172 
NATURE NOTES 
tells me that on one occasion last year the effect was to pose 
a ship on top of the Island, as she and her friends plainly saw. 
A remarkable case is recorded as having occurred at Hastings, 
on July 26, 1798, when the French coast, fifty miles distant, was 
clearly seen for three hours. 
I have myself seen in the deserts of India, Arabia, and Egypt, 
the same mirage deceptions that have frequently been described 
by travellers, but I do not think it is usually known that objects 
are sometimes much magnified in a thin fog. I have observed 
this at sea, but was particularly struck by it a few years ago on 
Dartmoor. I had been fishing below Post-Bridge, and, raising 
my eyes from the river on nearing the village in the evening, 
saw the first cottage enlarged so as to look like some huge giant’s 
dwelling. I then noticed that the mist was driving down the 
valley. On approaching the cottage it of course dwindled to 
its real size. It is obvious that such enlargement could not be 
seen in a dense fog, for the object would not be visible till you 
were quite close to it. 
Giles A. Daubeny. 
July 7, 1900. 
P.S. — Since writing the above I have discussed the phenomena 
at the Needles with a friend who has just graduated at Harvard 
University, and we have together worked out the following 
explanation. 
We think that, when I first looked at the Needles, there lay 
about them a stratum of air that was several degrees hotter than 
that m which I was, the consequence being that the portion 
A B of the rocks was, by refraction, repeated at a 5 as shown in 
the section, sketch Is. 
Then a layer of colder air than that in which I was, was 
creeping round the Isle of Whght, and, coming down the Solent, 
got between me and the horizon in front of the Needles, raising 
that horizon, by refraction, so as almost to hide the rocks. See 
section in sketch I Is., where the ordinary horizon H is raised to /i, 
hiding the lower part of the rock at z. 
Of course in the transformation there was a moment when 
the hot and cold layers were of equal power and neutralised one 
another, making the rocks look normal. 
The fourth horizon in the distance was raised by another cold 
layer beyond the Island. I have not represented this in sketch Hs., 
as it would probably lie far out of the paper. The fourth horizon 
may have been visible throughout, though I did not notice it at 
first. 
A portion of the near edge of cold air melted gradually, we 
think, as I have suggested. The thin edge of the wedge was to 
my right, as shown by the drooping third horizon in sketch II. 
In sketches Is. and Hs. the horizontal distances between my 
eye, the ordinary horizon and the front of the Needle rock, are on 
a scale of half a mile to an inch. The vertical scale has had to 
