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XXIII. On the Formation of the Cumulus Cloud. By Thomas 

 Hopkins, Esq.* 



TN the summer of last year, 1839, I went to the top of Snow- 

 -■- don, and found the whole of the mountain covered with 

 a thick mist or cloud. While descending from the upper part 

 of it, about two o'clock in the afternoon, I looked back and 

 observed the summit quite free from cloud. In June last I 

 again ascended the mountain, and again found it enveloped in 

 the same kind of thick mist ; but remembering that on my 

 previous visit the mist had cleared away in the afternoon, I 

 resolved to wait on the top. About two o'clock in the after- 

 noon the mist began to break, driving along from the south- 

 west and passing round the summit of the mountain. The 

 wind was moderate, and the mist for some time concealed the 

 country below to the north and the east ; it, however, in a 

 short time disappeared, and left the country open to view. 



Towards the end of August I was at New Brighton and 

 Waterloo near Liverpool, when the wind was also moderate 

 and generally from the south, south-west, or west, and I made 

 use of the opportunity which then presented itself, to notice the 

 appearances of the clouds, and took notes at the time, of which 

 the following are a sample : — 



"New Brighton, Aug. 26, 184-0. — At six in the morning a 

 slight wind from the west; the sea covered with a darkish cloud, 

 apparently resting on the water; the land also covered with low 

 cloud, but it was less heavy than that over the sea. As the sun 

 rose in the heavens the lower portion of the thick cloud disap- 

 peared from the part immediately over the sea, and cumulus 

 clouds formed over the land, apparently near to the two chains 

 of the Lancashire and Welsh mountains. These increased in 

 size from about nine o'clock in the morning until one in the 

 afternoon, and became fine massive clouds. There being a 

 slight breeze from the west they slowly floated eastward, where 

 they assumed a darker appearance. Other cumuli, which 

 during the afternoon remained over the sea, rose higher in 

 the atmosphere, and the tops gradually wasted away, the whole 

 mass becoming elongated, and looking like large fish floating 

 in the air. As the sun went down in the west these clouds be- 

 came more like dark lines, and when the sun had set the sky 

 soon became clear, and the stars shone out brightly." 



For a fortnight afterwards the weather was similar in its 

 general character, and it may be described as follows: — At 

 sun- rise a thick mist rested on the Irish Sea, so as to conceal 



* Communicated by the Author ; having been read before the Literary 

 and Philosophical Society of Manchester in 1 840. 



