30 



peratnre falling ; splendid pre-glow, and glow in morning ; 

 peculiar streaky clouds coming up. Iridescent clouds at noon, 

 liemarkable sun appearances at sunset — (see description in 

 report of the Mathematical Society, Port Adelaide, 1885). 



"April 17, D.B.,59°; AV.B., 51"; max. temp., 65"; min. temp., 

 48^; m. bar., 3016 ; very fine pre-glow and delicate change in 

 colour of clouds, some being of transcendent beauty ; filmy 

 clouds formed, and became iridescent. Halo changed from 

 pink to ice-halo. No glow in evening. 



"April 22nd, D.B., 67"; W.B., 55"; max. temp., 75"; min., 52°; 

 m. bar., 30'21 ; iridescent clouds ; rather high clouds. 



"April 30th, D.B., 66°; W.B., 52"; max. temp., 76"; min., 50°; 

 m. bar., 30'32 ; cirrus clouds, rather heavy ; beautifully irides- 

 cent at various times. 



" May 1st (see account of notes further on)." 



The dates on which these notes were taken show that the 

 iridescent clouds are not specially connected with any new 

 factor in meteorology, and that they are not connected with 

 any particular kind of sky glows, unless, indeed, glows are con- 

 nected with some peculiar form of water, and that the condi- 

 tions required for glow appearances render the existence of 

 iridescent clouds more or less possible. 



The recorded observations of many persons are such that 

 they must have mistaken portions of ordinary cloud halos for 

 iridescent clouds, as the descriptions given in their cases are 

 actual descriptions of halos in different positions, with the 

 misnomer, "iridescent clouds." 



There are various apparent changes in breadth of the limb 

 of a cloud halo, as its distance from the horizon varies, that 

 render it very possible for an inexperienced observer to fail in 

 recogiiising a halo in every portion. It is important that 

 future observers should discern the difference between the two 

 classes of phenomena ; and the two appended descriptions are 

 therefore fuUv extracted from mj meteorological notes. 



Note 1st. — April 17, 1885. Eeadings are for the previous 

 twenty-four hours — Dry bulb, 59" ; W.B., 51"; max. temp., 65" ; 

 min. temp., 18°; mean bar., 3016; barometer falling slowly; 

 temperature rising. Most beautiful sunrise and pre-glow ; very 

 fine change of colour, first from the higher clouds, when cross 

 polarization was evident. Then the lower clouds became 

 illuminated in a beautiful manner with various tints, all tints 

 ending in a yellow, after which clouds became white. The 

 clouds, all of a delicate nature, became iridescent when near 

 the sun about 10 a.m. The colours bore no reference to the 

 angular distance from the sun within certain limits ; thus the 

 colours were not observed in the cloud patches, whose angular 

 distance from the sun exceeded that of the limb of the pink 



