November 6, 1919] 



NATURE 



19: 



to an increase of pressure. Spectrum analysis dis- 

 closed not only the chemical composition of the 

 prominences, but also to a certain extent their 

 physical state. 



4. The lines of the prominences are often dis- 

 placed and distorted. This phenomenon was cor- 

 rectly attributed to the movements of the vapour 

 in the direction of the observer; it was "the first 

 real verification of the velocity displacements 

 which have since become of such great importance 

 in astronomy. 



This first series of investig-ations is set forth in 

 some detail, because it represents magnificent 

 work ; it is an example for all, and has its place 

 marked out in the history of science, especially 

 as it was carried out with simple means. The 

 greatest discoveries, as one knows, have not been 

 made in the largest laboratories, and the capacity 

 of the man is always of more consequence in re- 

 search than that of his instruments. In his in- 

 vestigations Sir Norman Lockyer has shown a 

 power, an acuteness of mind, and a creative 

 imagination which are truly exceptional. These 

 are the qualities of men who, like him, have over- 

 come all difficulties placed in their way in order 

 to pursue fixed ideas and follow vocations which 

 they have fully resolved to adopt. 



In the succeeding years Sir Xorman organised 

 several eclipse expeditions under Government 

 auspices; all the important solar eclipses since 

 1868 have been observed by him or by his assist- 

 ants, with programmes laid down by the Solar 

 Physics Committee, of which he was a member. 

 At the same time, he undertook extensive work 

 which may be summarised in the words: "Com- 

 parative study of terrestrial spectra and the spec- 

 trum of the sun, extended afterwards to stars, 

 nebulae, and comets. Special and general conse- 

 quences drawn from them." After fifty years of 

 continuous labour the work has certainly been 

 advanced, but it is not yet completed. It was 

 carried on at first in his own observatory, then 

 from 1879 in the establishment at South Kensing- 

 ton which the Government had created for the 

 development of the new methods and placed under 

 his direction. 



The astrophysical observatory at South Ken- 

 sington was a model of its kind ; it consisted of 

 two parts, quite distinct but closely related, 

 namely, an observatory properly so called and a 

 physical laboratory. The astrophysicist must pass 

 constantly from one to the other, and, in fact, 

 the number of publications issued from South 

 Kensington has been nearly the same in the two 

 sections. It has been said that an astrophysical 

 observatory is merely a physical laboratory 

 NO. 2610, VOL. 104] 



oriented towards astronomy, the astronomical 

 instruments being in reality nothing more than 

 physical apparatus of large dimensions ; and it 

 is therefore necessary to attach to them men who 

 have been trained by the study of physics and 

 capable of immediately applying to the celestial 

 bodies the most recent discoveries made in the 

 laboratory. 



In this connection Sir Norman has trained at 

 South Kensington several investigators, including 

 Prof. Fowler, Dr. Lockyer, and Messrs. Shackle- 

 ton, Baxandall, and Butler, at once physicists and 

 astronomers, and well known by their publica- 

 tions. Prof. Fowler, now president of the Royal 

 Astronomical Society, is already distinguished ; 

 we owe to him important discoveries and some 

 fine series of precise measurements. 



In 1912 the land occupied by the observatory 

 at South Kensington was required for the exten- 

 sion of the Science Museum, and the observatory, 

 with all its instruments, was transferred to Cam- 

 bridge. Sir Norman, having passed the age- 

 limit, was obliged to retire from the directorship, 

 but, feeling that his work was not yet accom- 

 plished, and still vigorous in body and mind, he 

 forthwith set up another observatory — the Hill 

 Observatory — with the aid of several friends of 

 science. The site chosen, at Sidmouth, is very 

 favourable for astronomical observations, and as 

 the first buildings were erected very quickly and 

 provided immediately with some fine instruments, 

 the researches commenced at South Kensington, 

 especially those on stellar spectra, have been 

 continued with but little interruption. It -is hoped 

 to establish there an astrophysical observatory 

 comparable with the American observatories and 

 worthy of the United Kingdom. 



The new facts gathered together in the course 

 of these fifty years are extremely numerous ; they 

 are set forth with the inferences drawn from them 

 in 200 memoirs, and it is impossible to give any 

 detailed analysis of them here. Fortunately, the 

 author, who has an affection for great generalisa- 

 tions, has always sought to connect the facts in 

 a few leading ideas which are for him " working 

 hypotheses," and he has expounded each hypo- 

 thesis in a special book. The volume on "The 

 Chemistry of the Sun " (1887) deals with the dif- 

 ferences of spectrum emitted by different parts 

 of the sun, and explains them by the dissociation 

 hypothesis, according to which the molecules and 

 atoms are grouped in different ways or are split 

 up into simpler elements. In his book on "The 

 Meteoritic Hypothesis " (i8go) the author explains 

 all the celestial bodies by collisions of meteorites; 

 it is a simple and fertile idea, which has been 



