Survey-book of Länge

Survey-book of Johann Christian Heinrich Länge on September 13, 1774 (NLA HA, BaCl Hann. 84a, Nr. 252, f. 31r.)

Project (2020)

“One of Geometry’s Nicest Applications”: Crafting the Georg-Tiefer Stollen (1771–1799)

In the second half of the eighteenth century, mine surveying in German ore mines was gaining steam. Methods were improving, due to both the foundation of mining academies and to the publication of new textbooks, just as new challenges had to be met. In the Harz region, ground water was an increasing threat to the silver mines, making a new draining tunnel necessary. The construction work of the Georg-Tiefer Stollen lasted for twenty-two years, finally opening in 1799. Contemporary observers and current historians alike are amazed by the technical achievement and the ability to meet precisely the deadline and the budget.

This research project aims at showing that this prowess relied above all on a groundbreaking use of subterranean geometry (Markscheidekunst). The first part of the project analyzes the planning phase of the project (1771–1777), during which numerous surveys gathered the material on which collective decisions could be made. The second part explores the interactions between the mining administration and Jean-André Deluc, fellow of the Royal Society and natural scientist, as he visited the Harz three times  during that period, and local mining officials helped test and refine his barometric formulas.