Such investigation as could be hurriedly carried out during the day, by signal and wireless, revealed the fact that a yacht and a trawler on patrol on the night of the 7th–8th had sighted strange lights, but without identifying the vessel carrying them, and it became apparent that a German surface mine-laying vessel had been at work. The night had been somewhat misty. Directions were at once sent by wireless to the 4th Light Cruiser Squadron, still at sea, to proceed at full speed towards the Horn Reef to endeavour to intercept the returning mine-layer, and the 1st and 2nd Light Cruiser Squadrons, from Rosyth, were also sent out for the purpose; the Admiralty was also informed, and as a result the Harwich force was sent on the same mission. As the other squadrons proceeded, the 4th Light Cruiser Squadron was directed to the Skagerrak in case the mine-layer endeavoured to return by that route, whilst the remaining light cruiser squadrons made for the Horn Reef. All the mine-sweepers and the destroyers engaged in the anti-submarine operation mentioned earlier were recalled to fuel with all despatch, and sweeping by the Fleet mine-sweepers, trawlers and destroyers, organised on a large scale, was begun on the 9th and continued until clear routes for the ships at Cromarty and for merchant-ships, gradually extending to 10 miles in width, had been swept on both the northern and southern shores of the Moray Firth. These sweeping operations were greatly delayed by persistent fog, although a clear channel sufficiently wide to admit of the exit of the squadrons at Cromarty was quickly swept. The _Campania_ was sent to Cromarty, so that her sea-planes might assist to locate the mines, but in the rather thick waters of the Moray Firth they were of no use for this purpose. On the afternoon of the 9th news was received that the destroyer _Lynx_ had been sunk by a mine at 6 A.M. that morning in a position stated to be two miles to the northward of the mine-field as then located. It was very regrettable that only three officers and 21 men were saved out of her fine ship’s company; those lost included her captain, Commander John F. H. Cole, an officer of great promise. The loss of such a comparatively shallow draft vessel showed that some of the mines had been laid near the surface, and mine-sweeping operations were suspended near the time of low water.