oceanographical work.

The Lucas Automatic Sounding Machine was situated on the port side
of the forecastle head. It was suitable for depths up to six thousand
fathoms, being fitted with a grooved wheel so as to be driven by a rope
belt from a steam-winch or other engine. The wire was wound in by means
of a small horizontal steam-engine which had been specially designed for
the 'Scotia', of the Scottish Antarctic Expedition (1902) and was kindly
lent to us by Dr. W. S. Bruce.

The wire as it is paid out passes over a measuring wheel, the
revolutions of which record on a dial the number of fathoms out. A
spring brake, which is capable of stopping the reel instantly, is kept
out of action by the tension of the wire, but when the sinker strikes
the bottom, the loss of tension allows the brake to spring back and stop
the reel. The depth can then be read off on the dial.

A hollow iron tube called a driver is attached to a piece of hemp line
spliced into the outer end of the sounding wire. This driver bears
one or two weights to the bottom and detaches them on striking it; a
specimen of the bottom being recovered in the hollow part of the tube
which is fitted with valves to prevent water from running through it
on the way up. Immediately the driver and weight strike the bottom, the
reel automatically stops paying out wire.

To obtain a deep-sea sounding on the 'Aurora', the vessel was stopped,
turned so as to bring the wind on the port-bow and kept as nearly
stationary as possible; the engines being used to balance any drift of
the vessel due to wind or sea.

The difficulties of sounding in the Southern Ocean were much increased
by the almost constant, heavy swell. The breaking strain of the wire
being only two hundred and forty pounds and the load it had to carry to
the bottom weighing nearly fifty-six pounds in air, it could easily be
understood that the sudden strain imposed by the violent rolling of
the vessel often resulted in the parting of the wire. We soon learnt to
handle both vessel and sounding machine in such a way as to entail the
least possible strain on the wire.

Of all the operations conducted on board the 'Aurora', deep-sea trawling
was the one about which we had most to learn. Dr. W. S. Bruce gave me
most valuable advice on the subject before we left England. Later, this
was supplemented by a cruise in Australian waters on the 'Endeavour',
of the Commonwealth Fisheries Investigation. Here I was able