entrance was formed of rough blocks of lava; there were three branches or lanes, the principal one, which I more particularly observed, was 60 to 70 feet long. Round the walls was a band of ice about 7 feet wide and 3 feet high, completely surrounding a little pond of water which did not exceed 2 to 3 feet deep near the mouth, but at the farther extremity I could not reach the bottom with my mountain staff, 8 feet long. At the farther extremity was what the neveros (ice collectors) call El hombre de nieve, the man of snow; on close inspection it proved to be a honeycombed mass of lava, on which the water had dripped from the roof, and had frozen into what might, in the obscurity of the place, be thought to resemble a human figure. I think the sides of the cave show that it has been a crater of emission, for the surfaces are rounded, as if they had been acted on when in a plastic state. I was further confirmed in this opinion by observing a short distance below the cave a stream of lava, which had evidently not flowed from the Rembleta above. Some of the lava had a wrinkled or corrugated appearance, as if it had issued out in a half-fluid state, and had rapidly cooled as it trickled forwards by its own weight. It was extraordinary that the water could be retained in this basin of porous lava, but I think that the surface of the bottom had been glazed over in a similar manner as the sides, by the action of heat; besides, it was covered over with a bed of ice, on which the water rested; this was evident, as wherever I plunged my pole, it struck on ice. The ice-collectors I employed during my first attempt to ascend, assured me that they had often seen smoke or steam issue out of the cave, but I saw neither when I was there.

In three quarters of an hour after leaving the cave we arrived at a small plain of pumice, called the Rembleta, situated 11,721 feet above the sea; this plain appeared to have been the ancient crater of the Peak, from which most of the currents of lava had proceeded previous to the formation of the present cone, or Pilon (sugar-loaf), which rises nearly in the centre of this plain to an elevation of 479 feet. The foot of the cone was encircled by water entirely frozen over; it was no doubt derived from the snow which fell on the sides of the cone melting, which thus formed the narrow belt of water around it.

Although the actual elevation of the cone was small, yet I found the ascent the most difficult and fatiguing part of the journey. The surface is a light pumice and ash, with small pieces of porphyritic lava covered with an ochreous crust occasionally protruding through it. Some idea may be formed of the steepness of the cone when I mention that at the bottom the slope forms an angle of 35°, gradually increasing till, near the top, the angle is

42, which is nearly the greatest angle the body can ascend in walking without falling backward. The pumice and ashes gave way under my feet, and often caused me to slide back many yards before it was possible to stop myself, then I was arrested by some of the protruding pieces of porphyritic lava. In forty minutes after leaving the Rembleta, I seated myself on the highest pinnacle of the Peak, 12,200 feet above the level of the sea.

The Peak is a solfatara, that is (see Plate II.), a half-extinguished volcano The crater is much smaller and more shallow than I expected; round the summit runs a wall of porphyritic lava of an elliptical form, about 150 feet long, 100 broad, and 50 deep; the surface of the lava was coated with a soft white mass like dough, caused by the sulphurous acid vapours having acted upon the argil of the lava, and turned it into a sulphate of alumina. As I only paced the crater once for the purpose of measuring it, I am not certain that the dimensions I. have given are perfectly correct. The bottom of the crater was unpleasantly hot, and the air so filled with vapours of sulphurous acid that I was continually sneezing, and the lungs felt sore and pained. The surface was covered with most beautiful trimetric crystals of sulphur, some of a yellowish white, others of a reddish and greenish colour. In some little caves, only a few feet deep, were some small apertures covered with splendid crystals of octahedral sulphur; on breaking some of them, I found in the interior a glistening white substance something like opal, only that it had a crystalline structure; on my return to England it was analyzed, and found to contain 91 per cent. of silex, and the rest water. The pasty substance on the surface of the lava, proved to be sulphate of alumina, muriate of ammonia, and a small quantity (0-5 per cent.) of sulphate of ammonia. Round the walls of the crater were several small apertures, like small pipes, about an inch in diameter, some of which were emitting steam, and others sulphurous acid vapours, which show that they must have proceeded from different sources, although some of the holes were only a few inches apart. The heat of the steam was considerable, for when I placed a thermometer graduated to 133° within their influence, the bulb burst.

The extreme dryness of the atmosphere and the radiation of the sun's rays were distressing; the lips cracked; the nails became brittle; the mahogany box, containing a Daniell's hygrometer, became unglued, and the case of a small pocket-sextant split across. The evaporation of the wet-bulb thermometer was so rapid that it was necessary to watch it closely, otherwise the muslin would be dry before the observation could be made.

The basaltic lava and the trachytes of the Peak were magnetic and had polarity, but I had no means of measuring it.

The following were the observations made on the wall surrounding the crater, and a few feet below the highest point:—

Although the atmosphere appeared perfectly clear, yet when I looked across the sun's rays from the shade of a rock, there was an evident dust-haze, probably brought over by the wind from the neighbouring desert of Africa.

The view from the top was most magnificent, the masses of cumuli, which had been resting at an elevation of 5,000 feet above the level of the sea, had entirely disappeared; with the exception of the islands of Forteventura and Lanzarote, the whole of the Canarian archipelago seemed to be close under my feet, the mountains of Grand Canary appeared as if on the island below, Palma 46 miles distant, and Gomera with Hierro were quite distinct.

I think it must be allowed that the Peak is a volcano of eruption, but there are strong evidences that it is nearly surrounded by a more ancient and enormous crater of elevation, termed the Cañadas, which form an atrium 23 miles in circumference.

The Cañadas are surrounded by cliffs of lava, varying from 540 feet to about 1,000 feet high; the plain of this crater is 4,383 feet lower than the mean elevation of the cone of the peak, which rises like a great mole-hill nearly in the centre of this atrium. From the cliffs of this atrium, various ridges of mountains spring out like the spokes of a wheel; some of them rise to an elevation of 8,950 feet, such as the Risco de Guajara, which is part of the elevated chain of mountains surrounding the Cañadas from the E. to W.S.W. These ridges of mountains, forming as it were buttresses, have radial valleys between them, running for some miles towards the sea.

As you pass over these currents and mountains of lava, the view is so bewildering, that it requires two or three visits before you can understand the system of these volcanic mountains, which can be done only by making a preliminary observation from a very elevated position, so as to take a bird's-eye view of the whole island, and then making more observations in detail on foot.

These various mountain ridges have all the appearance of having been at one time joined together, for when I examined their respective strata I found that they intercalated in the same manner; for instance, No 3 stratum in one ridge would be of the same type as No. 3 in an opposite one, though they were some miles apart.

Some idea may be formed of the great antiquity of the streams of lava that run towards the sea, by a careful examination of the