Page:The ocean and its wonders.djvu/33

 through it, into which was fixed a sliding rod, the end of which, covered with grease, projected several inches beyond the ball. By an ingenious and simple contrivance, the cannon ball was detached



when it reached the bottom of the sea, and the light rod was drawn up with specimens of the bottom adhering to the grease.

With this instrument the Americans went to work with characteristic energy, and, by always using a line of the same size and make, and a sinker of the same shape and weight, they at last ascer-