"NOTWITHSTANDING the range of press sizes and shapes you'll observe in these pages, the basic technology of the letterpress changed little during its roughly five hundred year development: its object is the impression of type into paper. After Gutenberg, letterpress invention was but a series of refinements on this one idea. There are many ways to approach the presses in the Museum; browsing is as easy as clicking an image or a name. For serious browsing, we've sorted the presses by Type, based on the central mechanism or form of each press."
Briar Press Museum
This is an excellent historic resource on letterpress and type history.