "British destroyer, _Knat_." The fog lifted again, and this time Lawless could see the decks thronged with anxious passengers and the captain leaning over the port bridge-rail. "What ship are you?" he shouted. "The _Cotswold_, for Hull. Just sighted an enemy submarine and opened fire on her," came the answer. "A submarine! How long ago?" "About ten minutes. She was using her machine-gun." "Why don't you provide your look-outs with spectacles?" answered Lawless wrathfully. "It was me you sighted, not a submarine!" "I saw her periscope," answered the skipper of the _Cotswold_. "Saw your grandmother! You opened fire on me and I replied." "Then it was your business to hail me. Pity you haven't something better to do than take pot shots at passenger boats," answered the merchant skipper with some heat.