78 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



sea withdrew into these crust-cavities, and at the same time 

 the areas of denser precipitation became land. Volcanic 

 eruptions invariably originated in these primitive air and vapour 

 chambers in the earth's crust, which were moreover frequently 

 connected with one another by crust-fissures. 



It is unnecessary to enter into the further details of De 

 la Metherie's Theory. Two years after its publication, 

 Bertrand, another French geologist, wrote New Principles of 

 Geology*^ a work contesting De la Metherie's conceptions, but 

 not in itself contributing any new facts of value to science. 

 Ballenstedt, a German pastor, was the author of a book 

 entitled Die Urwelt (or the Primeval World\ which was 

 widely read in scientific and literary circles. It endeavoured 

 to " expound the Biblical stories in a sensible way," and went 

 so far as to affirm that all human races had not descended 

 from the one pair in Paradise, but that there had been 

 originally several well-defined human species. 



Scipio Breislak (1748-1826), an Italian, deserves to be 

 remembered for his determined opposition to the Neptunian 

 doctrines. In his Text-book of Geology he tries to demon- 

 strate that the earth was originally in a fluid state, but that the 

 volume of water now present on the globe would be absolutely 

 insufficient to dissolve the solid material of the crust. 



Further, the presence in earlier epochs of a much greater 

 volume of water was a mere hypothesis, so also was the con- 

 ception of internal crust-cavities into which large quantities of 

 water might have withdrawn after the separation of the rock- 

 precipitates. Again, there was no positive evidence that the 

 surface of the ocean had sunk. The cases of apparent retreat 

 of the sea from the coasts of Scandinavia, or in the Gulf of 

 Naples, might be just as well explained by oscillatory move- 

 ments of the earth's crust as by the supposed general lowering 

 of the sea-level. After Breislak had demonstrated the im- 

 possibility of a fluid state of the earth with water as the 

 solvent, he tried to prove that the primitive fluidity of earth 

 substances had been due to their intimate admixture and 

 combination with heat-particles. Breislak imagines the earth 

 in its first periods of formation as a confused cosmic mass 

 soaked in heated matter, and therefore more or less molten. 

 Two modes of heat are distinguished by Breislak, free heat, 

 which calls forth the sensation of heat, and combined heat, 

 which is not perceptible to the senses, but whose combination 



