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Whorl Tracing

The technique of whorl tracing depends upon the establishment of the

focal points--the deltas. Every whorl has two or more. When the deltas

have been located, the ridge emanating from the lower side or point of

the extreme left delta is traced until the point nearest or opposite

the extreme right delta is reached. The number of ridges intervening

between the tracing ridge and the right delta are then counted. If the

ge traced passes inside of (above) the right delta, and three or

more ridges intervene between the tracing ridge and the delta, the

tracing is designated as an inner--I (fig. 280). If the ridge traced

passes outside (below) the right delta, and three or more ridges

intervene between the tracing ridge and the right delta, the tracing

is designated as an outer--O (fig. 281). All other tracings are

designated as meeting--M (figs. 282 to 287).

Tracing begins from the left delta. In no instance is a tracing to

begin on a type line. In figure 288, tracing begins at the short ridge

which is the left delta. It is true that inasmuch as the short ridge

ends immediately the type line is next followed, but this is only

because the type line is the next lower ridge. Its status as a type

line is independent and has no bearing on the fact that it is being

traced. This point is illustrated further in figure 289. This pattern

shows an inner tracing. It will be noted that the delta is at the

point on the first recurve nearest to the center of the divergence of

the type lines. It will be further noted that tracing begins at the

point of delta on the left and continues toward the right, passing

inside of the right delta, with three ridges intervening between the

tracing ridge and the right delta. This shows the tracing to be an

inner tracing. If, in this case, the type line were traced (which

would be the incorrect procedure), only two ridges would intervene

between the tracing ridge and the right delta, resulting in an

erroneous meeting tracing. Figure 290 is another example of the

application of this rule. This illustration is also an inner whorl.

When the ridge traced ends abruptly, and it is determined that the

ridge definitely ends, the tracing drops down to the point on the next

lower ridge immediately beneath the point where the ridge above ends,

continuing from there. Figure 291, therefore, is an outer whorl.

In this connection it should be noted that the rule for dropping to

the next lower line applies only when the ridge definitely ends.

Short breaks in a ridge which may be due to improper inking, the

presence of foreign matter on the ridges, enlarged pores, disease, or

worn ridges should not be considered as definite ridge endings. The

determination of what constitutes a definite ending will depend, of

course, upon the good judgment of the classifier. When the question

arises as to whether a break encountered in the ridge tracing is a

definite ending, or whether there has been interference with a natural

impression, the whole pattern should be examined to ascertain whether

such breaks are general throughout the pattern. If they are found to

be common, consideration should then be given to the possibility that

the break is not a definite ridge ending. Appropriate reference

tracing should be done in all such cases.

Whenever the ridge traced bifurcates, the rule for tracing requires

that the lower limb or branch proceeding from the bifurcation be

followed. This is illustrated in 292.

Accidentals often possess three or more deltas. In tracing them only

the extreme deltas are considered, the tracing beginning at the

extreme left delta and proceeding toward the extreme right delta, as

illustrated in figure 293.

In a double loop or accidental the problem of where to stop tracing is

sometimes presented. The rule is, when the tracing passes inside of

the right delta, stop at the nearest point to the right delta on the

upward trend, as in figure 294. If no upward trend is present,

continue tracing until a point opposite the right delta, or the delta

itself, is reached (figs. 295 and 296).