(Here follows a description of the spectrum, and the mode in which a delineation by the lines was obtained.) [Sidenote: March 6, 1874. Capt. Maclear suggests whether a low barometer has to do with the absence of red.] (4.) At 8 P.M., March 6th, 1874. This was a slight Aurora, seen to the southward; after this the clouds changed to high cirrus. Capt. Maclear suggests whether a low barometer has any thing to do with the absence of red in the spectrum, the normal state of the barometer being an inch lower in those regions than in more temperate latitudes. [Sidenote: Barometer falls after the Aurora, and strong gale from the S. or S.W. follows.] Edin. Encyc. vol. iii. article “Aurora.” Dr. Kirwan observed that the barometer commonly falls after the Aurora. Mr. Winn, in the seventy-third volume of the Phil. Trans., makes the same remark, and says that in twenty-three instances, without fail, a strong gale from the south or south-west followed the appearance of an Aurora. If the Aurora were bright, the gale came on within twenty-four hours, but was of no long continuance; if the light was faint and dull, the gale was less violent, longer in coming, and longer in duration. [Sidenote: Pale yellow glow rare in the Aurora Borealis.] The pale yellow-coloured glow referred to by Capt. Maclear is, in my experience, rare in the Aurora Borealis. It is probably the “æqualiter et sine eruptionibus aut radiis _fulvi_,” described by Seneca (_antè_, p. 1), and may probably belong to more southern climes. [Sidenote: Spectrum of Auroræ Australes extends more into the violet.] We shall see too, by-and-by, that these Auroræ Australes as to spectrum extend more into the violet than the Aurora Borealis. The yellow, as complementary to violet, is likely thus to make (in the absence of the red) its appearance. It is, however, somewhat singular that Carl Bock found almost exclusively yellow Auroræ in Lapland. In Proctor’s ‘Borderland of Science,’ article “The Antarctic Regions,” we find quoted a passage from a letter by Capt. Howes, of the ‘Southern Cross,’ in which a graphic description is given of a Southern Aurora:— [Sidenote: Capt. Howes’s description of a Southern Aurora.] “At about half-past one on the 2nd of last September the rare phenomenon of the Aurora Australis manifested itself in a most magnificent manner. Our ship was off Cape Horn, in a violent gale, plunging furiously into a heavy sea, flooding her decks, and sometimes burying her whole bows beneath the waves. The heavens were as black as death, not a star was to be seen, when the brilliant spectacle first appeared. [Sidenote: Balls of electric fire resting on mast-heads &c.]