52 Eminent Living Geologists : Rev. Osmond Fisher. 



felt compelled to give up the contraction theory in its original form. 

 Crust-folding he still attributed to lateral pressure brought into 

 action by a shrinking interior, and he refers, though not with entire 

 approval, to the view which he repeated in the first edition of his 

 future work that the earth consists of a solid crust and nucleus with 

 an intervening liquid layer,' 



The third of the Cambridge memoirs, read in February, 1875, shows 

 that his belief in such a constitution had gradually strengthened ; for 

 he investigates the form into which a uniformly thin flexible crust 

 would be thrown if the support of the liquid substratum were from 

 any cause withdrawn. 



About this time, the direction of Mr. Fisher's inquiries was slightly 

 changed. Mr. Mallet had shortly before published his well-known 

 memoir dealing with the origin of volcanic energy. There is 

 a fascination about the theory he advanced, but Mr. Fisher's 

 quantitative analysis at once laid bare its weak point, though several 

 months elapsed before the controversy was closed. 



The evening of an active life can hardly be better employed than 

 in revising the work of earlier years, and this is especially the 

 case when that work has been devoted mainly to the solution of 

 a connected series of problems. It can then be regarded almost 

 as calmly as if it were another man's ; there is ample time for 

 considering criticisms without bias, for filling up gaps, and for 

 exhibiting all the different portions in their true relations to one 

 another. In 1880, at the age of 63, Mr. Fisher began the work 

 with which his name will always be connected. The " Physics 

 of the Earth's Crust " is, bowevei-, not merely a reprint or revision. 

 It included, indeed, all those parts of his memoirs which seemed 

 to him worthy of preservation, but the additional material forms 

 a notable fraction of the whole. The book was published at the 

 end of 1881, and in spite of its highly technical character, has from 

 the very first met with a considerable sale. 



Many a man, after so great a success, might have been content to 

 rest upon his laurels. But Mr. Fisher seems to have regarded this 

 first edition as a mere instalment, as a kind of guarantee that his 

 work should not be wasted by sudden illness or death. During the 

 years which followed he has not ceased to strengthen his theory, by 

 building up fresh defences and by raids into the enemy's country. 

 By 1889 a second edition had in his opinion become necessary (the 

 remainder of the first being withdrawn from sale), and in 1891 this 

 was supplemented by an appendix of three additional chapters. 



Besides the papers incorporated in the " Physics of the Earth's 

 Crust," Mr. Fisher has written many others, which have appeared 

 in different scientific journals. The last of the series was published 

 only seven months ago in the Philosophical Magazine, and deals 

 with the residual effect of a former Glacial epoch upon underground 

 temperature. 



The Geological Society, always so ready to welcome the contribu- 

 tions of mathematical geologists, awarded Mr. Fisher the balance of 



1 At present he regards the solidit_v or otherwise of the nucleus an open question. 



