30 DEPTHS OF THE OCEAN 



tation to the various uses of accumulators, dynamometer, brake, 

 correct register, and governor." 



On board the " Michael Sars " we employed the sounding 

 machine constructed by Lucas. It was selected originally 

 because it had been extensively used by the telegraph cable 

 ships, and because it was the smallest and the cheapest. Weights 

 used as brakes in Thomson's machine are replaced by spiral 

 springs, which can be tightened or slackened with a screw, 

 and can at the same time be relied upon in a high sea as 

 accumulators (see Fig. 7, which explains the construction). 



During the winter of 1877-78 the United States Coast 

 Survey steamer "Blake" undertook a cruise in the Gulf of 



Fig. 7.— Lucas Sounding Machine. 



Mexico, under the command of Captain Sigsbee and under the 

 Wire rope for pcrsonal supcrvision of the late Alexander Agassiz. As it 

 dredging. ^^g proposed to Carry out investigations with the dredge and 

 trawl along the bottom, Agassiz suggested the use of a wire 

 rope instead of hemp ropes. Thanks to Sigsbee's inventive 

 genius and practical methods, this plan was successfully adopted, 

 and has since been adhered to by every expedition of any 

 importance. 



Fig. 8 shows sections of the "Challenger" hemp lines, 

 3 inches, 2^ inches, and 2 inches in circumference (a, d, c), and 

 of the wire rope, i|- inch in circumference, used by the 

 " Blake " (d). 



