1840-1881] EARTH-MOVEMENTS 131 



evidence I will never admit that a dike joins on rectangularly Letter 486 

 to a stream of lava. Your argument about the perpendicu- 

 larity of the dike strikes me as good. 



The map of Etna, which I have been just looking at, 

 looks like a sudden falling in, does it not ? I am not much 

 surprised at the linear vent in Santorin (this linear tendency 

 ought to be difficult to a circular-crater-of-elevation-be- 

 liever), I think Abich l describes having seen the same actual 

 thing forming within the crater of Vesuvius. In such cases 

 what outline do you give to the upper surface of the lava in 

 the dike connecting them ? Surely it would be very irregular 

 and would send up irregular cones or columns as in my 

 above splendid drawing. 



At the Royal on Friday, after more doubt and misgiving 

 than I almost ever felt, I voted to recommend Forbes for 

 Royal Medal, and that view was carried, Sedgwick taking 

 the lead. 



I am glad to hear that all your party are pretty well. 

 I know from experience what you must have gone through. 

 From old age with suffering death must be to all a happy 

 release. 2 



I saw Dan Sharpe 3 the other day, and he told me he had 

 been working at the mica schist (i.e. not gneiss) in Scotland, 

 and that he was quite convinced my view was right. You 

 are wrong and a heretic on this point, I know well. 



1 Geologische Beobachtungen liber die vulkanischen Erscheinungen 

 und Bildimgen in Unter- und Mittel-Italien. Braunschweig, 1841. 



3 This seems to refer to the death of Sir Charles LyelPs father, which 

 occurred on Nov. 8th, 1849. 



3 Daniel Sharpe (1806-56) left school at the age of sixteen, and 

 became a clerk in the service of a Portuguese merchant. At the age 

 of twenty-four he went for a year to Portugal, and afterwards spent 

 a considerable amount of time in that country. The results of his 

 geological work, carried out in the intervals of business, were published 

 in the Journal of the Geological Society of London (Quart. Journ. Geol. 

 Soc., Vol. V., p. 142 ; Vol. VI., p. 135). Although actively engaged in 

 business all his life, Sharpe communicated several papers to the Geo- 

 logical Society, his researches into the origin of slaty cleavage being 

 among the ablest and most important of his contributions to geology 

 (Quart. Journ. Geol. Soc., Vol. III., p. 74; Vol. V., p. ill). A full 

 account of Sharpe's work is given in an obituary notice published in the 

 Quart. Jotirn. Geol. Soc., Vol. XIII., p. xlv. 



