69 
previous expeditions to be absent from their public duties for any 
large portion of this time, it was resolved that there should be 
three separate cruises, one on the west coast of Ireland, the Porcu- 
pine Bank, and the channel between Rockall and the coast of 
Scotland, under the scientific charge of Mr Gwyn defines, F.R.S . ; 
a second to the north of Rockall, leading northwards to the point 
where the expedition of 1868 left off, under the charge of Dr 
Thomson ; and the third to work over the “ Lightning Channel ” 
and check the former observations, under the direction of Dr 
Carpenter. 
Mr Gwyn Jeffries was favoured with remarkably fine weather, 
and found it possible to dredge during seven days at depths greater 
than 1200 fathoms, and on four days at less depths. His deepest 
dredging was 1476 fathoms, and the whole of them yielded an 
abundance of novel and interesting results in every invertebrate 
sub-kingdom. 
Captain Calver was accustomed to minute accuracy in surveying, 
and thoroughly versed in the use of instruments and in the bear- 
ings of scientific investigation. His crew were chiefly known and 
tried men, Shetlanders who had spent many successive summers in 
the “ Porcupine ” under his command. Aided by a staff of zealous 
officers, Captain Calver soon obtained so entire a mastery over the 
operation of dredging that he made it almost a certainty at depths 
at which this kind of exploration would have been previously 
deemed out of the question. Wyville Thomson at once recognised 
these favourable conditions, and having found that the experiences 
of the previous year, and all their anticipations for the present, had 
been realised, at least for the depth of nearly 1500 fathoms, and 
that even at that depth nearly all the types of living marine inver- 
tebrata were represented, though the number of species seemed 
reduced and the size of the animals dwarfed, he suggested that it 
would be desirable that the second cruise should he made in deeper 
water than had originally been intended, and pointed out the 
position of the deepest water easily accessible, 250 miles west of 
Ushant, as a fitting place for the next observations. 
The Hydrographer cordially acquiesced in this proposed change 
of plan, and it was arranged that the next dredging should be done 
at this spotj in water 2500 fathoms deep. Professor Wyville 
