ejected from volcanos in a liquid form, and which subsequently acquiring a consistency, is tufa, peperino, or piperno, 5. The lavas, or other volcanic matters, which have been decomposed, either by the action of air, water, acids, or any other menstrua, such as the white lava, and other substances of the solfaterra and piscerilla. 6. Matters, which, after having been ejected from volcanos, in some one of the preceding forms, have been dissolved by water, and afterwards coagulated and crystallized into new forms, as the hydropales de Vicence, the Volcanic breccias of the valley D'Agno, and the crystallized substances in lavas.

There is, however, one unclassed volcanic ejection, which is, perhaps, the most striking phænomenon in nature. This is the roche rouge in Velay, in France. This basaltic rock is girt round by granite, and has no where near it the vestige of a crater, or of lava. It seems to have been driven through the mass of granite; and with fragments of the granite clinging to its sides, to have fixed itself, when at the enormous height of one hundred feet, and of the circumference of sixty feet. Nothing can be more extraordinary, than the sight of the granite girdle which thus surrounds it, to the height of seven

feet. * When or how the explosion took place, it is impossible to explain. The monument, however, is an awful one. A crystallized lava, with a zone of granite, is what must surprise, if not perplex every beholder.

Let us now have done, recollecting, however, before we part, that we are greatly indebted to all the natural destruction we have been talking of, for all the artificial preservation which now gives such delight to the artist, the antiquary, and the man of taste. When Greece was dismantled by the Romans, and Rome by the Goths and by Christians, had it not been for volcanos and earthquakes, the inestimable works of antiquity would have been wrested from us for Bigotry and barbarism would have laid waste the works which had been the glory and the admiration of ages. But, Herculaneum and Pompeia were buried from ignorant research; Rome, likewise, in 345, had the earth shook upon some of the finest marbles, and hence they remain to us at this hour, and may continue to ages yet unborn.

LETTER XLII.

THERE is no subject on which philosophers have so much differed, nor concerning which they probably have more widely departed from truth, than that of time. Placed on one of the smallest planets in the infinite system of the universe, and which is, as it were, lost amidst the innumerable multitude of worlds, the child of this little spot fixes with himself an absolute criterion for the commencement of time; and gives it the existence of but a few insignificant centuries. This idea, pressed upon us in our infancy, forms the cloud, which obscures the horizon of our first thoughts. The recent origin of time is the first link of that great chain of error which fetters reason. How truly might we join with the Egyptian priest, in his reply to Solon: "You still are infants, or are very like them. You know of nothing older than yourselves. Puffed up with your own superiority, you are ignorant of all that has gone before you: you even believe, that with you the world began to exist." The uncertain opinion of nations, indeed, respecting their origin; the palpable evidence of their contradictions; and the distance there is between their general, as well as their comparative ideas, with respect to the antiquity of the earth, have, it must be confessed, afforded a plausible pretext for the doubtings of scepticism on the one hand, and to the assumption of infallibility on the other. But, the circumstances on which their respective pretensions are grounded, will, perhaps, be found to yield the strongest proofs of revolutions on the surface of this globe, and of the consequent close and regeneration of ages.

But, what is duration, or what is permanency? It is to common sense, nothing more than to exist free from destruction. Yet Locke says, "the more I endeavour to investigate the nature of time, the less I comprehend it. Time that unravels all things, is itself incomprehensible to me." All this mystery may, however, I conceive, be unravelled in a few words. The idea of duration is no other than what we have of a being, or action, which is neither discontinued nor destroyed. * The measure of du ration, by the regular revolution of some sensible object, as the annual course of the sun, the monthly monthly of the moon, or the diurnal of a hand on the dial-plate of a clock, is time. These notions appear as clear as possible; and whoever should attempt to set them in a clearer light, would not act wiser than he who should endeavour to explain in what manner two and two make four, and not five.

Amidst the extravagant traditions with which nations are universally replete, we may always find one which goes back to creation, and systematically details the origin and progressive formation of the world. This first existence we analogically trace from our own infantine situation.". As we have had a beginning, so must we suppose the system in which we are contained to have had its peculiar and appropriate birth. None, indeed, agree as to the epoch of this extraordinary occurrence. All, however, fix a moment, and calculate it exactly by ages. Thus, the greater part of modern historians and chronologers have divided the age of the world into six different epochas; but, even these historians and chronologers are not agreed between themselves with regard to the number of years contained in each interval. Those who place the creation six thousand years before the birth of Christ, make the interval between the creation

and