None of these people took the reading. The record of each shows the shape.
Joseph Bazalgette (1819 to 1891)
Between 1858 and 1875 the engineer Joseph Bazalgette built 82 miles of brick main sewers for London, fed by about 1,100 miles of street drains and made far larger than the city then needed; more than 80 miles of them are still in full use. A system sized for a city that did not yet exist, and still working more than a century after its maker died, shows the shape from outside.
Sources: londonmuseum.org.uk, english-heritage.org.uk
Andrés Bello (1781 to 1865)
Andrés Bello spent about fifteen years writing the Civil Code of Chile, building chiefly on the Spanish law already in force; promulgated in 1855 and adopted with few changes by Ecuador and Colombia, it is still in force in Chile. Old law reworked into a clearer whole, and still in use more than a century and a half later, shows the shape from outside.
Sources: bcn.cl, memoriachilena.gob.cl, en.wikipedia.org