Here's almost 8500 historic medical texts available online for free:
The Medical Heritage Library (MHL) is a digital curation collaborative among some of the world's leading medical libraries. The MHL promotes free and open access to quality historical resources in medicine. Our goal is to provide the means by which readers and scholars across a multitude of disciplines can examine the interrelated nature of medicine and society, both to inform contemporary medicine and strengthen understanding of the world in which we live.
The Museum's got ~175 items at the Internet Archive (search for otishistoricalarchives) and when we figure out how to link them, we'll add them to this digital resource. Some of ours are unique, like the Pleasants Photograph Album, which is full of pictures of wounded soldiers who made the album as a 'thank you' for being tutored in reading.