184 ALEXANDER AGASSIZ 



to Agassiz. The object of this expedition was to run a 

 series of lines of dredgings from the northeastern edge 

 of George's Shoal to the vicinity of Charleston. In this 

 way a portion of the Atlantic was explored that had 

 been left untouched by the Challenger, and an extension 

 was made into deep water of the ground already occu- 

 pied in part by the United States Fish Commission. 



On the lines off Charleston and in the Gulf Stream 

 Agassiz was much disappointed in the poverty of the 

 fauna ; this was probably owing partly to the very grad- 

 ual slope of the continent toward deep water, and partly 

 to the fact that the strong current of the Gulf Stream 

 sweeps everything off the bottom along its course ; so 

 that there is little food for the deep-water animals, and 

 it was only along the edges of the Gulf Stream, where 

 mud and silt accumulated, that he made satisfactory 

 hauls on the southern lines. It was not until he reached 

 the steep slope of the Gulf Stream plateau south of Cape 

 Hatteras, where the bottom is fine mud and Globigerina 

 ooze, that he made a rich harvest again. The richness 

 of the northern hauls, however, amply compensated for 

 those further south, and the expedition was as successful 

 as its predecessors. 



Captain Sigsbee accompanied this cruise to superintend 

 the working of an extremely ingenious invention of his, 

 known as the Sigsbee Gravitating Trap. 1 Agassiz and 

 he had often talked together about the best method of 

 determining the depth to which animal life extended 

 below the surface of the ocean. On the first cruise of 

 the Blake they had endeavored, unsuccessfully, to de- 

 vise a self-closing net. Before the departure of the last 

 cruise Sigsbee contrived an instrument by means of which 



1 Described in Three Cruises of the Blake, p. 36, vol. i. 



