Somnambulic sleep is one of the most extraordinary and unaccountable anomalies of our nature. The almost endless variety of mental and physical combinations it presents; the adaptation and precision of action to effect a definite purpose; and the apparent power to overcome obstacles to its accomplishment, not only strike the mind with amazement, but involve it in an inexplicable labyrinth of doubt and uncertainty.

The vast number of cases recorded in this department of our subject, should afford abundant material from which to determine the laws regulating its operations. But upon critical examination, few of them offer more than undefined and imperfect sketches of its phenomena; and for a philosophical inquiry, furnish but a slight foundation on which to rest a theory.

In considering somnambulism, the questions arise, is the subject cognisant of surrounding objects? - and if so, by what means? - so that the relation of mind and body may be defined, as well as the causes which propel their operations.

The mind, in somnambulic, is circumstanced the same as in ordinary sleep, so far at least as regards its causes of excitement; but its activity is infinitely more intense. Sleep walking and sleep talking occur in the stages of either dreaming or torpor, and are governed by their laws. In all perfect cases of somnambulism, the mind is as ignorant of the external relations of the body as it is during sound sleep, so far as knowledge is derived through the organs of special sense; and therefore we conclude that it can have no memory of either the mental or physical acts during the paroxysm. But it will be recollected, that, when speaking of dreams being remembered in part, and in part forgotten, the physical condition was in a state of transition, - vacillating between dreaming and torpor. And so it is with regard to somnambulism; a part of the acts are remembered, sometimes as a dream; and a part forgotten, according to the stage of sleep in which it occurred.

"Hortius mentions a young nobleman, who was observed by his brother to rise in his sleep, put on his cloak, open the casement, mount by a pulley to the roof of the citadel of Brenstein, where he was, tear a magpie's nest to pieces, wrap the young ones up in his cloak, return to his room, place the cloak with the birds in it near him, and go to bed. In the morning he told the adventure as a dream, and was astonished when shown the magpies in his cloak, and, when led to the roof, to behold the remains of the nest."* In this case the object in view was paramount, the senses in a measure impressible, the perception of their impressions clear, and consequently the circumstances were remembered.

By what means does the mind discover that the physical acts have in sortie cases been erroneous, as in the instance of the individual shortly to be cited, who corrected errors he committed in writing musical airs ? The inference is, that the same state here existed that we find in mesmeric sleep, both of which, with the information we at present possess, are inexplicable; but that neither the errors nor corrections were made through the assistance of vision, the experiments conclusively determine.

To illustrate, let us take some of the cases recorded in the "Cyclopaedia of Practical Medicine - London." "This somnambulist was a young priest in a Catholic seminary; the witness and reporter of the facts, the Archbishop of Bordeaux, who used to go into his chamber after the priest was gone to sleep, and observe his proceedings. He sometimes arose from his bed, took paper, and wrote sermons. After finishing a page, he read (if the act was properly reading) the whole aloud; and, if necessary, erased words, and wrote his corrections over the line with great accuracy. I have seen the beginning of one of his sermons which he had written when asleep; it was well composed, but one correction surprised me : having written at first the words 'ce divin enfant,' he had afterwards effaced the word divin, and written over it adorable. Then perceiving that the ce could not stand before the last word, he had dexterously inserted a t, 90 as to make the word cet.

* Binns' Anatomy of Sleep.

"The witness, in order to ascertain whether he made use of his eyes, put a card under his chin, so as to intercept the sight of the paper which was on the table; but he continued to write without perceiving it. Wishing to know by what means he judged of the presence of objects which were under his eyes, the witness took from him the paper on which he was writing, and substituted others repeatedly. He always perceived this by the difference of size, for when a paper of exactly the same shape was given to him, he took it for his own, and wrote his corrections on places corresponding to those on the paper which had been taken away from him. The most astonishing thing is, that he could write music with great exactness, tracing on it at equal distances the five lines, and putting Upon them the clef, flats, and sharps. Afterwards he marked the notes, at first white, and then blackened those which were to be black; the words were written under, and once happening to make them too long, he quickly perceived that they were not exactly under the corresponding notes; he corrected this inaccuracy by rubbing out what he had written, and putting the line below with the greatest precision."

This somnambulist had a clear mental perception of the results of his operations, but he could not have seen them, because an opake body was interposed, between the organ of vision and the object Is there any evidence that he even felt the paper upon which he wrote or the pen held in bis hand? The experiment of changing the paper for one of a different size is not conclusive, for he possessed the power of perceiving, without the intervention of sight, and probably also without the sense of touch.

"One of Gassendi's somnambulists used to rise and dress himself in his sleep, go down to the cellar, and draw wine from a cask: he appeared to see in the dark as well as in a clear day; but when he awoke either in the street or in the cellar, he was obliged to grope and feel his way back to his bed. He always answered his wife as if awake, but in the morning recollected nothing of what passed." The sense of touch did not guide the wanderer here, because the moment this faculty was restored to the mind by wakefulness, it was scarcely sufficient to conduct him back;. "he groped his way." All the other senses are as perfectly closed as sight and feeling. The somnambulist does not hear, but he perceives sounds, and replies to their influence. The blast of a trumpet may be blown upon him and he hears it not; but the gentle vibrations of a whisper, when in harmony with his train of thought, may be perceived.