When this letter, which was in typewriting, was compared with another letter that had unquestionably been written in that office it was found that the faults of alignment in both were identical. Wherever a letter, or combination of letters, in the one fell above or below the line, the same thing occurred in the other, and wherever there was unequal spacing between two letters the distances were invariably equal in both cases. In addition to this, the ink, which was of the violet type, contained the same pigment, and the watermarks on the two sheets of paper were the same. There could, therefore, be no reasonable doubt as to the two letters having been written upon the same machine. As a matter of fact, this proof of collusion did not carry the weight that had been expected, for the case was decided upon issues that were not affected by such proof. With the aid of a measuring-scale upon the eyepiece of the microscope it is possible to measure the thickness of strokes of writing only ten thousands of an inch across, and in some cases to prove in this way that a certain part of a document was written at a different time or with a different pen than the remainder of the writing. In attempting to reproduce a signature a forger will probably make a preliminary outline with a blacklead pencil and then go over this with ink. The imperfect removal of the pencil marks may then betray the fraud, as in the Whalley will case described on another page. In some instances the particles of the graphite may be seen with the aid of the microscope to project beyond the upper layer of ink. Additions and alterations made to the letters in writing are clearly visible when magnified, and may be demonstrated in court by means of a photographic enlargement. Any irregularities in the edges of the letters or any break between one part of a letter and another appear much more pronounced when examined in this way, for all faults are enormously intensified. Thus the figure "0" might be altered into "9" by the addition of a stroke, or a "3" turned into an "8," but it would be practically impossible to do this in such a manner as not to show when slightly magnified. The accompanying illustrations, for which the writer is indebted to Mr. A. S. Osborn and the proprietors of _Knowledge_, will make these points clearer. In Fig. A is shown the result of an attempt to change the number "11" into "17" by the addition of a stroke to the top of the second "1." The small inset represents the appearance of the fraudulent alteration, while beneath it is seen the microscopical enlargement, in which the joining of the added portion is plainly visible. Occasionally it happens in fraudulent alteration of writing that a stroke or part of a letter may touch some of the original writing, and betray itself by being above instead of below the older letter.