NA TURE 



563 



THURSDAY, JANUARY 23, 1913. 



A PIONEER IN APPLIED SCIENCE. 

 Collected Papers in Physics and Engineering. By 

 Prof. James Thomson, F.R.S. Selected and 

 arranged with unpublished material and brief 

 annotations by Sir Joseph Larmor, Sec. R.S., 

 and James Thomson. Pp. civ + 484. (Cam- 

 bridg-e : University Press, igi-!.) Price i5i. 

 net.) 



WHEN Sir Joseph Larmor edited the scientific 

 papers of Lord Kelvin and Prof. Fitz- 

 gerald he did work which nobody else could have 

 done so perfectly ; his time, however valuable, was 

 spent to advantage. The editing of these papers 

 of Lord Kelvin's brother might have been under- 

 taken by many others, but now that the excellent 

 result is before us we cannot regret it, and we 

 must confess that we did not expect to find in 

 the editor such a perfect sympathy with James 

 Thomson's methods of study. He shares with 

 Prof. Thomson's son the honour and credit of 

 this publication. The book begins with about a 

 hundred pages of biography and comment upon 

 Thomson's works — excellent reading. Then we 

 have 153 pages of papers relating to fluid motion, 

 dating from 1852 to the Bakerian lecture of 1892; 

 nearly eighty pages on congelation and liquefaction 

 from 1849 to 1888; forty pages on the continuity 

 of states in matter from 1869 to 1873; seventy 

 pages on dynamics and elasticity from 1848 to 

 1887; and about eighty pages on geological and 

 miscellaneous subjects from 1848 to 1892. 



James Thomson was very exact in his use of 

 language and in his ways of thinking. Even 

 although in some of our studies we are quite exact, 

 most of us are quite slipshod about other things 

 that we think we know. If it were necessary to 

 give examples the reader might be referred to 

 paper 14 of this collection. Thomson there refers 

 to the usual methods of study of the flow of water. 

 He says: "The theoretical views so arrived at 

 and very generally promulgated are in reality only 

 utterly false theories based on suppositions of the 

 flow of the water taking place in ways which are 

 kinematically and dynamically impossible, and are 

 at variance with observed facts of the flow, and 

 even at variance with the facts as put forward 

 by the advancers of those theories." After giving 

 some examples, he says: "Now this method is 

 pervaded by false conceptions and is thoroughly 

 unscientific." Although Thomson constructed his 

 famous turbine sixty years ago and put in simple 

 language the principles on which nearly all modern 

 water and steam turbines are now being con- 

 structed, these papers of his are so little known 

 NO. 2256, VOL. Qol 



that nearly all books on hydraulics are still per- 

 vaded with the old false conceptions and un- 

 scientific methods. 



He was free from the common fault of 

 self-deception. There is no vagueness in any 

 of his explanations of phenomena. When he 

 explains such a thing as the tears of strong 

 wine and refers to surface tension he is as exact 

 as Prof. Boys or Lord Rayleigh, and he demands 

 from his reader the same carefulness. When he 

 is not perfectly sure of a thing he tells you so 

 frankly. The results of Thomson's thought in 

 so far as physics is concerned are known to all 

 of us ; they are to be found in all text-books ; I 

 wish we could say the same about his work in 

 engineering. But both physicist and engineer will 

 get much education in reading the original papers. 

 They will come in contact with a true scientific 

 mind, absolutely honest, intensely observant, 

 afraid of self-deception, concentrative, persistent 

 and tireless. I have no hesitation in saying 

 that the hydraulic engineer who has not read 

 these papers has a great deal to unlearn and 

 learn. 



Only the very simplest mathematical or scientific 

 knowledge is needed by the reader, but he must 

 have common sense and humour and the same 

 inclination to laugh at pretentious, ignorant 

 notions as the author himself. I think myself that 

 in a few cases Thomson ought to have worked 

 with higher mathematics. For example : water 

 being supposed to be frictionless and to flow from 

 two similar vessels with similar and similarly 

 placed orifices, he thought it necessary to prove 

 that the lines of flow are similar. If this is so, 

 it is evident that if I and L are the dimensions, 

 p and P the pressures, v and V the velocitie s at 

 similar places, then P/p = 'L/l and Y/v= \/L/l. 

 His proof of the similarity is ingenious. Applied 

 to the case of vessels moving through water it 

 is Froude's law, but in this case, unlike Thomson's 

 own, viscosity enters into the real phenomena in 

 an all-important way, and the assumption that the 

 proposition has been proved is very dangerous. 

 Thomson used his proposition in getting a rational 

 formula for the measurement of water by his tri- 

 angular notch, and in proving that the empirical 

 formula of Dr. Francis for rectangular notches 

 is really a rational formula. It is curious that it 

 should be necessary to tell engineers that the 

 Francis formula is correct and that the usual 

 formulae of the text-books are quite incorrect. 



Now that long proof given by Thomson in his 

 1876 paper (given by him to students in his classes 

 for fifteen years previously) seems to me unneces- 

 sary. In one of his vessels A the flow is natural, 

 and in the other B he guides the flow in stream 



