366 Formation and Characteristics 



cirro-stratus were observed, which rapidly separated into very 

 minute and beautiful masses of cirro-cumulus. There are 

 four distinct sizes of cirro-cumulus, which, for the sake of 

 distinctness, I have ventured to name secundus, tertius, quar- 

 tus, and quintus; secundus being the largest, and quintus the 

 smallest. The minute masses just spoken of are specimens 

 of the variety quintus. These rapidly augmented in size, 

 until they formed well-marked specimens of quartus. At 

 this time, several well-marked and beautiful, but very thin, 

 specimens of about the same size were observed, which exhi- 

 bited most decidedly a hairy-form structure. The whole of 

 these masses continued to increase in size, until tertius was 

 produced. On this occasion, three distinct gradations were 

 observed, independently of the size; namely, the beautiful 

 thin hairy-form masses, the spherical masses, and some 

 clouds that in their general appearance were thin, but, instead 

 of exhibiting the hairy-form structure above noticed, pre- 

 sented a somewhat nebulous appearance, but were well defined. 

 The formation of all these clouds from the longitudinal variety 

 of cirro-stratus was well traced. While these phenomena 

 were occurring, some well-marked specimens of quintus were 

 seen forming on a clear blue sky, and rapidly augmenting in 

 size, until the third series (tertius) was attained. It was re- 

 marked that, while the masses were augmenting in size, each 

 retained its relative position with respect to those surrounding 

 it ; so that when a nucleus was formed, that nucleus, which at 

 first was very near the surrounding nuclei, retained its rela- 

 tive position with respect to them, although, as the mass 

 increased in size, its centre was farther removed from the 

 centres of the others. This process continued during the 

 afternoon, which was windy. The motion of the cirro-strati 

 and cirro-cumuli was s. w. 



May 30. 1833. — About noon, I noticed the inferior position 

 of crinis fibratus, which is a modification of cirrus, and is 

 generally observed in the higher regions of the atmosphere. 

 Some well-marked specimens were seen distinctly projected 

 on a fine blue sky, which was quite destitute of any nebulosity. 

 These specimens appeared between two ranges of cumulus, 

 the varieties prevalent in fine weather: the fibrati appeared to 

 penetrate some of the specimens. The general arrangement 

 of the fibrati indicated a polarisation s.w. and n.e. ; and they 

 were moving from the n.w. As they approached the zenith, 

 they assumed the character of mares' tails, the points being 

 drawn out towards the N.w. The colour of these clouds 

 was beautifully white, and their outlines sharp and well defined. 

 The upper specimens of cumulus were moving with an easterly 



