the surveying-ship Lightning was granted, and with it a cruise was made in the North Atlantic Ocean in August and September, 1878. Among the results of the expedition was the procuring of evidence that animal life was varied and abundant at depths of between six and seven hundred fathoms; that great masses of water at different temperatures were moving about, each in its particular course; and that many of the deep-sea forms of life were closely related to fossils of the Tertiary and Cretaceous periods.
In 1869 the surveying-ship Porcupine was lent for exploration, and made a survey of the west coast of Ireland, under the scientific direction of Mr. Gwyn Jeffries, and of the Bay of Biscay and the track of the Lightning's survey under Professor Thomson. The Porcupine was lent again in 1870, but Professor Thomson was prevented by ill-health from engaging in the surveys, and they were conducted to Gibraltar by Mr. Gwyn Jeffries, and in the Mediterranean by Dr. Carpenter. By the time the Porcupine's survey was completed, and under the promptings of the results obtained in the previous surveys, an extensive scientific interest in work of this kind was awakened. A representation was made to the Government by the council of the Royal Society, urging that an expedition be dispatched to investigate the great oceans and take an outline survey of their bottoms. The proposition received general support, and was acceded to by the Government, who granted the Challenger, a main-deck corvette of 2,306 tons, for the use of the expedition.
Captain G. S. Nares, R. N., was called from the survey of the Gulf of Suez to take charge of the vessel, and the second place in command was given to Commander J. P. Maclear, R. N., son of the late Astronomer Royal at the Cape of Good Hope. Professor Thomson was given the scientific direction of the expedition, and took as his associates Mr. J. J. Wild, of Zurich, private secretary; Mr. J. Y. Buchanan, of Edinburgh, chemist; and Mr. II. A. Moseley, Dr. von Willemoes Suhm, and Mr. John Murray, naturalists. The vessel was fitted up with all the appliances which the forethought of the naval experts and scientific men interested in the preparation for the expedition could devise for making the delicate and often complicated observations which were to be undertaken, some of which had hardly been attempted before on other than an experimental scale. The plans were prepared by the Admiralty in conjunction with a committee of the Royal Society, and reasonable liberty of variation from them, when circumstances might make it expedient, was allowed to the two chiefs. The personal composition of the expedition was changed during the voyage by the recall of Captain Nares, to take charge of an Arctic expedition, and by the death of Dr. Willemoes Suhm. Otherwise the plan was carried out essentially as arranged in the beginning. The special object of the expedition was to investigate the physical and biological condition of the great ocean-basins.