This photo from the early 20th century shows what a hair loss treatment called the Thermocap looked like. This pseudoscientific gem was marketed towards men who were balding. The device consists of a tall metal hat that looks like something a Martian in a sci-fi cartoon would be wearing.
The metal cap used a special combination of heat and light to apparently make people's hair grow back faster. I have a feeling that this did not yield any hair regrowth. Wearing the cap around town as a fashion statement could be a way to cover up baldness, though.
From Vintage-Minds0:
"The Thermocap promised to stimulate dormant hair using heat and blue light — because apparently, baldness just needed a little electricity and optimism. People were already chasing the dream of 'miracle hair growth'… one questionable invention at a time."
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