i88i.] SIR JOSEPH HOOKER'S ADDRESS. 425 



Keep your spirits up, for I am convinced that you will 

 make an excellent address. 



Ever yours, affectionately, 



Charles Darwin. 



[In September he wrote : — 



" I have this minute finished reading your splendid but 

 too short address. I cannot doubt that it will have been 

 fully appreciated by the Geographers of York ; if not, they 

 are asses and fools."] 



C. Darwin to John Lubbock. 



Sunday evening [1881]. 



My dear L., — Your address * has made me think over 

 what have been the great steps in Geology during the last 

 fifty years, and there can be no harm in telling you my im- 

 pression. But it is very odd that I cannot remember what 

 you have said on Geology. I suppose that the classification 

 of the Silurian and Cambrian formations must be considered 

 the greatest or most important step ; for I well remember 

 when all these older rocks were called grau-wacke, and 

 nobody .dreamed of classing them ; and now we have three 

 azoic formations pretty well made out beneath the Cambrian ! 

 But the most striking step has been the discovery of the 

 Glacial period : you are too young to remember the pro- 

 digious effect this produced about the year 1840 (.^) on all our 

 minds. Elie de Beaumont never believed in it to the day of 

 his death ! the study of the glacial deposits led to the study 

 of the superficial drift, which was formerly never studied and 

 called Diluvium, as I well remember. The study under the 

 microscope of rock-sections is another not inconsiderable step. 

 So again the making out of cleavage and the foliation of the 

 metamorphic rocks. But I will not run on, having now 

 eased my mind. Pray do not waste even one minute in ac- 

 knowledging my horrid scrawls. Ever yours, 



Ch. Darwin. 



* Presidential Address at the York meeting of the British Association. 



