[Sidenote: Capt. Maclear’s Aurora Australis, 3rd March, 1874. Light of pale yellow tint only.] In a letter dated from H.M.S. ‘Challenger,’ North Atlantic, April 10th, 1876, Capt. Maclear was good enough to communicate to me some particulars of an Aurora Australis seen 3rd March 1874, in lat. 54° S., long. 108° E. The letter is mainly descriptive of the spectrum (which will be described in connexion with the general question of the spectrum of the Aurora). It states that the red line was looked for in vain, and that the light appeared of a _pale yellow_, and had none of the rosy tint seen in the northern displays. [Sidenote: Capt. Maclear’s Auroræ described in ‘Nature.’] Capt. Maclear has since contributed to ‘Nature,’ of 1st November 1877, a description of four Auroræ seen from the ‘Challenger’ in high southern latitudes (including the one communicated to me). He speaks of the opportunity of observing as not frequent, either from the rarity of the phenomena, or because the dense masses of cloud prevalent in those regions prevented their being seen except when exceptionally bright. There were four appearances described:— [Sidenote: Feb. 9, 1874.] (1.) At 1.30 on the morning of February 9th, 1874, preceded by a watery sunset, lat. 57° S. and long. 75° E., bar. 29·0 in., ther. 35°; brilliant streaks to the westward. Day broke afterwards with high cirrus clouds and clear horizon. [Sidenote: Feb. 21, 1874.] (2.) At 9.30 P.M., February 21, 1874, lat. 64° S., long. 89° E., bar. 28·8 in., ther. 31°; one bright curved streamer. The Aurora preceded a fine morning with cumulo-stratus clouds, extending from Jupiter (which appeared to be near the focus) through Orion and almost as far beyond. Under this a black cloud, with stars visible through it. Real cumuli hid great part of the remainder of the sky, but there were two vertical flashing rays which moved slowly to the right (west). Generally the Aurora was still bright. [Sidenote: March 3, 1874. Auroral line found in light to southward.] (3.) At midnight, March 3rd, 1874, lat. 53° 30´ S., long. 109° E., bar. 29·1, ther. 36°, after some days’ stormy weather, a brilliant sunset, followed by a fine morning. Soon after 8 P.M. the sky began to clear and the moon shone out. Noticing the light to the southward to be particularly bright, Capt. Maclear applied the spectroscope, and found the distinguishing auroral line. [Sidenote: Brilliant white clouds seen.] About midnight the sky was almost clear, but south were two or three brilliant light clouds, colour very white-yellow, shape cumulo-stratus. From about west to near south extended a long feathery light of the same colour, parallel with the horizon, and between south and west there appeared occasionally brilliant small clouds. The upper edges seemed hairy, and gave one the idea of a bright light behind a cloud. The forms changed, but no particular order was noticed.