JOURNAL AND LETTERS OF DAVID DOUGLAS. 437 very clear. This part was of gradual ascent, and its summit might be considered the southern part of the dome. The snow became very deep, and the influence of the sun melting its crust, which concealed the sharp points of the lava, was very unfavourable to my progress. From this place to the North towards the centre of the dome, the hill is more flattened. Rested a short time, and a few moments before noon, halted near the highest black, shaggy chimney to observe the sun's passage. In recording the following observations, I particularly note the places, in order that future visitors may be able to verify them. To the S. W. of this chimney, at the distance of one hundred and seventy yards, stands a knoll of lava, about seventy feet above the gradual rise of the place. The altitude was 104 52' 45 /x . This observation was made under highly favourable circumstances, on a horizon of mercury, without a roof, it being protected from the wind by a small oilcloth: bar. 18.953; therm. 41; in the sun's rays 43 5'; and when buried in the snow, 31; the dew-point at 7; wind S. W. The summit of this extraordinary mountain is so flat, that from this point no part of the island can be seen, not even the high peaks of Mouna Kuah, nor the distant horizon of the sea, though the sky was remarkably clear. It is a horizon of itself, and about seven miles in diameter. I ought, ere now, to have said that the bird-catcher's knowledge of the volcano did not rise above the woody region, and now he and my two other followers were unable to proceed further. Leaving these three behind, and accompanied by only Calipio, I went on about two miles and a half, when the Great Terminal Volcano or Cone of Mouna Roa burst on my view: all my attempts to scale the black ledge here were ineffectual, as the fissures in the lava were so much concealed, though not protected by the snow, that the under- taking was accompanied with great danger. Most reluctantly was I obliged to return, without being able to measure accurately its extraor- dinary de^oh. From this point I walked along the brink of the high ledg-e, aiong the East side, to the hump, so to speak, of the mountain, the point which, as seen from Mouna Kuah, appears the highest. As I stood on the brink of the ledge the wind whirled up from the cavity with such furious violence that I could hardly keep my footing within twenty paces of it. The circumference of the black ledge of the nearly circular crater, described as nearly as my circumstances would allow me to ascertain, is six miles and a quarter. The ancient crater has an extent of about twenty-four miles. The depth of the ledge, from the highest part (perpendicular station on the East side) by an accurate measurement with a line and plummet, is twelve hundred and seventy feet; it appears to have filled up considerably all round; that part to the North of the circle seeming to have, at no very remote period, undergone the most violent activity, not by boiling and over- flowing, nor by discharging- under ground, but by throwing- out
