July 28, 192 1] 



NATURE 



675 



committee were doubtless full of interest and in- 

 formation to the members, it unfortunately hap- 

 pens that the Report will not contribute anything 

 substantial towards a solution of the desperate 

 problem with which the country remains con- 

 fronted. 



A War Memorial. 



The Scientific Papers of Bertram Hopkinson. 

 Collected and arranged by Sir J. Alfred Ewing 

 and Sir Joseph Larmor. Pp. xxvii + 480 + plates, 

 (Cambridge: At the University Press, 1921.) 

 635. net. 



BERTRAM HOPKINSON 'S scientific friends, 

 including his Cambridge staff, decided well 

 when they determined that no memorial could be 

 more suitable or permanent than a collected 

 edition of his writings on mathematical and engin- 

 eering science. The editors and the syndics of 

 the Cambridge University Press alike have earned 

 our thanks by the manner in which their shares of 

 the publication have been carried out. 



There is no need to tell at length the tragic 

 story of his life. Called home from Aden in 1898 

 by the death of his father, brother, and two 

 sisters on the Dents de Veisivi, he took up his 

 father's work as a consulting engineer with the 

 aid of his uncle Charles, and carried out various 

 important undertakings. Five years later he 

 became professor of mechanism at Cambridge, 

 and in the same year he married. For the next 

 eleven years he was fully occupied in the develop- 

 ment of the work of his chair. The papers in 

 the volume under review form his contributions 

 to science during that time, but they do not 

 constitute by any means the whole of the debt we 

 owe to him. To quote from Prof. A. V. Hill's 

 appreciation in the Alpine Journal, at Cambridge 



*' a professor of mechanism can hope to make a 

 school essentially in touch with the traditions of 

 the place only on condition that his interests are 

 largely, if not mainly, scientific. In Hopkinson 

 Cambridge had an ideal professor, and the pupils 

 trained in his school have already, especially 

 during the war, raised a memorial to him by 

 their work." 



The war, when it came, claimed him at once, 

 at first as a teacher at Chatham, then at the 

 Admiralty, where he conducted some most im- 

 portant experiments which led to the modern 

 methods of protection of large ships against tor- 

 pedoes. Finally he joined the Royal Air Force 

 as an officer in charge of experimental work of 

 all kinds, becoming in June, 191 8, Deputy Con- 

 NO. 2700, VOL. 107] 



troUer of the Technical Department ; on August 26 

 of that year he was killed in a flying accident. 



The papers in the volume fall naturally into 

 three main groups, dealing respectively with elec- 

 trical engineering, with certain metallurgical ques- 

 tions, and with the problems of the internal-com- 

 bustion engine. In addition, the first paper of 

 the series, one on sources and vortices, which 

 was contributed to the London Mathematical 

 Society in 1898, deserves mention as indicating 

 the width of his knowledge and interests. He 

 was an electrical engineer by profession ; his 

 father had placed the construction of electrical 

 machinery on a scientific basis by the paper on 

 dynamo-electric machines written in conjunction 

 with his uncle Edward, and published in the 

 Phil. Trans., and it was not unnatural that the 

 son's early work as professor should deal with 

 similar problems. 



His first paper in the Proceedings of the Royal 

 Society on the shunting of alternate-current 

 machines gave a satisfactory explanation of the 

 phenomenon, and seems to have been inspired in 

 part by the behaviour of a small machine in the 

 Wimbledon Power House near his home. 



Electrotechnics did not for long retain his main 

 attention. Papers on the elastic properties of 

 steel at high temperatures, brittleness and duc- 

 tility, and the endurance of metals under alter- 

 nating stresses of high frequency, followed during 

 the next few years, and each served to bring out 

 his versatility and his power of getting at the heart 

 of a subject and of explaining in clear and con- 

 cise language the results of his investigations. 



Two remarkable papers on the magnetic pro- 

 perties of iron and its alloys in strong magnetic 

 fields, and on manganese steels, were published 

 with Sir Robert Hadfield in 191 1 and 1914, and 

 have added greatly to our knowledge of mag- 

 netism, Hopkinson was able to show that the 

 magnetism of saturation might, in the case of 

 the carbon steels, be predicted from the composi- 

 tion by treating each steel as a mixture of iron 

 and of less magnetisable carbide. With mangan- 

 ese, however, no such simple relation was found 

 to follow. 



The work, however, by which Hopkinson will 

 probably be best remembered is that on the in- 

 ternal-combustion engine. It began with a British 

 Associatioa paper in 1904, which led in 1907 to 

 an investigation into the efficiency of the gas 

 engine ; in the course of this research the 

 well-known Hopkinson indicator was developed, 

 and it was shown that indicator diagrams, pro- 

 perly drawn, could be used satisfactorily for the 

 measurement of efficiency. In 1906 a most im- 



