128 
Sir H. Davy on the formation of mists. 
source, it must always be produced to a great extent upon 
the ocean in calm weather during the night, particularly 
under the line, and between the tropics, which the journals 
of voyages sufficiently prove is not the case. I have myself 
had an opportunity of making some observations which coin- 
cide with this view. During a voyage to and from Pola, I 
passed the nights of September 3, 5, and 6, off the coast of 
Istria ; there was very little wind on either of the nights, and 
from sun-set till nearly midnight it was perfectly calm in all of 
them. On the3d it was cloudy, and the lightning was perceived 
from a distant thunder storm, and the vessel was never far 
from the shore : but on the 5th and 6th the sky was perfectly 
clear, and the zodiacal light, after sun-set, wonderfully dis- 
tinct- and brilliant, particularly on the 5th, and we passed by 
the help of oars from two to eight miles from the shore. 
The temperature of the sea at sun-set was 7 6° F. on the 5th, 
77 0 F. on the 6th, that of the atmosphere immediately above 
it 78° F. and 79 0 F. On the 3th, at midnight, about five 
miles from the shore, the temperature of the sea was 74° F. 
and that of the atmosphere 75 0 F., and on the 6th, at the same 
hour, at about four miles from the shore, the temperature of 
the sea was 73 0 F. and that of the atmosphere 75 0 F. There 
was not the slightest appearance of mist on either of these 
nights on the open sea, or at any distance from the land : but 
close under the hills of Istria there was a slight line of haze 
visible before sun-rise, which was thickest under the highest 
land; and as we approached at sun-rise, on the 7th, the moun- 
tains of the Friul, the tops of those nearest to Trieste were seen 
rising out of a thick white mist, which did not reach a quarter 
of a mile from the shore. 
