Person
Flinders Petrie
The surveyor who measured Giza in 1880 to 1882 and published The Pyramids and Temples of Gizeh in 1883. His figures are still the baseline.
Emőke Dénes, “The Great Pyramid of Giza”, CC BY-SA 4.0, via Wikimedia Commons
Petrie went to Giza partly to test the pyramid-inch theories of Charles Piazzi Smyth, and his survey ended them: the measured base did not fit. He gave the Great Pyramid’s casing angle as 51°52′ ± 2′ and its base as about 230.4 metres. Every modern reading of constants in the stone, including Grant’s, uses Petrie’s numbers or their descendants.