CHAP. 1. 8. OF CLOUDS. 25 



dark coloured cumulus which the sailors call 

 scud. In cases of more settled and continued 

 rain, these processes go on slower, and therefore 

 are less likely to be taken notice of. The best 

 time for viewing the progress of nimbification 

 is in stormy weather; cumuli may then be seen 

 rising into mountains and becoming cumulo- 

 strati, while long strata of cirrostratus permeate 

 their summits; and the whole phenomenon 

 has the appearance of a range of mountains, 

 transfixed by the mighty shafts of giants. After 

 having existed some while in this form, they be- 

 come large and irregular, and they get darker by 

 intensity, till all seem concentrated in a dense 

 black mass, with a cirrose crown extending from 

 the top, and ragged cumuli entering from be- 

 low; and eventually the whole resolves itself 

 into rain.* 



* Previous to the coming up of a storm, a dead calm, 

 which may have for some time existed, is followed by a gale. 

 The approach of a storm, thus ushered in by wind, is ad- 

 mirably described by Virgil: 



Qualis ubi ad terras abrupto sidere nimbus 

 It mare per medium; miseris heu praescia longe 

 Horrescunt corda agricolis: dabit ille rtiinas 

 Arboribus stragemque satis, ruet omnia late 

 Antevolent sonitumque ferunt ad littora venti. 



Virg. Acncid. xii. 451. 



