Sir Francis Galton | Tripartite Classification

Sir Francis Galton, Charles Darwin's cousin, was a well-known English scientist.

It was when Galton was asked to give a lecture on personal identification in 1888, he became interested in fingerprints.

In preparation for the talk, he researched Bertillonage, which was the current method of personal identification at that time.

He became a critic of anthropometry after examining its usage for criminal identification. Bertillonage's prolonged usage as a means of criminal identification, he believed, would result in an unacceptably high proportion of false identifications.

He also mentioned that taking Bertillon measurements took time and that the results could vary depending on who was performing this measurement analysis.

Galton investigated the use of fingerprints for personal individualization as a result of his dislike for anthropometry.

His research led him to Faulds' article published in Nature and a response letter from Sir William Herschel in the following year, in which Sir William Herschel claimed to have found fingerprint individualization for the first time and had been using it in India since 1860.

Galton began corresponding with Herschel shortly after and got his fingerprint collection.

Galton released his famous book Finger Prints (1892) after four years of intensive study and investigation, in which he showed that fingerprints are both permanent and distinct.

He also realized that for fingerprints to become a viable means of personal identification, a system of fingerprint categorization that was systematic, comprehensible, and applicable had to be devised.

Galton proposed a classification system based on the alphabetical enumeration of the three fingerprint patterns: L denoted a loop, W denoted a whorl, and A denoted an arch in his book.

The pattern for each finger was labeled with one of these three letters to categorize a set of fingerprints.

In his Tripartite classification formula, the letters for the index, middle, and ring fingers on the right hand were grouped together, followed by the letters for the index, middle, and ring fingers on the left hand. The letters for the right thumb and right little finger were recorded after this string of letters, followed by the letters for the left thumb and left little finger.

[Right (IMR), Left (IMR), Right (Thumb & Little), Left (Thumb & Little)]

Now let's take an example where if a person has a whorl pattern in all fingers of the right hand except for the little finger has a loop and in the left hand, having loop pattern in all fingers except for the little finger having a whorl would be classified as:

WWWLLLWLLW

This classification code would then be written down on a card, which would then be filed alphabetically by classification. Galton's basic fingerprint classification technique was implemented into the Bertillonage files at Scotland Yard two years after the publication of his book.

The 3 basic pattern classes devised by Sir Francis Galton in which the arch is the rarest pattern observed in the population of only 3% whereas the loop pattern is found in about 60 to 65% of the population and is considered as the commonest observed pattern. And the whorl pattern is observed in the remaining 30 to 35 % of the population.