Life of the Waters 



369 



And how does the biologist obtain his knowledge of the 

 denizens of the deep, of their comings and goings, their num- 

 bers and their whereabouts 4 / The science of oceanography 

 goes back to the earliest days when men went ''down into the 

 sea in ships" and cast their nets into the great waters, 

 and the earliest instruments of the oceanographer were the 

 compass, the plummet, the seine and the trawl. From all 

 depths of the ocean are brought forth creatures, great and 

 small. With harpoon and bomb lance, with heavy dredge 



BLAKE DEEP SEA TRAWL 

 Courtesy of the U. 8. Bureau of Fisheries. 



and trawl, with hand line, seine and nets innumerable, down 

 to those of the finest gauze used for sifting the whitest of 

 our flours, man has searched the" seven seas from top to 

 bottom and from pole to pole in quest of hidden treasure. 



The inhabitants of the ocean floor are brought up from 

 their hiding place by means of dredge and trawl. The dredge 

 is essentially a long rake or hoe attached to a stout iron frame, 

 with a bag of steel or twine netting projecting behind. If 

 the latter, it may be protected by an external covering of 

 canvas open behind. As the toothed or straight bar which 

 acts as rake or hoe is dragged over the bottom, it scrapes 



