4 io HISTORY OF SCIENCE. 



tures attracted such a degree oPgeneral attention to geology as it had 

 never before received. From this period geology began to take the 

 form of a systematic science. Werner was the first to point out the 

 great practical advantage to miners of a knowledge of general geo- 

 logical principles. He also showed the various industrial uses of 

 minerals, and the influence of the nature of rocks and soils upon the 

 wealth and pursuits of the races of mankind. 



Werner's lectures were very eloquent, and attracted great numbers 

 of auditors and disciples from every country in Europe, and many 

 eminent men of science studied the German language with the view 

 of learning the principles of the new science from the lips of the 

 great teacher of the day. As he had a distaste for writing, and pub- 

 lished only two small essays, his general views were spread chiefly by 

 his pupils, who always returned from their studies in the mining school, 

 to which Werner had imparted the rank of a university, inspired with 

 unbounded confidence in their teacher's doctrines, and full of admira- 

 tion of his personal qualities. These doctrines at least, as they were 

 generally understood in the latter part of the eighteenth century were 

 briefly something like the following. The different rocks of which the 

 earth is composed were counted to number thirty-six, and they were 

 not promiscuously mixed, but had a definite relative position with re- 

 spect to each other. In general, they extend over the earth in layers 

 enclosing the central nucleus, and lying one upon another like the 

 several coats of an onion ; but from several causes they by no means 

 exhibit the kind of continuity and regularity which the comparison 

 suggests. They rise and fall with more or less abrupt inclination from 

 one place to another ; at some parts they are entirely absent, either 

 having never been deposited, or having been removed by some cause 

 after their deposition. The position of the different rocks as super- 

 imposed upon each other determines their classification. The rocks 

 which are supposed to have had a common origin are called a. forma- 

 tion, and of these formations five were recognized, viz. : i. Primitive ; 

 2. Transition; 3. Floetz; 4. Alluvial; 5. Volcanic. The rocks which 

 constitute the Primitive formation do not by any means everywhere lie 

 at the greatest depth below the surface. On the contrary, they fre- 

 quently constitute mountain chains ; and, in fact, the loftiest mountains 

 are composed of this formation. The Transition and Floetz formation 

 also frequently form mountains. The Primitive formation itself con- 

 sists of five kinds of rock, always following each other in the same 

 order, which, beginning from the lowest, is granite, gneiss, mica slate, 

 clay slate, porphyry. It is true there are certain other kinds of rock 

 interposed occasionally and to a limited extent between these, but 

 they are regarded as merely subordinate. Such are primitive traps, 

 quartz, flinty slate, gypsum, etc. The Primitive rocks contain no 

 " petrifaction " and no fragments of other rocks ; they must, therefore, 

 have been formed antecedently to all others. The Transition forma- 



