4io 



NATURE 



[Feb. 26, 1880 



less, and, there being no moan, the stars shone brightly. The 

 atmosphere was beautifully clear, and the night was one of great 

 quietude. At the above-named hour I went on deck, and at 

 once observed a streak of white matter on the horizon bearing 

 south-sonth-west. I then went on the bridge and drew the 

 third officer's attention to it. In a few minutes it had assumed 

 the shape of a segment of a circle measuring about 45° in length 

 and several degree- in altitude about its centre. At this time it 

 shone wiih a peculiar but beautiful milky whiteness, and re- 

 sembled (only in a huge mass, and greater luminous intensity) 

 the nebula? sometimes seen in the heavens. We were steaming 

 to the southward, and as the bank of light extended, one of its 

 arms crossed our path. The whole thing appeared so foreign to 

 anything I had ever seen, and so wonderful, that I stopped the 

 ship just on its outskirts, so that I might iry to for n a true and 

 just conception of what it really was. By this time all the 

 officers and engineers had assembled on deck to witness the 

 s;ene, and were all equally astonished and interested. Some 

 little time before the first body of light reached the ship I was 

 enabled, with my night glases, to resolve in a meas.ire what 

 appeared, to the unas isted eye, a huge mass of nebulous matter. 

 I distinctly saw spaces between what again appeared to be 

 waves of light of great lustre. These came rolling on with 

 ever-increasing rapidity tdl they reached the ship, and in a short 

 lime the ship was completely surrounded with one great body of 

 undulating light, which soon extended to the horizon on all 

 sides. On looking into the water it %vas seen to be studded 

 with patches of faint, luminous, inanimate matter, measuring 

 about two feet in diameter. Although thee emitted a certain 

 amount of light, it was most insignificant when compared with 

 the great waves of light that were floating on the surface of the 

 water, and which were at this time converging upon the ship. 

 The waves stood many decrees above the water, like a highly 

 luminous mist, and obscured by their intensity the distant 

 horizon ; and as wave succeeded wave in rapid succession, one 

 of the most gr.nd and brilliant, yet solemn, spectacles that "ne 

 could ever think of was here witnessed. In speaking of waves 

 of light I do not wish to convey the idea that they were mere 

 ripplings, which are sometimes caused by fish passing through a 

 phosphorescent sea, but waves of great length and breadth, or in 

 other words, great I lies of light. If the sea could be converted 

 into a huge mirror and thousands of powerful electric lights » ere 

 made to throw their ra;s across it, it would convey no adequate 

 idea of this strange yet grand phenomenon. 



"As the waves of light converged upon the ship from all 

 sides they appeared higher than her hull, and looked as if they 

 were ab rut to envel >pe her, and as they impinged upon her, her 

 sides seemed to collapse and expand. 



" Whilst this was going on the ship was perfectly at rest, and 

 the water was like a millp md. 



"After about half an hour had elapsed the brilliancy of the 

 light somewhat abated, and there was a great paucity of the 

 faint lu irons patches which I have before referred to, but still 

 the body of light was great, and, if emanating from these patches, 

 was out of all proportion to their number. 



"This light 1 do not think could have been produced without 

 the agency of electro-magnetic currents exercising their exciting 

 influence upon some organic animal or vegetable substance ; and 

 one thing I wish to point out is, that whilst the ship was stopped 

 and the light yet some distance away, nothing was discernible in 

 the water, but so soon as the light reached the ship a number of 

 luminous patches presented themselves, and as these were equally 

 as motionless as the ship at the time, it is only natural to assume 

 that they exi ted, and were actually in our vicinity before the 

 light reached us, only they were not made visible till they became 

 the transmitting media for the electro-magnetic currents. This 

 hypothesis is borne nut by the fact that each wave of light in its 

 passage was distinctly seen to pass over them in succession, and 

 as the light gradually became less brilliant, they also became 

 less distinct, and had actually disappeared so soon as the waves 

 of light ceased to exist." 



THE NE W HYDROGEN LINES OBSER VED B V 

 PHOTOGRAPHY, THE STAR LINES, AND 

 THE DISSOCIATION OF CALCIUM 1 



TN the month of July, 1879, * published in the Reports of the 

 Royal Berlin Academy of Sciences, some photographs of 



the spectra of Gi issler rubes, filled with rarefied hydrogen. In 

 1 By Dr. H. W. Vogel, from the Photographic News of February 20. 



these photographs are visible, besides the old well-known 

 hydrogen lines, H, a, /3, y, S, a great many other lines in the 

 violet and ultra-violet at the extreme end, very thin and faint, 

 but of a character very similar to the old well-known hydrogen 

 lines. One of the most intense of these new lines coincided 

 almost exactly with the H line (Fraunhofer) of the sun-spectrum. 



I inclined to the idea that these new lines, whose wave-length 

 I published six months ago, were real hydrogen lines, but aa 

 objection was made to the effect that the hydrogen employed 

 would not have been quite pure. I will mention here that I get 

 exactly the same lines with hydrogen of different sources. 



I have recently repeated my experiments, and filled Geissler 

 tubes with the purest hydrogen, developed by electrolytical 

 decomposition. The photographs of the spectra of these tubes 

 show nearly all the same lines as 1 have published, and I venture 

 now to declare these new lines to be real hydrogen line-, so that 

 this body, besides its four chief lines in the visible spectrum, has 

 certainly five chief lines at least in the ultra-violet part. 1 



The wave-lengths of these new lines, which 1 have published 

 in the Reports of the Berlin Academy, 1S79, p. 590, are as 

 follows : — 



396S bright lines coincident with II (Fraunhofer) 



3SS7 



3S34 fainter lines 



5795 

 The fifth line was not very distinct ; its wave length, which I 

 have not published till now, is nearly 3770. 



I have received Nature, which contains an abstract of 

 Huggins's highly interesting paper read before the Ro>al Society 

 on the photographs of the spectra of stars. Huggins gives a list 

 of the wave-lengths of the dark lines he obtained in the ultra- 

 violet part of the spectra of white star-, and I was much 

 astoni-hed to find that they corresponded almo-t exactly with my 

 hydrogen lines above mentioned. I put here Huggins's and my 

 own numbers together : — ■ 



My hydrogen til] 

 ultra-violet wave-length. 

 3968 



Huggins's star lines in th< 

 ultra-violet wave-length. 



3968 



3887-5 •• 

 3S34 ■• 

 3795 •• 

 3767-5- 



3^7 

 3834 

 3795 

 377° 



This conformity is so surprising that I venture the conclusion 



that the chief lines of the spectra of while stars are hydrogen lines. 



Lockyer, whose admirable investigations I highly esteem, but 

 with whose conclusions I cannot agree, regards the line 396S 

 (coincident with the calcium line H, Fraunhofer) in the star 

 spectra as a calcium line, and deduces a dissociation of calcium 

 from the fact that the second calcium line K is not visible in the 

 star spectra. My opinion is that the line 396S in the white star 

 spectra is not a calcium, but a hydrogen line, and I base this 

 theory on the fact that the well-known hydrogen lines in these 

 spectra are much more intense and thicker than in the sun 

 spectrum. I may point out that this line is not exactly, but very 

 nearly, coincident with II (Fraunhofer) ; the first is a little less 

 refrangible. 



Lockyer supposes that calcium is also dissociated in the sun's 

 atmosphere. He mentions the observation of Prof. Young, who 

 observed the II seventy-five times and the K line only fifty times 

 in the atmosphere of the sun. My opinion is that the so-called 

 inver.-ed II line, if visible without K in the chromosphere, is not 

 the calcium line, but the fifth hydrogen line. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



Cambridge. — In the event — which seems most probable — of 

 the report of the Board of Natural Science Studies being adopted 

 by the Senate, the Natural Sciences Tripos will, in and after 1SS1, 

 be divided into two parts, each of which will include a practical 

 examination, and will extend over five days. The names of 

 those who have passed the first five days will be alphabetically 

 arranged in three classes, although this part of the examination 

 will be considered to test only the general proficiency of candi 

 dates in several branches of science. The subjects will be 

 grouped thus: (1) Chemistry, (2) Physics, (3) Mineralogy, (4) 



' I have only five in my photographs, because I worked with glass pr>m 

 and lenses, which absorb a good deal of the ultra-violet rays. 



