The Type Directors Club has an invaluable library of resources that you can view and scan for your research. Its Executive Director, Carol Wahler, and its members have been collecting original materials and books that are as old as the 18th century! Their collection is diverse and covers the vast history of typography.
You can visit the library by contacting the TDC and scheduling an appointment to use the library. You are not able to check-out any materials, but you are able to take photos and/or use the scanner. Carol also has a wealth of knowledge and can point you in the right direction and/or answer questions that you may have.
Below are photos from my recent visit to obtain copies of original type specimens: