Observation in naval warfare is of course also of great importance. In the work of detecting submarines, for instance, aeroplanes have proved of great value, for it is possible to detect submerged objects with greater ease from considerable heights than from the water surface. Writing to the _Matin_, a correspondent stated in the early part of the war that an aviator flying several hundreds of feet above the sea off Cape Helles, saw a black spot in the water beneath him. Circling round, to enable him to observe it more closely, he at last made out the form of a German submarine, under water, moving towards a British transport, which was heavily laden with troops and munitions. Immediately the aviator flashed a wireless signal to the transport, and then, swooping down to a few feet of the surface of the water he dropped two bombs. These did no damage to the submarine, but taking warning she sank to greater depths. When the enemy thought enough time had passed he raised his periscope above the surface, but the aeroplane was still circling close at hand and once more a couple of bombs fell close alongside the boat. Then the submarine finally disappeared. Many incidents of a similar nature have been recorded. It is, moreover, sometimes necessary to find out the position of our own submarines in such a case as when a submarine has disappeared and not returned to its base. Before the war, when one of our A Class boats sank off the Cornish coast, whilst out from Devonport for exercise, an aeroplane was successfully employed for finding its whereabouts. The boats in company with the lost boat laid buoys to indicate the position, but these had become shifted by heavy seas, and had become useless for the purpose. Observation work is frequently accompanied by direct offensive action; but the work is sometimes done purely with the view to the offence. For example, as early as September 23, 1914, naval airmen, namely, Squadron-Commander E. F. Briggs, Flight-Commander J. T. Babington, and Flight-Commander S. V. Lippe, carried out a raid over a mountainous route of 120 miles upon the Zeppelin sheds at Dusseldorf. And at a later date a similar raid was made on the sheds near Lake Constance.