ADDRESS. Ivi 



times as great as that calculated in the usual suppositions of the conductive 

 power of the terrestrial mass at enormous depths, being no greater than that 

 of the superficial sedimentary beds. Other modes of investigation which 

 Mr. Hopiiins has brought to bear on this question appear to lead to the 

 conclusion that the thiclcness of the earth's crust is much greater even than 

 that above stated. This would require us to assume that a part of the heat 

 in the crust is due to superficial and external, rather than central causes. 

 This does not bear directly against the doctrine of central heat, but shows 

 that only a part of the increase of temperature observed in mines and deep 

 wells is due to the outward flow of that heat. 



Touching those highly interesting branches of science, Botany and Zoology, 

 it may be considered presumptuous in me to off'er any remarks. I have, 

 however, not entirely neglected in my earlier days to inform myself of certain 

 portions of natural history, which cannot but be attractive to all who delight 

 in the wonderful beauties of natural objects. How interesting is the organi- 

 zation of animals and plants; how admirably adapted to their different func- 

 tions and spheres of life ! They want nothing, yet have nothing superfluous. 

 Every organ is adapted perfectly to its functions ; and the researches of 

 Owen, Agassiz, Darwin, Hooker, Daubeny, Babington, and Jardiiie fully 

 illustrate the perfection of the animal and vegetable economy of nature. 



Two other important branches of scientific research, Geography and 

 Ethnology, have for some years been united, in this Association, in one 

 Section, and that probably the most attractive and popular of them all. We 

 are much indebted to Sir Roderick Murchison, among other Members of the 

 Association, for its continued prosperity, and the high position it has 

 attained in public estimation. The spirit of enterprise, courage, and perse- 

 verence displayed by our travellers in all parts of the world have been 

 powerfully stimulated and well supported by the Geographical Society ; and 

 the prominence and rapid publicity given to discoveries by that body have 

 largely promoted geographical research. 



In Physical Geography the late Baron von Humboldt has been one of the 

 largest contributors, and we are chiefly indebted to his personal researches 

 and numerous writings for the elevated position it now holds among the 

 sciences. To Humboldt we owe our knowledge of the physical features of 

 Central and Southern America. To Parry, Sir James Ross, and Scoresby, 

 we are indebted for discoveries in the Arctic and Antarctic regions. Geo- 

 graphy has also been advanced by the first voyage of Franklin down the 

 Copper Mine River, and along the inhospitable shores of the Northern Seas, 

 as far as Point Turn Again ; as also by that ill-fated expedition in search of 

 a north-west passage ; followed by others in search of the unfortunate men 

 who perished in their attempt to reach those ice-bound regions, so often 

 stimulated by the untiring energy of a high-minded woman. In addition to 

 these, the discoveries of Dr. Livingstone in Africa have opened to us a wide 

 field of future enterprise along the banks of the Zambesi and its tributaries. 

 To these we may add the explorations of Captain Burton in the same con- 

 tinent; and those also by Captain Speke and Captain Grant, of a hitherto 

 unknown region, in which it has been suggested that the White Nile has its 

 source, flowing from one of two immense lakes, upwards of 300 miles long 

 by 100 broad, and situated at an elevation of 4000 feet above the sea. To 

 these remarkable discoveries I ought to add an honourable mention of the 

 sagacious and perilous exploration of Central and Northern Australia by 

 Mr. M'Dougall Stuart. 



Having glanced, however imperfectly, at some of the most important 

 branches of science which engage the attention of Members of this Associa- 



