The value of the microscope in this field of research is so great and the facts elicited by it so vital, I wish to emphasize its practical utility as strongly as possible. Of course the principal object in such an examination of written or printed documents is the erasures or additions; then the coloring of different inks applied and the mode of their execution. As to erasures, this can be accomplished in two ways, either by the use of a penknife or by a chemical preparation. The former is the one most commonly resorted to, and is effected in the following manner. With a well sharpened knife blade the surface of the paper is carefully scraped until all objectionable lettering and wording appear to the naked eye to have been effaced; but under a microscopical examination the impression made by the strokes of the pen may easily be detected, while the different colors of the inks are still plainly visible under the microscope. The second method is by the application of a chemical preparation by which the ink is made soluble and is then easily removed from the paper by means of a blotter or absorbent cotton. Of course this method is also an imperfect one and the letters can easily be traced by close observation. When a chemical preparation has been used for erasing purposes, I find that in most cases it leaves a stain and also that the fibres of the paper are more or less destroyed by the chemical used; thus always leaving evidence that the document has been tampered with. George E. Fell in his excellent paper says: "The eye of the individual making the erasures is certainly not sufficient, and even with the aid of a hand magnifier, the object might not be effectually accomplished. We will find that the detection of an erasure made by the knife is a very simple matter and may be detected by the novice. An investigation may be made by simply holding the document before a strong light and this is usually all that is necessary to demonstrate the existence of an erasure of any consequence. "This is, however, a very different matter from making out the outlines of a word or detecting the general arrangement of the fibres of the paper, so as to be able to state whether writing has been executed on certain parts of the document; and again, when we enter into the minutiae of the subject, we will find that the compound microscope will give us results not to be obtained by the simple hand magnifier."