Noice!
And this Also Anon…
The Tamarack Mines Mystery
By Donald E. Simanek
English measurement units (feet and inches) are used throughout this document, because those were the units used by the experimenters in 1901 and the units used in all of the source documentation.
The essence of the story, as usually told, goes something like this. In the fall of 1901 J.B. Watson, Chief Engineer at the Tamarack copper mine (S. of Calumet, Mich.) suspended 4250 foot long plumb lines down mine shafts. Measurements showed that the plumb lines were farther apart at the bottom than at the top, contrary to expectations. Thus arose one of the long-standing mysteries of science.
https://www.lockhaven.edu/~dsimanek/hollow/tamarack.htm