i8o 



NATURE 



IDec. 20, 1883 



whole phenomenon on the 4th inst. was the most in- 

 structive. These are my notes : — 



4.34 p.m. sundown ; usual sunset effect, golden ; 

 massive horizontal streaks of neutral tint cloud, from 5° to 

 20' above horizon, with intervals, coloured Indian red ; 

 cirrus above light crimson. 4.50, all over, clouds no 

 longer illuminated, sky on horizon dull >cllow. 5 p.m., 

 yellow band turned pale i;>ren ; lav clouds remaining quite 

 dark (not illuminated), upper transparent cirrus pink or 

 light \>v,r^\e, gradually fading off into blue atmosphere, 

 which remained decidedly blue although the moon and haze 

 circle round her (= four moon diameters) were decidedly 

 greenish. 5.15, purple fan receded or contracted some- 

 what, and more crimson in colour ; .green tint on horizon 

 fainter. 5.25, upper purple tint quite gone ; light down 

 on horizon bright red like conflagration (or iron heated 

 to redness) ; inoon greenish ; lieai'y cloud streaks guile 

 dark; and here 1 will say that although I noticed in 

 Madrid a very slight breeze from north-west, all clouds 

 remained to all appearance perfectly stationary from 

 beginning to end. 5.35, at this moment the lower clouds 

 (say to 20° above horizon) were reillujninated as at sun- 

 set from beneath (Indian red), after remaining forty-five 

 minutes in total shade. At 5 45 this new illumination began 

 to fade, and the red glow on the horizun had ri^en some- 

 what, and was dusky. 5.50, only a few red streaks under the 

 clouds; glow as before, apparently more intense, owing to 

 increasing darkness. 6.0, glow dull, and low down on hori- 

 zon, nearly all on the north side of the sun's setting point. 

 6.15, all over. Barometer 702 mm. (say 27"65 in.); 

 thermometer 12° C. 



Since December i the whole phenomenon, without 

 losing intensity, has become reduced in extent, z>. the fan 

 of light (so to speak) is getting smaller, especially in the 

 direction of its length on the horizon. Yesterday (5th) I 

 noticed the same reilluniination of cloud ; to-day we had 

 heavy clouds and rain at the time, and barometer 699 mm. 

 and thermometer 6" 5 at six. F. GlLLMAN 



Quintana 26 (Barrio Arguelles), Madrid, Dec. 6 



There has been a very fine "glow '' this evening, with 

 the delicate rose tint which is so unusual. 1 observed the 

 bands at C and D very strongly marked, and also a faint 

 band at about a, and another about half way between 

 C and D. This is the best marked evening glow that we 

 have had here since about the end of last week. 



Dublin, December 14 J. P. O'REILLY 



SiGNOR Denz.'V, Director of the Central Cibservatory 

 at Moncalieri, writes that these sunsets were seen from 

 November 25 to l;ecember i, and again from December4 

 to December 7, throughout the whole of Italy from the 

 Alps to the extremity of Calabria, and everywhere with 

 great intensity. A vast number of reports have been 

 received at the Central Observatory, generally to the 

 same effect. So vivid was the glow, that by many ob- 

 servers it was taken for an aurora borealis, the prevailing 

 colours oscillating between red and deep orange, and 

 afterwards passing through all the tints to the most deli- 

 cate pink. During the evenings of November 28 and 29 

 nearly the whole sky was lit up, and the phenomenon was 

 followed first by storms, fogs, and rain, and later on by 

 snow. Observed with the spectroscope, the light pre- 

 sented nothing but the usual absorption lines of the 

 vapour of water, but very intense. Before dawn and after 

 sunset the zodiacal light was seen very distinctly. 



Numerous letters have appeared in the Times on the 

 sunsets during the past week : — 



Mr.G. J. Sy.mons sends the following extract from the 

 Meteorological Report from Adelaide Observatory, South 

 Australia, for C)ctober, 18S3 : — "On every clear even- 

 ing during this month, and the last fortnight of 

 September, a peculiar phenomenon has been apparent 

 in the western sky. Shortly after sunset a red glow 



will make its appearance, at an altitude of about 

 50°, being very faint at first, but as the brightness of 

 the sky near the horizon dies away with the receding 

 sun, the red glow will e.xpand downwards, becoming at 

 the same time more brilliant, until at last the whole 

 western sky will be lit up with a beautiful light, varying 

 in colour from a delicate pink to a most intense scarlet, 

 and the spectacle presents a most brilliant appearance. 

 The upper part will then gradually fade away until the 

 colour is noticeable only 7 or 8° above the horizon, at 

 which time the light is at about its brightest. Afterwards, 

 a secondary glow will sometimes make its appearance at 

 an altitude of about 50", and gradually spread downwards 

 until the sky is again lit up. In the secondary pheno- 

 menon the colours are generally more delicate. The 

 whole thing will fade away about 8 p.m. This pheno- 

 menon has been noticed all over the south eastern portion 

 of this continent, from Port Augusta (lat. 32° S.) to Mel- 

 bourne ; and in India the sun has at times presented a 

 most peculiar appearance, being green at rising, then 

 gradually changing to a blue at noon, and inversely from 

 noon to sunset. Various theories have been started to 

 account for the phenomena.'' 



Col. Stuart- Wortlev states that in 1862 he spent a 

 year in South Italy on purpose to study the formation of 

 clouds by the aid of photography. " During that time I 

 spent some time at Naples while the great eruption of 

 that year was going on, and was struck with the unusual 

 colours of the sunsets during and after the eruptions. I 

 still have photographs of both sunrises and sunsets in- 

 dorsed with memoranda as to unusual and exceptional 

 colours." Four years ago, while sailing in the Pacific, 

 Col. Stuart VVortley was much struck with the fact that 

 very frequently the whole vault of heaven was overspread 

 with magnificent and glorious colouring, and that in the 

 higher regions of the air colours were found that were 

 never seen at the horizon or below a certain height. 

 "Now, this exceptional magnificence and peculiarity of 

 colouring only occurs in certain latitudes and in well- 

 defined belts, and I venture to suggest that, seen in the 

 light now thrown on the subject by Mr. Norman Lockyer 

 and others, the constant stream of volcanic matter thrown 

 nut by the great volcanoes in the mountain ranges of 

 South .America, and possibly from elsewhere, form an 

 almost permanent stratum of floating matter, carried in 

 certain directions and kept in certain positions by alter- 

 nating currents in the higher regions of the air, and that 

 to this stratum of volcanic matter much of the excep- 

 tional colouring found to be associated with sunrises and 

 sunsets in portions of the Southern Pacific Ocean is due." 



Mr. W. H. Preece writes : — " I think 1 can add one 

 link to Mr. Lockyer's chain of reasoning. If we assume 

 that the mass of volcanic matter projected with such force 

 into the atmosphere in the Straits of Sunda was highly 

 electrified, then it must have been electrified with the 

 same sign as that of the earth — viz. negative. Therefore, 

 when the force of projection had exhausted itself, the 

 cloud of matter woula be subject to two other forces be 

 sides gravity— the repulsion of the electrified earth, and 

 the selt-repulsion of each particle of electrified dust. The 

 first would determine the tenuity of the cloud, for the 

 lighter the particles the further they would be repelled, 

 and the heavier the particles the quicker they would 

 descend. It is quite possible to conceive that they might 

 be so minute and so highly electrified as to reach the 

 utmost confines of our atmosphere, where they would 

 remain as long as they remained electrified. The second 

 repulsive force would cause the particles to spread out 

 continuously in a horizontal plane until they would cover 

 an area determined only by their quantity. When we 

 take into consideration the movements of the atmosphere 

 and the rotation of the earth, I see no reason to doubt 

 that an immense cloud of highly electrified matter, pro- 

 jected into the atmosphere in Java, could spread itself in 



