Reader, have you a brain? If so, you can be made (apparently) to see it
by the following little experiment, which you can try for yourself with
no more complicated apparatus than a lighted candle, a black cloth, and
a dark room.
Secure a piece of black cloth about three feet square, and pin this
onto a wall at such a height that its lowest edge is about on a level
with your eyes, when seated or standing, as the case may be. The cloth
should be smooth and free from wrinkles. The room should be completely
darkened, and a lighted candle should be provided.
The experimenter should then take up his position, about three feet
from the black cloth and, while keeping the head level and the chin
down, he should elevate the eyes to an angle of about forty-five
degrees, so that he is now looking at the centre of the black cloth.
While holding the head and eyes in this position, the lighted candle
should be held at a distance of about six inches from the nose--that
is to say, the flame of the candle should be about this distance.
The candle is now moved slowly across the face, from side to side,
at a speed of about two seconds for each movement. The length of the
sweep should be about eight inches. Care should be taken, during this
process, that you do not blow on the candle flame, as it should be kept
as evenly lighted as possible.
If these instructions have been carried out accurately, and the head
kept well down with the eyes turned-up, the experimenter will see
slowly forming before him in space what appears to be a phantom image
of his own brain.
On a pinkish-gray background, he will begin to see innumerable tiny
veinings resembling those seen in the leaf of a tree. These are usually
black in color, and ramify in all directions unequally. As soon as
this image begins to form, the experimenter should keep his eyes fixed
upon it, without allowing his eyes to waver in the least. This black
ramifying network consists really of the blood vessels, which are
seen against the lighter background. It should be noted that only the
experimenter himself can see this effect, and that other persons in the
room cannot see anything until they try the experiment for themselves.
Practically everyone can see it, however, if he will but follow out the
directions carefully.
This is, of course, merely an optical illusion. The sight seems to be
turned inward, instead of outward, for the time being. Nothing exists
objectively in space. It is merely a hallucination, but it is one which
corresponds with the inner structure of the eyes and brain.
It has, of course, been claimed that what is really seen is not the
brain itself, but the retina at the rear of the eye-ball. It is this
which the light of the candle illuminates, and which is actually
perceived in the above experiment. As a practical “stunt” for parties,
however, it is much more interesting to think that the brain itself is
seen in this manner, and in fact what is perceived does very closely
resemble the convolutions of the human brain.
Try it for yourself, and see if you do not obtain an interesting result.