Dec. 20, 1883] 



NATURE 



^77 



with a superstitious awe at the red lowering aspect of the 

 sun ; and indeed there was reason for the most enlightened 

 person to be apprehensive, for all the while Calabria and 

 part of Sicily were torn and convulsed with earthquakes, 

 and about that juncture a volcano sprang out of the sea 

 off the coast of Norway." 



Those who are familiar with the letters and poems of 

 Cowper will remember his references to the same pheno- 

 mena in that year, as in "The Task," Book ii. — 



" Fires from beneath, and meteors from above . 

 Portentous, unexampled, unexplained. 

 Have kindled beacors in the skies ; and th' old 

 And crazy earth has had her shaking fits 

 More frequent, and foregone her usual rest." 



Mrs. Somerviile, in her " Physical Geography," traced 

 the origin of these atmospheric phenomena to the great 

 eruption of Skaptar, one of the volcanoes in Iceland, 

 which broke out May 8, and continued till .August, send- 

 ing forth clouds of mingled dust and vapour, which 

 spread over the whole of northern Europe. Mr. Hender- 

 son, in his work on Iceland, and Dr. Daubeny in his 

 work on volcanoes, also describe this eruption, and the 

 enormous quantities of volcanic dust sent by it into the 

 atmosphere. 



Mr. Norman Lockyer ascribes the recent abnormal 

 sunrise and sunset phenomena to the clouds of volcanic 

 dust from the great eruption of Krakatoa on September 

 2. The different effect caused by a tropical eruption and 

 one in northern legions would be such as Gilbert White 

 observed, and what we have lately witnessed. In the 

 eruption of 1783 the stratum of dust and vapour must 

 have been at a low level compared with that of iScJj. 

 We know in a general way the course of the circulation 

 of the atmosphere, as we do that of the ocean : the tluw 

 of currents from the Poles to repla;e the ascending 

 volume of air in the equatorial zone, which gradually 

 diffuses itself in the upper regions of the atmosphere. 

 But of the direction and velocity of these lofty strata we 

 know little in detail ; just as we have variations and uir- 

 e.xplained diversions even of oceanic currents, but in the 

 atmosphere to far greater extent. From Humboldt and 

 Arago we have been taught to believe that the pumice 

 and vapour clouds from volcanoes are raised to enormous 

 altitudes, and the dispersion of these may be too irregular 

 to admit of calculating the exact time after a tropical 

 eruption when atmospherical phenomena would appear 

 in particular localities. The fact remains that abnormal 

 atmospheric effects have resulted from the presence in 

 upper regions of the air of pumice dust in unusual 

 quantity. 



In some regions of the earth these phenomena have 

 been frequently observed, as on the coasts of Peru, where 

 we would expect a large amount of volcanic dust to be 

 present. In Ellis's "Voyage to the Sandwich Islands," 

 he describes just such appearances as we have been re- 

 cently seeing. " Towards evening and in early morning 

 I have seen clouds of every hue in different parts of the 

 heavens, and such as I had never seen before : for in- 

 stance, rich and perfect green, amber, carmine; while 

 the hemisphere round the rising and setting sun has been 

 one blaze of glory." Similar sunlight effects are de- 

 scribed by Bishop Heber in his narrative. " Besides 

 tints of crimson, flaine-colour, &c., there were large tracts 

 of translucent green in the immediate neighbourhood of 

 the sinking sun, and for some time after sunset ; with 

 hues such I have never seen before, except in a prism, 

 and surpassing every effect of paint or glass or gem." 

 These effects were such as aqueous vapour alone could 

 not have produced, and were doubtless due to foreign 

 matter in the upper regions of the atmosphere. 



In the meteorological observations of Luke Howard 

 there are several records of similar abnormal sunlight 

 effects when the sky was " deep blood-red after sunset, 



with hues passing through crimson and a gradation of 

 lighter reds and orange and flame colour." Whether 

 these appearances can be connected with particular 

 volcanic disturbances or not, they seem to have been due 

 to the presence of foreign matter in the upper strata of 

 the air ; and there are rarely periods when some volcanic 

 region is not in active eruption. 



On more than one evening in December the metallic- 

 green colour of the moon attracted general notice. This 

 was not due to the laws of complementary colour, for it 

 remained when not a vestige of red or crimson could 

 affect the vision. Mr. Edward Whymper states that the 

 peculiar hue recalled to him the same appearance as 

 witnessed by him in South America when the atmosphere 

 was charged with volcanic dust. 



James Macaulay 



In 1880, when travelling in Southern Algeria, I was 

 talking with some colonists about a simoom, when a 

 Frenchman present exclaimed " C'est la premiere fois 

 que j'ai vu le soleil bleu." Upon interrogation I was 

 assured by the whole company that the sun, seen through 

 the fine dust of a Sahara wind, had a decidedly blue 

 colour. I do not know whether this is always the case 

 when a storm is blowing from the desert ; but the fact, 

 even if not a regular one, throws some light upon the 

 East-Indian green sun. It confirms evidently the opinion 

 that the green colour and the remarkable weakness 

 of the sun's light, as observed in India, were due to 

 volcanic dust from Krakatoa. An eruption like that 

 of August must throw up into the highest layers of the 

 atmosphere dust not only in enormous quantities but also 

 of extraordinary fineness. .And I ste no difficulty in 

 assuming that this dust, transported by air currents over 

 Africa and Europe, was the cause of the "lemaikable 

 sunsets,'' the more so, as the latter phenomenon is 

 evidently a wandering one. At Constantinople the first re- 

 markable sunset was observed on November 20 (splendid), 

 and suosequently we saw the same t:low of the heavens in 

 the morning and evening of the first five days of December, 

 though partially masked by clouds. Afterwards the ob- 

 servation was rendered impossible by bad weather. 



Constantinople, December 12 Dr. Budde 



I HAVE read with great interest the accounts of the 

 extraordinary sunsets we have had lately. I have watched 

 all the effects most carefully for the last fortnight, and it 

 may be of some interest to you to hear my account. The 

 fir-t time I noticed anything very odd was on the evening 

 of the 24th. I was then calling on a (riciid who lives on 

 this lake, and it was dark enough to have candles, when 

 on looking up at his studio window I saw three or four 

 masses of cumuli piled up against each other, and all of 

 unusual, or rather I should say unnatural, colour. I said 

 to my friend, " Well, I never saw such a sky or clouds, it 

 is exactly like an old master p cture, liKe a rich Titian 

 sky." ... 1 said this because what oiiijht to have been 

 blue sky was quite a rich green, and some of the clouds 

 rich amber, others red brick colour, and others a yellow 

 green. There was a high wind ; the^e clouds were in the 

 north, or nearly opposite the sunset, and very near. I 

 was startled, because I knew some of the colours to be 

 unnatural, especially at that time of day (4.30); itwasnota 

 green or an amber I had ever seen, and 1 have watched the 

 sky very carefully for many years. Then, about a week ago, 

 I saw the same effect again, and on looking round towards 

 the sunset my eye caught the crescent moon ; it was of a 

 pale blue i^ieen. Two evenings before this, I was startled 

 on looking up from my book (and some time after candles 

 had been brought in) to see quite a red glare behind the 

 "Old Man"; as it was almost night, I thought it was some 

 large fire, but on going out I saw that it was merely a 

 glare from the sunset ; and more to the cast near the 

 horizon there were lurid masses of red cloud very far off 



