Science. The Recent Sunsets.

Waikato Times, Volume XXII, Issue 1872, 5 July 1884, Page 2 (Supplement)

Science. The Recent Sunsets.

The brilliant and varied tints in which nature has painted our grey winter sky so frequently during the past few months, at sunrise and sunset, have evoked alike our wonder and admiration. We thought at first that we had been especially favored. But first came letters from different parts of the Continent, giving us vivid descriptions of the gem-like coloring of the heavens at eventide and the gorgeous afterglows; while others later on, dated from San Francisco, Honolulu, Hobart Town, and other remote places, affording accounts of blue suns and blue moons, deep orange skies, with purple overhead and gorgeous vermilion coloring, which lasted two and three hours after sunset, prove the extent of the area in which the phenomena have been visible. It is natural, therefore, that men of science should endeavor to account for appearances at once so beautiful and so unusual, and first one hypothesis and then another^ is started. According to Professor Piazzi Smith and Mr. Norman Lnckj er, the brilliant coloring of the sky at sunset and sunrise is due to the reflection of the sun's rays on clouds of the finest volcanic dust, which were thrown off during the late eruption in Java, and have remained suspended in the air. Others, amongst whom is M. Eenou, of the Eoyal Academy of Sciences in Pari*, while admitting the dust theory, maintain that the phenomena are caused by clouds of meteoric dust, net volcanic, and Mr. Mattieu Williams also appears to shaie this opinion. At a meeting of the Royal Astronomical Society lately, he exhibited a small test tube containing a black sediment obtained from 75 ozs. of snow which had fallen a few days previously at Harrow. The object in collecting it was to determine the nature of the particles floating in the air which weie supposed to hwe caused the unusual coloring and afterglow we have all noticed. On analysing the residue, he found it to contain laige quantities of black oxide of iron, which waa easily separated by the magnet from the remainder of the materials mixed up with the snow. Some of his experiments led him to infer the presence of nickel in the iron, which is characteristic of meteoric iron — pure iion, or iron unalloyed with nickel, ne\er being found in its native state in the earth. But he could not speak with certainty )especting the presence of nickel in the Bediment. However, he considered it quite impossible that such heavy particles as those contained in volcanic dust could by any means or possibility have remained suspended in the air since the eruption of Krakatoa, and consequently rejects Professor Piaz/i Smith's theory. He stated that he had observed two distinct glows in the sunsets. The first was similar to that seen in ordinary sunsets, in which the color is reflected ■ from the under surface of the cloud. This faded away, and then he noticed a brightening up of the colois, and the clouds appeared like dark objects projected on a rosy back ground, showing that the matter, whatever it was, which caused the afterglow, was puspended to a great height in the atmosphere, high above the cloud 3. Mr. Eangard, who was also present at the meeting, examined some of the snow residue, and found it satisfactorily free from tcrrestial dust, no effeivescence taking place on the application of hydrochloric acid, which he had applied to it as a test. lie thought it possible that the black particles found in the sediment alluded to might be volcanic ; but if so, it was difficult to conceive how they should have remained so long in the air. On the other hand, Mr. McPherson.who h&salsonwlean analysis of some snow, states that he has found crystals of hypersthene, pyioiJne, magnetic iron, and volcanic glass in the residue, all of which are present in the volcanic ashes collected after eruption in Java, and sent on to Paris for analysis. He considers this a conclusive proof in Lwor of Professor Piazzi Smith's theory. Mr. Preeco, another t,avant, is of the opinion that veiy finely divided dust may remain puspended in the upper regions of the atmosphere, ov/ing to the particles of which it consists having an electrical charge of the same sign as the earth, and being thereby repelled and kept in suspense in opposition to gravity. It is also stated that, as meteoric bodies coming into contact with the earth's atmospheie require an intense degree of heat and become incandescent, it is unlikely that even minute particles should be deficient in momentum to produce the same results. Consequently, if the glorious celestial phenotnena which surprised and delighted us of late are due, as M. Kenou and Mr. Mattieu Williams suppose, to the presence of an extraordinary amount of meteoric dust in the air, they should have been preceded by a brilliant nocturnal illumination of the heavens. If, however, the meteoric dust theory i 3 untenable, it is also difficult to understand how the volcanic dust arising from the eruption in Java could cover the whole earth, for the solar phenomena, as we have already stated, have been observed in every quarter oE the globe; also why they should have occurred so long after the catastrophe had taken place, and should not be present whenever a sunset is visible. The circumstance of volcanic matter being found in enow is certainly not of itself sufficient proof, for there are active volcanoes quite near enough to us for us to be able to account for its presence in other ways. The most plausible theory advanced hitherto seems to be that the very remarkable sunsets we have witnessed, with their gorgeous after-glow, are due to the presence of an aqueous belt in the higher atmosphere. We all know how greatly vapor contributes to the brilliancy of a sunrise or sunset, and that, if we desire to enjoy these in all their beauty, we must see them, not in high and dry localities, but in low-lying, marshy districts like the Landes and Haremma. We have certainly seen very glorious ones in Switzerland, but there was little variety of coloring, and the sunset owed half its beauty to its surroundings. Without the snow-capped mountains, dark pine forests, and ruined castles, we should probably have termed them very tame affairs. The finest we saw whilst travelling there was on the Bigi. But there we have vapor arising from the lake of Lucerne. They were, however, nothing to compare, as regards brilliancy and variety of coloring, to those we have watched from the Bergstrasse near Heidelberg. The whole plain? at our feet on this occasion would be flooded with a golden haze, which changed to a rosy red as the sun sank lower behind the distant Vosges mountains, marking their dark-blue outlines in red and gold as he slowly disappeared from view. Here again we owe the beauty of the phenomenon to the mists arising from the marshy districts on the left bank of the Bhine, near Manheim. We have heard Russians speak rapturously of the beauty of the solar phenomena on the Steppes. It is, no doubt, the case, as there would be nothing but a fe<v stunted trees here and there to break the view. Mountains and buildings give variety to the tableau ; but if we wish to itudy a sunset in ali its grandeur, we must aeek it at sea or on a plain. The finest we have seen in England, as far as regards coloring, have been at Herneßay ; but a great deal of the beauty of the effect was owing to the wet, shingly beach, which refieoted the gorgeous tints of the sky. Col. Stuart Wort- j ley, in a letter which appeared lately, in the columns of the Tivies, speaks warmly of the beauty of the sunsets and sunrises in the Pacific Ocsan. He is a convert to the volcanic dust theory, and attributes the magnificent coloring of the sky at such times to the constant stream o! volcanic matter thrown out

by the volcanoes in the mountain ranges in South America. We have now stated the three different causes to which men of science attribute the late celestial phenomena. It is scarcely likely, however, that they will ever be accounted for to the satisfaction of everyone. — The Queen.