Another method of detecting forgery is afforded by the internal evidences of fraud of the writing itself, with or without the aid of comparison with genuine writing.  These evidences may consist of alterations, erasures, additions, crowding, etc., as above referred to; tracing a genuine writing by means of ink or pencil, afterwards retraced, etc.

The copy of a genuine signature may be free-hand or composite, by which is meant that the writing is produced discontinuously or in parts.  Comparison of the separate letters of the doubtful specimen of writing with the separate letters of the genuine writing of the supposed imitator or imitated always exhibits less uniformity if imitation has been attempted, the copyist being frequently led into an approach to his ordinary handwriting or into an oversight of some special characteristics of the writing he is simulating.  Even minor points do not escape the expert’s critical attention.  The dotting of the i’s, or crossing of the t’s, curls, loops, flourishes, intervals between words and letters, connections, characteristics of up and down strokes are all carefully noticed.

A glass of low magnifying power will, as a rule, exhibit erasures, and even bring to view the erased letters.  In tracing, the forger frequently fails to cover over the first outlines, which can be plainly distinguished.  The places where the pen has been put upon and removed from the paper may sometimes be noticed, which is in itself strong evidence of fraud.

With the aid of a microscope the character of the alterations, certain characteristics due to age, emotion, etc., the kind of pen used and how it was held, the nature of ink, order of writing, with regard to time, whether produced by the right or left hand, standing or sitting, can often be determined.  Indentations made by heavy strokes or a sharp pen, as well as those employed as guides for the signature subsequently written, will also be brought into prominence.  Forged signatures placed under the microscope have generally a patched appearance, which results from the retracing of lines in certain portions not occurring in genuine writing.

In case of disputed handwriting photography has also been employed to great advantage.  Of course the writing in question should, whenever practicable, be compared with the original, photographic copies being looked upon with disfavor and considered by most courts as secondary evidence.  Still, photographic enlargements of genuine and disputed signatures are very useful in illustrating expert testimony.  Certain characteristics, differences in ink, attempts to remove writing, etc., may be brought to view, which would be entirely overlooked by direct examination.  The wonderful power of the camera has recently been illustrated in a very striking manner.  A large ocean steamer was photographed, and on receipt of the proof the owners were surprised to see a hand bill posted on the side of the hull.  Examination of the ship disclosed no hand bill there, but another photograph exhibited the same result.  A searching inspection revealed the presence of the mysterious paper buried beneath four coats of paint, but defying the superficial scrutiny of the human eye.