81 years ago, 4 inmates were ‘baked’ to death in a Philly jail. This summer, 1,000 are still locked up without AC.

As summer heat waves wash over Philadelphia and the city extends hours for cooling centers and public pools, there’s one group of residents with very few options for staying cool.

Those are the men incarcerated at the Detention Center in Philadelphia without air-conditioning. The dorms at the Detention Center are known to be miserable in July and August, “almost uninhabitable,” one longtime defense lawyer said. “The din, the smell, and the body heat, on top of 100-degree temps, is ungodly for inmates [and for the staff]."

A spokesperson for the Philadelphia Department of Prisons said about 1,000 people were jailed at the Detention Center during last weekend’s heat emergency, and that ice water and fans were available at all times. She could not provide an estimate of the staff there.

“The prisons tend to be an intensifier of whatever the weather is,” said Allen Hornblum, who taught literacy in Philadelphia jails through the 1970s. “If it was 95 outside, it was 105 inside where I taught my classes.”

While there, he observed dozens of inmates wandering around with tape and medical bandages — for, as it turned out, dermatological experiments conducted by University of Pennsylvania scientists. Decades later, Hornblum would publish his first book, Acres of Skin: Human Experiments at Holmesburg Prison, an investigation into those practices.

Now, seven books later, Hornblum is finishing his first fictionalized historical account, which returns to the Philadelphia jails for an even more infamous episode that took place 81 years ago this summer, made front-page headlines across the country, and has since been largely forgotten.

“That weekend of Aug. 20, 1938, was much like the weekend we just had here in Philly,” Hornblum said.

Men at Holmesburg Prison in Northeast Philadelphia had been on a hunger strike over the quality of prison food, and 23 of the leaders were punished with a weekend in the Klondike, the nickname of a small concrete isolation block frequently used for punishment.

“There was a practice that had been in existence for a number of years of shutting the windows, turning off the water, turning up the heat, and that’s how they punished the men,” Hornblum said. But that weekend, with 98-degree temperatures outside, it was well over 100 degrees inside the Klondike, and hot steam was pouring in. “The inmates were crying, pleading, and screaming to open the windows.”

On Monday morning, guards opened the doors to find a number of the men unconscious. Four were dead.

“They came to their deaths by violence,” the coroner told The Inquirer that day.

“Nothing suspicious,” a homicide detective told a skeptical Inquirer reporter, who summed up the police theory of events as follows: “A battle to the death, which, by curious coincidence, took place between two couples of convicts who became temporarily insane.”

To Hornblum, who’s hoping to spin the tale into a television project, the context is key: “In the ’30s, Philly was a very, very corrupt town. If you were a cop and you weren’t on the take, you were a rare individual. Everybody was getting paid to shove something under a rug.”

The Klondike “bake-oven” deaths drew press from all over the country to State Road. (Hornblum says the Press Bar got its name that way, though no one answered the phone there Tuesday to corroborate that.)

His story centers on the coroner, Charles Hersch, who wouldn’t allow the cover-up. While the district attorney and the police refused to take up the case, Hersch insisted on conducting an investigation that found two chiefs and 12 staffers criminally negligent. ″The coroner was willing to end his own career, because that’s what he was threatened with."

By June 1939, 10 faced charges of murder or manslaughter.

Then, the episode — described at the time as one of the most egregious prison abuse cases in American history — was all but forgotten, even to the most avid historians of Philadelphia.

“I think I know why that is,” Hornblum said. “What happens in September 1939? The world goes to hell — something much bigger and more devastating than the Klondike takes place.”

That, of course, was the greater horror of World War II. But he thinks it’s time Philadelphia remembered its own dark history.