ANNIVERSARY ADDRESS OF THE PRESIDENT. 



Ixv 



the force of tlie argument, if not pushed beyond its legitimate bounds. 

 No one can contemplate future changes in physical geography with- 

 out foreseeing that the varying altitude and extent of polar and equa- 

 torial lands may give rise to an intensity of solar heat or glacial cold, 

 such as is not experienced now, and may never have been expe- 

 rienced on the earth ; for the combinations of circumstances on which 

 the climate of the globe most depend are so varied, that no one can 

 define or guess how far heat, cold, moisture, and other conditions, 

 may deviate from a mean state of things in the course of ages. But 

 speculations of this kind belong equally to the future, the past and 

 the present, and imply no inconstancy in the general condition of our 

 planet, such as is assumed in the hypothesis of its passage from a 

 chaotic to a fixed, stable and perfect state. Living as we do in an 

 sera which has immediately followed the glacial epoch, we are able to 

 comprehend the state of the northern hemisphere in European lati- 

 tudes, when cold like that of the arctic and antarctic circles extended 

 further from the poles towards the equator. We may also reason 

 philosophically on the state of the globe during the carboniferous 

 epoch, when there may have been little or no ice even at the poles. 

 We may conclude that in those days a warmer, damper, and more 

 uniform climate prevailed, when the Sigillaria, Lepidodendron, 

 Caulopteris, Calamite, and other fossil plants flourished, and when 

 there were reefs of coral in the adjoining seas. Such organic remains 

 may betoken, as our Foreign Secretary, Mr. Bunbury, has argued, 

 rather the absence of frost than, as many botanists once thought, an 

 intense tropical heat. M. Adolphe Brongniart, in his admirable 

 Essay on the genera of Fossil Plants, published in the year 1849*, has 

 questioned, and apparently with reason, the proofs hitherto adduced 

 in favour of the existence of any true palms in the coal-measures, 

 and Mr. Bunbury considers their absence as affording an additional 

 argument to that derived from the universal preponderance of ferns 

 in favour of a mild temperature in the atmosphere, — a warm, moist 

 and uniform climate, not a tropical one. The flora, he says, of the 

 London clay was of a much more tropical character. In this man- 

 ner we may now reason philosophically on the remote carboniferous 

 sera according to strict rules of induction ; but had we lived in that 



* Tableau des genres, etc. Dictionnaire Universelle d'Histoire Nat., Art. Vege- 

 taux Fossiles. 



