436 SCIENCE PROGRESS 



Antlitz der Erde (vol. ii. 1889), Jukes-Brown's Handbook of 

 Physical Geology (1892), Bonney's Story of our Planet (1893), 

 Geikie's Text-book of Geology (1893), Kayser's Lehrbuch der 

 allgemeinen Geologie (1893), Walther's Allgemeine Meereskunde 

 ( 1 893) and Einleitung in die Geologie ( 1 893), Penck's Morphologie 

 der Erdoberfldche ( 1 894 ; embayments are briefly considered), 

 Leconte's Elements of Geology (1895), Supan's Grundziige der 

 physischen Erdkunde (1896), Credner's Elemente der Geologie 

 (1897), Scott's Introduction to Geology (1897), Toulet's Ocean 

 (1904), de Lapparent's Traite de Geologie (1905), Haug's Traite 

 de Geologie (1907), Wagner's Lehrbuch der Geographie (1908), 

 de Martonne's TraitS de Geographie Physique (1909), Tarr and 

 Martin's College Physiography (1914), Pirsson and Schuchert's 

 Text-book of Geology (1915 ; embayments are very briefly 

 mentioned), or Lake's Physical Geography (191 5 ; embayments 

 are considered). 



Instability of Scientific Opinion. — It is interesting to review 

 certain articles cited above, which appeared shortly after 

 Murray had announced his still-stand theory of reef formation, 

 whereby Rein's previously announced theory of atolls was 

 brought into prominence. In spite of the incomplete analysis 

 of the problem then presented, the mere possibility of the for- 

 mation of atolls by upgrowth from stationary submarine banks 

 proved singularly disconcerting to many persons who had before 

 accepted Darwin's theory of subsidence, as if it were the only 

 possible theory. It was as if they said : — " Another method 

 of making atolls has now been proposed ; therefore the one 

 we have hitherto accepted is wrong." Such persons would 

 have been less disposed to abandon their former belief if they 

 had given due consideration to the evidence, which Darwin 

 pointed out for the subsidence theory, that is found in its 

 capacity to bring various kinds of reefs — fringing, barrier, and 

 atoll — into reasonable correlation, for the Rein-Murray theory 

 is deficient in this respect : still less would they have been 

 disposed to abandon Darwin's theory if they had perceived 

 that it accounts for the structural features associated with 

 fringing and barrier reefs — namely, the embayments of the 

 shorelines that they border, and the unconformable contact of 

 their limestones on eroded foundations — while the Rein-Murray 

 theory accounts only for atolls. 



Furthermore, the unchanging relation of land and sea-level 



