NATURAL HISTORY OF THE EIGHTEENTH CENT. 407 



which took the lead in the revival was that in which arose the first rays 

 of the dawn of geological inquiry. Cardano, in a work published in 

 1552, explained the presence of fossil shells in the mountains by the 

 sea having formerly reached the places where the fossils are found. 

 Majoli suggested that the shells might have been cast up by some sub- 

 marine volcanic eruptions. It would be tedious to enumerate all the 

 early Italian writers and their opinions ; but it may be remarked that, 

 long before similar inquiries were pursued in other countries, we find 

 Steno, a professor of Padua, teaching many of the fundamental facts of 

 geology. He recognized a secondary formation, in which fragments 

 of other rocks were imbedded ; he distinguished marine from fresh- 

 water strata, and he believed that all such strata were originally hori- 

 zontal, but had been inclined by the action of fires from below up- 

 heaving the earth's crust. Scilla, a Sicilian artist, published a work 

 on fossils in 1670, in which he found it necessary to argue in favour of 

 their being the remains of animals which once really existed. Scilla 

 seems to have supposed that all fossil shells were traces of the effects 

 of the Mosaic Deluge. This view was subsequently advanced again 

 and again ; it was as often shown to be inadequate to explain the facts. 



A few authors there are who wrote at the close of the seventeenth 

 century, whose geological speculations deserve some attention as the 

 precursors of the more modern doctrines. We will first name Leibnitz, 

 who was so illustrious by his attainments in many different branches 

 of learning and science. In a work published in 1680, Leibnitz pre- 

 sents a sketch of his general views, and even in the present day it would 

 be difficult more clearly to describe the probable course of the evolu- 

 tion of the earth, such as we now see it, from the molten glowing mass, 

 which he assumes to have been its primordial state. He supposes that 

 the outer crust cooled down and solidified into certain fundamental 

 rocks. The crust, in solidifying, formed cavernous hollows, and when 

 it had become sufficiently cool to allow of the deposition of aqueous 

 vapours a vast sea enveloped the earth; but, by the breaking in of the 

 vaulted hollows in the crust, the level of this ocean was. lowered. The 

 disruptions of the crust of the earth and these submarine disturbances 

 must have caused great oscillations of the water, which would wear 

 down much solid matter that in times of quiescence would fall to the 

 bottom of the sea. The strata so formed would, by consolidation, be 

 brought into compact masses. By the repetition of similar frequent 

 alternations a succession of strata would be produced, until the causes 

 of disturbance would be reduced to a nearly balanced condition, and 

 a more permanent state of things would result, after the face of the 

 earth had been many times renewed. 



Among the " Posthumous Works of Robert Hooke," published in 

 1705, appeared a "Discourse on Earthquakes." Hooke was, as we 

 have already had occasion to remark, a very extraordinary man, with 

 regard to the extent of his acquirements and the originality and sug- 



