Jaws from Bulldog sounder and sampler used during telegraph survey operations

Jaws from ‘Bulldog’ sounder and sampler for gauging the depth of the sea floor and collecting sediment samples, designed by marine engineer Mr. Steil, assistant engineer Mr. Roughton, and the ship’s naturalist George Charles Wallich aboard the paddle steamer HMS Bulldog during telegraph survey operations around the Faroe Islands, Iceland and Greenland, 1860.

Submarine cable laying operations provided an impetus for the study of the ocean floor. It was not only important to obtain accurate measurements of the depth of the sea bed, but also samples of the ground over which cables were to be laid, and sea bed temperatures (which affected the insulating properties of the gutta percha insulation of cables, and thus signal transmission times). Such expeditions resulted in innovation in the methods used for sounding and sampling.

What became known as the Bulldog sounder, after the ship on which it was designed, enabled surveyors to collect larger samples of sea floor sediment than existing devices. It had a pair of scoops kept open by the weight of sinking weights. On reaching bottom, the sinker fell awayc, and the scoops were closed by a rubber band. Provided that no stones were trapped between the jaws of the scoop, a fair sample from the top few inches of the sea bed was collected and brought to the surface.

Wallich subsequently took out two patents for this sounder, but before then it had been superseded by more sturdy and efficient apparatus, notably the Hydra and Baillie sounders.