ANjriVERSAKr ADDRESS OF THE PRESIDENT. XXXV 



But though the tendency of his researches in geology was mainly 

 towards the investigation of the phenomena connected with changes 

 in the outhne of the surface, he did not neglect the study of minerals 

 and rocks, in which he had been trained under Jameson. Previously 

 to 1836, with the view of learning more of the history of ancient 

 geological upheavals, he had examined " the trap rocks of our own 

 island, the ophites of the Pyrenees, and the serpentines of Anglesea 

 and the Lizard — the porphyries of I*[orthern Italy — the granite veins 

 of Mount's Bay and Glen Tilt — the ancient volcanoes of Auvergne, 

 the Eifel, the Siebengebirge, and of Eome — and the modern volcano 

 of Yesuvius." In December 1835 he gave to the Eoyal Society of 

 Edinburgh a narrative of his researches in central France, dwelling 

 more especially on the analogies between the volcanic rocks of that 

 district and the trappean masses of his own country. Throughout 

 his narratives of foreign travel, also, we everywhere meet with 

 indications that, though busied with what had become his own more 

 special branch of the science, he remained no indifferent observer of 

 the rocks among which his journeys led him. He retained his fond- 

 ness for mineralogy to the end. When I last saw him at St. 

 Andrews he showed me a collection of veined agates which he had 

 accumulated in the course of years, and with which he used 

 often to beguile a little leisure in trying to speculate upon the 

 manner in which the concentric siliceous coatings might have been 

 formed. 



In concluding this sketch of the late Principal's geological labours, 

 I must not forget that some of his researches, though in themselves 

 dealing with more or less distinctively physical questions, had often 

 important geological bearings. Such were some of his meteorological 

 investigations, and his carefully conducted experiments upon the 

 temperature of the earth at different depths and in different soils near 

 Edinburgh. These experiments were, I believe, the first made in 

 this country, with any degree of precision, to determine the rate at 

 which the temperature of the surface is conducted downwards, and 

 the variations due to differences in the nature of the material through 

 which the heat is transmitted. 



Sir David Brewster was born at Jedburgh in December 1781, 

 and had thus attained the advanced age of more than eighty-six years 

 when he died in Eebruary of last year. During this long life his 

 scientific activity was incessant, and the stream of his original 

 papers, some 300 in number, flowed on without a check. 



Nor did this singular fertility by any means exhaust Sir David 

 Brewster's energies. He wrote in the Reviews frequently and well ; 

 he edited the ^ Edinburgh Encyclopaedia,' and shared in editing the 

 ' Edinburgh Philosophical Journal,' the ' Edinburgh Journal of 

 Science,' and the ' Philosophical Magazine.' He founded the 

 Scottish Society of Arts, and helped to found the British Association ; 

 he was Principal of St. Andrews, and afterwards of Edinburgh IFni- 

 versity ; he was long Secretary of the Royal Society of Edinburgh, 

 and he died the President of that learned body. 



