The observations made for deep-sea temperatures gave some remarkable results. Here, among the icebergs, a band or stratum of water was found, at a depth of eighty to 200 fathoms, _colder_ than the water either above or below it. Take one day as an example: on the 19th of February the surface temperature of the sea-water was 32°; at 100 fathoms it was 29·2°; while at 300 fathoms it had risen to 33°. In the Atlantic, on the eastern side about the tropics, the _bottom_ temperature was found to be very uniform at 35·2°, while it might be broiling hot on the surface. Further south, on the west side of the Atlantic below the equator, the bottom was found to be very nearly three degrees cooler. It is believed that the cold current enters the Atlantic from the Antarctic, and does not rise to within 1,700 fathoms of the surface. These, and many kindred points, belong more properly to another section of this work, to be hereafter discussed. [Illustration: THE NATURALIST’S ROOM ON BOARD THE “CHALLENGER.”] The _Challenger_ had crossed, and sounded, and dredged the broad Atlantic from Madeira to the West Indies—finding their deepest water off the Virgin Islands; thence to Halifax, Nova Scotia; recrossed it to the Azores, Canary, and Cape de Verde Islands; recrossed it once more in a great zig-zag from the African coast, through the equatorial regions to Bahia, Brazil; and thence, if the expression may be used, by a great angular sweep through the Southern Ocean to Tristan d’Acunha _en route_ to the Cape, where they made an interesting discovery, one that, unlike their other findings, was most interesting to the _discovered_ also. It was that of _two_ modern Robinson Crusoes, who had been living by themselves a couple of years on a desolate rocky island, the name of which, “Inaccessible,” rightly describes its character and position in mid ocean. Juan Fernandez, the _locale_ of Defoe’s immortal story, is nothing to it now-a-days, and is constantly visited. On arrival at the island of Tristan d’Acunha, itself a miserable settlement of about a dozen cottages, the people, mostly from the Cape and St. Helena, some of them mulattoes, informed the officers of the _Challenger_ that two Germans, brothers, had some time before settled, for the purpose of catching seals, on a small island about thirty miles off, and that, not having been over there or seen any signs of them for a long time, they feared that they had perished. It turned out afterwards that the Tristan d’Acunha people had not taken any trouble in the matter, looking on them as interlopers on their fishing-grounds. They had promised to send them some animals—a bull, cow, and heifer—but, although they had stock and fowls of all kinds, had left them to their fate. But first as to this little-known Tristan d’Acunha, of which Lord George Campbell(29) furnishes the following account:—“It is a circular-shaped island, some nine miles in diameter, a