the last were seventy. Everything about them is made as light as
possible; so that they can skim along in about two feet of water at an
outside speed of nearly fifty (land) miles an hour. They are really
the thinnest of racing shells fitted with the strongest of lightweight
engines. They are all armed with depth charges, which are bombs that
go off under water at whatever depth you set them for when attacking
submarines. The biggest scooters also carry torpedoes. The scooters
did well in the war. Whenever the hovering aircraft had spotted a
submarine they would call up the scooters, which raced in with their
deadly depth charges. Even destroyers were attacked and torpedoed.
One day a German destroyer off Dunkirk suddenly found itself surrounded
by scooters which came in so close that a British officer had his cap
blown off by the blast from a German gun. He and his scooter, however,
both escaped and his torpedo sank the Hun.

Fourthly, come the submarines, those sneaky vipers of the sea that seem
made on purpose for the underhand tricks of ruthless Germans. Deadly
against unarmed merchantmen, and very dangerous in some other ways, the
submarine is slow under water, no match for even a destroyer on the
surface, and "tender" to attack by gunfire, to bombs dropped from
aircraft, to "sea-quaking" depth charges, and, of course, to ramming.
We shall presently hear more about these inventions of the devil.

[Illustration: Seaplane Returning after flight.]

Fifthly, come the seaplanes, that is, aircraft which can light on the
water as well as fly. We began the war with a fair number of
comparatively small planes and ended it with a great number of large
ones, a few of which could drop a ton-weight bomb fit to sink most
battleships if the shot went home. But these monsters of the air were
something more than ordinary seaplanes. For out of the seaplane there
gradually grew a regular flying boat which began to make it hot for
German submarines in 1917. Commander Porte, of the Royal Navy, went on
inventing and trying new kinds of flying boats for nearly three years
before he made one good enough for its very hard and dangerous work.
He had to overcome all the troubles of aircraft and seacraft, put
together, before he succeeded in doing what no one had ever done
before--making a completely new kind of craft that would be not only
seaworthy but airworthy too. Porte's base was at Felixstowe, near the
great destroyer a