192 



NATURE 



[November 6, 1919 



amongf men. He was one of the pioneers of 

 astrophysics, the new branch of astronomy which 

 is now of such importance. For fifty years, with 

 untiring activity, he has carried on a multitude 

 of researches in the three observatories estabhshed 

 by him and in the physical laboratories associated 

 with them ; and, like a true philosopher, he has 

 presented a general synthesis of celestial pheno- 

 mena. The title " Nature " might be justly given to 

 the record of his personal achievements, to which 

 the remarks which follow are particularly devoted. 



Sir Norman Lockyer is not the product of a 

 university ; he may be termed a self-made man 

 of science. He was at first employed in a Govern- 

 ment Department, where he remained for more 

 than ten years ; but he was irresistibly drawn 

 towards science, and especially to astronomy, the 

 wonder of which exercises a powerful attraction. 

 All his leisure and all his personal resources were 

 devoted to scientific pursuits. Spectrum analysis 

 had come into being, and its application to celes- 

 tial bodies opened up the widest horizons. Sir 

 Norman Lockyer attached a small spectroscope to 

 a modest equatorial telescope of 6-in. aperture, 

 which constituted his private observatory, and he 

 studied the light emanating from the solar spots. 

 The first results were summarised in a note pre- 

 sented to the Royal Society in 1866, where the 

 author discussed the bearing of his observations 

 on the two rival theories which were then to the 

 front as to the nature of sun-spots. He foresaw 

 the possible daily observation of the red flames, 

 or prominences, which up to that time had only 

 been observed on the outer edges of the sun 

 during total eclipses. He conceived the idea that 

 the spectroscope might be able to reveal them at 

 ordinary times under the same conditions as those 

 which caused the appearance of bright lines in 

 the new star in Corona Borealis. This star had 

 appeared a few months previously, and, as ob- 

 served by Huggins, had presented a stellar 

 nucleus surrounded by a relatively feeble nebu- 

 losity; but in the spectroscope the light of the 

 nucleus was spread out in a continuous spectrum 

 and thereby enfeebled, while the atmosphere 

 showed the bright lines of hydrogen with great 

 brilliance. 



This idea was really a flash of genius, because 

 it contained the germ, or the principle, of the 

 method which, for fifty years, has revealed to 

 us at all hours of the day the gaseous atmosphere 

 of the sun. The first application of the method 

 to the sun's edge, however, gave no result; the 

 spectroscope employed was not suflficiently power- 

 ful. Two years later the observations in India of 

 the total-eclipse of the sun of -August, 1868, gave 

 NO. 2610, VOL. 104] 



valuable information — the solar prominences were 

 gaseous, and showed the red and green lines of 

 hydrogen with very great intensity. 



On October 20, 1868, Sir Norman Lockyer, at 

 last provided with a powerful spectroscope, for 

 which he had waited two years, discovered, at 

 Hampstead, a prominence on the sun's edge, and 

 made a drawing of it two days later. The 

 discovery was communicated to the Royal Society 

 on October 20 and to the Academy of Sciences 

 at I'aris on October 26. By a striking coinci- 

 dence, at the same meeting of the Academy, a 

 letter sent from India by the French astronomer 

 Janssen announced the same result. During the 

 eclipse Janssen had recognised in the spectro- 

 scope the nature of the prominences, and was 

 able to see them again on the following day with 

 the same instrument. Janssen continued to 

 observe them daily during three weeks, and found 

 that they were composed principally of hydrogen, 

 and were subject to remarkable variations of form 

 which were often very rapid. The astronomer 

 Faye then pointed out that the first idea of the 

 method was certainly due to Lockyer, but that 

 the first application had been realised by Janssen, 

 and since then the two names have been justly 

 united in connection with the discovery. 



During the weeks and months which followed, 

 Sir Norman, with praiseworthy activity, continued 

 the studv of the sun by the new method without 

 intermission, and he successively recognised 

 several new facts of the first importance, 

 namely : — 



1. The prominences emanate from a gaseous 

 layer of the same composition, which envelops 

 the entire sun, and reaches a height of 8-10 sees, 

 of arc. This layer is of a rose colour, like that 

 of the prominences themselves, and Sir Norman 

 Lockyer gave it the name of the chromosphere ; 

 it had alreadv been glimpsed in preceding eclipses, 



but its existence was not crenerallv acknowledtred. 



2. The yellow radiation of the prominencejfl||^H 

 which had been attributed to sodium by the eclips^^^ 

 observers, proclaimed in reality the existence of 



a new gas, to which Sir Norman gave the name 

 of helium. It was the first recognition of the 

 famous gas which was afterwards obtained from 

 terrestrial sources by Ramsay in 1898; it is 

 emitted by radio-active bodies, and now can be 

 used for the inflation of dirigibles. 



3. The green line of hydrogen becomes broader 

 in passing from the summit to the base of a 

 prominence. From a series of experiments on 

 hydrogen at low pressures, carried on in the 

 chemical laboratory of his friend, Frankland, Sir 

 Norman concluded that this widening is simply due 



