PREFACE TO THE SECOND EDITION. 



readers as are well acquainted with the syllogistic logic to 

 pronounce upon the comparative simplicity and power of 

 the new and old systems. For other acute objections 

 brought forward by Mr. Eobertson, I must refer the reader 

 to the article in question. 



One point in my last chapter, that on the Results and 

 Limits of Scientific Method, has been criticised by 

 Professor W. K. Clifford in his lecture 1 on " The First 

 and the Last Catastrophe." In vol. ii. p. 438 of the 

 first edition (p. 744 of this edition) I referred to certain 

 inferences drawn by eminent physicists as to a limit to 

 the antiquity of the present order of things. " According 

 to Sir W. Thomson's deductions from Fourier's theory of 

 heat, we can trace down the dissipation of heat by con- 

 duction and radiation to an infinitely distant time when 

 all things will be uniformly cold. But we cannot similarly 

 trace the Heat-history of the Universe to an infinite 

 distance in the past. For a certain negative value of the 

 time, the formula give impossible values, indicating that 

 there was some initial distribution of heat which could 

 not have resulted, according to known laws of nature, 

 from any previous distribution." 



Now according to Professor Clifford I have here mis- 

 stated Thomson's results. " It is not according to the 

 known laws of nature, it is according to the known laws 

 of conduction of heat, that Sir William Thomson is speak- 

 ing. . . . All these physical writers, knowing what they 

 were writing about, simply drew such conclusions from 

 the facts which were before them as could be reasonably 

 drawn. They say, here is a state of things which could 

 not have been produced by the circumstances we are at 

 present investigating Then your speculator comes, he 

 reads a sentence and says, ' Here is an opportunity for 

 me to have my fling.' And he has his fling, and makes a 

 purely baseless theory about the necessary origin of the 



1 Fortnightly Review, New Series, April 1875, p. 480. Lecture re- 

 printed by the Sunday Lecture Society, p. 24. 



