a precipice, a sense of apprehension instantly
suggests itself; the nervous system recoils;
the circulation of the blood within the brain
on a sudden becomes irregular; dizziness
ensues and a total loss of command over the
voluntary muscles. Man is probably the
only being in whom this occurs; the stag,
the goat, the antelope, will gaze unmoved
down the chasms of the deepest Alpine
precipices. The dizziness which is felt on
ascending an elevation, arises undoubtedly from
mental alarm, which modifies the impressions
received by the eye, which no longer correctly
estimates the relations of distance. Accordingly
we are told by Mr. Wilkinson in his
"Tour to the British Mountains," that a blind
man, who was the scientific and philosophic
Mr. Gough, ascended with him to the summit
of one of the Cumberland Mountains; and
in walking along, he described to him the
fearful precipices which he pretended surrounded
him; but soon he repented his
inventive picturesque description, for the
blind man, mentally affected by the supposed
peril of his situation, became suddenly dizzy,
and screaming with the apprehension that he
was tumbling down the rocks into the abyss
below, fell upon the ground. In cases of
sleep-walking upon dangerous heights, there
is no apprehension or fear—the mind is
intently absorbed in the object pursued; all
the muscular movements are performed with
confidence and with unerring precision; and
under these circumstances the gravitation of
the body is supported on the most slender
basis.

One of the most curious and indeed inexplicable
phenomena connected with somnambulism
is, that persons in this condition
are said to derive a knowledge of surrounding
objects independent of the organs of the external
senses. The Archbishop of Bordeaux
attested the case of a young ecclesiastic, who
was in the habit of getting up during the night
in a state of somnambulism, taking pen, ink,
and paper, and composing and writing sermons.
When he had finished one page he would read
aloud what he had written, and correct it. In
order to ascertain whether the somnambulist
made any use of his eyes, the archbishop held
a piece of pasteboard under his chin to prevent
his seeing the paper, upon which he was
writing; but he continued to write on without
being in the least degree incommoded.
He also, in this state, copied out pieces of
music, and when it happened that the words
were written in too large a character, and did
not stand over the corresponding notes, he
perceived his error, blotted them out, and
wrote them over again with great exactness.
A somnambulist is mentioned by Gassendi,
who used to dress himself in his sleep, go
down into the cellar, draw wine from a cask,
in perfect darkness—but if he awoke in the
cellar, he had then a difficulty in groping his
way through the passages back to his bed-room.
The state of the eyes during somnambulism
is found to vary considerably—they
are sometimes closed—sometimes half closed—
and frequently quite open; the pupil is
sometimes widely dilated, sometimes contracted,
sometimes natural, and for the most
part insensible to light. This, however, is not
always the case. The servant girl, whose
case was so well described by Dr. Dyce, of
Aberdeen, when this state was impending felt
drowsy—a pain in the head, usually slight, but
on one occasion very intense, then succeeded—
and afterwards a cloudiness or mistiness
came over her eyes. Occasionally her sensations
were highly acute; the eyelids appeared
shut, though not entirely closed; the pupils
were much contracted, and there was great
intolerance of light. She could not name
objects when the light of the candle or fire
shone fully on them, but pointed them out
correctly in the shade, or when they were
dimly illuminated. At other times, however,
the pupil of the eye was quite insensible to
light. Her feelings also appear to have been
very excitable. During one of her paroxyms
she was taken to church; attended to the
service with every appearance of devotion, and
was at one time so much affected by the sermon,
that she shed tears. The sensibility of the
eye was also observed, in the case of Dr.
Bilden; when a degree of light, so slight as
not to affect the experimenter, was directed
to the lids of this somnambulist, it caused a
shock equal to that of electricity, and induced
him to exclaim, " Why do you wish to shoot
me in the eyes? " These are exceptions; as
a general rule, the eye during somnambulism
is insensible, and the pupil will not contract,
though the most vivid flash of light be directed
upon it. It also should be observed .that
although somnambulists will light a candle, it
does not follow that they are guided by its
light; or that they really see anything by it.
Their movements may still be purely automatic.
This curious circumstance is finely
illustrated by Shakespeare, who describes the
Lady Macbeth walking in her sleep with a
lighted taper in her hand:—

   " Gentlewoman.—Lo, yon, here she comes: This
is her very guise, and upon my life, fast asleep.
   " Doctor.—How came she by that light?
   " Gentlewoman. Why, it stood by her. She has
light by her continually—'tis her command.
   " Doctor.—You see her eyes are open—
   " Gentlewoman.—Aye—but their sense is shut."

It is related of Negretti, a sleep-walker,
that he would sometimes carry about with
him a candle as if to give him light in his
employment; but on a bottle being substituted,
he took it and carried it, fancying that
it was a candle. Castelli, another somnambulist,
was found by Dr. Soane, translating
Italian into French, and looking out the words
in his dictionary. His candle being purposely
extinguished, he immediately began groping
about, as if in the dark, and although other
candles were in the room, he did not resume