$0 Objervations on the Fog of 1783. 
refinous ftrong-fmelling fubftance in horizontal ftrata, whick 
could be eafily divided into laminz of from one to two inches 
in thicknefs; but, in other refpects, the lava of this volcano 
exhibits nothing but what has been feen in the other extin- 
guifhed volcanoes in the neighbourhood. The Val di Noto 
is the only part of Sicily where traces of ancient volcanoes 
are found. Travellers, who imagined that they found fome 
of the like kind in other provinces, were either miftaken, or 
fuffered themfelves to be deceived by faife marks, 
XVIE. Obfervations on the Nature of the Fog of 1783. By 
M. Dr Lamanon, Corre/pondent of the Academy of Sci- 
ences at Paris*, 
V y HEN this fog, which may be called an eleétric fog, 
began to appear, I was at Sallon de Crau, in Provence, In 
order to free my neighbours and countrymen from uneafi- 
nefs as much as poffible, I wrote a letter to M. Artaud, 
editor of the Courier d’ Avignon, in which, after {peaking of 
the nature of the fog, I faid it would be deftroyed by the 
florms that would not fail to enfue. The event fully juftified 
this kind of prediétion. Having learned from the public 
papers that this phenomenon was not local, but almoft ge- 
neral throughout Europe, I made new obfervations, and tra- 
verfed the higheft Alps of Provence, Dauphiny, and Pied- 
mont; and, during the courfe of my travels, colleed inform- 
ation refpecting the fog, and the effects of the thunder. “But 
before I offer that explanation of the phenomenon, which 
appears to me mott probable, let me endeavour to give an 
accurate defcription of it. 
I. Nature and Effeéis of the Eleéiric Fog. . 
1. In almoft all countries the fog was preceded by a ftorm. 
2. It began the fame day at places very remote from each” 
other; as Paris, Sallon, Turin, Padua, &c. where it ap- 
peared, for the firft time, on the 18th of June. M. Senebier 
* From the Journal de Phyfique. 
wrote 
