ANIMAL MAGNETISM.--But for the fact that COL. STONE's Letter on Animal Magnetism, containing an account of a remarkable interview between the author and Miss LORAINA BRACKETT, of Providence, (R. I.,) while in a state of somnambulism, is the theme of conversation and newspaper comment, in every section of the country, we should be tempted to occupy three or four of these pages with the extraordinary facts therein narrated. As it is, we shall simply run the risk of being the first to apprize some half dozen American, and an hundred or two foreign readers, that the work records, in easy and exciting detail, an imaginary visit of Miss BRACKETT to this city, while in a state of somnambulism, portions of which she describes with astonishing accuracy; that she accompanies the author to his own house, where she describes, with wonderful minuteness, localities, furniture, pictures, etc.--and all this, without ever having been in New-York in her life, or hearing or knowing any thing in relation to the scenes and objects visible to her mind's eye! We are not believers in animal magnetism--oh, no! Yet we are not exactly skeptics, either. A '_state of betweenity_' aptly expresses our situation in regard to these strange matters. A NEW THEORY OR ANIMAL MAGNETISM.--Since the above was placed in type, Messrs. WILEY AND PUTNAM have issued a coarsish volume, of some two hundred and twenty pages, entitled, 'Exposition of a New Theory of Animal Magnetism, with a Key to its Mysteries: Demonstrated by Experiments with the most celebrated Somnambulists in America;' together with 'Strictures' upon the Letter noticed above. By C. F. DURANT. At the present writing hereof, we have but time and room to say, that so far as we have advanced in the work, Mr. DURANT seems to be probing the whole matter quite thoroughly, and to have recorded his proceedings in a style of laughable mock-irony, though in language generally not a little careless, and sometimes--shade of Priscian!--sadly ungrammatical; the result, doubtless, of hasty publication.