214 THE DEPTHS OF THE SEA. [chap. v. 



H.M.S. ' Cyclops' in 1857.^ He used iron wire braces 

 to support the sinker, as these detach more freely 

 than slings of rope ; he replaced Brooke's round-shot 

 by a leaden cylinder to diminish the resistance and 

 thus increase the velocity in descending; and he 

 adapted a valve opening inwards, to the terminal 

 chamber in the rod, to prevent the washing out of 

 the sample. Commander Dayman seems to have 

 found the apparatus thus improved to answer well. 

 He used it throughout his important survey of the 

 ' telegraph plateau.' 



The ' Bull-dog ' sounding machine (Fig. 40) is now 

 probably the most generally known of these dredging- 

 leads. This instrument is an adaptation of Sir John 

 Boss' deep-sea clamms, with the addition of Brooke's 

 principle of the disengaging weight. It was invented 

 during the famous sounding voyage of H.M.S. ' Bull- 

 dog' in the year 1860, and Sir Leopold M'Clintock 

 gives the chief credit of its invention to the assistant- 

 engineer on board, Mr. Steil.2 A pair of scoops a 

 close upon one another scissor wise on a hinge, and have 

 two pairs of appendages b, which stand to the open- 

 ing and closing of the scoops in the relation of scissor 

 handles. This apparatus is permanently attached to 

 the sounding-line by the rope F, which in the figure 

 is represented hanging loose, and which is fixed to 



1 Deep-Sea Soundings iu the North Atlantic Ocean, between 

 Ireland and Newfoundland, made in H.M.S. 'Cyclops,' Lieut. -Com- 

 mander Joseph Dayman, in June and July 1857. Published by 

 order of the Lords Commissioners of the Admiralty. London : 1858. 



^ Eemarks illustrative of the Sounding Voyage of H.M.S. 'Bull- 

 dog' in 1860; Captain Sir Leopold M'Clintock commanding. Pub- 

 lished by order of the Lords Commissioners of the Admiralty. 

 London: 1861. 



