Rainbows.—Caused by reflection and refraction from and through drops of water—colours vary with size of drops, the smaller the drop the lighter the colours and nearer to the violet end of the spectrum—hence white rainbow as seen on the Barrier, very small drops.
Double Bows—diameters must be 84° and 100°—again from laws of refraction—colours: inner, red outside; outer, red inside—i.e. reds come together.
Wanted to see more rainbows on Barrier. In this connection a good rainbow was seen to N.W. in February from winter quarters. Reports should note colours and relative width of bands of colour.
Iridescent Clouds.—Not yet understood; observations required, especially angular distance from the sun.
Auroras.—Clearly most frequent and intense in years of maximum sun spots; this argues connection with the sun.
Points noticed requiring confirmation:
Arch: centre of arch in magnetic meridian.
Shafts: take direction of dipping needle.
Bands and Curtains with convolutions—not understood.
Corona: shafts meeting to form.