CHAP. 2. 6. OF CLOUDS. 61 



one that did not extend very high, which in 

 December, 1813, ushered in the long frost, 

 that continued through January and February 

 of the succeeding year. This fog seems by 

 its topological history to have travelled from 

 the West, Eastward, and Northward over our 

 island. See some curious remarks about fogs, 

 and particularly the extraordinary fog in France 

 of 1783, in Bertholon, De 1'Electricite des 

 Meteors, Tom. II. Chap. 4, where the observa- 

 tions of different persons on this phaenomenon 

 are duly noticed. 



SECTION VI. 



Of the Varieties of the Twaincloud. 



WHETHER this cloud is formed with visible 

 conjunction of different modifications, whether 

 cumuli spontaneously assume its form, or 

 whether it appears of itself previously, we must 

 regard it as a stage towards nimbus. The very 

 dense and black appearance of this cloud coming 

 up with the wind, and just ripening into a 

 Storm, must be familiar to every body. Where 

 the Rain has actually begun to fall, the blackness 



