already mentioned dredged by his son at a depth of 300 to 400 fathoms off the Loffoten Islands.  I propounded my views to my fellow-labourer, and we discussed the subject many times over our microscopes.  I strongly urged Dr. Carpenter to use his influence at head-quarters to induce the Admiralty, probably through the Council of the Royal Society, to give us the use of a vessel properly fitted with dredging gear and all necessary scientific apparatus, that many heavy questions as to the state of things in the depths of the ocean, which were still in a state of uncertainty, might be definitely settled.  After full consideration, Dr. Carpenter promised his hearty co-operation, and we agreed that I should write to him on his return to London, indicating generally the results which I anticipated, and sketching out what I conceived to be a promising line of inquiry.  The Council of the Royal Society warmly supported the proposal; and I give here in chronological order the short and eminently satisfactory correspondence which led to the Admiralty placing at the disposal of Dr. Carpenter and myself the gunboat Lightninq, under the command of Staff-Commander May, R.N., in the summer of 1868, for a trial cruise to the North of Scotland, and afterwards to the much wider surveys in H.M.S. Porcupine, Captain Calver, R.N., which were made with the additional association of Mr. Gwyn Jeffreys, in the summers of the years 1869 and 1870."[1]

[Footnote 1:  The Depths of the Sea, pp. 49-50.]

Plain men may be puzzled to understand why Dr. Wyville Thomson, not being a cynic, should relegate the “Land of Promise” to the bottom of the deep sea, they may still more wonder what manner of “milk and honey” the Challenger expects to find; and their perplexity may well rise to its maximum, when they seek to divine the manner in which that milk and honey are to be got out of so inaccessible a Canaan.  I will, therefore, endeavour to give some answer to these questions in an order the reverse of that in which I have stated them.

Apart from hooks, and lines, and ordinary nets, fishermen have, from time immemorial, made use of two kinds of implements for getting at sea-creatures which live beyond tide-marks—­these are the “dredge” and the “trawl.”  The dredge is used by oyster-fishermen.  Imagine a large bag, the mouth of which has the shape of an elongated parallelogram, and is fastened to an iron frame of the same shape, the two long sides of this rim being fashioned into scrapers.  Chains attach the ends of the frame to a stout rope, so that when the bag is dragged along by the rope the edge of one of the scrapers rests on the ground, and scrapes whatever it touches into the bag.  The oyster-dredger takes one of these machines in his boat, and when he has reached the oyster-bed the dredge is tossed overboard; as soon as it has sunk to the bottom the rope is paid out sufficiently to prevent it from pulling the dredge directly upwards, and is then made fast while the boat goes ahead.  The dredge is thus dragged along and scrapes oysters and other sea-animals and plants, stones, and mud into the bag.  When the dredger judges it to be full he hauls it up, picks out the oysters, throws the rest overboard, and begins again.