In many ways, the Coney Island of the early 20th century was the Internet of its day, a place where people went to learn and to gawk in equal measure. Among the sideshows and oddities were new mechanical wonders and cutting-edge technologies that had yet to make it into the mainstream. And there was also another exhibit, nestled among the curiosities and the technological demonstrations, that was a little bit of each. Between 1903 and 1943, babies born prematurely were rushed to a state-of-the-art neonatal intensive-care unit—one that happened to also be one of the most popular attractions on Coney Island. Run by a doctor named Martin Couney, it was, for most of its existence, the only facility in the U.S. designed especially for the care of severely premature infants.

In the mid 18th century, the standard of care for premature births was to focus on the health of the mothers, as the babies rarely survived. That began to change in 1880, when the French obstetrician Étienne Stéphane Tarnier, inspired by poultry-warming chambers he saw at the Paris Zoo, built the first warm-air infant incubator for the premature babies he treated at L'Hôpital Paris Maternité. These first incubators functioned the same was as their modern counterparts, replicating the conditions of a woman’s uterus to allow babies to continue the gestation process until they could survive on their own.

Initially, the incubators failed to catch on. In 1888, another Parisian obstetrician, Pierre Budin, began publishing reports detailing Tarnier’s success, but most medical professionals at the time dismissed the technology as pseudo-scientific at worst, ineffective at best. Determined to change the medical community’s perception of the incubators, Budin asked his protégé,  the physician Martin Couney, to accompany him to the Berlin World’s Fair in 1896 to supervise a display of six premature babies in incubators. The “Kinderbrutanstalt” or “child hatchery” was such a success that Couney, hoping to introduce the technology to a broader audience, raised enough money to kick off a world tour.

Over the next seven years, Couney showed off the incubators at the Victorian Era Exhibition in London, the Trans-Mississippi Exposition in Omaha, the 1900 Paris Exposition, and the Pan-American Exposition in Buffalo, New York. In 1903, he decided to permanently relocate to America, and settled in a place with an insatiable appetite for the new and unusual: Coney Island.

The Coney Island exhibit was, for all intents and purposes, a small-scale hospital, a sterile environment staffed by doctors and nurses constantly attending to the infants. Couney hired a staff of wet nurses to feed the infants, and a team of cooks to feed the nurses, with the instructions that they were forbidden to prepare hot dogs or any of the other typical boardwalk fare of the neighborhood. He also tried to minimize the nurses’ stress levels as much as possible, often offering them advice and gifts out of fear that unhappiness would impact the quality of their milk.

Aware that he operated on the fringe of accepted medical practice, Couney implemented strict guidelines for all aspects of his Coney Island operation, including a no-joke policy for the exhibit guides who shepherded curious onlookers past the babies. “We run this place ethical,” he informed his staff, “not like a sideshow.”

Even so, he was a talented showman. He positioned Coney Island “barkers”—including a young Cary Grant—outside the exhibit to urge people inside, and instructed the nurses to dress the infants in unnecessarily large clothing so as to highlight their small size. He also ran frequent publicity stunts, holding “graduation” ceremonies for babies who had outgrown the incubators, and reunions for former patients, the first of which was held in Coney Island in 1904 to allow curious crowds to see the longitudinal effects of his treatment. Eventually, Couney took his incubator show back on the road to destinations like Portland, Mexico City, Rio de Janiero, Denver, San Francisco, Chicago, and Atlantic City.

The visitors at Coney Island approached Couney’s incubators with a combination of excitement and confusion; the doctor was frequently asked where he obtained the “eggs” gestated in the incubators, and he got the occasional request to have sexual intercourse with the incubator device in an attempt to conceive. Despite being one of the most costly attractions at Coney Island, the incubators saw a substantial number of return visitors, many of whom came regularly to check in on the development of a particular infant to whom they’d taken a liking.

But the novelty of the incubators was both an asset and a hindrance: At a time when severely premature babies rarely survived, people were reluctant to financially back an experimental technology for their care—and their amusement-park prominence didn’t help the case that the incubators had a place in mainstream medical practice.

Even without financial backers, Couney did not charge the parents of the incubated babies for their care, instead funding the operation entirely with the money earned from admission tickets—10 cents a person in 1903, 25 cents during the height of the exhibition’s popularity, and 20 cents when it closed in 1943. It was enough to pay for the equipment, facility, and a staff of doctors, nurses, and staff, serving as early model for crowdfunded medical treatments.

In a pattern that would hold true with future reproductive technologies like in-vitro fertilization, many of the people who visited Couney’s incubated babies some voiced concern over they  would develop into “normal,” moral people.

“They are good, normal, respectable people, all of them, I bet,” Couney said in a 1939 article in The New Yorker. “I get letters every year from people who their parents told them they were raised in my incubators. I never yet got a letter from a jail.” (The article also noted that “prematurely-born girls seem to get married as frequently as any other kind, and every year Dr. Couney receives about a dozen announcements of weddings of incubator alumnae.”)

The families of Couney’s patients did their part to help the infants when they handed them over. According to the New Yorker article, one Swedish family pulled the baby through the legs of its father’s trousers in order to imbue the child with the father’s strength; some Orthodox Jewish babies were given to Couney with a red string tied around the right arm, called the nachora bendel, while some Italian infants arrived wearing amulets to ward off the malocchio—both protections against the evil eye. An Armenian infant once arrived with a chain of garlic around its neck in order to “make it robust.”

Even without the superstitions, though, something was clearly working: At a time when most full-term babies weighed approximately six pounds, Couney declared that he had nursed thousands of three-pound babies back to health. Of the roughly 8,000 premature babies brought to Couney at Coney Island, around 6,500 survived.

Couney moved the incubator exhibit from Coney Island to Flushing Meadows, Queens for the 1939-1940 New York World’s Fair. At this stage, the incubator babies were competing for attention with such futuristic technologies as a talking-and-smoking robot, models of new cars, and an early television. But the success of Couney’s exhibit was also, in the end, its downfall: After nearly four decades on display at Coney Island, the incubators no longer seemed like the cutting edge of medical treatment. By 1939, mainstream medicine had started to adopt Couney’s methods in regular clinical practice. In 1943, he closed his Coney Island exhibit, declaring his mission accomplished.

“All my life,” he said, “I have been making propaganda for the proper care of preemies.”