Wally Beatty, age 12, of Glendale, Ariz., for his question:

WHEN WAS FINGERPRINTING FIRST USED?

Historians tell us that the Chinese used thumbprints to sign documents long before the birth of Christ. This was probably the first use of fingerprinting.

Through the years, many persons looked for ways to set up a scientific basis to use the character of fingerprints as a means of identification. And the breakthrough came in 1858 when a British government official in Bengal, India, was the first to devise a workable method of fingerprint identification. His name was Sir William J. Herschel.

Herschel used a simple form of fingerprint identification to prevent impersonations that were then common among the people.

But historians really credit Sir Francis Galton with founding the present system of fingerprint identification. In the 18809, he established a bureau in England for the registration of civilians by means of fingerprints and measurements.

In 1891, Juan Vucetich of Argentina developed a method of classification that could be applied to criminal investigations. Sir E. R. Henry, who later became chief commissioner of the London Metropolitan Police, developed a simplified system for classifying and filing fingerprints in 1901. Most bureaus of identification in the United States use this system.

The use of fingerprint identification forms an inseparable part of law enforcement today. In this connection, the Federal Bureau of Investigation (FBI) of the United States Department of Justice has developed the largest collection of fingerprints in the world. The FBI has about 200 million fingerprints on file in its Identification Division offices.

Fingerprints are the impressions made by ridges on the bulbs or end joints of the fingers and thumbs. No two fingerprints have yet been found to be exactly alike. Therefore, fingerprints are a foolproof means of identification.

Fingerprinting is the chief method of identifying a person with absolute certainty.

Fingerprints can be classified according to the types of patterns and the number of ridges appearing between designated points within the patterns. They fall into three main groups: the arch, the loop and the whorl.

In arch patterns, the ridges extend all the way across the bulb and rise slightly in the center or make a more definite tented rise. In loop patterns, ridges curve into a hairpin turn. Both ends of a loop ridge stop on the same side of the bulb. In the whorl pattern, the ridges follow a spiral or circular direction.

There are eight subclassifications of the main pattern types.

To make a permanent fingerprint record, a person first coats a small piece of glass or metal with a thin film of printer's ink. Next, he presses the finger and thumb ridges against the inked surface. Finally, he presses the inky bulbs against a white card, where the prints are reproduced in exact detail.