Voyage of the Scotia 1902-04

People of the Expedition

Man using sounding apparatus over side of the Scotia

Here we see a Lucas automatic sounding machine in operation over the side of SY Scotia during the 1902-1904 Scottish National Antarctic Expedition. This apparatus could measure depths of up to about 11,000 metres (6,000 fathoms).

As the wire was paid out, it passed over the outer measuring wheel. The revolutions of this were recorded on a dial, and the corresponding number of fathoms calculated.

During this process a sprung brake, which could stop the reel instantly, was prevented from acting by the tension of the wire under the weight of a sinker. When the sinker reached the bottom, the loss of tension caused the brake to operate, enabling the final depth to be read from the dial.