Archive Gallery: Science Solves Crimes

How earographs, invisible ink detectors, and the famed "Stamp Detective" used science to catch unsuspecting crooks.
Earographs: November 1932
In the fall of 1932, Dr. Theron W. Kilmer declared the latest weapon against crime: earographs. At the seventh annual convention of the National Identification Association, Dr. Kilmer told police how they could classify offenders by the shape of their ears. Ears, Dr. Kilmer said, are as varied as licensed plates. For years, Dr. Kilmer photographed the ears of his family and friends, until he could identify a person by their ears alone. He even built a special camera for photographing ears clearly. Kilmer figured that while earographs would never replacing fingerprinting, they'd be useful for identifying criminals who were smart enough to wear gloves. Crooks create a variety of elaborate disguises, he said, but few bother to cover their ears (we're guessing this was before ski masks became a popular disguise.) During his studies, Dr. Kilmer also noticed that 64 percent of criminal offenders tend to have "flap ears." Dubbing this phenomenon "criminal ear," Dr. Kilmer theorized that neglected children develop protruding ears ("because they oftenest slept on them while folded over"). Childhood neglect causes criminal tendencies, so criminals have ears that stick out. Popular Science

There’s something timeless about a good detective story. At the end of a long day, it’s nice to know that the clues check out, the crooks get caught, and everyone goes home happy. During the early 1930s, Popular Science capitalized on the mystery genre by running a series of articles detailing how the modern detective incorporates science into crime detection. We were enthralled by scientists who could trace a bullet to its weapon simply by examining it under a microscope. We were thrilled that a person’s gender and age could be determined from a single strand of hair.

Nowadays, we’re so used to seeing forensics dramatized on TV that we take criminology for granted, but for a generation raised on Edgar Allan Poe, Sir Arthur Conan Doyle and Agatha Christie, these developments were nothing short of marvelous.

Like the first article in our series says, science has trumped Sherlock Holmes as the most trustworthy detective. It takes a clever man to detect circumstantial evidence, but a few damning clues can’t compare to solid proof that a week-old bloodstain comes from a particular person. To help our readers understand how the scientists glean knowledge from trace evidence, we visited experts like firearms identification pioneer Calvin Goddard, who used his helixometer, to show us how uses microscopic grooves to differentiate between bullets.

Sometimes we covered cases that were less violent. In a feature called “Hidden Crime Clues Bared by Chemist’s Magic,” we described how scientists could decode messages written in invisible ink by dipping them in various fluids. A couple of years later, police squads nationwide intercepted similar messages by using amphibian airplanes to trail carrier pigeons owned by the underworld. If that sounds a little quaint, you’ll laugh at archive gems like our feature that lauded earography, the science of identifying criminals by their ears.

As silly as it sounds, the earograph apparatus isn’t the strangest tool detectives-turned-scientists used during the early days of modern forensics.

Science, the New Sherlock Holmes: August 1931
Introducing the Black Light: October 1931
X-Ray Photos: November 1931
Chemistry Catches Crooks: November 1931
Reading Bullets: November 1932
Flying Police: August 1933
High-Tech Gambling: November 1933
New Weapons: August 1936
Stamp Detective: December 1937