the fun. As much as reafon is decried, yet the most incoherent enthusaist will attempt to fupport his dogmas with what reafon he can command. To represent the value and utility of the facred Scriptures---the work of Chrift, and the character of God in him---to promote fcriptural tempers and conduct---and to inculcate univerfal good-will towards men, are our leading views. May the Father of lights continue to blefs our attempts to his own glory.

We mean to improve our Mifcellany in paper and type in the next year. Are thankful to our correfpondents for their favours---hope for the continuance of them---and are happy in announcing to our friends at large that the number of w ters for our work is increasing.

LONDON, December 24, 1799.

THE

Univerfalist's Mifcellany

For JANUARY, 1799.

I

NATURAL HISTORY.

(Continued from vol. ii. p. 365.)

T now remains that we explain the caufes of Volcanoes, or, to speak more properly, that we mention the opinions of philofophers concerning them; for the real causes of them are perhaps ftill unknown, notwithstanding all that has been faid upon that fubject.

The moft elaborate theory that has yet appeared is that of Mr. Houel (fee his Voyage Picturesque). According to him water is neceffary for the formation of all volcanoes. He obferves, that volcanoes, in general, are near the fea: that they are even extinguished when the fea retires from them; for we can still perceive the craters of volcanoes in several lofty inland mountains, which discover what they have been formerly. He fuppofes that a long feries of ages was neceflary for the formation of a volcano, and that they were all formed under the furface of the sea: the firft explosion which laid open the foundations of the deep would poffibly be preceded by an earthquake the waters would be parted by a vaft globe of burning air, which would iffue forth with a tremendous noife, opening at the fame time a large and wide vent for the immenfe flame which was to follow; and which, as it iffued from the bottom of the fea, would be spread over its furface by the firft gufts of wind which followed. A fire which was to burn through thousands of years could not be faint or feeble when it was first lighted up; its firft eruptions, therefore, would have undoubtedly been very violent, and the ejected matter very copious. For a long feries of ages it would continue to difcharge VOL. III.

B

torrents

torrents of lava from the bofom of its native earth, and its firft crater would be compofed of the fragments of the fame earth. Thus, according to our author, the foundations of the burning mountain would be laid in the bottom of the fea; and even then it would have an hollow cup, or crater on the top, fimilar to that which is to be found on all volcanoes at present. But the queftion now very naturally occurs, By what means was the internal fire preferved from extinction by the waters of the ocean which were recumbent upon it? To this he replies, that "the fire having disposed the substances in fufion to make an eruption, next laid open the earth, and emitted as much matter as it could discharge, with force fufficient to overcome the column of water which would oppofe its afcent; but as the ftrength of the fire diminished, the matter difcharged was no longer expelled beyond the mouth; but by accumulating there, foon clofed up the orifice. Thus only fmall orifices would be left fufficient for giving vent to the vapours of the volcano, and from which only fmall bubbles of air could afcend to the furface of the water, until new circumftances, fuch as original ly gave occafion to the eruption, again took place in the bowels of the earth, and produced new eruptions, either through the fame or other mouths. The appearance of the fea over the new-formed volcano, in its ftate of tranquility, would then be fimilar to what it is betwixt the islands of Bafilizzo and Pariaria: columns of air-bubbles are there afcending at the depth of more than thirty feet, and burft on their arriving at the furface. This air would continue to difengage itself with little difturbance, as long as it iffues forth only in fmall quantity, until, at the very inftant of explofion, when prodigious quanti ties, generated in the burning focus, would make their way all at once, and the fame phenomena which originally took place, would again make their appearance."

A volcano, while under water, cannot act precisely as it does in the open air its eruptions, though equally strong, cannot extend to fo great a distance: the lava accumulates in greater quantity round the crater; the fands, afhes, and pozzolano are not carried away by the winds, but are depofited around its edges, and prevent the marine fubftances which are driven that way by the waters from entering; thus they agglomerate with thefe bodies, and thus a pyramidal mount is formed of all the materials together.

In this manner Mr. Houel fuppofes, that the mountain was gradually raised out of the fea, by the accumulation of lava, &c. at every eruption, and that the cavern of the volcano was

gradually

gradually enlarged, being worked down further into the earth by the continued action of the ftones which the volcano is perpetually throwing up and receiving back again; and that, at laft, the matter being in a proper state of fufion, it was thrown out at the top of the mountain to accumulate on its fides.--Mr. Houel's opinion about the volcanic fire, is as follows--"We cannot form any idea of fire fubfifting alone, without any pabulum, and unconnected with any other principle. We never behold it but in conjunction with fome other body, which nourishes it, and is confumed by it. The matter in fufion, which iffues from the focus, is but the incombuftible part of that which nourishes the fire, and into the bofom of which that active principle penetrates in search of pabulum. But as the fire acts only in proportion to the facility with which it can diffolve and evaporate, I am of opinion that it is only the bottom of the volcano on which it acts; and that its action extends no farther than to keep these substances which it has melted in a conftant ftate of ebullition; that fufible matter being discharged from the mouth of the volcano, and hardening as it is gradually cooled by the action of the air, produces that fpecies of ftones which are diftinguifhed by the name of lavas. This lava, even when in the focus, and in a state of fluidity, muft alfo poffefs a certain degree of folidity, on account of the gravity and density of its particles; it therefore oppofes the fire with a degree of refiftance which irritates it, and requires, to put it into a state of ebullition, a power proportioned to the bulk of the mafs."

"That quantity of matter, when diffolved by the action of the fire, must conftantly refemble any other thick fubftance in the fame ftate. Small explotions are produced in various parts over the furface of every fuch fubftance while in a state of ebullition; and, by the bursting of these bubbles, a great number of small particles are scattered around. This is the very process carried on in the focus of a volcano, though on a fcale immenfely more large; and the vaft explofions there produced expel every body which lies in their way with the utmoft violence; nor is there any piece of lava which falls down from the upper part of the arch of weight fufficient to refift this violent centrifugal force."

No estimate can be made of the power of thefe explosions, but by obferving the obftacles they overcome, and what enormous bodies are raised up and thrown to an immenfe height and distance. Such vaft pieces of lava are to be feen on the top of Vefuvius and Lipari, that the projectile force by which they

B 2

have

have been thrown out, appears altogether incredible. No per fon can harbour the leaft fufpicion of their having been laid there by any human power; and the appearance of them demonftrates that they have been ejected from the bottom of the volcano, not in a ftate of fufion, but coherent and folid. A piece of lava lies on the top of Ætna of more than a cubic fathom in bulk, and whofe weight, therefore, cannot be less than fixteen tons. What an amazing force, then, must it have required, not only to raise this enormous mafs from the volcanic focus, but to make it defcribe a parabola of about a league in diameter, after it had come out of the crater!"

"When we confider how much the volcanic focus is funk below the base of the mountain, that the mountain itself is 10,000 feet high, and that confequently there must have been a power fufficient to raise fuch a mass 12,000 feet perpendicular, the boldest imagination must be loft in amazement.

This

may serve to give us fome idea of the nature of that power which operates in the foci of volcanoes; a power which is unknown and inconceivable, and may justly be reckoned among the mysteries of nature."

The pabulum by which the internal fire is fupported, Mr. Houel thinks to be fubftances contained in the mountain itself, together with bitumen, fulphur, and other inflammable materials, which may from time to time flow into the focus of the volcano in a melted state, through fubterraneous ducts; and the explosions he ascribes to water making its way in the fame manner: the water is converted into fteam, which fills the cavern, and pushes the melted lava out at the crater. This opinion is corroborated by the copious smoke which always pre cedes an eruption. But, combined with the water, there is always a quantity of other substances whofe effects precede, accompany, or follow the eruptions, and produce all the various phenomena which they difplay. The eruption of water from Ætna in the year 1775, proceeded undoubtedly from this cause. The fea, or fome of the refervoirs in Ætna or the adjacent mountains, by fome means discharged a vast quantity of water into the focus of the volcano: the water was inftantly refolved into vapour, which inftantly filled the whole cavern, and issued from the mouth of the crater. As foon as it made its way into the open atmosphere, it was condensed again into water, which ftreamed down the fides of the mountain in a dreadful and deftructive torrent.

Thus we have given a view of Mr. Houel's theory; according to which volcanoes originally began at the bottom of the