The routine of naval espionage is very similar in character to that followed by military spies. The naval spy, however, must be a rather more intelligent and highly trained man than his military confrere, and cases that have come to light prove that his position is one of more responsibility, and that he is entrusted with more funds for the carrying out of his work. It is an interesting fact that, for many years past, officers and men of the German naval service have been employed along the East coast of England in compiling extremely detailed plans of places and fortifications. The accuracy of these plans is ascertained by persistent redrawing done by new members of the naval espionage staff, and all changes in building, roadmaking, bridge-construction, and as far as possible the interior work of fortifications, are duly recorded on the Berlin maps. Not that this information is of definite working value at the present time, but the principle of secret-service headquarters is that no item is too trivial for record, and information is acquired without regard to its direct uses, but in view of the fact that it may possibly be of some use at a future date. The adoption of such a principle involves an immense amount of work in checking and sorting the masses of information obtained, but beyond doubt the principle itself has gone far to assure such successes as German arms have obtained, either on land or at sea. In addition to the work of fixed naval posts, stationed at dockyards and harbours, the work of spies at sea must not be overlooked, either in time of peace or in war. In the former case an innocent-looking trawler or private yacht is useful for taking soundings, ascertaining channels, and even locating naval mines used for purposes of harbour defence and fired by land contact. In time of war the services which may be performed by such vessels are even more valuable; the reports of the sinking of three British cruisers by German submarine attack are fairly unanimous with regard to the presence of a trawler in the vicinity of the spot at which the engagement took place. All that can be definitely learned with regard to this trawler is that she was not a British boat, and it is reasonable to assume that her business consisted in signalling to the submarines particulars which they may have been unable to obtain themselves, or in shielding them from sight during their approach towards the cruisers. Although there are no substantial proofs of this assumption, it is hardly likely that the vessel was a trawler engaged in usual and legitimate business.