2G THi: DEPTHS OF THE SEA. [chap. i. 



Dr. Wallich's is the only book Avhicli discusses fully 

 and systematically the various questions bearing 

 upon the biological relations of the sea-bed, and his 

 conclusions are in the main correct. 



In the autumn of the year 1860 Mr. Tleeming 

 Jenkin, C.E., now Professor of Engineering in the 

 University of Edinburgh, was employed by the 

 Mediterranean Telegraph Company to repair their 

 cable between Sardinia and Bona on the coast of 

 Africa, and on January 15, 1861, he gave an interest- 

 ing account of his proceedings at a meeting of the 

 Institution of Civil Engineers.' 



This cable was laid in the year 1857. In 1858 it 

 became necessary to repair it, and a length of about 

 30 miles was picked up and successfully replaced. 

 In the summer of 1860 the cable completely failed. 

 On taking it up in comparatively shallow water on 

 the African shore, the cable was found covered with 

 marine animals, greatly corroded, and injured appa- 

 rently by the trawling operations in an extensive 

 coral fishery through w^hich it unfortunately passed. 

 It was broken through in 70 fathoms water a few 

 miles from Bona. The sea-end was however recovered, 

 and it was found that the cable which thence traversed 

 a wide valley nearly 2,000 fathoms in maximum 

 depth, was perfect to within about 40 miles of Sar- 

 dinia. It was then picked up from the Sardinian end, 

 and the first 39 miles were as sound as when it was 

 first laid down. At this distance from the shore there 

 was a change in the nature of the bottom, evidenced 

 by the different colour of the mud, and the wires were 



^ Minutes of Proceedings of the Institution of Civil Engineers, 

 with Abstracts of the Discussions. Vol. xx. p. 81. London, 1861. 



