46 



ASTEONOMICAL PHENOMENA AND PEOGEESS. 



mand of the English expedition, gives the fol- 

 lowing account of photographic operations, in 

 a letter to Prof. G. B. Airy, the Astronomer 

 Eoyal, dated Guntoor, April 18th: 



The morning was very promising, and, if it had fol- 

 lowed the course of its predecessor, we would have 

 had a magnificent clear sky, but it clouded over the 

 east with thin cumulo-strati, which, while hardly 

 stopping vision, interfered very much with the photo- 

 graphic energy ; and the result was that every nega- 

 tive was under-exposed, and we have little more 

 than very dense marks, showing the protuberances. 

 The six plates arranged for were duly exposed, but 

 the heat so concentrated the nitrate of silver solution, 

 that, besides showing but faint traces of any corona, 

 they are all covered with spots. Still, we may make 

 something of them, and will try. 



Captain Branfill reports the protuberances unpolar- 

 ized, and the corona strongly polarized everywhere, in 

 a plane passing through the centre of the sun. 



Complementarily, I have to report a continuous 

 spectrum from the corona, and one of bright lines 

 from the prominence I examined. I am, I believe, 

 safe in saying that three of the lines in the spectrum 

 of the protuberances compared to C, D and b. I saw 

 a line in the green near F, but I had lost so much 

 time in finding the protuberance (owing to the finder 

 having changed its adjustment since last night), that 

 I lost it in the sunlight before measuring it, and I be- 

 lieve I saw traces ot a line in the blue near G, but to 

 see them clearly involves a very large change in the 

 focus of the telescope, which was out of the question 

 then. I conclude that my result is, that the atmos- 

 phere of the sun is mainly of non-luminous (or faintly 

 luminous) gas at a short distance from the limb of the 

 sun. It may have had faintly luminous lines, but I 

 had to open the jaws a good deal to get what I could 

 see at first, and consequently the lines would be dif- 

 fused somewhat ; still, I think I should have seen 

 them. The prominence I examined was a very high 

 narrow one, almost to my eye like a bit of the sun 

 through a chink in brightness and color (I could see 

 no tinge of color), and somewhat zigzagged like a flash 

 of lightning. It must have been three minutes high, 

 for it was on the preceding side of the sun near the 

 vertex, and was a marked object both in the last 

 photo-plate, just before the sun reappeared, and to 

 the eye. 



Captain Branfill saw the prominence colored, as 

 did two other gentlemen ; but one in my observatory 

 (like myself) only saw it white. I should, however, 

 say that for long, I never saw Alpha Orionis markedly 

 red, nor Antares, and I may not catch red soon, 

 though I cannot conceive this being so. 



In conclusion, I may note that the darkness was 

 very slight, and the color not half so gloomy as in 

 the eclipse of 1857, which was partial at Dehli, where 

 I was then. 



/ The London News, of August 25th, says : 



Telegrams have been received almost simultane- 

 ously from Major Tennant, who commanded the ex- 

 pedition sent out by the Astronomical Society, and 

 from Dr. Janssen, who commanded the French expe- 

 dition. Major Tennant states that light fleecy clouds 

 covered the sky, but that the eclipsehas been, in the 

 main, successfully observed. This news is very prom- 

 ising, because his party had undertaken the duty 

 of photographing the eclipse. The Government of 

 India had obtained from England a Newtonian re- 

 flector, especially constructed for the occasion ; and 

 arrangements had been made by means of which it 

 was hoped that six photographic pictures would be 

 taken during the totality. Major Tennant would 

 hardly have described the observation of the eclipse 

 as successful, unless several trustworthy photographs 

 had been taken. 



M. Janssen states that the ech'pse has been suc- 

 cessfully observed. The spectrum of the red protu- 



berances which are seen around the black disk of the 

 moon during totality, and which have long since 

 been proved to belong to the sun, has been found to 

 present a very remarkable and unexpected appear- 

 ance. What this appearance is he does not ten us ; 

 but one conclusion drawn from the nature of the 

 spectrum is that the protuberances themselves are 

 gaseous. It will interest our readers to know that, 

 whatever dubiety must still be attached to the results 

 of the observations made by M. Janssen, we may ac- 

 cept at once this general conclusion of his as beyond 

 a peradventure. There are few observations more 

 simple and conclusive than those by which the gen- 

 eral character of a self-luminous object is determined 

 by spectroscopic analysis. The rainbow - colored 

 streak of light which indicates that the source of 

 light is a luminous solid or liquid ; the colored streak 

 crossed by dark lines which indicates that before 

 reaching us the light from such a source has passed 

 through absorptive vapors ; and the spectrum consist- 

 ing of bright lines only, which indicates that the 

 source of light is a luminous gas ; all these spectra 

 are so readily distinguishable inter se that it is impos- 

 sible for the veriest beginner to mistake one for an- 

 other. Thus it may be looked upon as absolutely 

 certain that the nature of the colored prominences 

 has now been definitely settled. Those enormous 

 masses of luminous matter, some of which exceed the 

 earth many hundreds of times hi volume, are now 

 known to be great gas-heaps. It had been supposed 

 that they were solar clouds, formed by the condensa- 

 tion of the metallic vapors which exist within the 

 solar atmosphere into liquid globules, in a manner 

 precisely corresponding to the formation of aqueous 

 clouds in our own atmosphere. This view will now in 

 all probability have to be definitively abandoned. 

 Yet that the prominences are formed by some sort of 

 condensation taking place within the solar atmos- 

 phere seems almost indisputable ; so that the evi- 

 dence we now have seems to show that, as a modern 

 astronomer has suggested, the fierce heat which ex- 

 ists hi the sun's immediate neighborhood is sufficient 

 to " melt solid matter, turn liquids into vapors, even 

 vapors into some still more subtle form." 



Dr. Hermann Yogel, who accompanied the 

 North-German expedition to Aden, as photog- 

 rapher, writes to the Augsburg Gazette. His 

 experiences were : 



At 4 o'clock on the 18th of August, we left Aden, 

 where the expedition had established its headquar- 

 ters. Nine-tenths of the sky was overcast, and we 

 endeavored to feel as resigned as possible to our prob- 

 able disappointment. Our object was to obtain as 

 many photographs as could be taken of the phenom- 

 ena during the three minutes they would last, and 

 in order to do this we had practised with our ma- 

 chine, like soldiers with fire-arms. Dr. Frische was 

 charged with the preparation of the plates, Dr. Zen- 

 ker with putting the slides into the machine, Dr. 

 Therle with drawing them out when they had been 

 exposed a sufficient time, while my business was in 

 the tent. With this division of labor we found that 

 it would be possible to obtain six photographs in the 

 three minutes. As the important moment approached, 

 to our delight we saw, through a break it the clouds, 

 the disk of the sun, partially covered by the moon. 

 The landscape around us assumed a strange hue, 

 neither sunlight nor moonlight the chemical-color 

 rays were exceedingly weak. As a test, we exposed a 

 plate in the machine 'for fifteen seconds, and obtained 

 a good impression of the clouds ; as the disk of the 

 sun grew smaller the clouds opened out. The last 

 minute before the total eclipse arrived, Dr. Frische and 

 I crept into our tent our work began. The first plate 

 was experimentally exposed five and ten seconds, in 

 order to be sure of the right time. Mohammed, our 

 black servant, brought me the first slide into the tent. 

 I prepared the plate, and anxiously watched to see 

 what would appear. Just then my light went out. I 



