31 



lialo visible at tlie same time. This "halo was beautifully clear 

 and merged into an azure sky. The cloudlets, or cloud-patches, 

 as thej approached this pink space became variegated with most 

 beautiful tints. In some cases these tints seemed to follow 

 roughly the sinuosities of the clouds, pink being always at the 

 edge. This pink was brighter than that of the halo into which 

 it merged. The character of the clouds was that of cirrus, or 

 cirro-cumulus. The structure was very delicate, resembling 

 filaments of cotton wool in very loose heaps, with changing 

 iridescent hues. As the clouds approached the sun they got 

 brighter in colours, and as they got within about 6-8 degrees 

 from the sun the edges nearest became tinted with the ordinary 

 colours seen so frequently round the moon, and also round the 

 sun when it is viewed by reflection from a surface of water 

 contained in a vessel deep and black. The iridescent tints 

 observed were pink, green, blue, orange, and mauve; pink 

 being in all cases at the edges. As the clouds coming up, or 

 forming, changed in character to that of cirro-stratus, the colour 

 of the pink halo changed and had a colder tint, until it became 

 overclouded with cirro-stratus. By this time there was no pink 

 halo, but its limb had been gradually becoming more sharply 

 ■defined and bright, so that by noon it had assumed the definite 

 limb of an ice-cloud halo. As soon as the clouds had taken 

 the character of cirro-stratus completely, the whole phenomena 

 of iridescence ceased. In the evening there was no glow proper, 

 but the clouds becoming a little thinner the halo assumed a 

 pinkish hue. Cross-polarization was observable before sun- 

 set. There was a greenish twilight, though not so clear as it 

 is when the clouds are lower and a low pressure area is ap- 

 proaching from the west. 



The second note relates specially to the rare phenomenon of 

 a double halo. 



:Note 2nd.— May 1st, 1885. D.B., 67°; W.B., 53°; max. 

 temp., 75° ; min. temp., 50° ; m. bar., 30*26. Barometer 

 falling slowly. "Wind E.jN'.E. A bright sunrise ; sky full of 

 various tints from very high clouds. Character of clouds, 

 cirrus and cirro-stratus, the colours of the clouds augmented 

 by cross-polarization. At 8.30 a cloud halo was obserrable, 

 being very perfect, and nearly circular to the sun. The 

 colours, as seen in order from the sun, were red, orange, 

 yellow, green, bluish ; the angular distance from sun varied 

 from 18° to 23°. There was a second halo at an angulax 

 -distance of about 46°, not quite so central as the smaller one. 

 The distance was measured. The colours were in same order 

 as the first series. Both the rings existed until 10 a.m., when 

 the outside one vanished, and the clouds became thicker. The 

 inside halo of about 23° lasted all day, with varying degrees of 



