appears to subsist between it and the Formation of Clouds. 29 



banded in a W.N.W. to E.S.E. direction. At ll h 30 m the arch 

 was divided into two by a process in the N.N.W., the apex of 

 the larger being N. and of the other N.W. This process at 

 length moved upwards and to E., so that the western arch was 

 in turn the larger. After this the arches united, forming a single 

 arch, which was again divided by a similar process moving fromW. 

 At 12 h the altitude of the under or inside of the arch was about 

 15° or 16°. A most remarkable circumstance was, that some 

 cirrostrati kept constantly in the same position, sometimes 

 fading into a light fleecy aspect, and again becoming better 

 defined as the aurora brightened. A small dense cirrostratus 

 cloud in particular remained almost invariably in a position 

 about 16° above the N.N.W. point. At h 40 m a.m. a scud 

 came over from W., and the aurora immediately became more 

 active, shooting its rays into the clear space within the arch, and 

 also upwards to the coronal point. The auroral rays now began 

 to move, as it were in procession, from W. to E. in alternate 

 light and dark bars, and the cirrostrati, or a portion of them, 

 moved briskly in the same direction. Indeed the whole behaviour 

 of the cirrostrati on this occasion showed in the clearest manner 

 a connexion with the aurora, as was evinced from their remaining 

 for hours ia the same position, with but little variation in form, — 

 their extraordinary swinging motion like that of a ship at anchor, 

 as if fascinated by the auroral influence, and their fading and 

 brightening simultaneously with the streamers. The wind during 

 the whole display blew fresh from W. 



"August 10, ll h 15 m p.m. Sky almost quite overcast with 

 fleecy cumulus and cirrostratus clouds, moving very slowly from 

 S.E. A series of rapid pulsations traversed the whole sky, ren- 

 dering these clouds faintly and fitfully luminous. These sheets 

 of faint lightning moved from W. to E., or at right angles to 

 the major axes of the clouds which lay N. to S. No appearance 

 of an aurora. 



" August 11, from 6 h to 10 h P.M. Beautifully distinct luminous 

 cirrostrati extended in unbroken lines from N.W. by N. to S.E. 

 by S. 



"August 24, 9 h p.m. A fine display of cirrostrati ranging 

 N.N.W. to S.S.E. The dark streaks were beautifully regular 

 and well defined, being relieved against a hazy luminous ground, 

 which caused them to present the appearance of alternating light 

 and dark stripes stretching quite across the sky. These experi- 

 enced several alternations in distinctness, often instantaneously, 

 as if by an electric discharge. The cirrostrati soon after grew 

 broader and assumed a nimbus aspect, and by 10 h p.m. the 

 whole sky was overcast with hazy nimbi, from which rain began 

 to fall. H3 zuoiiifflisi &cLt noon/ Ji^-sld dh. mmtio 



