Henry Classification System
The Henry Classification System is a long-standing method used to sort ten-print fingerprint records based on physiological characteristics, facilitating "one-to-many" searches for criminal identification. Developed in the late 19th century, it served as the foundation for modern Automated Fingerprint Identification Systems (AFIS) until the 1990s.
Historical Development
- Key Figures: While named after Sir Edward Henry, the system was developed in British India with essential contributions from Qazi Azizul Haque (who created the mathematical formula) and Hem Chandra Bose (who improved sub-classification methods).
- Inspiration: The system expanded upon Sir Francis Galton’s work, which identified three main patterns: loops, whorls, and arches.
- Replacement of Anthropometry: In 1900, the Henry System officially replaced Bertillonage (anthropometry)—a system of measuring body parts—after a commission found fingerprints to be a more effective means of identification.
The Four Major Classifications
The system organizes records into primary groupings to reduce the effort needed to search large databases. It assigns each finger a number from 1 (Right Thumb) to 10 (Left Pinky).
1. Primary Classification
This classification is based specifically on the presence of whorl patterns.
- Numerical Values: Fingers are assigned values based on their location, but only if they contain a whorl. Non-whorl patterns (arches/loops) are valued at zero.
| Finger Numbers | Assigned Value (if Whorl) |
|---|---|
| 1 & 2 (R. Thumb, R. Index) | 16 |
| 3 & 4 (R. Middle, R. Ring) | 8 |
| 5 & 6 (R. Little, L. Thumb) | 4 |
| 7 & 8 (L. Index, L. Middle) | 2 |
| 9 & 10 (L. Ring, L. Little) | 1 |
- The Formula: The sum of even-numbered finger values plus 1 is the numerator; the sum of odd-numbered finger values plus 1 is the denominator. The resulting fraction ranges from 1/1 to 32/32.
2. Secondary Classification
This focuses on the Index Fingers (fingers #2 and #7).
- Alphabetic Codes: Letters represent the patterns found on these fingers: A (Plain Arch), T (Tented Arch), U (Ulnar Loop), R (Radial Loop), and W (Whorl).
- The right index value is placed in the numerator and the left index in the denominator.
3. Sub-Secondary Classification
This utilizes the index, middle, and ring fingers of both hands.
- Loops: Classified by ridge counting, denoted as I (Inner) or O (Outer) based on specific count thresholds for each finger.
- Whorls: Classified by ridge tracing, denoted as I (Inner), M (Meeting), or O (Outer) based on the distance between the tracing end and the right delta.
4. Final Classification
The final classification is derived from the little fingers.
- It consists of the actual ridge counts of loops or whorls on these fingers.
- The right little finger count is the numerator, and the left little finger count is the denominator.
Impact and Modern Status
- IAFIS Integration: The Integrated Automated Fingerprint Identification System (IAFIS) originally emulated the Henry process, using its pattern types as a basis for digital classification.
- Shift to Ridge Flow: In recent years, the Henry System has largely been replaced by ridge flow classification and minutiae-based technology.
- Legacy Systems: While not essential for modern automated systems, it is still used in some local forensic solutions for manual paper-file management.
Clarification: Would you like a practice exercise on calculating a Primary Classification score using a hypothetical set of fingerprints?
Refrence :
- James Cowger; “Friction Ridge Skin- Comparison & Identification of Fingerprints”, CRC Press, NY, 1993
- B.R Sharma, “Forensic Science in Criminal Investigation & Trials”, Universal Publishing Co., New Delhi, 2003.