August i8, 192 i] 



NATURE 



789 



solution satisfactory to himself, those who knew 

 him little might believe him indifferent. He would 

 gather himself together, and in a few words would 

 show how far his thoughts had taken him into the 

 fundamentals of the subject. During the last year 

 of his life he devoted much attention to relativity, 

 and on his last voyage from Havre to New York 

 he spent most of his days discussing it with 

 Prof. Michelson. The work Prof. Lippmann 

 leaves behind him is of capital importance ; but it 

 represents only a part of the thoughts of a man 

 of science with views acute and deep whom 

 the search for perfection and a reserved tempera- 

 ment kept far from noise and strife. 



Capt. W. E. Rolston. 



The sudden death, on August 9, at forty-five 

 years of age, of Capt. W. E. Rolston will be 

 greatly regretted by many old students of the 

 Royal College of Science, South Kensington, 

 where he received his scientific training. Capt. 

 Rolston was the founder and managing editor of 

 the Cologne Post — the admirable daily paper 

 published by the British Army on the Rhine — but 

 he was well known in astronomical circles by his 

 work with Sir Norman Lockyer, and at Cam- 

 bridge. He entered the Royal College of Science 

 as a Teacher in Training, and for about a year 

 assisted in the demonstrations in the course of 

 astronomical physics there, gaining also some 

 experience in solar physics work. In 1899 

 Rolston took up a teaching post, but returned 

 again to the Solar Physics Observatory at South 

 Kensington in 1901, and remained on the staff of 

 the observatory until he joined the Buffs in 191 5. 

 He was with Sir Norman Lockyer for twelve 

 years before the transfer of the observatory to 

 Cambridge in 191 3, where he continued to be a 

 member of the staff. 



After some preliminary work in the general 

 routine of the observatory, Rolston became mainly 

 responsible for several specialised branches of the 

 investigations in progress. One of the most im- 

 portant of these was an attempt to apply the prin- 

 ciples of Stokes's Law of Radiation to the deter- 

 mination of the relative temperatures of stellar 

 atmospheres. A fundamental feature of Sir 

 Norman Lockyer 's Kensington classification of 

 stellar spectra required the recognition of different 

 temperature levels, and to investigate this a special 

 prismatic camera, with quartz-calcite optical train, 

 was obtained and mounted on one of the equatorial 

 telescopes. Pairs of stars were photographed on 

 the same plate under conditions as nearly identical 

 as possible, with controlled exposures designed to 

 give equal photographic intensity for the region 

 H^-H^ By then measuring the relative inten- 

 sity of the red and violet regions respectivelv, it 

 was possible to arrange the various spectra in 

 order of temperature level. These observations ex- 

 tended over about three years, and the results 

 were communicated in a paper to the Royal 

 Society in 1904 on the " Temperature Classifica- 

 tion of Stars." In addition to taking a share in 

 NO. 2703, VOL. 107] 



the observational routine work, both day and 

 night, on solar and stellar spectra, Rolston re- 

 peated much of the reduction work on old obser- 

 vations of widened lines in sunspot spectra, and 

 brought the summaries up to date. 



From 1907 to 191 2 Rolston was chiefly occupied 

 with the reduction of orientations, and with stone 

 circles and temples in various parts of the world, 

 these being regarded as having originally been 

 designed by their constructors to serve for the 

 determination of time and season in the regulation 

 of the economic and religious life of the early com- 

 munities. The results of these researches were 

 extremely suggestive, and were communicated by 

 Sir Norman Lockyer to the Royal Society. 



During the last two years before the transfer- 

 ence of the observatory to Cambridge Rolston was 

 engaged in preparing a comprehensive account of 

 the observations of novae from the discussion of 

 all available material, and this was published as 

 a separate volume entitled " Phenomena of New 

 Stars." After transference to Cambridge he took 

 charge of the Huggins spectroscopic equatorial, 

 and also assisted in the reductional work on stellar 

 spectra. 



Throughout his connection with the Solar 

 Physics Observatory Rolston took great interest 

 in the dissemination of scientific knowledge, 

 and was most successful as a writer and as 

 a popular lecturer. For a number of years 

 before the war he wrote the notes fof Our 

 Astronomical Column, and also contributed 

 numerous articles and reviews. The experience 

 thus obtained was turned to excellent account 

 when in March, 1919, he founded the Cologne 

 Post, the unique daily newspaper which has had 

 such valuable influence in revealing British thought 

 to Germany. His success showed the value of a 

 scientific training to business management and 

 literary balance, and the frequent articles and notes 

 on scientific and educational subjects published in 

 the columns of his journal commanded both atten- 

 tion and respect. Rolston was, indeed, a man of 

 sterling worth and sound knowledge, and all who 

 knew him will deplore that he has been taken 

 from them in the prime of life. 



Samuel Alfred Varley. 

 By the death on August 4 of Mr. S, A. Varley, 

 at eighty-nine years of age, we have lost almost 

 the last of those pioneers who were associated 

 with the application of electricity. A younger 

 brother of the late Cromwell Varley, F.R.S., and 

 an early student and disciple of Michael Faraday, 

 Mr. Varley was a notable inventor even com- 

 paratively early in life, when in the service of the 

 Electric Telegraph Company. His name and 

 fame will always be especially associated with 

 dynamo-electric machinery, the first example of 

 which he produced in 1866. This was a self- 

 exciting machine with soft iron magnets. Ten 

 years later Mr. Varley patented the original com- 

 pound-wound dynamo. This afterwards became 

 the subject of litigation, when Mr. Varlev's claims 



