the edge, though absolutely undefined, was perfectly even. But on the generally rainbow-tinted ground suffused with red—which perhaps might best be described by calling it a rainbow seen on a background of brilliant crimson—there were here and there blotches of black or of lighter or darker grey, caused apparently by vast expanses of cloud, more or less dense. Round the edges of each of these were little irregular rainbow-coloured halos of their own interrupting and variegating the continuous bands of the corona; while throughout all was discernible a perpetual variability, like the flashing or shooting of colour in the opal, the mother-of-pearl, or similarly tinted translucent substances when exposed to the irregular play of bright light—only that in this case the tints were incomparably more brilliant, the change more striking, if not more rapid. I could not say that at any particular moment any point or part of the surface presented this or that definite hue; and yet the general character of the rainbow, suffused with or backed by crimson, was constant and unmistakable. The light sent through the window was too dim and too imperfectly diffused within my vessel to be serviceable, but for some time I put out the electric lamp in order that its diffused light should not impair my view of this exquisite spectacle. As thrown, after several reflections, upon the mirror destined afterwards to measure the image of the solar disc, the apparition of the halo was of course much less bright, and its outer boundary ill defined for accurate measurement. The inner edge, where the light was bounded by the black disc of the Earth, shaded off much more quickly from dark reddish purple into absolute blackness.