CURIOUS EFFECT OF REFRACTION. 
171 
from one side of the channel to the other ; and, but for the 
treacherous nature of the sand-banks, it would not have 
been difficult to have walked over dry footed to the oppo- 
site side of it. The channel stretched away to the E. S. E., 
to a distance of seven or eight miles, when it appeared to 
turn south under a small sand-hill, upon which the rays of 
the sun fell, as it was sinking behind us. 
There was an innumerable flock of wild-fowl arranged 
in rows along the sides of the pools left by the tide, and 
we were again amused by the singular effect of the 
refraction upon them, and the grotesque and distorted 
forms they exhibited. Swans, pelicans, ducks, and geese, 
were mingled together, and, according to their distance 
from us, presented different appearances. Some were ex- 
ceedingly tall and thin, others were unnaturally broad. 
Some appeared reversed, or as if they were standing on their 
heads, and the slightest motion, particularly the flapping of 
their wings, produced a most ridiculous effect. No doubt, 
the situation and the state of the atmosphere were fa- 
vourable to the effect 1 have described. The day had been 
fine, the evening was beautiful, — but it was the rarefaction 
of the air immediately playing on the ground, and not the 
haze of sunset that caused what I have noticed. It is dis- 
tinct from mirage, although it is difficult to point out the 
difference. The one, however, distorts, the other conceals 
objects, and gives them a false distance. The one is clear, 
the other is cloudy. The one raises objects above theii tiue 
position, the other does not. The one plays about, the other 
