The Encyclopedia of the History of Science (ETHOS) is a new collaborative initiative (ISSN 2642-5890), publishing open-access, peer-reviewed articles in the history of science and technology. For more information, see About. Though most articles are solicited by Editors, suggestions for new articles and authors as well as corrections to existing articles are always welcome: Contact Us. We also maintain a list of experts based on authors’ and editors’ areas of speciality. Unless otherwise noted, images are courtesy of the Carnegie Mellon University Archives.