238 Mr C. Martins on the Nature and Origin of 



wind shifted in the evening to west-north-west. At St 

 Gothard the west-north-west wind blew from the evening 

 before the fog arrived. 



At Dijon the south-west had continued for three days, 

 and turned to the south at the moment of its first appearance. 

 On its second appearance, 22d June, the wind was from west- 

 north-west, north-west, or north. At Laon the fog arrived 

 accompanied by a very cold wind from the south. At Padua 

 it was preceded by numerous storms ; on the 17th the wind 

 blew from the north ; on the 18th from the west-north-west 

 in the morning, south-west at mid-day, and south-east in the 

 evening. At Narbonne the weather was calm and the heat 

 great for two days. At Rome it likewise came with a south- 

 west wind. 



We thus perceive that the fog appeared neither with the 

 same wind, nor in the same meteorological circumstances ; 

 in general, however, it appears to have been brought by a 

 south-west wind. When it had once overspread a country, 

 nothing could make it disappear, neither wind, rain, nor 

 storm. The following are some examples of this. At Man- 

 heim there were 23 days of rain, and twelve storms during its 

 continuance. On three days it thundered, while the fog was of 

 extreme density; on the 27th June its density was such that 

 one could not see a quarter of a league, and yet there was so 

 severe a storm, that the thunder broke in thirteen localities 

 in the neighbourhood. At Geneva, Senebier made the same 

 observations ; neither rain nor wind had the power of dissi- 

 pating it. On the 12th July, among others, there was a 

 frightful thunder-storm which struck eight houses in the 

 town. At Padua fourteen storms of lightning occurred 

 during the continuance of the fog. A tempest came on in 

 the morning of the 26th, accompanied with claps of thunder 

 which were heard from one sea to the other, and struck five 

 or six houses in the town of Vicence alone : the fog was not 

 dispersed. At Narbonne, the north wind blowing violently, 

 it almost wholly disappeared from the 4th to the 6th of July ; 

 but on the return of calm weather, it again enveloped, not as 

 formerly the whole celestial hemisphere, but a zone comprised 

 between and 20 degrees above the horizon. To the testi- 



