In all the states of the Union the laws are uniform on the proposition that experts may testify as to comparisons made and the results based on such comparisons, except that the paper admitted to be genuine shall not contain matter of a frivolous nature, etc.

In a broad, general way the element of common sense is the basework of an expert’s success in the business.  He cannot depend upon anything suggesting intuition.  Where two signatures or two specimens of writing are in question and one exhibit is a forgery and the other is genuine, or where both are genuine, yet in question, the expert is in the position of making his proofs and demonstrations convincing to the layman—­the hard headed citizen who insists that “you show me.”  Frequently this citizen is on a jury where he has had to admit that he is not particularly intelligent before he would be accepted for the place.

As a first proposition to such a man, however, the expert in chirography may put him to the proof that out of a dozen signatures of his own name no two will be alike in general form.  Then he may turn to the authentic and forged signatures in almost any case and show to the layman that the first question of forgery arose from the fact that these two signatures at a first glance are identically alike to almost the minutest detail.  With all the skill which the forger has put into his crooked work, he keeps to the old principle of copying the authentic signature which he has in hand, and the more nearly he can reproduce this signature in every proportion the more readily the forgery can be proved.

One of the most important facts from which the expert may begin his investigations of possible forgery is that every man using a pen in writing has his “pen scope.”  This technical term describes the average stretch of paper which a man may cover without lifting the pen from the paper and shifting his hand to continue the line.  In even the freest, swinging movements of a pen where the hand follows the pen fingers, there are occasional breaks in the lettering or undue stretch of space between the words which will indicate a characteristic scope of the pen if the specimens under investigation cover an ordinary paragraph in length.

As applied to the signatures of the ordinary individual, this pen scope will appear in some form in the signature.  The writer may lift his pen before he has spelled out a long Christian or surname, he may indicate it in the placing of a middle initial or in the space which lies between the initial and the last name.  In the case of the signature of one’s name, too, it should be one of the easiest and lest-studied group of words which he is called on to put upon paper.  In writing a letter, for example, the pen scope through it may show an average stretch of one inch for the text of the letter, while in the signature the whole length of the signature twice as long, may be covered.  But if the writer covers this full stretch of his name in this way the expert may prove by the necessary short pen scope of the copyist that the studied copy is a forgery on its face.  For however free of pen stroke the forger may be naturally, his attempts to produce a facsimile of the signature shortens it beyond the scope of the original signer.