Ixxvil 
that “the clouds threw down the picture”, for reflecting clouds 
would have placed the picture above themselves; and, to say 
nothing about inversion by reflection, it is obvious that, were 
there no intervening hills, any mirror that should place the 
picture where it was seen would have the spectator at its back.” 
The rays of light radiating from the points of the objects imaged 
must have deviated by refraction horizontally through an angle of 
nearly 90°; and vertically, first downwards, after cresting the Kea 
hills, through many degrees to the level of the spectators’ eyes ; 
and even below that level, afterwards to ascend as if coming up, at 
a little distance out, frum the bay beneath their feet ; so that here 
were considerable vertical refractions, the one succeeding the other, 
in opposite directions. Altogether I doubt if there is on record 
a more extraordinary instance of unusual atmospheric refraction. 
Such phenomena are so very uncommon with us that, on turn- 
ing over (truly with no great care) our Reports and Journals, I 
found only one other notice of a mirage; and, as.I am on the 
subject, I will say a few words about it, by way of taking stock 
of all we have published in that way. Besides, if a real mirage, 
as therein described (See Report for 1841), it was a very curious 
one,—perhaps unique. Through the spray and mist of Perran 
Porth the setting sun was seen, in part, through a slit (so to speak) 
in a cloud, and it looked red; while several red images of it were 
seen transiently flitting about near it ; not one red image appearing 
except in proximity to the sun. Besides these, however, there 
were unusual green images, which were much more abiding than 
the red ones, and were visible even against the dark cliffs at a 
distance from the sun. Now when we know that ordinary luminous 
impressions upon the retina only last one-third of a second of 
time before they fade away to re-appear as more persistent spectra 
of the complementary colours, bright enough to be visible when 
dark surfaces are looked at ; and when we remember that green is 
the complementary colour of red, we are led to suspect that the 
observer by regarding the sun with unsteady eyes, received from 
it detached luminous impressions upon his retina, the lingering 
spectra of which they transported against the cliff when the 
eyes were turned that way. It is not quite impossible that 
several images of the sun might have been produced by unusual 
refraction ; but the green ones leave no doubt in my mind that we 
have here an ocular illusion, and no mirage at all. 
There is nothing astonishing in the fact of even an accomplished 
scholar, with no knowledge of physiological optics, thus being de- 
ceived ; and it is well always to bear such a possibility in mind 
when reading accounts of rare optical phenomena, such as those 
concerning the Halo and accompanying appearances on the 5th 
