xperiments by which this result was at last
attained. The earliest attempts to detect submarines from the air were
made with seaplanes at Harwich in June 1912, and at Rosyth in September
of the same year. The shallow tidal waters were found to be very opaque,
but in clear weather a periscope could be seen from a considerable
distance, and in misty weather the seaplane, when it sighted a submarine
in diving trim on the surface, could swoop down and drop a bomb before
the submarine could dive.

Progress in bomb-dropping was not less. Nothing is easier than to drop a
detonating bomb, with good intentions, over the side of an aeroplane;
the difficulty of hitting the mark lay in determining the flight of the
bomb and in devising an efficient dropping gear. To drop a weight from a
rapidly moving aeroplane so that it shall hit a particular spot on the
surface of the earth is not an easy affair; the pace and direction of
the machine, its height from the ground, the shape and air resistance of
the bomb, must all be accurately known. They cannot be calculated in the
air; success in bomb-dropping depends on the designing of a gear for
dropping and sighting which shall perform these calculations
automatically. Very early in the history of aviation dummy bombs had
been dropped, for spectacular purposes, at targets marked on the ground.
The designing of an efficient dropping gear and the study of the flight
of bombs were taken up by the Air Department of the Admiralty from the
very first. Under their direction a very valuable series of experiments
was carried out at Eastchurch, at first by Commander Samson, and later
by Lieutenant R. H. Clark Hall, a naval gunnery lieutenant, who had
learnt to fly, and was appointed in March 1913 for armament duties with
the Royal Naval Air Service.

The whole subject was new. No one could tell exactly how the flight of
an aeroplane would be affected when the weight of the machine should be
suddenly lightened by the release of a large bomb; no one could be sure
that a powerful explosion on the surface of the sea would not affect the
machine flying at a moderate height above it. In 1912 a dummy
hundred-pound bomb was dropped from a Short pusher biplane flown by
Commander Samson, who was surprised and pleased to find that the effect
on the flight of the machine was hardly noticeable. In December 1913
experiments were carried out to determine the lowest height at which
bombs could be safely dropped fro