masses of glowing scoriæ shot up to an enormous height, and a stream of red molten lava appeared flowing down the western declivity of the mountain towards the plains."

The effects of the volcano on the rivers in the immediate western vicinity of the range, were sufficiently remarkable. The waters of the western Rangaa diminished very sensibly about mid-day on the 2nd, probably in consequence of the scoriæ and ashes that fell into and obstructed its upper course; but a few hours later its stream suddenly rose to an unprecedented height, and bearing on its surface huge masses of scoriæ, it swept with irresistible force onwards to the ocean. At the same time the temperature of the water became so much elevated, that the hand could not be kept in it for a moment, and hundreds of trout, in a half-boiled condition, were cast out upon the banks. But ere the night had fairly set in, the river had returned within its limits, and its waters in a short time regained their clear pellucid character.

On the morning of the first eruption, the atmosphere around the mountain was perfectly still, but from the rapidity with which the huge column of ashes travelled towards the south and east, it is evident that a powerful north wind blew in the upper regions of the air, shortly after the volcano burst forth. We have evidence that the shower of ashes and of volcanic sand extended far out to sea in this direction. The sloop Helena, Captain J. Larsen, was, at twelve o'clock a. m., on the 2nd of September, in 60-58 north latitude, and 9-43 longitude west from Greenwich. At nine p. m. on that day, a heavy cloud came driving over the ocean, and covered the ship's decks and sails with dark ashes, while a strong wind blew from the north-west. It follows, therefore, that in the space of less than twelve hours, the ashes from Mount Hekla passed over a distance of about 360 English miles, giving a velocity of above 30 English miles per hour. The showers of ashes fell in the Faro isles at the same hour, and in Shetland early on the morning of the 3rd of September. At the period of the year when the eruption took place, the sheep, which form no inconsiderable portion of the riches of the Icelanders, had not as yet been brought in from their summer pastures, and thousands of these animals were grazing on the high ranges around the volcano. The utmost anxiety was necessarily felt regarding their fate; but on the evening of the first day they arrived in troops at the several farms, with their fleeces blackened with ashes, and their flesh severely burned in many places by the red-hot scoriæ. Many, however, still remained upon the hills, and were not recovered for more than a week, when their feet were found to be dreadfully cut and bruised by the sharp lava, so that the lambs had to be carried home, and for a long time afterwards these were observed to feed in a kneeling position, as their feet were too sore to support the weight of the body. On the cast side of Hekla, which was the direction in which the showers of ashes principally fell, the flocks were widely dispersed. Scared by the fearful detonations from the mountain, and burnt by the glowing cinders falling around, the terrified animals fled to a great distance, and some forty or fifty head even made their way into the district of Skaptartunga, which lies nearly 60 miles to the east of Hekla. When the farmers and herdsmen subsequently traversed the eastern district in search of their lost herds, they observed the remarkable fact, that the boiling springs, so common about the Markar-fliot, had become only lukewarm, or about the temperature of new milk. One particular spring, at the eastern base of the Torfa Jokul, which had hitherto always been used by the Icelanders to prepare their coffee when in its vicinity, without the need of fire or of boiling apparatus, was now so cooled, as to be utterly unfit for that purpose.

The rate of progress of the lava stream, in its descent from the crater, was not accurately noted; by general report it was said, in the first twelve days of the eruption, to have advanced at the average of about fifty feet per hour. In seven days the new 'Roin' had progressed more than two miles from the foot of Hekla, but its cooling from that time went on rapidly, though when an iron bar was thrust into the rough scoriæ that composed its crust, it easily reached the melted mass below, and quickly became red hot. But it was somewhat dangerous to approach very near the melted mass, for if it encountered any obstacle in its course, such as a large stone or rock, it accumulated behind it, and then suddenly burst forth on either side in a stream of liquid fire. The depth of the new lava stream was generally estimated at from 40 to 50 feet, but when compressed within a cleft or defile, it often rose to 120 feet or more.

Up to the 12th of September, the lava stream had only flowed over beds of ancient lavas, and had not as yet reached the mountain pastures. On the 12th, the volcano, after eight days of comparative tranquillity, again became active, and poured forth additional showers of lava and scoriæ. The injurious effects of the rain of ashes soon became apparent in the vegetable world. Cabbages, &c. which were healthy and flourishing in the gardens on the 13th, were completely withered and dried up by midday on the 14th, and the same fate befell the herbage, wherever the ashes rested thereon. Still worse were the consequences when the ashes fell mixed with rain, as they then adhered more closely to the grass, marking each blade with a dull brown spot wherever the ashes adhered; and then, as these spots increased in number, they gradually blended with each other, and the whole plant became brown and sapless.

On the 14th of September, the detonations from the volcano were fearfully loud, and occurred with great regularity, at intervals of about a minute. They were always preceded by an active outburst of black smoke, probably ashes and steam, from the interior of the volcano. A new crater opened this afternoon on the southern part of the range, and emitted a copious torrent of lava. The ashes and sand rained down in such quantities over all the district to the south-east of Hekla, that in three hours' time the ground was covered to the depth of two inches. During the suceeding days, the lava stream, receiving fresh augmentation from the new crater, advanced on to the mountain pastures, and surrounded the Mel-Field, a small hill of Tufa, isolated among the green pastures at the foot of Hekla. By the 21st of September, the lava stream had progressed nearly 100 fathoms beyond the Mel-Field, through a deep valley on the northern side of that elevation. Throughout the month of October, the volcano continued active, though to a less degree, and though snow covered all the lower ranges, the mountain itself remained bare. On the 10th of November, the subterranean action seemed to have almost entirely ceased, but on the 13th of that month, a violent paroxysm again occurred, and on the 19th, the lava stream reached its furthest limits, having progressed during the preceding six days, at the rate of 1,250 feet per day. During the months of December and January, ashes repeatedly fell, but the loud detonations from the mountain were now replaced by a kind of continuous murmur. On the 26th of Marsh, 1846, the last paroxysm occurred, and Hekla has since then continued perfectly tranquil.

We have thus endeavoured to condense, as much as possible, Mr. Schythe's narrative of the eruption, as we felt it unnecessary to detail, as he has done, the phenomena of each succeeding day. From the observations collected from our author, it is evident that at least three craters or outlets for the pent-up fires within the mountain were opened at a very early period of the eruption. One of these was on the north-east point of the volcano, another on the central or highest part of the summit, and the third on its western declivity. The column of ashes was repeatedly measured by Gunlögsen, and was ascertained to range from 6,000 to 14,000 feet above the summit.

Our author could not learn that the great warm springs, the Geyser and Strokr, exhibited any remarkable variations during the eruption; but when he subsequently visited these celebrated fountains, he found that the depth of the pipe of the Geyser had diminished from 78 to 60 feet, while the water at the bottom exhibited a temperature of 115 centigrade, the boiling point being, it is needless to say, 100.

The fifth chapter of this book contains much of high interest to the scientific geologist. In it are described, from personal observations made during repeated and prolonged visits, the alterations produced in the mountain by the last eruption. We shall briefly condense these details, and by omitting much that is purely scientific, we hope to render them more acceptable to the general reader.

On the 5th of June, 1846, Mr. Schythe arrived at the farm of Næfrholt, the nearest to the base of Hekla, and distant only 150 yards from the still steaming lava of the recent eruption. It was not, however, till the 26th of this month that Hekla was sufficiently clear of mist to enable him to reach the summit, in company with the owner of Næfrholt, whose property had been greatly devastated by the eruption. On the top he found four recently formed craters in a line parallel to the extension of the range, viz., from south-west to north-east. From these craters there rose up an enormous quantity of dense steam, which, settling down on the sides and summit of the mountain, soon enveloped him in so impenetrable a fog, that at the distance of three paces he could not see his guide, and, at times, he could not even discern the ground on which he stood. We ourselves once encountered a similar fog on the summit of Vesuvius, while all below was calm and serene; but the steam was in this case so heavily charged with ammoniacal vapours, that respiration was nearly impeded, and it was with some difficulty that we escaped into a purer atmosphere. On the second of September, 1846, there was not a cloud during the whole day on the summit of Hekla, and Mr. Schythe was enabled to devote many hours to the exploration of the mountain. The morning was sharp and frosty, and the recent lava steamed vigorously in the cold air, for a large quantity of rain had fallen during the night, and this, soaking through the porous covering of scoriæ and ashes, rose again in steam when it came in contact with the still melted lava beneath. Mr. Schythe first examined the western crater, from whence the great stream of lava that had flowed down towards Næfrholt had evidently come. Here the now congealed torrent was seen piled in huge masses, and in the wildest confusion, as it issued from the mountain's side. The bottom of the crater was filled with new fallen snow to a considerable depth. The next crater was separated from the former by a very narrow ridge of porous slags of the most beautiful carmine red colour. The snow, melting at the bottom of the crater, and sinking through the scoriæ to the hot lava beneath, caused a considerable steam to rise, and emitted a constant sound, as it were, of boiling

water.

We have but space remaining for a brief extract of our author's theory of the rise and progress of the last eruption. It began, he believes, by the rending of the upper part of the mountain in a direction from south-west to north-east. It was not merely that vent was found for the subterranean forces by the four craters; but an actual disruption of the summit took place in the direction above stated. This rent or cleft did not occur, however, exactly along the line of the summit, but a little to the south of the highest elevated ridge; and, in consequence thereof, the craters and the portions of the rent still remaining open, are higher on their northern than on their southern sides. This circumstance, our author thinks, may have partially influenced the direction of the ashes and scoriæ. In the neighbourhood of the fourth or north-eastern crater, the great disruption was still visible, while parallel to it, at

VOL. XXV.-NO. XLIX.

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