576 



NATURE 



[Oct. ii, 1883 



assumption that these two absorptions existed in aqueous vapour 

 at once accounted for the green sun." In the sequel it will be 

 found that Dr. Schuster's observations quite confirmed Mr. 

 Lockyer's theory. 



By my friend Major A. T. Fraser, R.E., I have just been 

 favoured with a copy, which I now inclose to you, of a 

 Madras paper, dated September 12, giving not only the frightened 

 comments of a dozen different, unpractised observeis on the 

 grten sun, seen morning and evening over the south-east of 

 India during the two or three previous days, but also the spectr >• 

 scopic explanation thereof by Rev. Prof. Michie Smith, which 

 is so good that you may perhaps think well 10 introduce it into 

 your columns. 



The case too is further worth notice here, as an example of 

 (he occasional powers of the rain-band spectroscope over and 

 above the wet and dry bulb thermometers, to tell us what is in 

 the upper air now and will visit us soon below. For on those 

 days when the greenness of the sun was undoubtedly due to 

 being seen through strata of atmosphere inordinately charged 

 with watery vapour (much as I set forth in vol. xiv. of " Edin- 

 burgh Astronomical Observations," was the case .-o eminently at 

 Palermo in 1872), the air in contact with the dwellings of man 

 was dry. 



It has been so too for a considerable time, as testified by Mr. 

 Pogson at the Madras Observatory, both by his daily hygro- 

 ruetric observations, and by his record of rainfall for the year 

 being behind the usual quantity by about a third of the whole. 

 From this circumstance apparently, "some of th: learned old 

 men," but knowing nothing of spectroscopy, in that locality, 

 needlessly afflicted themselves and their neighbours also, by 

 proclaiming that the green sun, in place of being a sign of good 

 times coming, " was a bad omen for the country, and would 

 bring a famine this year." 



But though there was still a drought at Madras the same 

 paper involuntarily reports that abundant rain had begun to fall 

 further away to the south and west, or to the extent, at Tra van- 

 core, of 5 -91 inches, and at Malabar of 10 14 inches, in one 

 week. C. Piazzi Smyth 



15, Royal Terrace, Edinburgh, October 9 



We have just been having the curious phenomenon of a 

 greenish colour in the light of the sun. Letters to the Madras 

 papers show that the same thing has been noticed in many other 

 parts of Southern India. It is new to me, a' d t<> every one eke 

 who has seen it, so far as I have heard. The native astronomers 

 say that there is a planet wholly absorbed in the sun, and that if 

 it leaves the sun a green light will appear. Or, according to 

 others, if V r enus comes in contact with the sun, which, accord- 

 ing to their calendars, is the case now, a green light will be seen. 

 Both agree, however, in portending evil to the inhabitants of 

 this planet ; consequently there has been no little curiosity and 

 speculation awakened by this singular appearance, and more or 

 less of uneasiness in the minds of the ignorant and superstitious 

 natives. As I am principal of the High School in this place, 

 and teacher in a small way of science, they apply to me for the 

 scientific solution of the mystery ; but, farther than a mere con- 

 jecture, I have to confess myself quite as much in the dark a» 

 the rest. 



Doub less others of your correspondents have noticed the same 

 thing, and my description may be superfluous ; yet I venture to 

 give it, as it may at least corroborate the statements of other 

 observers. 



My attention was first called to the matter by one of my 

 teachers about four o'clock on the afternoon of September 10, 

 but I learn that the same thing was noticed el-ewhere the day 

 before. At the time of which I speak I noticed that the light 

 from the sun shining into the room through an open western 

 door threw a curious pale blue colour on the floor. I also 

 noticed that it had something of the effect upon colours that is 

 commonly seen in coloured lights. On looking out I saw that 

 the sun, which was somewhat dimmed by a haze, had a decidedly 

 greenish-blue tinge. The same thing was observed on the nth 

 and I2tb, both morning and evening; but my ob ervations were 

 confined to the ev nings. About four o'clock (at least I did not 

 notice it earlier) an indistinct bluish tinge appeared in the light. 

 This gradually passed into a greenish colour, and this in turn 

 became tinged with yellow as the sun approached the horizon. 

 As the sun sank, bands of smoky haze drifted across its disk. 

 After the sun was down, bright yellow, orange, and red ap- 

 peared in the west, a very deep red remaining for more than an 



hour after sunset ; whereas under ordinary conditions all traces 

 of colour leave the sky in this latitude within half an hour after 

 the sun disappears. At night the moon, just past the first quar- 

 ter was surrounded by a pale greenish halo some thirty degrees 

 in breadth. 



After sunset I observed a peculiar appearance in the haze 

 which covered the sky. It was not of sufficient density to be at 

 all visible, except where it reflected the direct rays of the sun. 

 There it had a singular mottled appearance, with a smoky look 

 along the borders of the denser portions, suggesting clouds of 

 -moke or dust in the upper regions of the atmosphere. 



Of ccur.-e the question which every one is asking now is, 

 What caused the green light ? very few, so far as I have learned, 

 having i.oticed anything else. The succession of colours which 

 I have mentioned, occurring exactly in the order of the solar 

 spectrum, would seem to indicate beyond a doubt the presence 

 of some highly refracting substance in the atmosphere which 

 resolved the sun's rays into primary col.urs and gave us in suc- 

 cession, according to the angle of the sun to the horizon, blue, 

 green, yellow, orange, and red, the two latter only appearing 

 as reflected from the under surface of the haze. On the evening 

 of the 13th the sun appeared to be perfectly clear, but after it 

 was below the horizon the western sky was seen to be covered 

 with a smoky haze of a singular appearance, which became 

 brilliantly illuminated with yellow, oiange, and red in the order 

 I have mentioned, counting upward from the horizon. These 

 sank one after the other, leaving at last an arc of brilliant red 

 along the west, the inner portion of the segment contained by 

 the arc being composed of orange. This disappeared in turn, 

 and the whole western sky became yellow again without any 

 distinct outlines, and this gradually deepened into red, which 

 remained for an hour or more after sunset. The latter pheno- 

 menon was not unlike an ordinary sunset, except in brightness 

 and duration. 



But what could the refracting medium be ? The air itself has 

 refracting power, and so have the minute particles of moisture 

 or ice which constitute the ordinary hazy clouds in the upper 

 regions of the atmosphere ; but it would be difficult to say why 

 the effects which I have described should not be of more fre- 

 quent occurrence if produced by either or both of these causes, 

 since they are always present in a greater or less degree, and 

 especially as there was apparently nothing unusual in the state 

 of the weather at the time. Neither would clcurls of smoke 

 alone produce such effects as I have mentioned. In my native 

 place in the United States, where vast tracts of prairie, and 

 often of woodland, are burned over every autumn, a smoky 

 haze i- a common thing at that season of the year. Sometimes 

 for da\s together the haze is so dense as almost to hide the sun, 

 yet I never heard of any other effect upon the light than this 

 obscuring of it, while the sunsets were especially dull and colour- 

 less. Nor do I see how these phenomena could be referred to 

 unusual electrical conditions, for in that ca e they should be 

 more common, as electrical storms are by no means unusual. 1 

 have been led, therefore, to wonder if the phenomena may not 

 -be the result of some fine transparent or semi-transparent dust 

 particles in the upper regions of the atmosphere, which form the 

 singular looking haze, and refract the light in the manner 1 have 

 described, and whether the whole may not be traceable to the 

 recent volcanic eruptions in Java. 



According to the telegrams, the city cf Batavia was darkened 

 for thirty-six hours by clouds of dust from the volcano. True, 

 we are a long distance from Java here, Ongole being in latitude 

 15° 30' N., and longitude 8o° 6' E. But it is well known that 

 the smoke and ashes from volcanoes are often carried to immense 

 distances, and in this case, if acted upon by the trade winds, they 

 would be carried away to the westward, and rising with the 

 upward currents might enter the return trades, and sd be swept 

 over Southern India in a north easterly direction — the direction 

 of our prevailing winds at this season of the year. However, I 

 only venture this solution of the problem as a timid conjecture, 

 the truth or falsity of w hich I have no means of demonstrating, 



Will not some of the readers of Nature who are better 

 informed in regard to such matters kindly give me their 

 opinions of the phenomena? I should be glad also to know it 

 such effects upon the light as I have described have ever been 

 noticed as the result of the smoke or dust or gases emitted by 

 volcanoes. 



Another thing which awakened about as much curiosity and 

 speculation in the minds of the natives as the coloured light was 

 the large spot now crossing the sun's disk. Ordinarily the 

 atmosphere is so clear that even at sunset the sun cannot be 



