It’s 1909 and your child has diarrhea. The cure, according to that year’s edition of the Guide to the Clinical Examination and Treatment of Sick Children, is opium.“Opium is a valuable remedy in childhood,” author John Thomson, M.D., writes. “It is chiefly of use in relieving pain and quieting the actions of the bowels.”Until recently, this window into early 20th-century pediatric medicine sat on a shelf deep in the stacks of the Cushing/Whitney Medical Library. Now the book is just a mouse click away through the online Medical Heritage Library, one of nearly 6,000 Cushing/Whitney rare books uploaded onto the site as of June 2012.The Medical Heritage Library is part of an effort by Open Knowledge Commons, a digital curation collaborative—a network of librarians, universities, students, lawyers, and technologists—to create free digital libraries. The organization, founded in 2008, invited Cushing/Whitney and other leading medical libraries, including those at Harvard, Columbia, and the U.S. National Library of Medicine, to upload works into the site. The works will be available to historians, amateur scholars, laypeople, and anyone interested in the history of medicine. As of this spring, more than 40,000 works had been stored in the library’s virtual stacks, with more going online every day.To avoid duplication, each library is assigned certain subjects. Cushing/Whitney’s topics include surgery, pediatric medicine, gynecology, obstetrics, homeopathy, and phrenology, said Sarah McGlynn, M.L.S., the library’s former preservation and collections management librarian. The eclectic collection includes textbooks, manuals, government pamphlets, self-help books, treatises on social issues, even novels and nonfiction—anything with a connection to medicine from the 19th and 20th centuries.Yale’s contributions include: The Nightless City, an 1899 “exposé” of Tokyo’s then-red light district that could have doubled as a guidebook; The Rules of Aseptic and Antiseptic Surgery, by Arpad Gerster, M.D., a seminal work from 1888; and the 1877 How to Teach According to Temperament in the School-Room and the Family, which applies phrenology—the belief that head bumps can be used as measures of personality and intelligence—to the hiring of teachers and instruction of children.As the 19th century progressed, scientific medicine supplanted home remedies, quackery, and superstition. Melissa Grafe, Ph.D., librarian for medical history, said that while the practices of yesteryear may repel, they were on the cutting edge at the time. “You look back and say, ‘Oh, my God, that’s crazy,’ ” Grafe said. “But, perhaps 100 years from now, people are going to look at us and say, ‘Oh, my God, that’s a little crazy.’ ”Grafe’s favorite Yale contributions are 19th-century “sexual hygiene” books offering women and girls advice on everything from improving the complexion to contraception. McGlynn’s best finds include a novel called The Lunatic at Large, with a whimsically beautiful cover; and a self-help book titled Talks with Homely Girls on Health and Beauty.Scholars are experimenting with data mining and other mass information extraction techniques to determine how best to use the trove, said John Gallagher, M.L.S., deputy director of public services for Cushing/Whitney.Digitizing the books is a laborious process, he said. “The scanning is the easy part.” A variety of library staff is involved in the project, reviewing, selecting, and cataloguing books as well as proofreading scanned texts. Volumes must be in good condition for the digitization machine, which automatically turns and photographs their pages. Because 19th-century works were often poorly made and are disintegrating due to the high acid content of their paper, they are given priority.An exhibit on display at the Cushing/Whitney Medical Library focuses on the digitization process and displays discoveries from the work. To visit the Medical Heritage Library, go tomedicalheritage.org.