Abstract

Astronomer Charles Piazzi Smyth’s 1864–65 expedition to measure the Great Pyramid of Giza was planned around a system of linear measures designed to guarantee the validity of his measurements and settle ongoing uncertainties as to the Pyramid’s true size. When the intended system failed to come together, Piazzi Smyth was forced to improvise a replacement that presented a fundamental challenge to the metrological enterprise upon which his system had been based. The astronomer’s new system centered around a small lump of basalt, now held at Cambridge’s Whipple Museum of the History of Science, which nucleated a wide array of material and scientific considerations. Through a bipartite analysis of the physical and narrative dimensions of Piazzi Smyth’s basalt Standard, I develop the implications of its use and construction for understanding the material constitution of scientific instruments. In particular, I illustrate how instruments are locally constituted through co-accountable systems and how their material features become integrally implicated in both their uses and meanings