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I want to clear a question that I have had for a number of years concerning tented arches and the presence of a delta "formation".

[b]Can a tented arch have a delta?[/b]

I was trained years ago that "arches contain no deltas". This is communicated in many training environments and on a FBI CJIS publication . Another CJIS publication states that arches "ordinarily" contain no deltas.

The leading fingerprint training manuals published by the FBI clearly do not spell out that "arches contain no deltas". The fingerprint training manuals state that the presence of a recurve is an element of a loop and in it's absence, the pattern cannot be a loop. The verbage only excludes the pattern as being a loop and does not specifically say it can not be a delta (on a tented arch pattern).

So what is it? Delta or no delta?

It may seems like an insignificant question, but I get challenged on this issue quite regularly.

Thank you for any responses,


Ted McDonald

In "The Finger Print Instructor", Frederick Kuhne, Munn&Company (1917) on page 33, it is written, "The core and delta are defined as the fixed points of an impression...(neither of them appearing in arches or tented arches)...). The author at one point uses the term 'supposed delta' in discussing a tented arch formation (p. 19).

I thought the existence of a delta was what MADE it the "tented" arch in some tented arch patterns.

"This form of tented arch, the one which approaches the loop, may have any combination of two of the three basic loop characteristics, lacking the third. These three loop characteristics are, to repeat:
A sufficient recurve
A delta
A ridge count across a looping ridge"

From The Science of Fingerprints, 11-79, page 37.

I was taught that a delta has 2 branches that open up to enclose the core.

If you apply this condition to the triradius in a tented arch then you hit a problem.

Again, I was taught that to define a core you must have a recurving ridge. Either one that enters and exits the print from the same side, or one that forms a complete circuit.

By definition a tented arch cannot have a recurving ridge. Therefore it has no core. Therefore it cannot have a delta.

This is however a semantic argument not a question of morphology. Tented arches, as Sharon said, by definition must contain a triradius. It's just a question of whether you can also call it a delta.

I prefer to think of deltas as a subset of triradii, peculiar to the pattern areas of the digits, in which 2 of the branches open up to enclose the core.

Mr McDonald, some tented arches do have deltas.

Mr Fairhurst, some tented arches do have recurving ridges.

Please check The Science of Fingerprints, my copy was revised 12-84 and has a green cover. See pages 36, 37, and 38 for comments on correctly classifying those types of tented arches. If your copy is more recent, those page numbers may be incorrect. Dan

I anticipated the conflicting interpretations.

It may seem like a trivial question because we can still interpret whether a tented arch is a tented arch irregardless whether it has a "delta", "delta formation" or "supposed delta". However, articulation, on what should be such a fundamental question, becomes problematic when we are training new examiners or even testifying in court. I think that training new examiners that "arches have no deltas" is not correct. It is more of a simple answer to a more complex analysis.

"The Science of Fingerprints" does say that a tented arch can be a pattern approaching a loop but it fails to lack one of the definitions of a loop being:

Sufficient recurve
Delta
Ridge count

If this is the case, then what about a pattern that lacks a sufficient recurve. Does it make the appearance of a delta any less a delta just because it does not have the recurve? Or does it just eliminate the pattern as being a loop? There is no verbage supporting the negation of a "delta" as a "delta" just because there is no recurve. I would argue the description in the Science of Fingerprints infers that a tented arch can have a delta based on the above wording.

Not wanting to beat a dead horse, but for those in a training environment, it really is an issue.

Ted

"Henry Is Dead" Long Live Henry.

If he is not dead he is dying. Just like Miracode, Battley SFS, The Valladares System, The Bertillon System, The Protivenski System, The Brussels System, The Klatt System, The Wehn System, The Roscher System, The Lebedeff System, The Gasti System, The Portillo System, The Smallegange System, The Pateer System, The Pottecher System, The Oloriz System, The Martinez System, The Windt Kodicek System, The Borgerhoff System, The Spirlet System, The Steegers System (MAYBE), The Harvey-Pacha System, The Cabezas System, The Lyonnese System, The Miranda Pinto System, The Lerich Method, The Jouenne Method, The Conlay System, The Collins SFS, The Larson SFS, The Oloriz SFS, The Borgerhoff SFS, The Stockis SFS, The Moran Code, The Born SFS, etc, etc. and I am tired of typing.

Notice I did not say Vucetich Method. That one may still have a lot of kick in it yet.

If i can get a clear enough picture would anyone mind if I put one of my prints up here as I am not sure whether I would class it as a tented arch or a loop.

It has a very clear delta right in the centre, so I'm not sure.

Any help would be appreciated.

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A spoiled loop (lack of sufficent recurve / no count across a looping ridge) has a delta and is a tented arch.
I was also under the misconception that the presence of a delta ruled out the classification of an arch. I learned even a plain arch may have a delta (contrary to a popular FBI classification poster). Theck the current FBI publication, THE SCIENCE OF FINGERPRINTS: page 32, figure 119. There's a plain arch with a delta....