conflict between the two opposing elements then becomes tremendous. The water is raised in its bed by the cooling and consolidation of the lava pouring into it, and overflows the adjoining lands; while, on the other hand, the melted masses convert the water into steam, with a most hideous tumult and noise. In the great eruption of the Skaptar Jokul, in 1783, the burning stream forced its way to the torrent of the Skaptaa at the point where its waters were precipitated into an abyss of unknown depth and of great extent. For a whole day, the fearful conflict of the elements lasted in this seething cauldron. Huge masses of flaming rock were seen swimming in the boiling water; the fish were thrown out, dead and parboiled, on to the land, while the explosions of steam projected large bodies of water into the air, with a sound resembling the discharge of the largest artillery. Fresh torrents of lava continued to pour in, and after a night of fearful tumult and terror, the deep abyss was in the morning completely filled, and the waters of the Skaptaa inundated the surrounding farms.

The third chapter of our author's monograph is devoted to the history of the former eruptions of Hekla, from the first recorded outbreak in 1104, to the present time. The Icelandic historians have supplied ample dates and details of these eruptions. The most fearful and the most disastrous, were those of 1300, of 1693, and of 1766. On the 13th of July, A.D. 1300, the whole mountain was, as it were, rent from top to bottom, huge masses of burning stone were projected into the air amid the column of smoke and ashes that rose from the crater, and fell at so great a distance, that the roof of the farm of Næfrholt, six miles from the mountain, was set on fire by them; while a hideous darkness covered the plains, so that none could find their way, and no boat could put to sea to prosecute the fishery.

The eruption of April 5th, 1766, commenced at four a. m. with the appearance of an enormous column of ashes and smoke on the summit of the mountain, intermingled with glowing scoriæ and constant gleams of forked lightning, while the most fearful sounds issued from the bowels of the mountain. The column of ashes, driven by a south-easterly wind, inclined towards the north-west, and fell in such vast quantities to the earth, that the surface was covered to the depth of an ell in the immediate vicinity of the volcano. In two hours' time five farms in the neighbourhood of Hekla were laid entirely desolate by the "rain of ashes," while the rivers Thiorsaa and Rangaa, bore on their waters such enormous quantities of scoriæ, that they impeded the progress of the fishing boats at a considerable distance from the land. On the 9th of April two craters could be seen pouring out vast quantities of lava, and one of these is supposed to have been the Raudöldur or red crater on the west side of Hekla, for this remarkable conical hill is not noticed by Eggert Olafsen in his visit to Hekla in 1753, though from the course he took in ascending the mountain, it could not have escaped his observation, if it had then existed. On the 23rd of April 1766, the height of the column of ashes and smoke was ascertained by measurement to be not less than sixteen thousand feet, and on previous days it had appeared to attain a still greater elevation. Counting from the first recorded eruption, we find that Hekla's periods of repose have been extremely unequal, they vary from six to seventy-four years. We subjoin these intervals in the order of their occurrence from the year 1104, viz., 53 years, 48, 16, 72, 6, 41, 48, 47, 74, 44, 24, 19, 22, 17, 57, 73. It has not been found that the length of the periods of repose have exerted any peculiar influence on the violence of the eruptions; for the great outbreak of the year 1300, took place only six years after that of 1294.

Our author next briefly notices the various ascents of Hekla that have been made by scientific travellers, from the first visits of Eggert Olafsen and Biarne Povelsen in 1753, to his own repeated observations from 1839 to 1846. The clouds, fog, and chilling winds on the summit of the volcano, have unfortunately proved most serious obstacles to scientific investigators on these occasions, save in the single instance of Eggert Olafsen's visit, and of some of our author's repeated and arduous expeditions in the same quarter.

The gradual cooling of the crater after the eruption of 1766, may be traced in the records of the various travellers, who have since, at successive periods, visited the summit of Hekla. Thus Banks and Solander, in 1772, found so hot a vapour rising in many places from cavities on the mountain, that they were unable to approach these to ascertain their temperature by the thermometer; while Thienemann in 1821, and Paul Gaimard in 1836, and

lastly, our anthor himself, in 1839, observed no signs of subterranean heat, save in one spot, where a small jet of steam raised the thermometer to '10° centigrade.' The fourth chapter of Mr. Schythe's book will undoubtedly present the greatest attractions to the general reader, as it embodies the history of the recent eruption of 1845-46, as collected and carefully detailed by one thoroughly competent for the task. From the slight jet of steam that Mr. Schythe had observed upon the mountain in 1839, he had ventured to predict, that the subterranean forces were again in operation, and that ere long, a serious outbreak might be expected. But for five years longer the volcano remained perfectly quiet, and it was not till the year 1845, that the peculiar condition of the atmosphere excited some little alarm among the inhabitants, as from ancient tradition it was well known that such alterations were commonly the precursors of an eruption. The winter of 1844-45, was remarkable for its extraordinarily mild character; the grass shot forth as early as the month of April, and the unvarying dryness of the summer was eminently favourable for the hay harvest. The medium température of the spring of 1845, was more than two degrees (centigrade) above that of the fourteen previous years. The barometer showed during this period extremely little variation. As the summer advanced, it was observed that less snow than usual lay in patches on the mountain, but the mild spring, and the very dry months that succeeded it, may perhaps account for this, without supposing an increase of subterranean heat. In the beginning of August it was universally remarked, that a great decrease suddenly took place in the quantity of the milk yielded by the sheep and cows, especially in the highly volcanic districts to the east of Hekla. Our author suspects that acid vapours may at this period have been rising from the earth, and tainting the grass, for such emanations were detected by him in abundance after the eruption. It was observed too by the inhabitants of the Rangaa valleys, that the numerous hot springs and vapour jets in the Reykiadal, near the Markar-fliot, had increased during the last year both in number and in power, but this rather tended to allay their fears of an eruption, as they hoped that in this way the subterranean fires of Hekla had found vent. Our author, however, regarded it rather as an indication that the subterranean heat was approaching nearer to the surface. The former eruptions of Hekla, and of other of the volcanoes of Iceland, had been frequently preceded by earthquakes, but on this occasion no such phenomena were observed, save two slight shocks at Reykiavik during the winter.

We shall avail ourselves, in describing the eruption of September 2nd, 1845, of the words of Mr. Schythe, though we could have desired a little more life and vivacity of colouring in his descriptions.

"The dry weather which had lasted during the whole of the spring and autumn of 1845, was succeeded on the 22nd of August by heavy rains, which continued during the rest of the month. September came in, dark and gloomy, with occasional drizzling rain, while a fearful stillness prevailed in this usually stormy part of the country. Such was the state of the atmosphere on Thursday, the 2nd of September, when after seventy-nine years of repose, the longest interval of quiet yet on record, the eighteenth eruption of Mount Hekla commenced. Dark heavy mists obscured all the mountain ranges on this eventful morning, but about nine a. m., the attention of the inhabitants of the neighbouring farms, was attracted by dull booming sounds like distant cannon shot, from the eastern range of Hekla, and at the same time, by some, a slight tremulous motion of the earth was observed. Many, who at that hour were proceeding to the fields on foot or on horseback, believed that what they heard was thunder, and others thought that a heavy storm was approaching from the east. But the ceaseless succession, and loud tone of the detonations, soon dispelled these ideas, while Ilekla and its whole range still continued wrapt in impenetrable mist. This fog however seems to have been less dense towards the east of the mountain, for the inhabitants of that district saw, about ten a. m., a dark cloud rising over the range, to the west and north-west of their position, and at the same time they heard with awe and terror, a constant noise as of a heavy cannonade, from the same quarter. All doubt respecting the origin of these sounds was however dispelled, when, about eleven in the morning, the dark cloud which had now spread itself over the whole horizon, began to rain down a thick shower of ashes and grayish scoriæ about the size of swanshot. (Raevehagl). Lower and lower did the dense canopy descend upon the earth, till, at mid-day, the darkness was as that of the obscurest winter night, and they who were surprised out in the fields, had the greatest difficulty in regaining their dwellings. After an hour's lapse, a sort of twilight reappeared, as when morning first breaks in the east, but day was not fairly restored till about three p. m. The shower of scoriæ continued for about an hour longer, and was succeeded by a fall of black volcanic sand, which lasted till mid-day on the 3rd, by which time the ground was covered with sand, scoriæ, and ashes, to the depth of an inch and a half."-p. 51.

On the western side of Hekla a similar obscurity pre

vailed, but no ashes fell in this quarter, as a strong northwest wind was blowing. The darkness over this district was caused by the sun's rays being intercepted by the column of smoke and ashes that rose from the mountain; it was, in fact, a novel sort of eclipse of the sun.

"Some of the farmers in this district, hastily consulted their almanacks, believing it to be a true eclipse of the sun, and such indeed it was, but not one predicted in the almanack."

It is curious that the first outburst of the volcanic forces was not accompanied with louder detonations, for in many places these were so indistinctly heard, that they were regarded as distant thunder, or as the noisy ebullitions of the ever active Geysers. Still more singular is it, however, that these detonations of the volcano were heard in the most distant quarters of the island. At Kirkiuvogr, 24 miles from Reykiavik, it was thought that a cannonade was going on at the latter town; while still further off, at Stappen, under the Sneefield Jokeln, it was believed that a whale of large size had got on shore, and was lashing his tail upon the rocks. Even in the desolate isle of Grimsey, on the north coast, booming shots were heard at three p. m., on the 2nd of September, and were supposed at the time by the inhabitants, to be cannon fired by the French cutter, cruising in that fishing ground.

The extent over which actual earthquakes were observed at the time of the eruption, may be comprised in two elliptical lines, extending about 24 miles in direct length, by about 10 at the greatest breadth between these, and thus enclosing the whole range of Hekla, from south-west to north-east. A slight tremulous motion of the earth was, however, observable at much greater distances.

: When the sky cleared about three in the afternoon of the 2nd of September, the huge column of smoke and ashes rising from the summit of the volcano, became for the first time apparent, and continued distinctly visible till night set in, about half-past seven.

"Just as the darkness closed, a louder detonation than any yet heard, spread terror all around, and the numerous dogs that attend on an Iceland farm, fled howling from their master's dwellings, far away into the district of Holterni, from whence many did not return for the lapse of a week. Night now fairly set in, and a bright flame rose high in the air from the volcano, while huge