None of these people took the reading. The record of each shows the shape.
King Sejong (1397 to 1450)
In 1446 King Sejong of Joseon issued the Hunminjeongeum, an alphabet of 28 new letters for Korean, which until then had been written in Chinese characters. His preface says the letters were made so that ordinary people could learn them easily. One finished change to how a whole country writes, issued in public under the maker's name, shows the shape from outside.
Source: media.unesco.org
Rachel Carson (1907 to 1964)
Rachel Carson published Silent Spring in 1962, a book on the harm done by pesticides such as DDT, and testified at a Senate hearing on pesticides on 4 June 1963. In 1972 the US Environmental Protection Agency canceled nearly all remaining uses of DDT. One public book, staked on changing how a country treats its land, shows the shape from outside.
Sources: environmentandsociety.org, epa.gov