July 2, 1903] 



NA rURE 



195 



making' of the greatest discoveries. He no less highly 

 appreciated the friendly welcome given him by the 

 Astronomer Royal, Airy, and the opportunity of ex- 

 ploring Greenwich Observatory, and of seeing in oper- 

 ation the first successful method of recording photo- 

 graphically the readings of magnetic and meteor- 

 ological instruments. With Thomson, Helmholtz did 

 not come into personal relation until August, 1855, 

 when they met at Kreuznach. Helmholtz describes 

 (in a letter to his wife) his astonishment when a man 

 whom he knew as one of the first of living mathe- 

 matical ph3sicists appeared to him as a " Jiingling 

 von ganz miidchenhaften Aussehen," but possessed of 

 a degree of acuteness, clearness, and versatility which 

 he had never before met with. It can well be imagined 

 how these two young- discoverers must have enjoyed 

 and profited by the exchange of thought on funda- 

 mental questions which each of them had done so 

 much to elucidate. 



The same year Helmholtz accepted the chair of 

 anatomy and physiology at Bonn, his motive for doing 

 so being that his wife, whose health was precarious, 

 might have the advantage of a milder climate. At 

 that time the two subjects were still united, so that 

 Helmholtz was obliged to resume the teaching of de- 

 scriptive anatomy. This drawback was, however, of 

 short duration, for two years later he was invited to 

 Heidelberg, where the conditions were much more 

 favourable. Notwithstanding the onerous nature of 

 Helmholtz 's professional engagements, the fifteen 

 years of his residence at Bonn and Heidelberg were 

 almost as productive as those which had preceded 

 them. It was at Bonn that he sent to the press the 

 first part of his famous treatise on physiological 

 optics, which was not completed until 1895, and there 

 also that he carried out many of the researches on 

 musical sounds which were embodied in his treatise 

 on " Sensations of Tone." At Bonn, too, he published 

 his first mathematical paper " On the Movement of 

 Fluids " (1858), which led on to his experimental re- 

 searches at Heidelberg in i860. During the whole 

 period it appears that he published some forty-six 

 papers of importance, of which thirty-seven, including 

 those on optics and acoustics, were on physiological 

 subjects, the remainder being physico-mathematical. 



After his appointment to the chair of physics at 

 Berlin, his only physiological publication was the 

 essay entitled "Thought in Medicine," in which he 

 illustrated in the most striking way the application 

 of the scientific method to pathological questions. 

 (The chapters of Koenigsberger's work which relate to 

 Helmholtz as a mathematician will be treated by 

 abler hands. Many readers who may not have leisure 

 to look into this admirable biography would have 

 been glad had it been possible to give some account 

 of Helmholtz's views as to the limits of a scientific 

 inquiry and the relation between the experimental 

 sciences and philosophy. Want of space forbids this.) 



In Koenigsberger's book the reader will find ample 

 material for the decision of the question which pre- 

 sented itself at the outset, that of the conditions which 

 led to the development of so splendid a character. To 

 the present writer it seems evident that Helmholtz's 

 NO. 1757, VOL. 68] 



personal qualities — his sagacity, modesty, truthful- 

 ness, and astonishing power of work — could be in 

 great measure attributed to home and school in- 

 fluences, and that his success as an investigator was 

 due in part to his having entered on his career as a 

 physiologist at a time when the progress of the exact 

 sciences had rendered their methods applicable to the 

 investigation of vital phenomena, and m part to his 

 singular good fortune in having as his fellow-students 

 such men as du Bois-Reymond, Ludwig, and Briicke, 

 each of whom was as enthusiastic as himself, and 

 scarcely inferior to him in intellectual endowments. 

 J. Burdon-Sandekson. 



II. 



Physico-Mathf.matical Researches. 



Herr Koenigsberger gives us an account of 

 Helmholtz which is extremely interesting, and 

 not unworthy of the investigator of whom he writes. 

 Though he paints for us a fascinating picture of Helm- 

 holtz as a man, it is with work as a great physiologist 

 and physicist that he chiefly deals. 



k review of that part of the biography which deals 

 with the education and physiological work of Helm- 

 holtz precedes this notice, which is confined to a brief 

 account of that part of the book treating of his 

 physico-mathematical writings. Helmholtz's first 

 mathematical paper was " On the Integrals of Hydro- 

 dynamical Equations which correspond to Vortex 

 Movements," and was published in 1858, during his 

 short stay in Bonn as professor of anatomy and physi- 

 ology. In the following year, after his migration to 

 Heidelberg as professor of physiology, appeared his 

 paper " On the Motion of Air in Pipes with Open 

 Ends." These two papers contain some of his most 

 brilliant mathematical deductions, and are charac- 

 terised by their freedom from the artificial or inaccurate 

 assumptions of his predecessors. Further work in this 

 direction was for the time prevented by family 

 troubles. In June, 1859, his father died of a sudden 

 stroke, and Helmholtz, worn out with sorrow at his 

 loss, with anxiety for his wife, and with his own bad 

 health, was obliged to turn to work requiring less 

 concentration of thought. At the end of the year his 

 wife died. For some time his health remained in an 

 unsatisfactory state, and he was subject to headache 

 and fainting fits. However, he forced himself to 

 work, " which alone could give him power to hold 

 out," and continued his hydrodynamical investi- 

 gations, publishing in April, i860, his paper ' On the 

 Friction of Viscous Fluids." His experimental re- 

 searches on sound then led him to study the mathe- 

 matical theory of violin strings and reed organ pipes. 



Continuing his researches in acoustics and optics, he- 

 was led by the consideration of the wave motion near 

 the end of an open cylindrical tube to investigate the 

 distribution of electricity near the circular intersection 

 of two surfaces. However, in this, the first of his 

 many papers on mathematical electricity, he had been 

 anticipated by Thomson. He then for some years 

 confined himself mainly to physiological work, and 

 it vt-as not until 1S68 that he was again led by his 



