"Its success has justified its extension. Great difficulties have been overcome, for the application of the idea of ploughing the floor of the ocean at depths of 90 to 450 fathoms had never before been attempted.
The nature of the sea bottom at every point in the course is of extreme" importance, Capt. Bloomer said. Rocks or other obstructions must be avoided, and so must sharp hollows and grounds generally of an uneven nature, A preliminary survey of the surface and composition of sea beg is made by the use, in addition to the plough itself and the usual sounding instruments, of a sounding tube and a clinometer.
The plough itself is equipped with four electrical recording devices coupled mechanically to parts whose position and movement have to be known on board.
Text read from the printed page and cleaned; old type leaves the occasional error.