176 REPORT— 1860. 



chronology of the earth, the observation of organic remains alone can never 

 supply reliable data for reasoning. If we should attempt to draw inferences 

 from biological analogies, and measure the duration of beds by the growth of 

 imbedded skeletons, we should be stopped by the probability that the first 

 species of every series were successively created in a stale of full-grown 

 maturity*, and by the intrinsic weakness of all comparisons instituted non 

 pari materia. 



Neither can any precarious mechanical analogies render the inquiry more 

 definite, or give a logical value to our conclusions. We are not entitled 

 to presume that the forces which have operated on the earth's crust have 

 always been the same. Were we to compare the beds of modern seas and 

 lakes with the ancient strata, and assume proportionable periods for their 

 accumulation, we must assume also that chemical and mechanical forces 

 were never in a state of higher intensity, that water was never more rapidly 

 evaporated, that greater torrents, fluid or gaseous, never flushed the lakes and 

 seas, and that more frequent elevations and depressions never gave scope for 

 quicker successions of animal life. To gain any real insight into these ob- 

 scure pages of ancient history, we must have recourse to a strict induction 

 of physical and chemical facts, and thence learn the probable course, and 

 causes, of the wonderful series of changes which geology unfolds. 



I am not aware that any full and connected statement has been published 

 of the facts which have been contributed by physical observations, and 

 chemical experiment, towards elucidating the conditions of those changes, 

 and propose therefore to preface the account which I have to give of experi- 

 ments designed to throw light upon them, with a sketch of the progress of 

 science in that department. 



Forty years have elapsed since the author of the ' Mecanique Celeste ' 

 drew attention to the fact that multiplied observations in deep mines, wells, 

 and springs, had proved the existence of a temperature in the interior of the 

 earth increasing with the depth. He remarked that, by comparing exact 

 observations of the increase with the theory of heat, the epoch might be 

 determined at which the gradually cooling globe had been first transported 

 into space ; he stated the mean increase, collected from actual data, to be a 

 centesimal degree for every 32 f metres, and added that this is an element 

 of high importance to geology. " Not only," he said, "does it indicate a very 

 great heat at the earth's surface in remote times, but if we compare it with 

 the theory of heat, we see that at the present moment the temperature of 

 the earth is excessive at the depth of a million of metres, and above all at 

 the centre ; so that all that part of the globe is probably in a state of fusion, 

 and would be reduced into vapour, but for the superincumbent beds, the 



* To suppose otherwise with regard to animals which take care of their young would be 

 absurd ; and hence it is probable also that this is the general system of creation. The most 

 remarkable fact which modern geology has disclosed is the continual succession of newly- 

 created species. It has been attempted to account for thes3 according to known laws ofpro- 

 geniture, by supposing numerous non-apparent links of transitional existence to fill up the 

 gaps in the chain of derivation by which one species is presumed to have descended from 

 another. But this is only twistiug a rope of sand ; conjectural interpolations cannot give 

 coherence to a set of chains which are destitute of all evidence of continuity one with 

 another, and between which, as far as our experience goes, Nature has interposed a prin- 

 ciple of disconnexion. 



In using the word creation, we acknowledge an agent, and own our ignorance of the 

 agency, with regard to which, in this case, we only know that it is systematic ; for we see 

 successive species accommodated to successive conditions of existence. 



t M. Babinet (Tremblements de Terre, 1856), taking M. Walferdin's measurement from 

 artesian borings, which gave 31 metres for 1° C. as the most exact, remarks, that the tem- 

 perature at the depth of 3 kilometres must be above the heat of boiling water, and at that 

 of 60 kilometres, about 2000° C, sufficing for the fusion of lava, basalt, trachyte, and 

 porphyry. 





