87 
assured that contemporaneous observations would throw 
much light upon the subject. 
The more important results obtained by Mr. Clarke dur- 
ing the past two months are : 
Ist: That atmospheric electricity in serene weather is 
invariably positive. 
2nd. That it is more intense. during fogs, especially if 
they occur during frosty weather. 
3rd. That in cloudy weather, (without rain,) the aerial 
electricity diminishes in intensity. 
4th. That during heavy rain, hail, snow, or sleet, (and 
particularly at their commencement,) the atmospheric elec- 
tricity is very intense. This electricity is, at first, invariably 
negative, but sometimes changes its state frequently during 
the storm. 
5th. That the periods of its diurnal changes of intensity 
vary considerably, the intensity being at a maximum (during 
the past two months) each day some time between 73, Ae Mey 
and 103, a.m. ; becoming almost evanescent at noon; and as- 
cending progressively for a few hours previous to sun-set. 
It acquires its nocturnal maximum some time between 9 and 
12, p. M.; when it again declines gradually until some hours 
after sun-rise. 
6th. That the nocturnal electricity, with or without dew, 
is stronger than the diurnal. 
The foregoing observations are for the most part con- 
firmed by those of Cavallo. But, the sixth observation does 
not agree with those of Canton, Abbé Mazeas, M. De 
Saussure, and Mr. Cross; the two former observers not 
having observed any electricity at night, and the two latter 
finding it weaker than by day. M. De Saussure conceived 
the electricity of the evening to be strong in consequence of 
the dew acting as a conductor,. whilst the author has ob- 
served it very strong when there was no dew. M. De Saus- 
sure has likewise stated the maximum of diurnal electricity 
