1867.] Louis Figuier. 171 



beholding such vivid representations of the manner in which nature 

 decked the earth at various times during a period of untold ages. 



The author seems to think that the internal heat of the earth 

 affected the temperature of the surface almost as much during the 

 Carboniferous period as it had done during the Silurian epoch. 

 Indeed, he imagines that our planet did not experience what we 

 call climate, until the commencement of the Tertiary period. " It 

 is a remarkable circumstance," he says,* "that this elevated 

 temperature combined with constant humidity does not seem to 

 have been limited to any one part of the globe ; the heat seems to 

 have been nearly the same in all latitudes from the equatorial 

 regions up to Melville Island in the Arctic Ocean, where in our 

 days eternal frost prevails; from Spitsbergen to the centre of 

 Africa, the Carboniferous flora is identically the same. When 

 nearly the same species, now extinct, are met with under the same 

 degree of development at the equator, as at the pole, we cannot 

 but admit that at this epoch the temperature of the globe was 

 alike everywhere. What we now call climate was then unknown, 

 in geological times. There seems to have been only one climate 

 over the whole globe. It was only at a later period, that is in 

 Tertiary times, owing to the gradual cooling of the globe, that the 

 cold began to make itself felt at the terrestrial poles. Whence then 

 proceeds this uniformity of temperature which we now regard with 

 so much surprise ? It was a consequence of the excessive heat of 

 the globe ; the earth was still so hot in itself that its own innate 

 temperature rendered the heat which it received from the sun 

 superfluous and inappreciable." That there existed a uniformly high 

 temperature over the whole globe, during the Carboniferous period, 

 does not necessarily follow from the character of the vegetation 

 alone. That a mild equable climate prevailed at that time rather 

 than a very elevated temperature is the more reasonable inference : 

 and we refer the reader to ' The Principles of Geology/f for an 

 admirable dissertation on the causes that might bring about such 

 a universally equable climate. The same inference concerning a 

 general prevalence of a high temperature over the earth might 

 seemingly be drawn from the nature of the plants of the Miocene 

 period, found in Iceland, North America, and Greenland, within the 

 Arctic circle. Professor Ramsay,! speaking on this subject, remarks, 

 " The meaning of this is not yet understood, for many of the plants are 

 of a nature that seem to bespeak a warmer climate than that of the 

 British Islands at the present day, and it is difficult to see how such 

 plants could grow in Arctic regions, where there is not the stimulus 

 of light during half the year. This is one of those things which 

 we cannot explain, and about which we are waiting for light." 

 Speaking of the genera of Carboniferous plants, Sir Charles Lyell§ 



* P. 120. t Ninth edition, p. 92. 



% ' Physical Geography and Geology of Britain.' § ' Principles/ 0th edition, p. 87. 



