125 
Sir H. Davy on the formation of mists. 
and from 6 1° to 54 0 F. during the night. Below Passau, the 
Inn and the Ilz flow into the Danube.* On examining the 
temperature of these rivers at 6 o'clock, A. M. June 11, that 
of the Danube was found to be 6 2 0 F., that of the Inn e, 6 ±° F., 
and that of the Ilz 56° F. : the temperature of the atmosphere 
on the banks where their streams mixed, was 54,°. The 
whole surface of the Danube was covered with a thick fog; 
on the Inn there was a slight mist, and on the Ilz barely a 
haziness, indicating the deposition of a very small quantity 
of water. About 100 yards below the place where the three 
rivers joined, the temperature of the central part of the 
Danube was 59 0 F., and here the quantity of mist was less 
than on the bed of the Danube before the junction ; but about 
half a mile below, the warmer water had again found its place 
at the surface, and the mist was as copious as before the union 
of the three rivers. June 12th, the evening was cloudy, and 
the temperature of the atmosphere remained till after dark 
higher than that of the river, being, when the last observation 
was made, 63° F. when there was not the slightest appearance 
of mist. The sky was clearer before sun-rise on the 13th, 
and the thermometer immediately after sun-rise, in the air 
above the river, stood at 55^-° F. the temperature of the 
Danube being 6i° F.; a thin mist was seen immediately above 
the river; but there being no mass of vapour to exclude the 
sun-beams, it rapidly disappeared, and was not visible a few 
feet from the surface ; and in half an hour the whole atmos- 
phere was perfectly transparent. 
In passing along the Rhine from Cologne to Coblentz, 
* The Danube was greenish, the Inn had a milky blueness, the Ilz was perfectly 
pellucid ; but from the rapidity with which the Inn descended, its waters at this spot 
give their tint to the whole surface. 
