THE STORY OF NINETEENTH-CENTURY SCIENCE 



is to say, if fossil A underlies fossil B in any given region, 

 it never overlies it in any other series ; though a kind of 

 fossils found in one set of strata may be quite omitted 

 in another. Moreover, a fossil once having disappeared 

 never reappears in any later stratum. 



From these novel facts Smith drew the common-sense 

 inference that the earth had had successive populations 

 of creatures, each of which in its turn had become extinct. 

 He partially verified this inference by comparing the 

 fossil shells with existing species of similar orders, and 

 found that such as occur in older strata of the rocks had 

 no counterparts among living species. But on the whole, 

 being eminently a practical man, Smith troubled himself 

 but little about the inferences that might be drawn from 

 his facts. He was chiefly concerned in using the key he 

 had discovered as an aid to the construction of the first 

 geological map of England ever attempted, and he left 

 to others the untangling of any snarls of thought that 

 might seem to arise from his discovery of the succession 

 of varying forms of life on the globe. 



He disseminated his views far and wide, however, in 

 the course of his journeyings quite disregarding the 

 fact that peripatetics went out of fashion when the 

 printing-press came in and by the beginning of our 

 century he had begun to have a following among the 

 geologists of England. It must not for a moment be 

 supposed, however, that his contention regarding the 

 succession of strata met with immediate or general ac- 

 ceptance. On the contrary, it was most bitterly an- 

 tagonized. For a long generation after the discovery 

 was made, the generality of men, prone as always to 

 strain at gnats and swallow camels, preferred to believe 

 that the fossils, instead of being deposited in successive, 



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