appearance of islands, sometimes in connection with vulcanism, sometimes as the result of other causes, thinkers were led to conceive the possibility of large land-masses, or even continents, undergoing elevation and subsidence. Areas were known which the sea had invaded, and other tracts were pointed out where submergence was plainly indicated. Thus Xenophanes, in the sixth century b.c., and after him Xanthus, Eratosthenes, Herodotus and others, not only entertained the idea of continental subsidence, but interpreted fossil remains of marine animals as evidence of former submergence. When we come to Aristotle, Posidonius and Strabo, we find that their opinions concerning oscillations of the sea-level and other progressive changes of the earth's surface are worthy of modern geologists. This phase of the subject has been so ably treated by Lyell in his 'Principles of Geology,' by Lasaulx, in his 'Geology of the Greeks and Romans,' and more recent writers, that it must be more or less familiar to all. That which is important to remember, however, is that local manifestations of vulcanism, dispersed over a wide region, and isolated examples of inconstancy of the sea-level, should have been viewed from the uniformitarian standpoint at a period so far antedating our own, should have been reduced to a general system, and should have led to the framing of hypotheses to account for them which have a singularly modern aspect. One can not but marvel that some of the most difficult problems in geology were solved by rational methods, and in the main accurately, by those ardent questioners of nature who often seem to have grasped intuitively that which has cost the rest of the world centuries of patient effort to rediscover.
The limits assigned to the present article do not permit us to examine Roman contributions to the study of vulcanism, interesting as such an inquiry would be. Nor have we attempted in this sketch to enumerate all of the lesser luminaries of Greek science who assisted, either by accumulation of facts, or by cleverness in putting them together, toward a fuller understanding of important principles of geology. Archelaus, Diogenes of Apollonia, Metrodorus of Chios, author of a famous 'Treatise on Nature,' Empedocles, whom a characteristic but probably apochryphal narrative reputes to have perished in Etna's crater,—these and various others have been passed over in silence. Enough has been said, however, to indicate the general trend of investigation and some of its fruitful conclusions. This brief sketch will have succeeded in its purpose if any shall become interested to pursue the subject independently in its details. Such retrospect has not only a broadening value, but is well-nigh incumbent upon all who would escape the fate against which Goethe so energetically warns us:
Wer nicht von dreitausend Jahren
Sich weiss Rechenschaft zu geben,
Bleibt im Dunkeln, unerfahren,
Mag von Tag zu Tage leben.
