NARRATIVE OF THK CRUISE. xlvii 



Islands, but his example was not much followed. In 1868 Professor Perceval Wright 1 

 proceeded to Setubal in Portugal, in order to investigate the occurrence of Hyahnema, 

 which was reported to be frequently taken on the lines of the shark -fishers who had long 

 pursued their calling, at the great depth of 500 fathoms. He succeeded in getting 

 abundance of specimens of Hyahnema, although six men were required to work the 

 dredge, and the depth of the water was 480 fathoms. " This dredging," says Professor 

 Wyville Thomson, "is of special interest, for it shows that although difficult and 

 laborious, and attended with a certain amount of risk, it is not impossible in an open 

 boat, and with a crew of alien fishermen, to test the nature of the bottom, and the 

 character of the fauna, even to the great depth of 500 fathoms." 2 But although 

 possible, such dredging is too laborious and dangerous to be frequently resorted to, and 

 for any systematic study of the depths of the sea more elaborate arrangements must be 

 made. 



The subject of deep-sea dredging was not being neglected in Great Britain. In the 

 spring of 1868 Professor Wyville Thomson, in a letter to Dr. W. B. Carpenter, urged 

 the emplo3 T ment of a Government vessel in a dredging expedition off the coast of 

 Scotland, and in consequence of this the Royal Society laid before the Admiralty a 

 statement of the advantages to science likely to result from a short dredging cruise 

 in the North Atlantic. The Admiralty responded by placing the surveying ship 

 " Lightning," Captain May, at the disposal of Drs. Thomson and Carpenter in the autumn 

 of the same year. The conditions of work in the " Lightning " were very unfortunate 

 both as regards the vessel and the weather which prevailed during the six weeks that 

 the cruise lasted. In spite of all the difficulties in the way, dredging was carried on to 

 a depth of 650 fathoms, and temperature observations of the greatest interest were 

 obtained, which ultimately led to the discovery of the Wyville Thomson Ridge in the 

 Faeroe Channel in 1880." Professor Wyville Thomson thus sums up the results of 

 the " Lightning" expedition : — 



" It had been shown beyond question that animal life is varied and abundant, repre- 

 sented by all the invertebrate groups, at depths in the ocean down to 650 fathoms 

 at least, notwithstanding the extraordinary conditions to which animals are there 

 exposed. 



" It had been determined that, instead of the water in the sea beyond a certain 

 depth varying according to latitude having a uniform temperature of 4° C, an indraught 

 of Arctic water may have at any depth beyond the influence of the direct rays of the sun 

 a temperature so low as —2° C; or on the other hand, a warm current may have at any 

 moderate depth a temperature of 6° "5 C, and it had been shown that great masses of 



1 See Notes on Deep-Sea Dredging, Ann. uml Mag. Nat. Hid., ser. 4, vol. ii, pp. 423-427, 1868. 



2 Depths of the Sea, p. 277, 1874. 



3 Exploration of the Fteroa Channel, Pror. Hoy. Soft Edin., vol. xi. pp. 638-717, 1882. 



(.NAUR. CHAIX. EXP. VOL. I. — 1885.) h 



