Spots which become apparent by using vapor of iodine are due to chemical agents whose strength has altered either the fibers of the surface, or the paste uniting them.

In a word, the test of a document or paper by vapor of iodine has the double advantage of indicating the place of the supposed alteration and operating afterwards with appropriate reagents to bring back the traces of ink.  It is only the reappearance of former letters or figures written or effaced that demonstrates forgery.  Much time may be profitably spent in merely scanning each letter of a document, and the writing by lines, paragraphs, and pages before a closer scrutiny.  Gradually, if the writing be genuine, its character will begin to reveal itself, and unconsciously a hypothesis as to the physical causes of the irregularities or characteristics will be formed.

When an entire document or page is forged, the ornamentation, flourishes, or the capitals at its head will often be seen to be out of keeping, either with its nature or with the supposed author’s habits in similar cases.  In a writing all must agree, place, day, year, handwriting, superscription or heading, signature, and material carrying the writing, especially paper, both as to constitution and color and ink.

See illustrations of various kinds of handwriting at end of this book.

CHAPTER XV

GUIDED HANDWRITING AND METHOD USED

The Most Frequent and Dangerous Method of Forgery—­How to Detect a Guided Signature—­What Guided Handwriting Is and How It Is Done—­Character of Such Writing—­Writing by a Guided Hand—­Difficulty in Writing—­Force Exercised by Joint Hands—­A Hand More or Less Passive—­Work of the Controlling Hand—­How Guided Writing Appears—­Two Writers Acting in Opposition—­Distorted Writing—­How a Legitimate Guided Hand is Directed and Supported—­Pen Motion Necessary to Produce Same—­Influence in Guiding a Stronger Hand—­Avoiding an Unnatural and Cramped Position—­Effect of the Brain on Guided Hand—­Separating Characteristics From Guided Joint Signature—­Detecting Writing by a System of Measurement.

Guided handwriting is one of the most frequent means of forgery and oftentimes the most difficult to detect.  It has been established that with care the elements of each handwriting can be detected and proven in a guided signature.  The leading handwriting experts of the world are unanimous in declaring that it is possible for holding another’s hand in making a guided signature to infuse the character of the guider’s hand into the writing.

Guided handwriting is the writing produced by two hands conjointly and is usually erratic, and at first sight, hard to connect with the handwriting of any one person.

The character and quality of writing in case of a controlled or assisted hand must depend largely upon the relative force, exercised by the joint hands.  The difficulty in writing arises from the antagonizing motion of one hand upon the other, which is likely to produce an unintelligible scrawl, having little or none of the habitual characteristics of either hand.