In the present edition of the Dissertation, beside the concluding Chapter of Part Third and its relative Note, which now appear for the first time, there are given numerous and extensive additions, both in the body of the work, and in the notes. These, as inserted, are all marked by their enclosure within square brackets. They are, however, to be divided into two classes, as derived from different sources. In the first place, Mr. Stewart's own interleaved copy of the original edition of both Parts of the Dissertation, contributes various corrections and amplifications. These have all been made use of, and their insertion is simply indicated by the brackets. In the second place, the other authorities from which new matter has been obtained, (but for Part Second only,) stand on a less favourable footing; in so far as whatever they afford was, after being written, omitted by Mr. Stewart himself from the Dissertation as published. These omissions, however, seem to have been made under an anxiety to bring the work, as connected with the Encyclopædia, within a narrower compass, (see p. 201,) and not in consequence of any rejection of the passages as in themselves either erroneous or redundant, Their insertion is, therefore, now marked not only by the brackets, but expressly as restorations; and though printed without other distinction, it should be mentioned that they also are founded on two several documents. They are partly taken from the original proof of the Dissertation; it being explained that Mr. Stewart was in use to have the whole, or a large portion of an intended publication, set up at once in type, and on this, at his leisure, he made any alterations which he thought expedient. Such a proof of Part Second is preserved, and it supplies much that is new and valuable. Again, there remains of the same Part a copy of the author's original manuscript, which exhibits, in like manner, many passages
