588 Proceedings of the Royal Society 
On consulting the Ordnance map of the district, done in 1818, 
and brought up to 1880, and drawing on it a line from Dover 
Castle to Kamsgate, we find at the distance of 12 miles from the 
latter place, a village called East Langdon with 22 buildings; a 
little farther north, another called Marten with 17 ; then Appleton 
with 6. The absence of contour lines prevents me from deter- 
mining the heights ; but, taking Vince’s statement that the hill is 
12 miles away, these villages must be just in such a position as to 
occupy seemingly the position of the lower parts of the Castle. 
Which then is the more credible : — That all the wonders just 
discussed should have been real : — or that an indiscriminating 
observer should have deluded himself by the fancy that some of 
these buildings were parts of the Castle 1 
Such things do not often occur in the history of physical science. 
Generally assertions by whomsoever made can be and are tested by 
the reproduction of the alleged circumstances ; but in a case such as 
that before us, no one can repeat or verify the observation, nor even 
make one analogous thereto ; and therefore it behoved the observer 
to have been particularly careful as to what he saw, and as to how 
he recorded it. We have seen that the record is an aggregate of 
impossibilities. 
It is indeed strange that such a gross substitution should not 
have been instantly detected ; and still more strange that Brewster 
should have transferred the account into the Encyclopaedia , and even 
improved the drawing, without having perceived that the mere fact 
of its being in perspective is absolute proof of its untruth. Just 
as a story is the less credible, so there would seem to be the less 
need for examination. This is seen also in the succeeding 
paragraph, wherein Sir David supports the idea of an atmospheric 
mirror by the evidence of a girl who, while gathering flowers on the 
hill-side, saw her image and her very features reflected from a thin 
mist rising from a marsh ; and he strengthens that evidence by the 
inquiry of her friends who were waiting for her below as to “ who 
was with you on the hill ? ” never perceiving that this question 
supplies the simple intelligible solution of the mystery : — that the 
young woman had mistaken another person for her own image. 
By such careless treatment of evidence the growth of these 
phantasies is encouraged. 
In a popular work on Astronomy which has had a considerable 
