THE ELEMENTS OF NATURAL PHILOSOPHY 203 



share of the task. In the revision of the proof sheets for the second edition, 

 Thomson's whole method of working seriously exercised the printers. 



Any new aspect which opened up to his mind as he read the pages of 

 the first edition led at once to expansion and interpolation, sometimes of the 

 most alarming dimensions. The great sheet on which the original page was 

 pasted became covered with the new matter ; bits were pasted on like wings 

 bearing precious symbols ; while, not unfrequently, the discussion overflowed 

 into extra sheets, subsection after subsection being piled on regardless of 

 space and proof correction charges. Difficult indeed was the proof reading 

 in such circumstances ; and both Kelvin and Tait felt always deeply grateful 

 to Professors Burnside and Chrystal and Sir George Darwin for the aid they 

 gave in the final correction of the sheets. The last-named, in fact, added 

 several sections to the second volume on the problems of tidal action. 



Richer and fuller and more complete in many respects though the second 

 edition was, it could not excel in beauty of printing the original first volume, 

 which though finally published in Oxford was printed by Constable of 

 Edinburgh. The authors refer to this very pointedly in the preface, as well 

 as to the great care with which the diagrams were made. 



No finer tribute to the remarkable influence of " T and T'" could be 

 penned than that with which Clerk Maxwell enriched the pages of Nature 

 (Vol. xx), when he reviewed the new edition, Vol. i, Part i, shortly before his 

 death. A few quotations form a fitting conclusion to this sketch of the 

 genesis and growth of one of the most important scientific publications of the 

 Nineteenth Century. 



" What," asked Maxwell, " is the most general specification of a material system 

 consistent with the condition that the motions of those parts of the system which 

 we can observe are what we find them to be? It is to Lagrange in the first place 

 that we owe the method which enables us to answer this question without asserting 

 either more or less than all that can be legitimately deduced from the observed facts. 

 But though the method has been in the hands of mathematicians since 1788, when 

 the Me"canique Analytique was published, and though a few great mathematicians, 

 such as Sir W. R. Hamilton, Jacobi, etc., have made important contributions to the 

 general theory of dynamics, it is remarkable how slow natural philosophers at large 

 have been to make use of these methods. 



" Now however we have only to open any memoir on a physical subject in order 

 to see that these dynamical theorems have been dragged out of the sanctuary of 

 profound mathematics in which they lay so long enshrined, and have been set to 

 do all kinds of work, easy as well as difficult, throughout the whole range of 

 physical science. 



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