Follow-up re blueprints/architectural drawings:

Frederick Law Olmstead National Historic Site
99 Warren Street
Brookline, MA  02146
(617) 566-1689

Their collection includes a huge number of
architectural/landscape drawings, so they may have a handle
on taking care of the beasts.
Another possible source:
Library of Congress
Preservation Office
101 Independence Avenue, SE
Washington, D.C.  20540
(202) 707-5000

Good luck, y'all.
Carol Edwards, USGS Field Records Library
Denver, CO
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