took the lowest calculation. My method was, to compare the height of the water with the diameter of the basin, which I knew to be fifty-one feet, and this jet was full twice that length. The width of the stream is not equally easily determined by the eye, on account of the steam and spray that envelops it: in most instances, not more, probably, than eighteen or twenty feet of the surface of the water is cast into the air; but it occasionally happens, as was the case now, that the whole mass, nearly to the edge of the basin, is at once heaved up: all, however, is not spouted to an equal height; for the central part rises the highest, but, having gained some elevation, the spray divides, and darts out little jets on every side, that fall some way over the margin of the basin. After this last discharge, the water subsided about fifteen feet in the pipe, and so remained some time; but in two hours the funnel was again filled to within two feet of the edge. As often as I tried the heat of the water in the pipe, I always found it to be 212°; but, when the basin also was full, on immersing the thermometer as far from the margin as I could reach with my arm, I never saw the

quicksilver rise above 180°; although the water in the centre was boiling at the same time. It seems probable that the height to which the Geyser throws its waters may have increased somewhat in the course of a few years; as, when Sir Joseph Banks visited Iceland in 1772, the greatest elevation to which the column ascended, was ascertained to be ninety two feet; while in the year 1789, its height was taken by a quadrant, by Sir John Stanley, and found to be near one hundred feet, and this day, if I am not mistaken, it was still greater. Povelsen and Olafsen were in all probability deceived, when they imagined they saw the loftiest jets reach to the elevation of sixty toises, or three hundred and sixty feet. Previously to the last eruption, Jacob and myself amused ourselves with throwing into the pipe a number of large pieces of rock and tufts of grass, with masses of earth about the roots, and we had the satisfaction to find them all cast out at the discharge, when many of them fell ten or fifteen feet beyond the margin. Some rose considerably higher than the jets which forced them up: others fell down into the basin, and were with the following eruption

a second time flung out. The stones were mostly as entire as when they were put in, but the tufts of grass and earth were shivered into numerous small black particles, and were thrown up by the first jet in quick succession, producing a very pleasing effect among the white spray. This whole day had been fine with but little rain.

Saturday, July 15.

At one o'clock this morning there was an eruption of the Geyser, which was repeated at half past three, and again at a quarter before eight, and at half past nine; after which, the fountain continued to spout water about every two hours. All these eruptions were attended by the same circumstances as those of yesterday, and were preceded by similar tremblings of the ground and subterraneous noises; but none of them threw the water to any great elevation; the highest not appearing to exceed fifty feet. Close to the edge of many of the hot-springs, and within a few inches of the boiling water, in places that are, consequently, always exposed to a considerable degree of heat, arising both from the water itself and the steam, I found Conferva limosa Dillw. in

abundance, forming large dark-green patches, which easily separated and peeled off from the coarse white kind of bolus that they were attached to. In a similar situation, also, I met with a new species of Conferva (belonging to the family called by Vaucher Oscillatoria), of a brick-red color, covering several inches of ground together, and composed of extremely minute unbranched filaments, in which, with the highest powers of my microscope, I was not able to discover any dissepiments. The margin of one of the hotsprings, upon a white bolus, which was in a state of puddle from its mixture with the heated water, afforded me the finest specimens of Jungermannia angulosa * I ever saw, growing thickly matted in such great

*Mr. Barrow, in his Voyage to Cochin-China, gives us a very interesting account of the hot-springs in the island of Amsterdam, which lies in latitude 38° 42′ south,

and longitude 76° 51′ east. "Some of them," he says,

are running freely, others ooze out in a paste or mud. In some of the springs Fahrenheit's thermometer ascended from 62° in the open air to 196°; in some to 204°; and in others to 212°, or the boiling point. In several places we observed patches of soft verdure, composed of a fine delicate moss, blended with a species of Lycopodium and another of Marchantia. These green

tufts, that I could with ease take off pieces

of five or six inches in diameter. The under side of these patches had much the ap

very

pearance of purple velvet, owing to the numerous fibrous radicles of that color which proceeded from the base of the stems, and suffered themselves to be detached, without difficulty, from the soil they had grown upon. In water, also, of a very great degree of heat, were, both abundant and luxurious, Conferva flavescens of Roth, and a new species allied to C. rivularis. After a day, almost the whole of which had been showery, with the wind in the south-west, a fine, but cold, morning, attended with a July 16. northerly wind, afforded me a most interesting spectacle, the idea of which is too strongly impressed on my mind, ever to be obliterated but with memory itself. My tent had been pitched at the distance of

Sunday,

patches were found to be floating on a hot paste, whose temperature, at eight or ten inches below the surface, upon which the roots of the plants spread, was 186°. This was the more remarkable, as the same species of Lycopodium, or club-moss, grows with great luxuriance, even in the winter season, on the black heaths of North Britain."