BROOKE S APPARATUS. 



27 



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 



BROOKE'S SOUNDLNG APPARATUS. 



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- 



