When babies are born early, they often have trouble surviving. But special containers called incubators help babies grow by keeping them warm and protected. At first, people in the medical world were skeptical about incubators. But some trailblazing doctors believed in the technology-and put it on display across Europe and the United States. "Incubator exhibits" showed the public how incubators saved lives. The controversial displays led people...

Vaccines have been used to safely introduce people’s bodies to diseases for centuries, and they save millions of lives each year. By giving people a weakened or dead version of a disease, a vaccine allows the body to develop antibodies which recognize and fight the disease later on. Early vaccinations used dry scabs from smallpox to promote smallpox immunity. Doctors and scientists across nations took and improved the method, developing vaccines...