chap. m.J THE CRUISES OF THE 'PORCUPINE: 135 



ing dissimilarity in Animal Life, and to trace this climatic 

 dissimilarity to its source ; as well as to carry down the like 

 survey to depths much greater than have been yet explored by 

 the Dredge. 



" This, it is believed, can be accomplished without difficulty 

 (unless the weather should prove extraordinarily unpropitious) 

 by the employment of a suitable vessel, provided with the 

 requisite appliances, between the middle of May and the middle 

 of September, The Ship should be of sufficient size to furnish a 

 Crew of which each ' watch ' could carry on the work con- 

 tinuously without undue fatigue, so as to take the fullest advan- 

 tage of calm weather and long summer days ; and should also 

 provide adequate accommodation for the study of the specimens 

 when freshly obtained, which should be one of the primary 

 objects of the Expedition. As there would be no occasion to 

 extend the Survey to a greater distance than (at the most) 400 

 miles from land, no difficulty would be experienced in obtaining 

 the supplies necessary for such a four months' cruise, by running 

 from time to time to the port that might be nearest Thus, 

 supposing that the Ship took its departure from Cork or Galway, 

 and proceeded first to the channel between the British Isles and 

 Iiockall Bank, where depths of from 1,000 to 1,300 fathoms are 

 known to exist, the Dredgings and Temperature-Soundings could 

 be proceeded with in a northerly direction, until it would be 

 convenient to make Stornoway. Taking a fresh departure from 

 that port, the exploration might then be carried on over the area 

 to the N.W. of the Hebrides, in which the more moderate 

 depths (from 500 to 600 fathoms) would afford greater facility for 

 the detailed survey of that part of the Ocean-bottom on which a 

 Cretaceous deposit is in progress — the Fauna of this area having 

 been shown by the ' Lightning ' researches to present features of 

 most especial interest, while the careful study of the deposit 

 may be expected to elucidate many phenomena as yet unex- 

 plained which are presented by the ancient Chalk Formation. A 

 month or six weeks would probably be required for this part of 

 the Survey, at the end of which time the vessel might again run 

 to Stornoway for supplies. The area to the N. and N.E. of 



