56 METEOROLOGICAL 



out having recourse to any other light. Moreover, 

 he questioned a person who had gone on foot from 

 Geneva to Annemasse, in Savoie, on the 22nd of 

 November: he had started at half-past ten at 

 night, and declared that he saw his way the whole 

 distance as if it had been a moonlight night. M. 

 Auguste de la Rive was, that same night, at some 

 distance from Geneva, and was also surprised at 

 the distinctness with which he saw his road and 

 the objects around him. 



The celebrated dry fog of 1783 was described 

 by M. Verdeil, a physician of Lausanne, as having 

 diffused at night, a luminosity sufficiently intense 

 to render distant objects visible, and this light was 

 equally spread in all directions. It resembled the 

 light of the moon seen through the clouds. 



This dry fog, in which objects could be seen at 

 night at a distance of 600 feet, lasted a whole 

 month ; it made its appearance nearly at the same 

 time in many distant places, spreading from the 

 north of Africa to Sweden; it was likewise ob- 

 served over a great portion of North America, 

 but was not seen to spread over the sea. It ap- 

 peared to reach higher than the summits of the 

 highest mountains, and neither winds nor rain 

 had any power to disperse it. In Europe this fog 

 exhaled a disagreeable odour, was remarkably dry, 

 did not affect the hygrometer, and possessed the 

 remarkable phosphoric quality I mentioned above. 



