262 THE POPULAR SCIENCE MONTHLY. 



been completed. Having learned what to look for and how to in- 

 terpret it when seen, we are as it were gifted with a new sense. 

 Every landscape comes to possess a fresh interest and charm, for 

 we carry about with us everywhere an added power of enjoyment, 

 whether the scenery has been long familiar or presents itself for 

 the first time. I would therefore seek at the outset to impress 

 upon those who propose to read the following pages that one of 

 the main objects with which this book is written is to foster a 

 habit of observation and to serve as a guide to what they are 

 themselves to look for, rather than merely to relate what has 

 been seen and determined by others." At the very outset in this 

 work, geology is regarded, "not as an amusement for the collector 

 and a means of learning where he will get pretty and curious 

 objects for his cabinet ; not as a field where the ingenuity or per- 

 versity of the classifying mind may delight itself with grouping 

 natural products as reason prompts ; not in any other of those 

 limited aspects beyond which it is feared the wisdom of some 

 geologists never reaches ; but as a history — the history of the 

 earth in ages long gone by." 



Believing that no branch of the study should be overlooked, 

 we find him lamenting, in 1871, that while in all that relates to 

 stratigraphic geology the British had kept ahead of other nations, 

 they had allowed petrography, or the study of rock species, to 

 fall into disuse. Matters had improved, partly perhaps under his 

 own influence, in 1880, when, writing of the Mineralogical Society 

 of Great Britain, he remarked upon a revival of interest in min- 

 eralogy, which had before been neglected for fossil-hunting. 



In one of the reviews of Prof. Geikie's Science Primer of 

 Geology, in 1874, a curious omission is remarked, in that the 

 author had not referred to Darwin's theory of coral islands as 

 a "proof that a part of the crust of the earth has sunk down" 

 — the reviewer suggesting that to lead pupils up to this theory, 

 and then test it as Darwin had tested it, was " an excellent exer- 

 cise in that peculiar kind of reasoning about past causation which 

 is of the essence of geology." Prof. Geikie appears to have built, 

 as the saying is, better than he knew ; for in 1884 he confessed 

 himself reluctantly compelled, in view of Mr. Murray's observa- 

 tions in the Challenger Expedition, to admit that Mr. Darwin's 

 theory could no longer be accepted as a complete solution of the 

 problem of coral reefs. 



Prof. Geikie has long taken an intense interest in the Ameri- 

 can geological surveys, and has followed them up with the 

 closest attention for many years ; and his notices of their reports 

 and summaries of their results constitute a very considerable 

 part of his frequent contributions to Nature. He was fully im- 

 pressed with the magnitude and extent of the geological phe- 



