After having skirted the sands of Cartier, of Hibernia, Seringapatam, and Scott, last efforts of the solid against the liquid element, on the 14th of January we lost sight of land altogether. The speed of the _Nautilus_ was considerably abated, and with irregular course she sometimes swam in the bosom of the waters, sometimes floated on their surface. During this period of the voyage, Captain Nemo made some interesting experiments on the varied temperature of the sea, in different beds. Under ordinary conditions these observations are made by means of rather complicated instruments, and with somewhat doubtful results, by means of thermometrical sounding-leads, the glasses often breaking under the pressure of the water, or an apparatus grounded on the variations of the resistance of metals to the electric currents. Results so obtained could not be correctly calculated. On the contrary, Captain Nemo went himself to test the temperature in the depths of the sea, and his thermometer, placed in communication with the different sheets of water, gave him the required degree immediately and accurately. It was thus that, either by overloading her reservoirs or by descending obliquely by means of her inclined planes, the _Nautilus_ successively attained the depth of three, four, five, seven, nine, and ten thousand yards, and the definite result of this experience was that the sea preserved an average temperature of four degrees and a half at a depth of five thousand fathoms under all latitudes. On the 16th of January, the _Nautilus_ seemed becalmed only a few yards beneath the surface of the waves. Her electric apparatus remained inactive and her motionless screw left her to drift at the mercy of the currents. I supposed that the crew was occupied with interior repairs, rendered necessary by the violence of the mechanical movements of the machine. My companions and I then witnessed a curious spectacle. The hatches of the saloon were open, and, as the beacon light of the _Nautilus_ was not in action, a dim obscurity reigned in the midst of the waters. I observed the state of the sea, under these conditions, and the largest fish appeared to me no more than scarcely defined shadows, when the _Nautilus_ found herself suddenly transported into full light. I thought at first that the beacon had been lighted, and was casting its electric radiance into the liquid mass. I was mistaken, and after a rapid survey perceived my error.