THREE CRUISES OF THE BLAKE 



171 



in deeper water it was impossible to prevent its falling 



on the wrong side, causing much delay and vexation. 



Agassiz devised a modification of this trawl that worked 



equally well on whichever side it 



fell. In order to bring up less mud 



the length of the net was reduced 



to fifteen feet and the meshes of 



the outer net made coarse, while 



only a small part of the bag was 



fine enough to allow the mud to 



accumulate. 



In writing of the equipment of 

 the Blake, Agassiz says in 1907: 

 "We built what is known as the 

 Blake trawl ; all subsequent French, 

 German, Italian, and Danish expe- 

 ditions have adopted it, as well as 

 the wire dredging rope and the 

 arrangement of the drums, first in 

 use by the Blake." 



Tangles consist of a number of 

 rope tails fastened to an iron bar, 

 which is attached to the end of the 

 dredge frame. This, under certain 

 conditions, is a most effective ap- 

 paratus for collecting, and often brings up a great 

 quantity of specimens tangled in its swabs. The tow net 

 is something like a huge butterfly net, which may be 

 towed at any given depth to collect specimens suspended 

 in the water. 



Not the least important piece of apparatus is the 

 sounding machine. It would seem at first glance to be 

 a very simple process to find out the depth of the ocean. 



Blake Trawl 



