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very just remark that “the man who first enunciates a theory may have considered it much more crudely than one who has not mentioned it outside the range of private conversation,' I could have understood it to relate to the occasions, few and far between, when I have been forced to make reclamations respecting results worked out to their completion by myself. But so far as my memory serves, I have never reclaimed a theory, or a scrap of one, in any sort or fashion, niggardly or otherwise; nor have I ever had occasion to do so, so far as I am aware. The second appendix to the first edition has been removed from the present, partly to make room for the added matter (which much exceeds it in extent), and partly as being somewhat too abstruse for a popular treatise. The chapters relating to the circumsolar region were in type before the news of the recent eclipse had reached England. If the present edition had been prepared a few months later, I should simply have substituted the overwhelming evidence derived from the late eclipse, for the equally complete but less striking evidence already available when I wrote. The results of the eclipse expeditions of December last can be readily summed up. In the first place, seventeen excellent photographs, agreeing admirably in all essential respects, have been obtained at Bekul, Dodabetta, Avenashi, and Jaffna. Next, the existence of Young's complex and relatively shallow atmosphere, giving a spectrum of multitudinous bright lines, has been finally established. Thirdly, Respighi has observed what Young had demonstrated, the fact, namely, that the gaseous matter of the inner corona extends upwards of 200,000 miles from the Sun's surface; for he saw three coloured spectral images of the corona with this degree of extension (two of these images being due to glowing hydrogen). Fourthly, Janssen has proved that besides Kirchhoff's 1474-line, the hydrogen lines and several other fainter lines exist in the gaseous spectrum of the corona, while he has been able to detect the solar dark lines (notably the sodium line) across the faint continuous spectrum of the corona. Lastly, the polarisation observations show that to a height of more than a million miles from the Sun the coronal luminosity contains reflected light. All these results agree perfectly with the theories enunciated in the present work. In particular my opposition to the ‘ atmospheric glare’ theory, which some had regarded as over-confident and too earnest, has been abundantly justified, as well by the observational overthrow of that theory as by the feeling now entertained that its enunciation was unfortunate. To quote the words of Janssen, “the question whether the corona is due to
the terrestrial atmosphere is now disposed of (tranchée), and we have before us the prospect of the study of the extra solar regions, which will be very interesting and fruitful.” Or, in Mr. Lockyer's words (and as I have been urging for the last two years), “steps should be taken in order that the question may be more closely investigated and more rapidly worked out than it is now.” There is at present no erroneous theory to interfere with the prosecution of such enquiries; and the only misfortune is that no total eclipse worth observing
WHEN I had completed my treatise on Saturn and its System, I formed the design of preparing a separate treatise on each of the planets Mars and Jupiter, and then another and larger treatise on the Sun. Circumstances, which it is needless to particularise, prevented me from carrying out this design at that time, and indeed threatened to withdraw my attention altogether from scientific pursuits. That my plans, though delayed, have not been lost sight of during the last four years, is evidenced by the appearance of many papers of mine on Mars, Jupiter, and the Sun, in several quarterly, monthly, and weekly journals. These, if collected, would of themselves suffice to form volumes of no inconsiderable dimensions on these several orbs; while my ‘ Other Worlds than Ours' presents a sort of summary of my researches on these and other astronomical subjects. But it is only quite recently that I have been able to resume my original design.
The delay has not been without its advantages, however. A work on the Sun has at the present time a far greater interest than it would have had four years since ; while I have been able to obtain a much wider and more complete view of the subject than I should probably have thought necessary had I completed the work at that time.
My primary object in the present volume has been to furnish a full account of the remarkable discoveries which have been effected by observers of the Sun, whether by means of the telescope, the spectroscope, polariscopic analysis, or photography. It will be seen that Chapters IV., W., and VI., in which I deal with these discoveries, together constitute more than one half of the main text. In these chapters the labours of the Herschels, Schwabe, Carrington, Secchi, De la Rue, Stewart, and others in examining the solar surface; the later observations of Huggins, Zöllner, Respighi, Secchi, Lockyer, Young, and others in the study of the prominences and chromatosphere; and the observations which have been made during the past two centuries on the phenomena presented by the solar corona, have been dealt with at considerable length.
But it seemed desirable that a separate and complete explanation should be given of all those matters which specially appertain to the application of spectroscopic analysis to the study of solar physics. Without an