PLATE 6 



17. The Campbell grab, named for its designer, Alex Campbell, 

 has a capacity of about 4.46 cu. ft., and weighs about 900 

 pounds; it was devised to take samples from hard-packed 

 bottoms; it is shown open, suspended in the A-frame on the 

 working deck of the I'ctrm 11'. Area covered, 6 sq. ft. 



18. It is attached to the cable and hoisted overboard, with its 

 trigger mechanism set to shut on striking bottom; the vents 

 to permit escape of air or water pressure, are visible at the 

 upper end of the shell; they are covered by flaps to prevent 

 escape of mud. 



19. The grab returns from the bottom with a load of mud; its 

 jaws close tightly so that even water is retained. 



20. It is hoisted over its large retaining tub and hooked to its 

 chains, which are mechanically pulled to open the grab. 



