dge
characteristics may vary slightly in actual shape or physical position
due to twisting, pressure, incomplete inking, condition of latent
print when developed, powder adhering to background, etc.
Identifications are based on a number of characteristics viewed in a
unit relationship and not on the microscopic appearances of single
characteristics.

Since the enlarged photographs appear in black and white, an ink other
than black or white should be used to line the chart. Such an ink
should be preferably translucent so that it will be possible to see
the ridges which it traverses. A translucent carmine drawing ink
serves well. In placing the lines on the chart, they should be
arranged so that they do not cross or touch.

The chart will present a clearer, neater, and more pleasing appearance
if it is numbered clockwise and the numbers are evenly spaced (fig.
429). It is not necessary, however, to place the numbers evenly around
the photograph.

[Illustration: 429. Chart illustrating method of fingerprint
identification.]

Ordinarily, the numbers are placed on three sides and the type of
print (latent or ink) noted at the bottom. In any case, the manner of
numbering should be subservient to an explanation of the
characteristics in an orderly sequence; and, if the situation warrants
it, all of the points may be illustrated on a single side of the
photograph.

A single line should be drawn from each characteristic to a numbered
point on the margin. Care should be taken to draw the line exactly to
the characteristic point, not short of it, beyond it, or obscuring it.
Erasures should be avoided. If the ink runs or blots, it is sometimes
possible to remove it with a cloth dampened in denatured alcohol,
without damaging the photograph.

If the enlargement is great, that is, 25 or 30 diameters, it might be
well to draw a small circle around each characteristic and then draw
the line from the circle to the number, since the ridge will be much
thicker than the illustrating line. All lines and numbers should be
checked for absolute accuracy. The expert should also study the
enlargements for _apparent discrepancies_ in the prints, which he
might be called upon to explain.

The charted enlargements are readily mounted on stiff cardboard with
rubber cement, which may be purchased in small tubes. After cementing
the photograph to the cardboard, it should be placed under a heavy
flat object which will cover the entire surfac