Voyage of the Scotia 1902-04

People of the Expedition

A crew member operating sounding equipment on the Scotia

The picture shows a Lucas Automatic Sounding Machine operating from the deck-house roof of the Scotia during the 1902-1904 Scottish National Antarctic Expedition. This apparatus could measure depths down to 11,000 metres (6,000 fathoms).

As the wire was paid out from the drum, it passed over a measuring wheel. The revolutions of this (and hence the number of fathoms) were recorded on a dial.

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 off the dial.