September 9, 1915] 



NATURE 



1>1 



Values of a'= \/(/)^+5*). Mean /) = mean g,=o. 

 S.d. of p = s.d. of g = io. 500 pairs taken. 



Experiment Theory 



Mean a' 125 i2-53±o-2o 



Standard deviation of a' ... 65 6-55 ±0-14 



Per cent, exceeding 25 ... 40 4-39 ±062 



the agreement being very close in all three values. 

 Manchester. H. E. Soper. 



Antarctic Fossil Plants. 



It should have been stated that Prof. Seward's 

 memoir (reviewed in Nature for August 26) is the 

 first dealing with the geological results of Capt. 

 Scott's Expedition. Two numbers of the Zoological 

 series had previously appeared — No. i of vol. i. on 

 June 27, and No. i of vol. ii. on July 25, 1914, 

 ^^ D. H. S. 



HENRY GWYN JEFFREYS MOSELEY. 



SCIENTIFIC men of this country have viewed 

 with ming-led feelings of pride and appre- 

 hension the enlistment in the new armies of so 

 many of our most promising young- men of science 

 — ^with pride for their ready and ungrudging re- 

 sponse to their country's call, and with appre- 

 hension of irreparable losses to science. These 

 forebodings have been only too promptly realised 

 by the death in action at the Dardanelles, on 

 August 10, of Henry Gwyn Jeffreys Moseley, 

 2nd Lieut, in the Royal Engineers, at the age of 

 twenty-seven. A son of the distinguished zool- 

 ogist, the late Prof. H. N. Moseley, of Oxford, 

 he was educated at Eton, entering as a scholar, 

 and passed to Trinity College, Oxford, where he 

 gained a Millard Scholarship. He obtained a 

 First Class in Mathematical Moderations, and 

 Honours in Natural Science. 



Moseley early showed marked originality and 

 an enthusiatic interest in science. A year before 

 his graduation he had decided to undertake 

 original work in physics, and visited Manchester 

 to discuss the matter with me. After graduation, 

 he was appointed lecturer and demonstrator in the 

 physics department of the University of Man- 

 chester, and immediately devoted all his spare 

 time to investigation. After two years he resigned 

 his lectureship in order to devote his energies 

 entirely to research, and was awarded the John 

 Harling Fellowship. During the past year he 

 [rent to Oxford to live with his mother, and to 

 )ntinue his experiments in the laboratory of Prof. 

 Townsend. He went out to Australia with the 

 K'tish Association, took an active part in the 

 iscussion on the " Structure of the Atom " at 

 [elbourne, and gave an interesting account of 

 recent work on the X-ray spectra of the rare 

 irths, in Sydney. On the outbreak of war he 

 It aside all thought of continuing the investiga- 

 )ns in which he was so vitally interested, and 

 rturned at once to England to offer his services 

 his country, and was granted a Commission in 

 Royal Engineers. He was later made signal- 

 ig officer to the 38th Brigade of the First Army, 

 id left for the Dardanelles on June 13. He took 

 irt in the severe fighting at the new landing on 

 NO. 2393, VOL. 96] 



August 6 and 8, and was mstantaneously killed 

 on the loth by a bullet through the head in the 

 act of telephoning an order to his division at a 

 moment when the Turks were attacking on the 

 flank only 200 yards away. 



Moseley was one of those rare examples of a 

 man who was a born investigator. He rapidly 

 acquired the technique of experiment and soon 

 gained a remarkably wide and accurate know- 

 ledge of modern physics. His undoubted origin- 

 ality and marked capacity as an investigator were 

 very soon ungrudgingly recognised by his co- 

 workers in the laboratory, while his cheerfulness 

 and willingness to help in all possible ways en- 

 deared him to all his colleagues. His first 

 research, published in the Proceedings of the 

 Royal Society, consisted in the determination of 

 the average number of beta particles emitted 

 during the transformation of an atom of radium B 

 and radium C — a difficult and important piece of 

 work. It then occurred to him to determine the 

 potential to which radium could be charged in a 

 high vacuum by the escape of its own beta par- 

 ticles. He was able to achieve such a high stage 

 of exhaustion — and this before the advent of the 

 molecular pump — that a small quantity of radip- 

 active matter retained itself at a potential of more 

 than 100,000 volts for several weeks. He devised 

 an ingenious method for detecting the possible pre- 

 sence of very short-lived radioactive substances, 

 and in conjunction with Fajans utilised the method 

 to determine the period of transformation of a 

 newly-discovered product in actinium, which was 

 found to be half transformed in 1/500 of a second. 



Moseley 's interest was greatly aroused by the 

 discovery of Laue of the diffraction of X-rays in 

 their passage through crystals, and in conjunction 

 with Mr. Charles Darwin he immediately started 

 an investigation to examine the quantity and 

 quality of the X-radiation scattered from crystals 

 at different angles. Prof. Bragg, who was 

 working simultaneously at Leeds on the same 

 problem, observed the presence of definite maxima 

 in the scattered radiation corresponding to definite 

 lines in the X-ray spectrum. This result was 

 confirmed and extended by Moseley and Darwin, 

 and they mapped out accurately for the first time 

 the spectrum of the characteristic X-radiation 

 from an X-ray tube with a platinum antikathode. 

 These pioneer investigations in Leeds and Man- 

 chester were of fundamental importance, for they 

 laid the foundation of the new science of X-ray 

 spectroscopy, which is now in the process of rapid 

 development. 



Moseley next decided to examine the X-ray 

 spectra of a large number of different elements 

 with the definite object of testing whether the 

 spectrum was connected in a simple way with the 

 atomic number of the element when arranged in 

 increasing order of atomic weight. Suggestions 

 had been previously made that the charge on the 

 nucleus of an atom, which defines its chemical 

 and physical properties, was possibly equal to the 

 atomic number. For this purpose he developed 

 the photographic method for accurate measure- 



