?o6 



NA rURE 



[July 25, 1901 



formulating both the facts and the theories of natural 

 philosophy which was the greatest part of his genius as a 

 physicist. Through the works and personal influence of 

 Hamilton he was led to the study of quaternions — the 

 source and inspiration of his most important contribu- 

 tions to pure mathematics. 



In i860 he was elected to the chair of natural philo- 

 sophy in Edinburgh, which he was to hold for forty years 

 with ever-increasing distinction. In that time a great 

 army of students ^ has passed through his class room, 

 and few have done so without carrying away with them 

 the image of a great man and a notable teacher. A 

 select number, not a few, have caught some of the 

 original fire of their master and have gone abroad upon 

 the earth to spread his ideas and practise his methods. 



Of late years, mainly from want of funds, the labora- 

 tory equipment of Edinburgh University has been 

 temporarily eclipsed by grander installations elsewhere ; 

 but it must never be forgotten that Tait was one of the 

 first teachers in Great Britain to organise laboratory 

 teaching for his students. Among his first ''researchers" 

 were a remarkable trio — Robert Louis Stevenson, William 

 Robertson Smith and John Murray. No man but Tait 

 could have drawn forth and brought together three men 

 so highly distinguished, so utterly different. The popular 

 estimates of the contributions of Murray and Stevenson 

 to science would likely be correct ; but it is probably not 

 generally known that Robertson Smith made at least one 

 important contribution to physical science, and was for a 

 time Tait's assistant. He visited his old master regularly 

 as long as he lived, and adored him, as everyone did, 

 without exception, who had once come under his 

 influence. 



It appears to have been about the time of his appoint- 

 ment to the Edinburgh chair that Tait first became 

 personally acquainted with Lord Kelvin. Kelvin (then 

 William Thomson) was also a Petei'house man, but had 

 left Cambridge before Tait came up, and was already, 

 independently and in conjunction with Joule, and con- 

 currently with liankine and Clausius, writing his classical 

 memoirs on the theory of eneigy. The first edition of 

 Tait and Steele's " Dynamics,"" published in 1856, does 

 not, so far as a rapid examination could detect, contain 

 either of the words work or energy. In its original form 

 it was founded on Pratt's " Mechanical Philosophy," and 

 wiitten on the old-fashioned Cambridge lines, which 

 knew not of Lagrange and Hamilton. Six years later it 

 is on record' that in his introductory lecture Tait handled 

 the notions of the " energetic " school with a freedom 

 which bewildered his uninitiated hearers, and laid down 

 the broad lines of a thoroughly modern course of natural 

 philosophy. Probably, therefore, he had come under the 

 influence of Joule and Kelvin before he became personally 

 intimate with the latter. The conjunction with Kelvin 

 produced the famous treatise on " Natural Philosophy," 

 by Thomson and Tait, now familiarly known as T and T'. 

 This wonderful book was published in 1S67, and at once 

 began to make a new era in mathematical physics. At 

 first, owing to its highly condensed structure, its influence 

 spread very slowly ; but now it would be impossible to 

 find an important treatise, or even a course of college 

 lectures, on natural philosophy that does not show traces 

 of its teaching. The work, it is true, is but a fragment, 

 but the continuation is to be found in dozens of treatises 

 written by men who have been nourished by the strong 

 meat of its serried pages. The collaboration was so 

 perfect that it is not easy to point out the parts due to 

 Kelvin and to Tait." During a somewhat intimate ac- 

 quaintance, extending well over twenty years, the present 

 writer never heard Tait drop a hint that would enable 



r The writer of an e.xcellent notice in the Scotsman has estimated the 

 number at about lo.ooo. 



- See an admirable appreciation of Tait in the Glasgow Herald. 



3 This is almost the only point on which we differ from the writer of the 

 Scotsman article. 



NO. 1656, VOL. 64] 



one to fix on any part of the great treatise as his special 

 work. Its authors always spoke of it and quoted it in 

 an oddly distant way, as if it had been the work of some 

 third person. The two distinguished coadjutors were 

 compelled, by diverging spheres of activity, to dissolve 

 their partnership in T and T' ; but, however divided their 

 spheres, they were in scientific aim, as in friendship, 

 undivided to the last. 



Since the last paragraph was written. Lord Kelvin has 

 favoured the writer with a note on Tait's early intimacy 

 with himself, and on their collaboration in T and T'. 

 This we reproduce verbatim for the readers of N.ATURE. 



" 1 first became personally acquainted wi'.h Tait a 

 short time before he was elected professor in Edinburgh ; 

 but, I believe, not before he became a candidate for the 

 chair. It must have been either before his election or 

 very soon after it that we entered on the project of a 

 joint treatise on natu'-al philosophy. He was then 

 strongly impressed with the fundamental importance of 

 Joule's work, and was full of vivid interest in all that he 

 had learned from, and worked at with, Andrews. We 

 incessantly talked over the mode of dealing with energy 

 which we adopted in the book, and we went most cor- 

 dially together in the whole aftair. He gave me a free 

 hand in respect to new names, and warmly welcomed 

 nearly all of them. 



" We have had a thirty-eight years' warover quaternions. 

 He had been captivated by the originality and extra- 

 ordinary beauty of Hamilton's genius in this respect, and 

 had accepted, I believe, definitely from Hamilton to take 

 charge of quaternions after his death, which he has most 

 loyally executed. Times without number I offered to let 

 quaternions into Thomson and Tait, if he could only 

 show that in any case our work would be helped by their 

 use. You will see that from beginning to end they were 

 never introduced." 



Tait's contributions to our text-book literature began 

 with Tait and Steele's " Dynamics," already mentioned. 

 His friend Steele (second wrangler and second Smith's 

 Prizeman in his own year) died early, and wrote 

 but a few chapters of the book. It was so much 

 altered in successive editions that the retention of his 

 name on the title-page became simply a pious tribute 

 to the memory of a friend. The "' Elements of Quater- 

 nions," begun in 1859, but, in deference to Hamilton, 

 not published till 1867, went through three editions, 

 and along with the " Introduction to Quaternions," 

 by Kelland and Tait (1873), formed, and still forms, the 

 best approach to the science of S, T and v. The 

 "Sketch of Thermodynamics" (186S), originating in 

 articles in the IVortk British Review (1S64), and Balfour 

 Stewart's " Heat" (1866), were for long the only readily 

 available source of information for English readers on 

 the theory of energy, and both contributed powerfully to 

 the growth of the "energetic" school of natural philo- 

 sophy. "Recent Advances in Physical Science" (1876), 

 a series of popular lectures for professional men, is one of 

 the raciest of his books, and the most useful for the 

 general reader. "Light" (1884), "Heat" (1884) and 

 "Dynamics'' (1895), republications of articles written for 

 the " Encyclopiedia Britannica," are all models of their 

 kind, clear, forcible and concise, like everything he wrote. 

 Those who wish to have an idea of how Tait taught 

 should read " Properties of Matter," which embodies a 

 considerable part of the course he usually gave to his 

 elementary class. 



Although Tait rarely spoke on matters relating to the 

 Unseen, and in general avoided theological controversy, 

 his intimate friends were well aware that he held decided 

 views on such matters. The writer well recollects the 

 grim humour of a Homeric battle at the Edinburgh 

 Evening Club between him and Thomas Stevenson 

 (father of Robert Louis), occasioned by the introduction 

 into the conversation, by some malicious friend, of the 



