The Late Eclipse

Abstract

I FIND in NATURE, vol. xiii. p. 86, a letter from Dr. Schuster, commenting on some remarks made by me last April respecting the photographic results of the late eclipse. He appears to consider that these remarks related to him personally, which certainly was not my intention. He speaks further of a mathematical solution promised by me, for which he has “had to wait already a considerable time.” I remember nothing of such a promise, nor can I conceive how I could have promised, instead of giving at once, the solution of so simple a matter. Dr. Schuster proves very readily that the spectrum of the corona can be photographed in one minute; but I am not aware that anyone has questioned the fact. What I questioned myself was whether the spectral images of the corona can be so photographed that the true extension of the corresponding coronal envelopes can be shown. To quote my own words (“Science Byways,” p. 168): “The whole light” [of the corona] “acting at once to form a photograph does not show the full extension of the corona, the outskirts simply losing themselves through excessive faintness. … How, then, can a minute portion of that light produce any photographic trace” [of the outskirts]? “How much less can this minute portion show the whole extension of the green solar envelope ?” It was the hope that this might be effected which I described as mathematically unsound.