Left in charge, Meredith prepared to make the best of his four hours' "trick." Experience had long since taught him that warmth and dryness were absolutely essential on night patrol. Clad in two thick woollen sweaters, serge-trousers and pilot-coat, and wearing woollen gloves, sea-boots, muffler, oilskins and sou'wester, he was well equipped for the work in hand. The three-sided erection known as the wheel-house afforded little protection from the spray, as the windows had to be kept wide open otherwise the moisture settling on the glass panes would render the mist still more baffling than it actually was. Right for'ard the dim outlines of the look-out could be discerned, as, crouching to dodge as far as possible the clouds of spray, the man peered through the darkening mist. It was his duty to see that M.L. 1071 kept fairly in the bubbling wake of the boat next ahead. Fifty yards astern another M.L., unseen but plainly audible, was likewise making use of the swirl of No. 1071's twin propellers as a guide through the fog-laden water. So well, so good. Provided the flotilla kept station in "single column line ahead," there was little cause for the science of navigation except on the part of the navigating officer of the leading M.L. It was a case of seamanship, a sort of marine follow-my-leader work, until on arriving at a certain rendezvous the boats had to work independently; and No. 1071 had been detailed for the Outer Patrol stunt. At a reduced speed of ten knots and an M.L. is a difficult craft to handle at slow speed--the flotilla plugged seawards. The short steep tide rip at the harbour's mouth gave place to the long sullen undulations of the North Sea. Although navigation was carried on without steaming lights, the chances of collision were hardly worth taking into consideration, since the noise of the exhausts could be plainly audible for a distance of a couple of miles. For the best part of an hour the flotilla held on then just before midnight came an order from the leading M.L. for the boats to proceed independently. Meredith, hitherto inactive, roused himself. "Port fifteen!" he ordered. "Course east a half north!" "East a half north it is, sir," repeated the coxwain.