The idea strongly suggested itself to Mr. Lefroy of converging streams of infinitely minute particles of matter passing through space at a distance from the earth at which its aerial envelope may have still a density sufficient by its resistance to give cosmic dust passing through it that illumination which it possessed. In about twenty minutes the streams of light had attained their maximum brightness. Their apparent figure was that of a nearly circular (slightly flattened) arc of an amplitude of 15° or 20°, as viewed from the middle point of its chord. The brightness and the convergence of the streams were both more marked towards the western horizon than the eastern. This same phenomenon was described in the ‘South-Australian Register’ as a beautiful lunar rainbow visible in the western heavens. Mr. Lefroy and other observers concurred in the impression that the minor lateral streams on the N. side of the main one intervened between the earth and the moon, and that one or more of them in their slow vibrations swept the surface of the moon and sensibly obscured its light. There can be hardly any question that the phenomenon observed was in fact an Aurora. [Sidenote: Suggestion as to collecting iron and nickel particles from the atmosphere.] It may be a question whether iron and nickel particles of meteoric origin do not ordinarily exist in the atmosphere in a greater degree than we suspect, and might be detected if special means, such as magnets, plates of glass covered with glycerine, &c., were adopted for the purpose of collecting and examining the cosmic dust. Larger gatherings than usual of iron and nickel particles during the presence of Auroræ would be in support of Mr. Lefroy’s theory. _The Aurora and the Planets Venus and Jupiter._ [Sidenote: The Aurora and planets Venus and Jupiter. The planet Venus’s halo during Aurora.] During a brilliant Aurora seen at Sunderland, February 8, 1817 (‘Annals of Philosophy,’ p. 250), about 8 o’clock, Venus was about 8° above the horizon, and displayed a very peculiar appearance. Her rays passed through a thin mist or cloud, probably electric, of a deep yellow tint. Her apparent magnitude seemed increased, and a halo was formed round her as sometimes appears round the moon in moist weather; but the stars that were in that part of the heavens shone with their accustomed brilliancy. [Sidenote: Dr. Miles’s observation of Venus during an Aurora.]