The Optical Magic Lantern Journal (September 1900)

112 seconds, and, what is of even greater importance, revealing to the skilled astronomer secrets respecting the nature and condition of the sun | which might remain for ever hidden were no such opportunity of penetrating into their mysteries afforded to him. The parts of the sun thus presented to view are, first the chromosphere or atmosphere, apparently consisting of vapours or gases in an intensely heated condition, amongst which the spectroscope enables the chemist to | recognise metals and other substances familiar | to us in a solid state, but apparently vapourised by the extremely high temperatures at which they exist in the sun; while in the opinion of Sir Norman Lockyer, and other eminent authorities, many substances which we have hitherto regarded as elementary, are probably resolved at those temperatures into vet simpler forms of matter. The chromosphere has. long been observed to throw out into space what are known as prominences, which resemble tongues of flame, usually of a brilliant red colour, and appear to be ejected with force sufficient to carry them thousands of miles above the general level of the chromosphere, their forms undergoing constant change like the wreaths of smoke arising from a furnace, or the ever varying flame jets which play over the surface of burning fuel. The chemical composition of the vapours of glowing hydrogen and other substances of which these prominences appear to consist, can indeed be studied without waiting for an eclipse, but the prominences themselves can only be seen on such an occasion, and their appearance and varieties of form, height, and position are among the features for observation of which the eclipse is eagerly anticipated and utilised to the fullest extent : possible; and an accurate photographic record of these objects (which is far more reliable than any hasty drawings which can be made, or mental impressions which can be received by the observer, however experienced and self possessed, during the brief moments of their | appearance) is of the utmost value, since it can be examined carefully and repeatedly long after the eclipse has passed away. But perhaps the part of the sun which has during recent years attracted the the beautiful mysterious halo of pale. silvery light which seems to surround the sun and to radiate from his central disc for thousands of iniles, until it gradually fades away almost luminous | the | most : attention, and for the observation of which the : eclipse is most eagerly anticipated, is the corona, |! The Optical Magic Lantern Journal and Photographic Enlarger. | the imperceptibly into the darkness of endless space ; fades so gently and softly that it can hardly be said to have a distinct outline, and | even practised eyes can scarcely discern its precise extent or the place of its ending. This is wholly hidden from our view excepting during the few moments of total eclipse, when it suddenly flashes out, like the halo round the head of a pictured saint, to the unbounded admiration of the beholder and the great alarm of the more ignorant and superstitious of mankind. The true nature and the varying forms of this most beautiful and mysterious of solar appendages have given rise to innumerable speculations, and may be considered as the leading problem in solar physics at the present time. Observations by the eye, however well trained, seem to give impressions rather than definite details of form and appearance, and probably no two eyes see it precisely alike, or no two minds receive exactly the same impression, however closely they may agree as to the leading features of the marvellous display. Hence the extreme value of photographic records, available for prolonged and leisurely examination, and unaffected by the personal equation and mental constitution of the individual observer, whose feelings and emotions cannot always be wholly suppressed or laid aside during the short opportunity afforded for his observations. (To be continued.) \1) Sithouele Ay oF Shadowgram SLIDES. By [udononeB pane ri a Gay Ya ie HE subject of the present mechanical Ws <4 silhouette slide is one that will mA |i : both young Vioed t appeal to all classes, both young \\/ rain <i! and old, for we are all, more or less, interested in and fascinated by an ) exhibition of conjuring and sleight-ofhand tricks. Moreover, though a glance at the accompanying diagrams might not leadhim to