Jan. 3, 1S84] 



NA TURE 



22 



silk, or a ploughed field glazed with crimson ice. These 

 effects may have been seen in the late sunsets, but they 

 are not the specific after-glow ; that is, without gloss or 

 lustre. 



The two things together, that is intensity of light and 

 want of lustre, give to objects on the earth the peculiar 

 illumination which may be seen in studios and other well- 

 like rooms, and which itself aftects the practice of painters 

 and ma}- be seen in their works, notably Rembrandt's, dis- 

 guising or feebly showing the outlines and distinctions of 

 things, but fetching out white surfaces and coloured stuffs 

 with a rich and inward and seemingly self-luminous 

 glow. 



(4) They differ in the reffidariiy of their colouring. 

 Four colours in particular have been noticeable in these 

 after-glows, and in a fixed order of time and place — 

 orange, lowest and nearest the sundown ; above this, and 

 broader, green ; above this, broader still, a variable red, 

 ending in being crimson ; above this a faint lilac. The 

 lilac disappears ; the green deepens, spreads, and en- 

 croaches on the orange ; and the red deepens, spreads, 

 and encroaches on the green, til! at last one red, varying 

 downwards from crimson to scarlet or orange fills the west 

 and south. The four colours I have named are mentioned 

 in Lieut. G. N. Bittleston's letter from Umballa : " The 

 sun goes down as usual and it gets nearly dark, and then 

 a bright red and yellow and green and purple blaze comes 

 in the sky and makes it lighter again.'' I suppose the 

 yellow here spoken of to be an orange yellow, and the 

 purple to be what I have abo\e called lilac. 



Ordinary sunsets have not this order ; this, so to say, 

 fixe'd and limited palette. The green in particular, is low 

 down when it appears. There is often a trace of olive 

 between the sundown and the higher blue sk\', but it never 

 develops, that I remember, into a fresh green. 



(5) They differ in the colours themselves, which are im- 

 pure and not of the spectrum. The first orange and the 

 last crimson flush are perhaps pure, or nearly so, but the 

 two most remarkable glows, the green and the red, are 

 not. The green is between an apple-green or pea-green 

 (which are pure greens) and an olive (which is a tertiary 

 colour) : it is vivid and beautiful, but not pure. The red 

 is very impure, and not evenly laid on. On the 4th it 

 appeared brown, like a strong light behind tortoiseshell, 

 or Derbyshire alabaster. It has been well compared to 

 the colour of incandescent iron. Sometimes it appears 

 like a mixture of chalk with sand and muddy earths. The 

 pigments for it would be ochre and Indian red. 



Now the yellows, oranges, crimsons, purples, and greens 

 of bright sunsets are beautifully pure. Tertiary colours 

 may of course also be found in certain cases and places. 



(6) Tliey differ in the texture of the coloured surfaces, 

 which are neither distinct cloud of recognised make nor 

 yet translucent mediums. Mr. Russell's observations 

 should here be read. I have further noticed streamers, 

 fine ribbing or mackerelling, and other more curious 

 textures, the colour varying with the texture. 



In ordinary sunsets the yellows and greens and the 

 lower reds look like glass, or coloured lic|uids, as pure as 

 the blue. Other colours, or these in other parts, are dis- 

 tinct flushes or illuminations of cloud or landscape. 



1 subjoin an account of the sunset of the i6th, which 

 was here ver\' remarkable, from my own obsen-ations and 

 those of one of the observatorj- staff. 



A bright glow had been round the sun all day and 

 became more remarkable towards sunset. It then had a 

 silvery or steely look, with soft radiating streamers and 

 little colour ; its shape was mainly elliptical, the slightly 

 longer axis being vertical ; the size about 20° from the sun 

 each way. There was a pale gold colour, brightening and 

 fading by turns for ten minutes as the sun went down. 

 After the sunset the horizon was, by 4.10, lined a long 

 way by a glowing tawny light, not very pure in colour and 

 distinctly textured in hummocks, bodies like a shoal of 



dolphins, or in what are called gadroons, or as the Japanese 

 conventionally represent waves. The glowing vapour 

 above this was as yet colourless ; then this took a beautiful 

 olive or celadon green, not so vivid as the previous day's, 

 and delicately fluted : the green belt was broader than the 

 orange, and pressed down on and contracted it. Above 

 the green in turn appeared a red glow, broader r.nd burlier 

 in make ; it was softly brindled, and in the ribs or bars 

 the colour was rosier, in the channels where the blue of 

 the sky shone through it was a mallow colour. Above 

 this was a vague lilac. The red was first noticed 45° 

 above the horizon, and spokes or beams could be seen in 

 it, compared by one beholder to a man's open hand. By 

 4.45 the red had driven out the green, and, fusing with the 

 remains of the orange, reached the horizon. By that 

 time the east, which had a rose tinge, became of a 

 duller red, compared to sand : according to my observ- 

 ation, the ground of the sky in the east was green 

 or else tawny, and the crimson only in the clouds. A 

 great sheet of hea\-)- dark cloud, with a reefed or 

 puckered make, drew off the west in the course of 

 the pageant : the edge of this and the smaller pellets of 

 clond that filed aero s the bright field of the sundown 

 caught a livid green. .At 5 the red in the west was 

 fainter, at 5.20 it became notably rosier and livelier ; but 

 it was never of a pure rose. A faint dusky blush was left 

 as late as 5.30, or later. While these changes were going 

 on in the sky, the landscape of Ribblesdale glowed with 

 a frowning brown. 



The two following observations seem to have to do 

 with the same phenomena and their causes. For some 

 weeks past on fine bright days, when the sun has been 

 behind a big cloud and has sent up (perspectively speak- 

 ing) the dark crown or paling of beams of shadow in 

 such cases commonly to be seen, I have remarked, upon 

 the ground of the sky, sometimes an amber, sometimes a 

 soft rose colour, instead of the usual darkening of the 

 blue. Also on moonlight nights, and particularly on 

 December 14, a sort of brown or muddy cast, never 

 before witnessed, has been seen by more than one 

 observer, in the sky. Ger.^rd Hopkins 



Stonyhurst College, December 21, 1SS3 



The remarkable phenomena after sunset which, ac- 

 cording to N.\TURE, were seen in the second half of 

 November in England, Italy, at the Cape, and a little 

 earlier in many parts of Asia, could be observed almost 

 all over .Austria and Germany. I saw them myself in an 

 especially distinct appearance here on November 22 and 

 29. Soon after sunset on November 22 (at 4.30 p.m.), a 

 crimson glow was seen in the direction of south-west, 

 and while everybody was supposing that some large 

 printworks lying in that direction were on fire, the glow 

 was getting more intense, and at 5 p.m. the whole of the 

 western sky assumed a bluish purple hue which rose up 

 to the zenith while the sun was sinking lower, so that the 

 glow could be attributed only to an atmospheric pheno- 

 menon. About an hour after sunset the colour of the 

 sky was almost violet, with which the phenomenon 

 disappeared. 



According to German papers, a phenomenon of this 

 kind and intensity was never before observed in Central 

 Europe. Dr. As^mann, director of the Meteorological 

 Observatory, Madgeburg, attempts to explain these phe- 

 nomena by the reflection of sunlight from the upper 

 strata of our atmosphere, highly saturated with aqueous 

 vapour, owing to its comparatively high temperature. 

 The phenomenon could not be attributed to electrical 

 causes, as at that time not the slightest magnetic dis- 

 turbance could be observed at the Prague Observatory. 

 In the spectrum of this light uncommonly strong " rain 

 bands" were seen. As the sun was about i8j° below the 

 horizon when the phenomena began (before sunrise) or 

 ceased (after sunset), the reflection was calculated to 



