Another distinctly modern type of cruiser is the "light cruiser", a fast unprotected vessel with light guns of 4-inch calibre, which has proved of immense value in the area of "liveliness" in the North Sea. The _Amphion_ opened the ball by sinking the German mine-layer _Königin Luise_ at the very opening of hostilities, but was very soon after herself blown up by a mine the latter had laid. She, like her sisters, was almost exactly like a big destroyer in appearance. The "Saucy" _Arethusa_ has proved a worthy descendant of the famous frigate after which she was named, and has more than once particularly distinguished herself, notably in the fight off Heligoland. But space forbids more than the mere mention of the smallest class of cruiser, the "scouts", of just under 3000 tons, which are also extremely useful little vessels, since it is necessary to give some account of destroyers and submarines. The destroyer was originally built to "destroy" the torpedo-boat, which, from its small size, had its limitations in anything of a sea-way. The earliest torpedo-boats were ordinary steamboats, such as are carried by most ships of any size, fitted with a long spar with a tin of gun-cotton at the end of it, which could be run out some way over the bows. The idea was to approach an enemy's ship under cover of the darkness, lower the outer end of the spar with its "torpedo" below the water-line, place it in contact with the enemy's ship, and explode the charge by means of an electric current. This seems a crude way of going to work, but several ships have been sunk by its means, notably the Confederate ram _Albemarle_, which was attacked by Lieutenant Cushing of the United States navy in this way in the course of the Civil War in America. Special boats were then made for this purpose, but the advent of the "Whitehead" automobile torpedo provided them with a much more formidable weapon. Naval powers built these "torpedo-boats" in considerable numbers, and they were considered such a menace to bigger ships that the destroyer, an almost exactly similar boat, but of larger size, was designed to cope with them. In point of fact it did destroy them, for it was found to be so much better an "all-round craft", not only for attacking torpedo-boats, but to act as one itself, that the smaller craft before long were entirely superseded by the destroyers. Beginning about 1897 with boats of about 180 tons, armed with 6-pounder guns, we have now improved our destroyers till at the present day our latest types are more than twice as big, and are armed with 4-inch guns, which give them a decided advantage over less heavily-gunned destroyers, as has been amply demonstrated in more than one encounter with German destroyers. The destroyer is used, generally speaking, for scouting purposes, and especially to attack an enemy's submarines, which, if caught at the surface, may be approached in a swift destroyer and sunk