Let us now glance at the history and progress of knowledge in these two chief domains of Vulcanicity, preparatory to a sketch of its existing stage as to both, and, by the way, attempt to extract a lesson as to the methods by which such success as has attended our labours has been achieved. It will be most convenient to treat of Seismology first in order. Aristotle--who devotes a larger space of his Fourth Book, Περἱ Κοσμου, to Earthquakes--Seneca, Pliny, Strabo, in the so-called classic days, and thence no end of writers down to about the end of the seventeenth century--amongst whom Fromondi (1527) and Travagini (1679) are, perhaps, the most important now--have filled volumes with records of facts, or what they took to be such, of Earthquakes, as handed down to or observed by themselves, and with plenty of hypotheses as to their nature and origin, but sterile of much real knowledge. Hooke's "Discourses of Earthquakes," read before the Royal Society about 1690, afford a curious example of how abuse of words once given by authority clings as a hindrance to progress. He had formed no distinct idea of what he meant by an Earthquake, and so confusedly mixes up all elevations or depressions of a permanent character with "subversions, conversions and transpositions of parts of the earth," however sudden or transitory, under the name of Earthquakes. A like confusion is far from uncommon amongst geological writers, even at the present day, and examples might be quoted from very late writings of even some of the great leaders of English Geology. From the seventeenth to the middle of the eighteenth century one finds floods of hypotheses from Flamsteed, Höttinger, Amontons, Stukeley, Beccaria, Percival, Priestly, and a crowd of others, in which electricity, then attracting so much attention, is often called upon to supply causation for a something of which no clear idea had been formed. Count Bylandt's singular work, published in 1835, though showing a curious _partial_ insight in point of advancement, might be put back into that preceding period.