CEUISE OF H.M.S. CHALLENGER. 
INTRODUCTION. 
Not many years ago, in fact within the memory of 
the present generation, our knowledge of anything 
below the ocean’s surface was extremely indefinite 
and obscure. It was even asserted that the specific 
gravity of the water at considerable depths would be 
so great that any heavy weight thrown into the sea 
must be arrested, and remain suspended for ever. It 
was argued that no animal life could possibly exist in 
the great depths of the ocean ; and only some fifteen 
years ago doubts were entertained whether some star- 
fish brought up by a line from 1200 fathoms bad not 
attached themselves to the line on its downward or 
upward course, and the very nature and habits of 
the animal were so modified as to suit this view. 
There can be no doubt that the invention of ocean 
telegraphy first stimulated the great desire as well as 
the necessity for a knowledge of the contour of the 
bed of the ocean. To insure success it was essential 
to know the configuration and the soundings of 
