It may be, and often is, the case that the peculiarities or tricks in the original have been imitated in the suspected writing. As the result of his experience in knowing what to look for in a copied document, the expert is not deceived. However good the copy, there are always apparent to the trained eye evidences that prove another and stranger hand, plain as the difference between the firm, clear line of the drawing master and the broken saw-edged effort of the pupil. Habitual observation trains the eye to an extent that would scarcely be credited unless proved by experiment. The art of observation cannot be taught; it must be the outcome of practice. The most the teacher can do is to indicate the lines on which the study should be carried out, and offer hints and suggestions as to what to look for. The rest is in the hands of the student.
CHAPTER II.
Measurement and its Appliances.
The appliances necessary for the work of examination are, a good magnifying or reading glass of the greatest power obtainable, a pair of fine compasses or dividers, a horn or celluloid protractor for measuring angles of slope, and a clearly marked scale rule. Suitable articles will generally be found in an ordinary case of mathematical instruments.
A simpler and equally accurate method of taking measurements of handwriting is by the aid of the transparent paper known as foreign letter paper. It is usually of quarto size, very thin and transparent, and is ruled horizontally and vertically, dividing the sheet into tiny squares. It is laid over the writing to be examined, and the various measurement marks are made with a finely pointed lead pencil. The lines and squares are used for measurement as the parallels of latitude and longitude are used on a chart. For example, a letter is said to be so many lines high, so many lines wide. One of the tiny squares should be carefully divided into two, or, if possible, four parts, so as to ensure finer and more accurate measurement. A letter may then be measured in parts of a line, being described, for example, as, height 6¾ lines, breadth 2½ lines. It is of course important that the same gauge of ruled paper be used uniformly, otherwise the measurements will vary. If the student has had practice in the use of the dividers and scale rule, he may prefer to employ these, but the ruled paper and a finely pointed lead pencil will be found sufficient for most purposes. A paper specially prepared for surveyors, ruled in squares of one-eighth of an inch may be obtained. For measuring the slopes of letters a transparent protractor is necessary. The letters measured are all topped and tailed small letters, and all capitals having a shank. Letters like O, C, Q, S, and X can only be measured approximately.
The method of applying the measurements of heights and angles of slope is shown in the case illustrated by the table on page [15].
The subject of enquiry was a signature containing the letters B, l, k, b.
The measurements of these letters in the forgery are given at the top of the table, and show the height in lines and angle of slope in degrees.