1793 – Mason and Dixon arrive in Philadelphia

Charles Mason and Jeremiah Dixon were a pair of English astronomers who were hired by Thomas Penn and Frederick Calvert, respectively the proprietors of Pennsylvania and Maryland, to resolve a boundary dispute between the two colonies in 1763. The two had worked together for two years before that, Dixon serving as Mason’s assistant.

The survey took three years to complete – and the pair remained in America for another two years after that, being admitted to the American Society for Promoting Useful Knowledge, in 1768, before they left American in the same way they had entered it: via Philadelphia.

Referenced in:

Sailing To Philadelphia — Mark Knopfler