On November 18th the mine-sweeping gunboats, whilst searching the Fair Island Channel, sighted a submarine on the surface and chased her at a speed of 18 knots, but could not overhaul her. The submarine subsequently dived. This incident was the first practical proof of the high surface speed possessed by German submarines. Destroyers were sent out immediately from Scapa to assist in the search, with orders to use their searchlights after dark in order to force the submarine to keep under water and so exhaust her batteries. The search, however, proved abortive, although continued for 24 hours. The use of searchlights for this purpose, begun on this occasion, became common later on. A submarine was sighted by the 2nd Battle Squadron at 9 A.M. on the 19th, well to the westward of the Orkneys, and this may have been the vessel chased by the mine-sweepers. During the gale on November 12th, the ships of the 10th Cruiser Squadron--the old “Edgar” class of cruisers--which were on patrol between the Shetlands and Faroe Islands had suffered much damage, many of them showing signs of leaking and straining; boats and ventilators were washed away; and water in large quantities found its way below. It became evident that these old ships were not sufficiently seaworthy to withstand the winter gales of northern latitudes without first undergoing a thorough repair, and arrangements were made to send them, three at a time, to the Clyde for survey and refit. The survey of the first three, however, revealed that some months’ work would be required to make them efficient for winter blockade duty, and it was then decided by the Admiralty to pay off the whole squadron, and to utilise the crews to commission armed merchant ships, which would be far more suitable, as they could keep the sea for much longer periods. The ships of the 10th Cruiser Squadron had been using Swarbachs Minn, a harbour in the Shetland Islands, as an occasional coaling base. This was evacuated on November 20th in consequence of the receipt of a report that a submarine attack on the harbours in the Shetland Islands was probable, all of these harbours being, at that time, defenceless against such attack. On leaving the base, the ships of the 10th Cruiser Squadron, not already at a refitting port, were ordered to dockyard ports to pay off. On November 20th, during practice, a lyddite common shell detonated in one of the 9.2-inch guns of the _Achilles_, and the muzzle of the gun was blown off, eleven of the gun’s crew being injured. This occurrence cast doubt on the safety of the whole of the lyddite shell afloat, and restrictions on their use were issued, but were eventually removed, after the withdrawal of all suspected shell of this nature.