THE VOYAGE OF H.M.S. CHALLENGER. 



the surging-drum of the donkey engine, from which it was taken by the men and 

 coiled on the pins. 



The implement which we employed throughout the several cruises of the Porcupine, 

 for bringing up animals from the bottom, was the naturalists' dredge, of the form first 



Fig. 3. — Sounding and Dredging from the Stem Derrick of the Pokcupine. 



devised by the late Dr Eobert Ball of Dublin, increased in size and otherwise slightly 

 modified to suit the size of the vessel and the command of steam-power. The con- 

 struction of the frame of one of the dredges which we used in the Bay of Biscay is 

 shown at figures 4 and 5. The length of the dredge-frame was 4 feet 6 inches, and it 



