AURORÆ: THEIR CHARACTERS AND SPECTRA. BY J. RAND CAPRON, F.R.A.S. “And now the Northern Lights begin to burn, faintly at first, like sunbeams playing in the waters of the blue sea. Then a soft crimson glow tinges the heavens. There is a blush on the cheek of night. The colours come and go; and change from crimson to gold, from gold to crimson. The snow is stained with rosy light. Twofold from the zenith, east and west, flames a fiery sword; and a broad band passes athwart the heavens, like a summer sunset. Soft purple clouds come sailing over the sky, and through their vapoury folds the winking stars shine white as silver. With such pomp as this is Merry Christmas ushered in, though only a single star heralded the first Christmas.”—LONGFELLOW. LONDON: E. & F. N. SPON, 46 CHARING CROSS. NEW YORK: 446 BROOM STREET. 1879. [Illustration] PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. TO PROF. CHARLES PIAZZI SMYTH, F.R.S.E., ASTRONOMER ROYAL FOR SCOTLAND, ONE OF THE EARLIEST SPECTROSCOPIC OBSERVERS OF THE AURORA AND ZODIACAL LIGHT, THIS VOLUME IS RESPECTFULLY DEDICATED BY THE AUTHOR. PREFACE. Probably few of the phenomena of Nature so entirely charm and interest scientific and non-scientific observers alike as the Aurora Borealis, or “Northern Lights” as it is popularly called. Whether contemplated as the long low quiescent arc of silver light illuminating the landscape with a tender radiance, as broken clouds and columns of glowing ruddy light, or as sheaves of golden rays, aptly compared by old writers to aerial spears, such a spectacle cannot fail at all times to be a subject of admiration, in some cases even of awe.