247 
Condensations of Humidify on Solid Surfaces. 
of a few minutes, when in depth it reached to the backs of the 
sheep, and bodies of the cows, its density and whiteness had con- 
siderably increased, and its agitated motion had begun to sub- 
side. Several large waves now made their appearance, rolling in 
various directions, and with a velocity that may be described as 
being neither slow nor quick. By the time its depth had ex- 
tended to the backs of the cows, only one extensive wave was to 
be seen, which traversed the whole width of the meadow, mov- 
ing sometimes in one direction, and at other times in another. 
When the large wave rolled over the meadow, and had got 
nearly to the opposite side, considerably accumulated, though 
its depth diminished backwards to the place from whence it set 
out, the grass was never perfectly uncovered, and the alternate 
concealment and exposure, or half exposure, of the sheep and 
cows thus produced, gave a curious variety to the scene. At 
last the mist disappeared as it were by enchantment, after ha- 
ving been visible from 15 to 20 minutes. At the instant of its 
disappearance, a distinctly perceptible motion took place in the 
lower atmosphere towards the west ; but this breeze communi- 
cated no apparent motion to the mist, which simply vanished, 
and in less than five minutes the atmosphere was again nearly as 
calm as at first. There was, however, no re-formation of the 
mist, the after-part of the evening was clear, the distant surface, 
as usual, slightly hazy, and there occurred a considerable depo- 
sition of dew. During the rolling of the mist, no such motion 
of the air would have been suspected by a person walking over 
the meadow, if the mist had been invisible, or if his attention 
had not been directed to its movements *; 
* A similar deception in regard to the absence of motion in the lower air oc- 
curs during calm hot weather, and on places that are exposed to the full influence 
of the sun’s rays. In walking over a level meadow, on such an occasion, a person 
might be led to suppose that the air was perfectly at rest ; but if he recline on the 
grass, and look in a horizontal direction over its surface, he will readily perceive not 
only motion, but a rapid agitation, and that, on some occasions, a considerable 
distance above the ground. On dry sandy plains, motion near the surface is 
less apparent, after the ground has become very hot. On some such occasions, 
may not the plain where the agitation is most considerable, be higher than the per- 
son’s head, when in the erect position ? And is it not probable that the vibratory- 
motion which some have supposed they had discovered in clouds having a fibrous 
