CHAP. I., 1.] 



PLAN OF THIS DISSERTATION. 



( 17 -) But the extended domain of the science of the 

 variety of ^ as ^ hundred years enhances vastly the difficulty of the 

 materials, subjects succinctly handled as one by Mr Playfair. 

 The mechanical and experimental sciences alone con- 

 stitute a body of knowledge so large that it is a respon- 

 sibility sufficient for one person to attempt to grasp 

 them all, and to set forth in order the steps of pro- 

 gress and improvement which have been so rapid, and 

 even so startling. Since some of these have scarcely 

 as yet been historically digested, and the broad 

 features of contemporary discovery have not been 

 gradually separated by the judgment of an impartial 

 posterity from those slighter though praiseworthy 

 details, which lapse of time and advance of know- 

 ledge will throw into the shadows of distance, this 

 difficult and most laborious task falls principally 

 upon the reviewer. The length and breadth of the 

 subject of Natural Philosophy, and the cumbrous 

 and scattered depositories of knowledge in which 

 its records must be sought, combine to render not 

 only the undertaking an arduous one, but the 

 result of it a good deal more bulky than might be 

 desired, or than was easily possible, in dealing with 

 the glorious, but compact, history of Newton's age. 

 It might be compared to the difference between writ- 

 ing a history of the Jews or Romans and that of the 

 whole of modern Europe. 



The mere magnitude of the undertaking, then, 

 m ^ n ^ we ^ excuse me from entering upon the cog- 

 nate, but exceedingly distinct, subjects of the Logic 

 of Inductive Discovery and the progress of the Pure 



Mathematics. But an equally sound reason might 

 be found in my consciousness of inadequacy to un- 

 dertake, whatever had been the dimensions of my 

 work, a threefold scheme of such magnitude and 

 difficulty. I do not think that any one person could 

 be found to treat the whole as it ought to be treated, 

 and I am certain that I am not that person. 



One attempt a bold and successful one has (19.) 

 been made, in our own day, to unite two of the Writings of 

 three departments, I mean the History and the ^^81^ 

 Philosophy of the Inductive Sciences. An English art Mill, 

 philosopher of wonderful versatility, industry, and 

 power has erected a permanent monument to his 

 reputation in a voluminous work bearing the pre- 

 ceding title. 1 A slight inspection of that work will 

 show how impracticable and self-destructive a plan it 

 would have been to attempt anything like a syste- 

 matic abridgment of such a mass of facts and specu- 

 lations within our present limits. Mr J. Stuart Mill 

 has also published a work bearing on the origin of 

 our scientific knowledge, diametrically opposed in 

 principle to the preceding one, yet marked by great 

 ability. 2 Such disquisitions belong more properly 

 to the philosophy of the human mind than of phy- 

 sics. After all, be it remembered that whatever has 

 been learnt or discussed concerning the means of 

 arriving at truth in Natural Science, it is not pre- 

 tended that we have recently become possessed of 

 any canons or rules of discovery superseding those 

 fundamental principles of observation and experi- 

 ment so well laid down by Bacon, and practised both 



the present volume will bear an enduring testimony. Playfair's original contributions to science were not so marked and consi- Character 

 derable as to justify me in including his name in the comparatively brief catalogue of discoverers chronicled in the succeeding of Professor 

 pages ; but his efforts are, nevertheless, deserving of notice, and indirectly were perhaps hardly less beneficial. He was a most Playfair. 

 patient and admiring student of the greatest mathematical writers of his time, and, when we consider the singularly backward 

 state of that science in Great Britain about the end of the last and commencement of the present century, it was of no slight im- 

 portance to find a man placed in the position of a public instructor able and willing to direct attention to the splendid achieve- 

 ments of the continental mathematicians. By his lectures both on Mathematics and Natural Philosophy by his luminous articles 

 in the Edinburgh Review by some of his original papers in the Transactions of the Royal Society of Edinburgh he contributed 

 to this useful end, and would have done so still farther had he been enabled to complete the Dissertation which he so ably com- 

 menced. He had an excellent mathematical capacity, and mathematical taste, rather than power. His explanations, even of 

 matters of inherent difficulty, are perspicuous and popular, qualities possessed by few of his contemporaries. His style has been 

 pronounced by the highest authorities to be a model of clearness and eloquence. He was extensively read in subjects of meta- 

 physics and morals, as well as of pure science ; and by a combination of talent rare, I am inclined to say, in a high degree, his 

 taste, though eminently mathematical, was also directed, with signal success (at first through his intimate friendship for Dr Button), 

 to the very opposite studies of Geology and Physical Geography, which may be said to have been the subjects of his predilection 

 during the last twenty years of his life. Nor were these labours of the closet merely ; he was far more intimately versed in the 

 mineral structure of the earth, from observation, than any except a few professed geologists ; and he exceeded them all in the 

 ability with which he expounded and maintained the striking doctrines of the Huttonian theory. Though professedly the "illus- 

 trator" of the principles specifically but obscurely laid down by Hutton, he certainly added much of his own. There is no rea- 

 son to doubt that Playfair first apprehended the moving power of glaciers as geological agents in modifying the surface of Alpine 

 countries, a matter which has of late been so earnestly discussed by the ablest geologists. 



What adds to the singularity of the combination of tastes and talents to which I have referred is, that he appears to have 

 had the slightest possible taste for that art of experiment which he eloquently advocated, with Bacon, as the grand distinction of 

 modern science. I may be wrong in stating it broadly, but I do not now recollect a single experimental novelty, much less dis- 

 covery, which we owe to Playfair, I mean in the department of Natural Philosophy; for we cannot include barometrical mea- 

 surements under this head, of which, indeed, it was the mathematical theory, and not the application to practice, which chiefly 

 occupied him. The same was the case in Astronomy, which, of the mechanical sciences, interested him most. In two capacities he 

 will be remembered, first, as the able, eloquent, and generally impartial and accurate Historian of Science ; secondly, as the 

 promoter, to so great a degree as to be considered a second founder, of modern Dynamical Geology. He was much beloved in 

 private life, and was singularly free from the tendency to carping criticism and personal prejudices sometimes, unfortunately, 

 found in men of letters. He was the intimate associate of Jeffrey and the other founders of the Edinburgh Review. 

 His character has been drawn in three words by Sir James Mackintosh, and as happily contrasted with that of his illustrious 



friend : " Playfair and Jeffrey ; the first a person very remarkable for understanding, calmness, and simplicity, the 



second more lively, fertile, and brilliant than any Scotchman of letters " (Life of Sir James Mackintosh, ii. 251). 



1 Whewell's History and Philosophy of the Inductive Sciences, 5 vols. 8vo. 2 Alill's Logic, 2 vols. 8vo. 



