No matter how definite fingerprint rules and pattern definitions are made, there will always be patterns concerning which there is doubt as to the classification they should be given. The primary reason for this is the fact that probably no two fingerprints will ever appear which are exactly alike. Other reasons are differences in the degree of judgment and interpretation of the individual classifying fingerprints, the difference in the amount of pressure used by the person taking the prints, and the amount or kind of ink used. Nothing can be done about faulty inking or pressure once the prints are taken. The patterns which are questionable merely because they seem to have characteristics of two or more types can be classified by strict adherence to the definitions in deducing a preference. The following section is devoted to such patterns with an explanation of each.
Figure 297 has two loop formations. The one on the left, however, has an appendage abutting upon the shoulders of its recurve at a right angle. The left portion of the impression, therefore, is of the tented arch type. The combination of two different types of patterns would be classified in the whorl group (accidental), but this impression has only the one delta. The right portion of the pattern detail contains a true loop which fulfills all the loop requirements, i.e., a sufficient recurve, a delta, and a ridge count across a looping ridge. In the choice existing between a tented arch and a loop, preference is given to the loop classification and this impression would be classified as a loop.
Fig. 297
[Fig. 297]
Figure 298, at a glance, seems to fulfill the requirements of a whorl (two deltas and a ridge making a complete circuit). The part of the circuit in front of the right delta, however, cannot be construed as a recurving ridge because of the appendage abutting upon it in the line of flow. This pattern, therefore, is a one-count loop.
Fig. 298
[Fig. 298]
Figure 299 is a very difficult and unusual pattern. It has characteristics of three types, the whorl, the loop, and the tented arch. It is given the preference of an accidental type of whorl (loop over a tented arch). This pattern should be referenced both as a loop and as a tented arch.
Fig. 299
[Fig. 299]
Figure 300 is shown for the purpose of explaining that in the whorl, as this print is, appendages at the top of the recurve will not spoil or affect the recurve. Hence, the impression is a good whorl of the central pocket loop type and needs no reference.
Fig. 300
[Fig. 300]
Figure 301 is classified as a whorl of the double loop type. There are present two distinct loops and two deltas (the right delta is not present as the impression was not rolled sufficiently). The pattern is unusual because the loops are side by side and flowing in the same direction. The tracing is an inner tracing.
Fig. 301
[Fig. 301]
Figure 302 should present no difficulty. It is classified as a plain arch for its ridge construction follows the rule of a plain arch, i.e., "enter one side and flow or tend to flow to the other."
Fig. 302
[Fig. 302]
Figure 303 is a plain arch. The dot at the center is not elongated enough to be considered an upthrust. A dot, even though as thick and heavy as the surrounding ridges, is not considered for any purpose but ridge counting or fixing a delta.
Fig. 303
[Fig. 303]
Figure 304 is a pattern somewhat similar to the previous illustration. As indicated before, dots are considered as ridges only in ridge counting and fixing a delta. This pattern, therefore, must be classified as a plain arch, rather than a tented arch with two ending ridges and a delta formation.
Fig. 304
[Fig. 304]
Figure 305, although showing an appendage upon each recurve on the left side, is classified as a whorl of the central pocket loop type, with two deltas and a recurve in front of each. To spoil the recurve of a whorl the appendage must be connected to the recurve at the point of contact with the line of flow.
Fig. 305
[Fig. 305]
In figure 306, the impression has two equally good loop formations. As it has but one delta, it cannot be classified as a whorl of the double loop type nor as a loop since it would be difficult to make a preferential choice between the two looping ridges. It is arbitrarily given the classification of a tented arch.
Fig. 306
[Fig. 306]
In figure 307, the difficulty lies in locating the delta. The only ridges answering the definition of type lines (ridges running parallel and then diverging to enclose the pattern area) have three ending ridges between them. The type lines, the delta, and the core are located as indicated. The pattern is classified as a six-count loop.
Fig. 307
[Fig. 307]
Figure 308 is classified as a tented arch, although it appears at first glance to be a loop. Closer inspection shows that the looping ridge does not tend to go out the side from which it entered but rather seems to proceed downward ending in an abutment forming a definite angle of 90°.
Fig. 308
[Fig. 308]
In figure 309, an impression is shown which at first appears to be a loop. Closer inspection will show that one of the elements of the loop type is missing, namely, a ridge count across a looping ridge; for it is to be borne in mind that the recurve of the innermost loop should be free of appendages abutting between the shoulders at right angles. The core, in this illustration, therefore, is placed where the appendage of the innermost loop touches the next ridge which is a good recurve. If an imaginary line is placed between delta and core, it will be seen that there are no intervening ridges; hence, there is no ridge count.
Fig. 309
[Fig. 309]
Figure 310 is a pattern which contains two elements of a loop but lacks the third. It is classified as a tented arch. Thus an impression having a delta and a recurve, but not having a ridge count across a looping ridge, falls into this classification.
Fig. 310
[Fig. 310]
It will be noticed that although this pattern has the resemblance of a plain arch, the center of the impression actually contains a partially formed loop. A recurving ridge enters from the right side and exits in the same direction. A delta also appears just below the recurve. In attemptingto obtain a ridge count, it is seen that the imaginary line drawn between the delta and the core runs directly along the ridge emanating from the former and which is joined onto the side of the recurving ridge. For this reason, no ridge count is possible.
Figure 311 is a tented arch. There are three loop formations, each one of which is spoiled by an appendage abutting upon its recurve between the shoulders at a right angle. It cannot be classified as an accidental as the patterns are all of the same type, i.e., tented arches. An accidental type of whorl is a combination of two or moredifferenttypes of patterns exclusive of the plain arch.
Fig. 311
[Fig. 311]
Figure 312 is a loop. It cannot be classified as a whorl of the double loop type because the formation above the lower loop is too pointed and it also has an appendage abutting upon it at a right angle.
Fig. 312
[Fig. 312]
Figure 313 at first glance appears to be a whorl of the double loop type. Upon closer inspection, however, it will be noticed that there are no delta formations other than on the recurves. There are, then, two tented arch formations. As two patterns of the same type cannot form an accidental whorl, the impression must be classified as a tented arch.
Fig. 313
[Fig. 313]
Figure 314 is an accidental whorl, combining a loop and a tented arch. The tented arch is directly beneath the innermost loop, and is of the upthrust type.
Fig. 314
[Fig. 314]
Figure 315 consists of a loop over a dot with an apparent second delta. This pattern must be classified as a loop, as a dot may not be considered an upthrust unless elongated vertically.
Fig. 315
[Fig. 315]
Even though a dot may be as thick and heavy as the surrounding ridges, it may be considered only in ridge counting or fixing a delta.
Figure 316 at first glance appears to be an accidental whorl, but on closer inspection it proves to be a loop. Although there are three delta formations present, it should be observed that recurving ridges appear in front of only one (D-1).
Fig. 316
[Fig. 316]
Figure 317 has the general appearance of a loop. The looping ridge A, at the center, has an appendage B abutting upon its recurve. The abutment is at right angles and therefore spoils the recurve. The pattern is a tented arch.
Fig. 317
[Fig. 317]
Figure 318 is a tented arch which approaches both the loop and the whorl type patterns. It cannot be considered a whorl, however, as the recurve on the left is spoiled by an appendage (figs. 58 and 59). Nor can it be a loop because there is no ridge count across a looping ridge. The pattern, then, is a tented arch of the type possessing two of the basic characteristics of the loop and lacking the third. The delta and the sufficient recurve are present but the ridge count is missing.
Fig. 318
[Fig. 318]
Figure 319 seems at first glance to be a double loop. It will be noted, however, that the inner delta formation would be located upon the only looping ridge of the upper loop formation. Since the delta would be located on the only recurve, this recurving ridge is eliminated from consideration. The pattern is classified as a loop.
Fig. 319
[Fig. 319]
Figure 320 is a loop of two counts, with the delta at B. There is a ridge making a complete circuit present, but point A cannot be used as a delta because it answers the definition of a type line. It should be considered a delta only if it presented an angular formation. Placing the delta upon the recurve would spoil that recurve.
Fig. 320
[Fig. 320]
Figure 321 shows two separate looping ridge formations appearing side by side and upon the same side of the delta. The core in such case is placed upon the nearer shoulder of the farther looping ridge from the delta, the two looping ridges being considered as one loop with two rods rising as high as the shoulder. The ridge count would be four (fig. 49).
Fig. 321
[Fig. 321]
Figure 322 is an accidental whorl. It is classified thus because it contains elements of three different patterns, the loop, the double loop, and the accidental. In such case the order of preference governs. The delta at the left is point A. The delta at the right is point C. This point becomes the delta since it is the point nearest the center of the divergence of the type lines. Point B is eliminated from consideration as a delta since type lines may not proceed from a bifurcation unless they flow parallel after the bifurcation and before diverging.
Fig. 322
[Fig. 322]
Figure 323 is a loop. There are two delta formations but the dots cannot be considered as obstructions crossing the line of flow at right angles. This precludes the classification of the central pocket loop type of whorl.
Fig. 323
[Fig. 323]
Figure 324 is a loop, the two recurving ridges have appendages and are considered spoiled. The pattern cannot, therefore, be a whorl even though two delta formations are present.
Fig. 324
[Fig. 324]
Figure 325 is classified as a tented arch. If examined closely the pattern will be seen to have an appendage abutting at a right angle between the shoulders of each possible recurve. Thus no sufficient recurve is present.
Fig. 325
[Fig. 325]
Figure 326 is a plain arch. There is present no angle which approaches a right angle. Points A, B, and X are merely bifurcations rather than an abutment of two ridges at an angle.
Fig. 326
[Fig. 326]
Figure 327 is a tented arch, not because of the dot, however, as it cannot be considered an upthrust. The tented arch is formed by the angle made when the curving ridge above the dot abuts upon the ridge immediately under and to the left of the dot.
Fig. 327
[Fig. 327]
Figure 328 consists of two separate looping ridge formations in juxtaposition upon the same side of a common delta. This pattern cannot be called a double loop as there is no second delta formation. In order to locate the core, the two looping ridges should be treated as one loop with two rods in the center. The core is thus placed on the far rod (actually on the left shoulder of the far loop), resulting in a ridge count of four (fig. 49).
Fig. 328
[Fig. 328]
Figure 329 is a loop of three counts. It cannot be classified as a whorl as the only recurve is spoiled by the appendage abutting upon it at the point of contact with the line of flow.
Fig. 329
[Fig. 329]
Figure 330 is a plain arch as there is no upthrust (an upthrust must be an ending ridge), no backward looping turn, and no two ridges abutting upon each other at a sufficient angle.
Fig. 330
[Fig. 330]
Figure 331 is a plain arch. The ending ridge at the center does not rise at a sufficient angle to be considered an upthrust, and it does not quite meet the ridge toward which it is flowing and therefore forms no angle.
Fig. 331
[Fig. 331]
Figure 332 is a plain arch. There are two ending ridges, but no separate delta formation is present.
Fig. 332
[Fig. 332]
Figure 333 is a plain arch. The rising ridge at the center is curved at the top forming no angle, and does not constitute an upthrust because it is not an ending ridge.
Fig. 333
[Fig. 333]
Figure 334 is a whorl of the double loop type. Two loops and two deltas are present. It is unusual because the loops are juxtaposed instead of one flowing over the other, and one delta is almost directly over the other. The tracing is a meeting tracing.
Fig. 334
[Fig. 334]
Figure 335 is a tented arch. Although there is a looping ridge, no ridge count can be obtained. The core is placed upon the end of the ridge abutting upon the inside of the loop, and so the imaginary line crosses no looping ridge, which is necessary.
Fig. 335
[Fig. 335]
Figure 336 is a plain arch. The ending ridge at the center cannot be considered an upthrust because it does not deviate from the general direction of flow of the ridges on either side. No angle is present as the ending ridge does not abut upon the curving ridge which envelopes it.
Fig. 336
[Fig. 336]
Figure 337 is a plain arch because the dot cannot be considered a delta as it is not as thick and heavy as the surrounding ridges.
Fig. 337
[Fig. 337]
Figure 338 is a tented arch consisting of two ending ridges and a delta. The short ending ridge is considered a ridge because it is slightly elongated and not a mere dot.
Fig. 338
[Fig. 338]
In figure 339, the only question involved is where to stop tracing. The rule is:when tracing on a ridge with an upward trend, stop at the point on the upward trend which is nearest to the right delta. X is the point in this pattern.
Fig. 339
[Fig. 339]
In figure 340, the question involved is also one of tracing. In this pattern, the tracing is not on a ridge with an upward trend. The tracing, therefore, is continued until a point nearest to the right delta, or the right delta itself, is reached. This tracing is a meeting tracing.
Fig. 340
[Fig. 340]
There are a few constantly recurring patterns which, though not questionable or doubtful as they appear, present a peculiarly difficult problem in classifying. The patterns referred to are usually double loops, though accidental whorls and loops sometimes present the same problems. The difficulty arises when a loop is so elongated that the recurve does not appear until near the edge of a fully rolled impression or an impression that is rolled unusually far, as in figures 341 to 344.
Figs. 341-342
Figs. 343-344
[Figs. 341-344]
Figure 341, if classified as it appears, would be an accidental whorl. Figures 342 and 343 would be double loops, and illustration 344, a loop. It will be observed that these prints are rolled more fully than normal. If, however, the next time the prints are taken, they are not rolled quiteso far, the patterns would require a very different classification, and would show no indication of any need for referencing to their true classification. The result would be a failure to establish an identification with the original prints. The only way in which such an error may be avoided is to classify such impressions as they would appear if not so fully rolled, and to conduct a reference search in the classification which would be given to the prints when rolled to the fullest extent. Applying this rule, illustration 341 is a tented arch, referenced to a whorl. Figures 342 and 343 are loops, referenced to whorls. Figure 344 is a plain arch, referenced to a loop.
No set rule can possibly be devised to enable a classifier to know with certainty where to draw the line when it is doubtful which classification should be given such a print. Individual judgment is the only standard. The test is:if the pattern, in the opinion of the classifier, is rolled to only a normal width, it should be classified as it appears. If it seems to be rolled to a width beyond the normal degree, it should be classified as if rolled only to the normal degree. Age, weight, size of fingers (as seen inthe plain impressions), heaviness of the ridges, and experience of the technician in taking fingerprints are all factors in arriving at the correct conclusion. The necessity for exercising the utmost care in dealing with this type of pattern cannot be too highly emphasized.
The patterns in figures 345 and 346 also have a second loop near the edge of the impression. In these two patterns, however, the second loop is very near the delta and consequently will almost invariably appear even though not rolled to the fullest extent. The foregoing rule is not applied to this type of impression. Both are classified as a whorl and referenced to a loop to take care of the rare contingency of nonappearance.
Figs. 345-346
[Figs. 345-346]
At this point it is necessary to mention that when prints are classified, markings are indicated at the bottom of each finger block to reflect the type. The following symbols are used:
● Under the index fingers the appropriate capital letters should be placed for every pattern except the ulnar loop.● Under all other fingers, the appropriate small letter should be placed for every pattern except the ulnar loop and the whorl as follows:
● Under the index fingers the appropriate capital letters should be placed for every pattern except the ulnar loop.
● Under all other fingers, the appropriate small letter should be placed for every pattern except the ulnar loop and the whorl as follows:
● Ulnar loops in any finger are designated by a diagonal line slanting in the direction of the loop.● Whorls in any finger are designated by the letter "W". The classification formula may be composed of the following divisions:
● Ulnar loops in any finger are designated by a diagonal line slanting in the direction of the loop.
● Whorls in any finger are designated by the letter "W". The classification formula may be composed of the following divisions:
The positions in the classification line for these divisions when completely applied are as illustrated:
The primary classification:For the purpose of obtaining the primary classification, numerical values are assigned to each of the tenfinger spaces as shown in figure 347. Wherever a whorl appears it assumes the value of the space in which it is found. Spaces in which types of patterns other than whorls are present are disregarded in computing the primary.
The values are assigned as follows:
Fig. 347
[Fig. 347]
[Enlarge]
In figure 347, it will be observed that the odd fingers (Nos. 1, 3, 5, 7, 9) contain the letter D, and the even fingers (Nos. 2, 4, 6, 8, 10) contain the letter N. The D indicates that the values of these fingers relate to the denominator, the N that they relate to the numerator. The summation of the numerical values of the whorl type patterns, if any, appearing in fingers 1, 3, 5, 7, 9, plus one, is the denominator of the primary. The summation of the values of the whorls, if any, in fingers 2, 4, 6, 8, 10, plus one, is the numerator of the primary. Where no whorl appears in a set of impressions, the primary, therefore, would be 1 over 1. The 1 that isassigned to the numerator and the denominator when no whorls appear is also added, for consistency, to the value of the whorls when they do appear. It will be understood why it was originally assigned to the no-whorl group when it is considered how easily a zero might be confused with an O, which is the symbol used for an outer whorl tracing.
To obtain the primary for the prints in figure 347, the number of whorls appearing in the odd fingers is ascertained to be 2. Their positions are noted (1 in No. 1 and 1 in No. 7) and the values assigned to whorls appearing in those fingers are added together (16 plus 2 = 18). To this sum the arbitrary 1 is added, giving us the total of 19, which constitutes the denominator for this set of prints. To get the numerator, it is ascertained that there are 3 whorls appearing in the even fingers (2, 4 and 6), the values of which are added together (16 plus 8 plus 4 = 28). To this sum the 1 is added, giving a numerator of 29, and a complete primary of 29 over 19.
By the word "whorl" is meant all types of whorls, including plain whorls, central pocket loops, double loops and accidentals. The tracing of the whorl does not enter into the determination of the primary.
The method of obtaining the primary can probably be shown best by illustrations. For example, assume that there is a whorl in the right index finger only. The value of a whorl in this finger is 16. When 1 over 1 is added the resulting primary is 17 over 1. If a whorl appears in the right thumb and right index finger, the value is 16 over 16 plus 1 over 1 giving a primary of 17 over 17. If whorls appear in both index fingers, the value is 16 over 2 plus 1 over 1 giving a primary of 17 over 3. When whorls appear in both thumbs and both index fingers, the primary is 21 over 19 and is obtained by the addition 16 plus 4 plus 1 over 16 plus 2 plus 1. If whorls appear in all 10 fingers, the primary is 32 over 32 (16 plus 8 plus 4 plus 2 plus 1 plus 1 over 16 plus 8 plus 4 plus 2 plus 1 plus 1). It will be noted that the primary classifications extend from 1 over 1 in the no-whorl group to 32 over 32 in the all-whorl group, providing 1,024 possible combinations. This does not mean that there are 1,024 even subdivisions of prints according to these primaries. Just as there is a preponderance of loops when the types of patterns are considered, there is also a preponderance of certain primaries, notably: the 1 over 1 primary, or no-whorl group; the 17 denominator; the 19 denominator; the 28 denominator, of which the 31 over 28 group is the largest; and the 32 denominator, including 2 large primary groups namely, 31 over 32 and 32 over 32. As a matter of fact, the 1 over 1 group, as a whole, contains over 25 percent of the total number of prints filed in the FBI. On the other hand, there are a number of primaries which rarely appear. It follows, therefore, that when a print is classified in one of these larger groups it is necessary to complete the classification to a greater extent than is necessary in the more unusual primaries, so that the group to be searched is small enough for convenience.
In connection with the counting of whorl values to obtain the primary, it might be noted that when the whorls outnumber the other patterns more speed can be achieved by counting those patterns and subtracting rather than by adding the whorls. This procedure should not be followed until enough experience is acquired so that it may be noted at a glance where whorls are not present.
The experienced classifier can tell in what fingers whorls are present by a glance at a primary classification. For example, a primary of 5 over 17 could mean that there are whorls in the thumbs only.
Fig. 348
[Fig. 348]
[Enlarge]
The secondary classification:After the primary classification, the fingerprints are subdivided further by using a secondary classification. Before going into detail, it should be noted that after the primary is obtained the entire remaining portion of the classification formula is based upon the arrangement of the impressions appearing in the right hand as the numerator over the impressions appearing in the left hand as the denominator. The arrangement of the even over the uneven fingers is discarded after the primary is obtained. The secondary classification appears just to the right of the fractional numerals which represent the primary. It is shown in the formula by capital letters representing the basic types of patterns appearing in the index fingers of each hand, thatof the right hand being the numerator and that of the left hand being the denominator (fig. 348). There are five basic types of patterns which can appear.
Fig. 349
[Fig. 349]
[Enlarge]
Secondary classification (small-letter group):Prints with an arch or tented arch in any finger or a radial loop in any except the index fingers constitute the small-letter group of the secondary classification. Such "small letters," with the exception of those appearing in the index fingers, are brought up into the classification formula in their proper relative positions immediately adjacent to the index fingers (fig. 349). A dash is used to indicate the absence of each small letter between the index fingers and another small letter or between two small letters, as
Thus, if a radial loop appears in the right thumb,the small letter "r" would be brought up in the numerator column of the classification formula and placed just to the left of the capital letter representing the index finger. Similarly, if an arch or tented arch or a radial loop would appear in the middle, ring, or little finger of the hand, the small letter representing such a pattern would be placed on the classification line to the right of the secondary in the numerator column if the letter is present in the right hand, and in the denominator column if in the left hand. When two or more small letters of the same type occur immediately adjacent to each other, they are indicated thus:
The small-letter groups are of vital importance to the classification system, as they are of relatively infrequent occurrence, constituting approximately 7 to 10 percent of all patterns. Generally speaking, since these patterns are of such rare occurrence, their very presence often enables the classifier to dispense with the usual subsecondary classification and the major division which in the majority of cases are used in the larger groups.
The subsecondary classification (grouping of loops and whorls):In classifying prints it is necessary to subdivide the secondary groups. This is accomplished by grouping according to the ridge counts of loops and the ridge tracings of whorls. The first of the groups filed in order, which it will be necessary to so subdivide, would ordinarily be the
group where no small letters appear. The Federal Bureau of Investigation, however, has found it necessary to extend this division to many of the small-letter groups which become cumbersome. The subsecondary is placed on the classification line just to the right of the secondary. Ridge counts are translated into small and large, represented by symbols I and O. The whorl tracings are brought up as I, M, or O denoting inner, meeting or outer ridge tracings of the whorl types. Only six fingers may be involved in the subsecondary—numbers 2, 3, 4, 7, 8, and 9.
A ridge count of 1 to 9, inclusive, in the index fingers is brought up into the subsecondary formula as I. A count of 10 or more is brought up as O. In the middle fingers a count of from 1 to 10, inclusive, is brought up as I, and 11 or more is O. In the ring fingers a count of from 1 to 13 is brought up as I, and 14 or more is O. A loop subsecondary could appear in the classification formula as
Analyzing this example of a subsecondary, one will know that in the index, middle, and ring fingers of the right hand there are counts of over 9, under 11, and over 13, while in the left hand there are in the index, middle, and ring fingers, counts of under 10, under 11, over 13, respectively. The subsecondary classification, therefore, relates to the groupings of the prints, and no difficulty should be experienced in ascertaining whether the I and O arrangement in thesubsecondary relates to loops or whorls when analyzing a classification, because this information can be obtained from the primary classification. Figure 350 is an example illustrating the subsecondary in addition to other divisions of the classification formula.
Fig. 350
[Fig. 350]
[Enlarge]
The chart, figure 351, will illustrate the manner in which the ridge counts are translated into the symbols I and O so they may be grouped and sequenced with the whorl tracings I, M and O.
Fig. 351
[Fig. 351]
[Enlarge]
The major division:The major division is placed just to the left of the primary in the classification formula. Where whorls appear in the thumbs the major division reflects the whorl tracings just as the subsecondary does. For example, a major division of I over M in the primary 5 over 17 would reflect an inner-traced whorl over a meeting-traced whorl in the thumbs. Where loops appear in the thumbs, however, a table is used to translate the ridge counts into the small, medium, or large groups, designated by the letters S, M, L. An expanding table is used for the right thumb when large-count loops appear in the left thumb, as shown in the chart (fig. 351). This table is used because it affords a more equitable distribution of prints as a whole, for filing purposes within the groups indicated.
Table for major divisions of loops:
The fingerprint card appearing in figure 352 shows a major division of L over L, which is obtained by counting the ridges (24 in the right thumb and 18 in the left thumb) which, according to the table, is translated into L in both thumbs.
The final:It is, of course, desirable to have a definite sequence or order of filing the prints within the subdivided groups. This order is attained through the use of the final, which is based upon the ridge count of the loop in the right little finger. It is indicated at the extreme right of the numerator in the classification. Note figure 352. If a loop does not appear in the right little finger, a loop in the left little finger may be used. It is then indicated at the extreme right of the denominator (fig. 353). If no loops appear in the little fingers, a whorl may be used to obtain a final, counting from left delta to core if in the right hand and from right delta to core if in the left hand. If there are two or more cores (usually applies to accidental whorls), the ridge count is made from left delta (right hand)or right delta (left hand) to the core which is the least number of ridges distant from that delta. An exception is made in the case of the double loop. The double loop is counted from the delta to the core of the upright loop. Where loops of a double loop are horizontal, the nearest core is used. Should both little fingers be a or t, no final is used. The use of a whorl in a little finger for a final is required only in connection with a large group or collection of prints, such as the 32 over 32 primary.
Fig. 352
[Fig. 352]
[Enlarge]
The key:The key is obtained by counting the ridges of the first loop appearing on the fingerprint card (beginning with the right thumb), exclusive of the little fingers which are never considered for the key as they are reserved for the final. The key, no matter where found, is always placed to the extreme left of the numerator of the classification formula (fig. 353).
Fig. 353
[Fig. 353]
[Enlarge]
The second subsecondary classification:When a group of fingerprints becomes so large that it is cumbersome and unwieldy, even though fully extended, it can be subdivided further by using a second subsecondary division, which is brought up into the classification formula directlyabove the subsecondary, and for which the symbols S, M and L are used. The following table is used:
If this table is referred to, a study offigure 352will demonstrate the use of the second subsecondary.
WCDX extension:In the extension used in the Federal Bureau of Investigation for the large whorl groups, the type of whorl is designated by the symbols W, C, D, or X for the index fingers and w, c, d, or x for all other fingers, according to its classification as defined in figure 354. These symbols are used for subclassification purposes only and are brought up into the classification formula directly above the subsecondary in their respective positions, the right hand being the numerator, the left hand being the denominator.
Fig. 354
[Fig. 354]
[Enlarge]
Special loop extension:In the all-loop group
the following special loop extension may be used, utilizing the ridge counts in fingers Nos. 2, 3, 4, 7, 8, 9, and, if necessary, No. 10:
The resulting values in this extension are brought up into the classification formula directly above the subsecondary in their respective positions, the right hand being the numerator, the left hand being the denominator.
In addition to the extensions already mentioned, fingerprint groups may be divided into male and female, and by age (either by year or by arbitrarily setting an age limit, beyond which a print bearing such an age would be filed separately in a "Reference" or a "Presumptive Dead" file).
In the files of the Federal Bureau of Investigation, all prints bearing an age of 55 through 74 are filed in the "Reference" group and all prints bearing an age of 75 years or more are filed in the "Presumptive Dead" file. Persons 75 years of age or older, in regard to crime, may be considered as generally inactive and thus are filed as "Presumptive Dead." Such a group provides for removing from the other files the cards concerning those of whom no notice is ever received as to death.
A separate file should be maintained for deceased persons, for possible future reference.
A separate file should be maintained for all prints bearing amputations and which have an unequivocal statement or marking from the contributor to that effect.
Permanent scars also may be utilized for this purpose, giving three more groupings: those prints having permanent scars in the right hand, those having a scar in the left, and those in which scars appear in both hands. A separate file may be maintained for mutilated prints whether or not the permanent-scar division is used. This is usually composed of prints so badly mutilated, or so mutilated about the cores and deltas, that intentional mutilation is suspected.
Emphasis should be placed upon the necessity for fully referencing all scarred patterns. In connection with their proper classification, the following rules should be observed: