In 2018, Barry Lawrence Ruderman, a rare map dealer from California, bought a folder of documents and blueprints related to the Statue of Liberty. What they didn't realize is that the lot contained almost two dozen original engineering drawings for the Statue produced by Gustav Eiffel's workshop. Ruderman and Alex Clausen, director of Ruderman's gallery, hope to eventually show the drawings at a museum but for now you can inspect scans they posted online. Greg Miller writes in Smithsonian:
Berenson thinks the drawings may nail down something that historians have long suspected but not been able to prove: that Bartholdi disregarded Eiffel's engineering plans when it came to the statue's upraised arm, electing to make it thinner and tilted outward for dramatic and aesthetic appeal. Several drawings appear to depict a bulkier shoulder and more vertical arm—a more structurally sound arrangement. But one of these sketches (below) was marked up by an unidentified hand with red ink that tilts the arm outward, as Bartholdi wanted. "This could be evidence for a change in the angle that we ended up with in the real Statue of Liberty," Berenson says. "It looks like somebody is trying to figure out how to change the angle of the arm without wrecking the support."
The date on that sketch, July 28, 1882, as well as dates on several pages of handwritten calculations and diagrams pertaining to the arm, suggest that this change was made after much of the statue had already been built. "It's really late in the game," Berenson says. (Construction of the statue stretched from 1876 to 1884; after being packed in crates and shipped to New York, it was finally dedicated on October 28, 1886.)