AGE OF THE EARTH AS AN ABODE FITTED FOR LIFE. 341 



" I am as incapable of estimating" and understanding the reasons which 

 you physicists have for limiting geological time as you are incapable of 

 understanding the geological reasons for our unlimited estimates." I 

 answered, "You can understand physicists' reasoning perfectly if you 

 give your mind to it." I ventured also to say that physicists were not 

 wholly incapable of appreciating geological difficulties; and so the 

 matter ended, and we had a friendly agreement to temporarily differ. 



9. In fact, from about the beginning of the century till that time 

 (1867), geologists had been nurtured iu a philosophy originating with 

 the Huttonian system ; much of it substantially very good philosophy, 

 but some of it essentially unsound and misleading — witness this from 

 Playfair, the eloquent and able expounder of Button: 



"How often these vicissitudes of decay and renovation have been 

 repeated is not for us to determine; they constitute a series of which, as 

 the author of this theory has remarked, we neither see the beginning 

 Bor the end; a circumstance that accords well with what is known con- 

 cerning other parts of the economy of the world. In the continuation 

 of the diiferent species of animals and vegetables that inhabit the 

 earth, we discern neither a beginning nor an end; in the planetary 

 motions, where geometry has carried the eye so far both into the future 

 and the past, we discover no mark either of the commencement or the 

 termination of the present order." 



10. Led by Hutton and Playfair, Lyell taught the doctrine of eter- 

 nity and uniformity in geology; and to explain plutonic action and 

 underground heat, invented a thermoelectric '^ perpetual" motion on 

 which, in the year 18(12, in my paper on the "Secular cooling of the 

 earth," ^ published in the Transactions of the Eoyal Society of Edin- 

 burgh, I commented as follows : 



"To suppose, as Lyell, adopting the chemical hypothesis, has done,^ 

 that the substances, combining together, may be again separated elec- 

 trolytically by thermo electric currents, due to the heat generated by 

 their combination, and thus the chemical action and its heat continued 

 in an endless cycle, violates the principles of natural philosophy in 

 exactly the same manner, and to the same degree, as to believe that a 

 clock constructed with a self-winding movement may fulfill the expecta- 

 tions of its ingenious inventor by going forever." 



It was only by sheer force of reason that geologists have been com- 

 j)elled to think otherwise, and to see that there was a definite beginning, 

 and to look forward to a definite end, of this world as an abode fitted 

 for life. 



11. It is curious that English philosophers and writers should not 

 have noticed how Newton treated the astronomical problem. Playfair, 

 in what I have read to you, speaks of the planetary system as being 

 absolutely eternal, and unchangeable; having had no beginning and 

 showing no signs of progress toward an end. He assumes also that 



' Reprinted in Thomson and. Tait, Treatise on Natural Philosophy, first and second 

 editions, Appendix D (g). 

 2 Principles of Geology, Chapter XXXI, edition 1853. 



