I have already pointed out, in dealing with problematic smudges, the need of understanding patterns apart from their actual orientation, which, in an unknown person’s case, may have to be assumed, an attitude which may be determined by official bias. This I have entered more fully upon in the Guide to Finger-Print Identification.
Holding this principle in view, then, let us now take some of the simpler elements of patterns in their very simplest forms, and first consider those grouped under the paired consonants.
Ch and J.
Each of these characters is taken to represent a hook with a short leg. Ch is considered as one consonant, and as C is not otherwise wanted, it might have been used alone but for its pronunciation being indefinite. If in the usual form of official imprint the hook, with its curve below, has its short leg facing to the left, thus, J, it is duly represented by the Roman letter of that shape. Observe that if you invert this character, or the type which represents it, thus
, it will still point the observer to the J part of the index, on getting the curve set right.
If the short leg of the figure points to the right it comes under Ch. If that happens to confront one in its inverted position it cannot be mistaken for a J figure, but must be looked for under Ch. In all cases the degree or direction of slope in the figures, with a few peculiar exceptions, is of no concern whatever, simplicity and directness of appeal being aimed at from the first.
B and P.
These consonants are used to denote a bow. B is the form of a simple bow with one lineation, or if two or more lineations blend into one, they are found on the left side when the convexity of the curve is upwards. P is such a bow, but strengthened, as it were, by one or more blended lineations on the right side, with the same position of the curve. A single line bow is never represented by P. If a bow with a plurality of blended lineations is inverted the reading is not at all affected.
T and D