48 



ASTRONOMICAL PHENOMENA AND PROGRESS. 



ty than that of his having succeeded in photo- 

 graphing the solar corona in presence of an 

 uneclipsed sun. But the evidence that he has 

 really accomplished this feat is deemed con- 

 clusive. In a recent lecture before the Royal 

 Institution, he gave an account of his experi- 

 ments, and in the course of his recital said: 

 "Much of thje light from the corona comes 

 from near the ultra-violet end of the spectrum, 

 and therefore it might be expected to be seen 

 through colored media exercising the requisite 

 selective absorption; but then comes in the 

 drawback that the particular rays in which 

 the corona is especially rich are near the limit 

 of the power of the eye, and have but a feeble 

 influence upon vision. I therefore looked to 

 photography for aid, especially as it is possible 

 to accentuate photographic effects, so that the 

 photograph is no longer true to nature." After 

 detailing several processes tried which resulted 

 in failure, he proceeds : " It has long been 

 demonstrated that chloride of silver is particu- 

 larly sensitive to the rays in which the corona 

 is relatively rich, so that salt I concluded to be 

 the best for my photographic operations. Then 

 came in the difficulty about the imperfect achro- 

 matism of the lenses of refracting telescopes 

 when used for photographic purposes; conse- 

 quently I employed, in the first instance, a New- 

 tonian reflecting telescope with a large and a 

 small mirror. With these appliances twenty 

 pictures were taken, on all of which coronal 

 appearances were visible." -In his later experi- 

 ments he discarded the use of the small mirror, 

 the sun reaching the larger one through a long 

 blackened and diaphragmed tube, thus getting 

 rid of reflections from two mirrors. The backs 

 of the photographic plates were also blackened 

 to prevent reflection from the back surfaces 

 of the light that passed through the photo- 

 graphic films. After all these precautions had 

 been taken, the coronal impressions were still 

 seen. Regarding the nature and cause of the 

 corona, he says: "There are five hypotheses 

 to account for it : 1. That it is a large gaseous 

 atmosphere around the sun. 2. That it is mat- 

 ter ejected from the sun. 3. That it is some- 

 thing of the nature of Saturn's rings, and con- 

 sists of meteoric matter. 4. That we see the 

 impouring of the tails of comets. 5. That 

 there are meteoric streams illuminated by the 

 sun, which are not revolving near the sun, or 

 falling into it, but are parts of the elliptical 

 orbits of comets." He is of the opinion that 

 there may be some truth in all these hypothe- 

 ses. That the corona is a very complex phe- 

 nomenon is abundantly proved by telescopic, 

 spectroscopic, and polariscopic observations of 

 it during total eclipses. Dr. Huggins's own 

 idea is that the corona is not caused by a solar 

 atmosphere, but by particles of matter, and 

 that a single atom in each cubic mile would be 

 sufficient to produce the corona as seen. Pho- 

 tographic experiments are still in progress at 

 the Cape of Good Hope by Mr. C. Ray Woods, 

 under the auspices of Dr. Huggins. 



Red Snnsets. This mysterious phenomenon, 

 which the scientific world is baffled to explain, 

 still continues. It follows the setting and pre- 

 cedes the rising sun, and is often called re- 

 spectively the after-glow and the fore-glow. 

 From the fact that it appeared immediately 

 after the great volcanic eruption of Krakatoa, 

 the belief obtained that the dust, gases, etc., 

 ejected with a force sufficient to throw them 

 to a height far above the influence of wind, 

 clouds, and rain, would account for all the 

 phenomena of this character the after-glow, 

 the fore-glow, and the noon-glow since ob- 

 served. By its long continuance, however, it 

 awakens doubt as to the truth of this hypothe- 

 sis, which by many is already abandoned. On 

 all occasions when the after-glow is very bright 

 and twilight short, three distinct glows have 

 been visible, following each other in regular 

 succession. The third or last glow is, even on 

 the most favorable occasions, very faint, and 

 might easily be overlooked. Another feature, 

 seen only in the east and exactly opposite the 

 sun, is a broad, crimson-colored arch, each end 

 resting on an abutment of the same color, some 

 ten degrees in length in azimuth, the two ap- 

 proaching quite near to each other, though 

 never meeting, there being four or five degrees 

 of untinted sky between. It is quite transi- 

 tory in duration, never lasting over ten min- 

 utes. It can not be seen at all during the 

 months of June, July, and August, in conse- 

 quence of prolonged twilight. 



During the spring months of 1885 there was 

 a partial subsidence, and, on some occasions, 

 an entire absence of the glow, and astrono- 

 mers were of the opinion that it was perhaps 

 abating, and would probably soon entirely 

 cease ; but about the middle of July it sudden- 

 ly reappeared with a brilliance almost equal- 

 ing that of the latter part of 1883. There ap- 

 peared to be occasional abatements, followed 

 by outbursts which were apparently governed 

 by no law, neither did they follow in regular 

 sequence. The after-glow on the evening of 

 September 14 was not surpassed by any previ- 

 ous display. 



Simultaneously with the appearance of the 

 sunset glows there was visible, surrounding 

 the sun at midday, a halo of light of a color 

 exceedingly difficult to liken to any terrestrial 

 tint, which, though fluctuating in brightness 

 and extent, continued visible for nearly two 

 years, and much interfered with delicate astro- 

 nomical observations. This simultaneity of the 

 appearance of the three glows argued strongly 

 in favor of their identity of origin, which was 

 very widely believed. The ease with which 

 hasty and erroneous conclusions are arrived at 

 in observing the ever-changing phenomena of 

 nature is strikingly illustrated in this instance, 

 for the fact that since the recent outburst of 

 the sunset and sunrise glows the noon-glow 

 has entirely vanished, shows decisively that the 

 connection between them is not an absolute 

 one at least, and probably does not exist. 



