260 On Natural Magic. 
cease of a friend. If in consequence, by the accidental presence 
before the eye of a proper object, or a suitable combination of light 
and shade, a spectral appearance is then produced, (it being sup- 
posed now partially dark), a superstitious person might very readily 
be led, with a little aid from imagination, particularly as the idea of 
his departed friend is now uppermost in his memory, to believe 
strenuously that he had seen the ghost of the deceased. ‘The child 
who goes alone at dusk is prone to watch any black object, espe- 
cially if it is made conspicuous by a prevailing whiteness of the ob- 
jects about or beyond it. We can easily see how, on his looking 
round, his young imagination may, and not without a cause, be star- 
tled into a troublesome activity. nies 
The writer well remembers with what sensations he has in child- 
hood watched the spectres that on moonlight nights used to haunt 
the black garments hanging upon the white wall of his apartment. 
Any one may observe such phenomena very favorably on waking at 
dawn, by fixing the eyes for a considerable time (one minute or 
even less will suffice for an experiment) steadily upon a dark col- 
ored object projected or situated on a white or whitish ground, and 
then looking off towards the white ground, when directly he will 
perceive a white representation of the object he has been viewing, 
either upon the white ground, or between it and himself, according 
to his fancy. One can make it, when it is of a middling brightness, 
disappear and again reappear, by simply giving his attention for a 
moment to something beyond, and then again to the image. If the 
eye has been kept constantly upon the same point of the dark ob- 
ject previously viewed, the white image of the latter will be a dis- 
tinct and faithful representation. Otherwise it will be varied, and 
might by a startled imagination be easily conjured into the most 
frightful shapes. If a person is at twilight travelling towards a hill 
(or even a level space) covered with snow, and steadily watches 
another person in a dark dress, advancing a short distance before 
him, whose figure is projected towards the snow, he sees on looking 
aside, a white spectre in human shape. It will in some instances 
appear to be roving, the observer all the time thinking that he fol- 
lows it with his eyes, while in fact it depends for its motion upon 
this same movement of the eyes. Should it, before it fades into 
obscurity, arrive before some dark retreat, it there vanishes, for its 
appearance depends upon the light coming from objects beyond it. 
A result similar to those already described, might surprise a person 
