218 



1H E DEP THS OF THE SbA. 



[CHAP. v. 



apparatus is so adjusted, that when 

 the weight is attached and the instru- 

 ment hanging ready for use, as repre- 

 sented in the figure, the rod F main- 

 tains a horizontal position. When the 

 instrument strikes the ground, the 

 tension on the har F is relieved, the 

 weight draws the rod D off the claw 

 and slips off, at the same time filling 

 the scoop. When hauling up, all the 

 instrument falls into a nearly vertical 

 line, and the scoop comes up full in 

 the middle, the weight of D keeping 

 its mouth closed up against its lid. 



The apparatus used during the 

 cruise of the ' Porcupine," where 

 sounding was carried on to the utmost 

 attainable accuracy and at great 

 depths, was a somewhat elaborate 

 modification of Brooke's sounding 

 machine which had been previously 

 employed by Captain Shortland in 

 the voyage of H.M.S. ' Hydra,' sound- 

 ing across the Arabian Gulf prepara- 

 tory to laying the Indian Cable. 



This special modification, which cer- 

 tainly answered remarkably well, ap- 

 pears to have been due entirely to 

 Mr. Gibbs, the blacksmith on board 

 the vessel. 1 W r e christened it the 



1 Sounding Voyage of H.M.S. ' Hydra,' Captain 

 P. F. Shortland, 1868. Published by order of the 

 FIG. 42 -The 'Hydra' j j0rc [s Commiss. of the Admiralty. London : 1869. 



Sounding Machine. 



