The Science of Fingerprints Part 7

[Ill.u.s.tration: 159]

[Ill.u.s.tration: 160]

An upthrust, then, must not only be an ending ridge rising at a sufficient degree from the horizontal plane, but there must also be a s.p.a.ce between the ending ridge and the ridge immediately beneath it.

_This, however, is not necessary for a short upthrust or spike, or any upthrust which rises perpendicularly._

In connection with the proper cla.s.sification to be a.s.signed to those borderline loop-tented arch cases where an appendage or spike is thrusting out from the recurve, it is necessary to remember that _an appendage or a spike ab.u.t.ting upon a recurve at right angles in the s.p.a.ce between the shoulders of a loop on the outside is considered to spoil the recurve_.

If the appending ridge flows off the looping ridge smoothly in such a way that it forms a bifurcation and not an abutment of two ridges at a right angle, the recurve is considered as remaining intact. The test is to trace the looping ridge toward the appendage, and if, when it is reached, the tracing may be continued as readily upon the appendage as upon the looping ridge, with no sudden, sharp change of direction, the recurve is sufficient. Figures 161 to 184 should be studied with this in mind.

[Ill.u.s.tration: 161. Tented arch.]

[Ill.u.s.tration: 162. Tented arch.]

[Ill.u.s.tration: 163. Tented arch.]

[Ill.u.s.tration: 164. Tented arch.]

[Ill.u.s.tration: 165. Tented arch.]

[Ill.u.s.tration: 166. Tented arch.]

[Ill.u.s.tration: 167. Tented arch.]

[Ill.u.s.tration: 168. Tented arch.]

[Ill.u.s.tration: 169. Loop.]

[Ill.u.s.tration: 170. Loop.]

[Ill.u.s.tration: 171. Loop.]

[Ill.u.s.tration: 172. Loop.]

[Ill.u.s.tration: 173. Loop.]

[Ill.u.s.tration: 174. Loop.]

[Ill.u.s.tration: 175. Loop.]

[Ill.u.s.tration: 176. Tented arch.]

[Ill.u.s.tration: 177. Tented arch.]

[Ill.u.s.tration: 178. Tented arch.]

[Ill.u.s.tration: 179. Loop.]

[Ill.u.s.tration: 180. Loop.]

[Ill.u.s.tration: 181. Loop.]

[Ill.u.s.tration: 182. Loop.]

[Ill.u.s.tration: 183. Loop.]

[Ill.u.s.tration: 184. Loop.]

Figures 185 to 190 show additional examples of tented arches.

[Ill.u.s.tration: 185]

[Ill.u.s.tration: 186]

[Ill.u.s.tration: 187]

[Ill.u.s.tration: 188]

[Ill.u.s.tration: 189]

[Ill.u.s.tration: 190]

The reason that figure 185 is given the cla.s.sification of a tented arch is because of the presence of all the loop requirements with the exception of one, which is the recurve. In this pattern appear three ending ridges. The lowest ending ridge provides the delta, and the other two by the convention explained previously, provide the ridge count. It is a tented arch, then, of the type approaching the loop, with two of the characteristics, but lacking the third, a recurve.

Figures 186 and 187 are tented arches of the same type. A close examination of these prints will reveal that when the imaginary line is drawn between delta and core no ridge count across a looping ridge can be obtained. It must be remembered that the core of a loop may not be placed below the shoulder line. Lacking one of the three characteristics of a loop, these patterns must be cla.s.sified as tented arches. When figure 188 is examined, it will be noticed that the recurve is spoiled by the appendage ab.u.t.ting upon it between the shoulders at a right angle, so it must also be cla.s.sified with the tented arches. In figure 189, the only possible delta must be placed upon the looping ridge, thus preventing a ridge count although delta and recurve are present. Figure 190 is a.s.signed the cla.s.sification of a tented arch. One of the requirements of a loop type is that the ridge enters on one side, recurves, and makes its exit on the side from which it entered. This, of course, makes it necessary that the ridge pa.s.s between the delta and the core. It will be noted from this figure that although this ridge pa.s.ses between the delta and the core, it does not show any tendency to make its exit on the side from which it entered, and therefore the loop cla.s.sification is precluded, and it is a tented arch.

_The whorl_

The patterns to which numerical values are a.s.signed in deriving the "primary" in the extension of the Henry System of fingerprint cla.s.sification used by the Federal Bureau of Investigation are the whorl-type patterns, which occur in about 30 percent of all fingerprints.

_The whorl is that type of pattern in which at least two deltas are present with a recurve in front in each._ Figures 191 to 193 reflect the minimum requirements for the whorl.

[Ill.u.s.tration: 191]

[Ill.u.s.tration: 192]

[Ill.u.s.tration: 193]

It is important to note that the above definition is very general; however, this pattern may be subdivided for extension purposes in large groups where whorls are predominant. Even though this extension may be used, all types of whorls are grouped together under the general cla.s.sification of "Whorl" and are designated by the letter "W".

The aforementioned subdivisions are as follows: The Plain Whorl, The Central Pocket Loop, The Double Loop, and The Accidental.

_The plain whorl_

The "plain whorl" consists of the simplest form of whorl construction and is the most common of the whorl subdivisions. It is designated by the symbol "W" for both general cla.s.sification and extension purposes.

_The plain whorl has two deltas and at least one ridge making a complete circuit, which may be spiral, oval, circular, or any variant of a circle. An imaginary line drawn between the two deltas must touch or cross at least one of the recurving ridges within the inner pattern area. A recurving ridge, however, which has an appendage connected with it in the line of flow cannot be construed as a circuit. An appendage connected at that point is considered to spoil the recurve on that side._