▁perfect ing ▁the ▁T ables . ▁▁ 1 7 6 1 ▁trans it ▁of ▁Ven us ▁ ▁In ▁ 1 7 6 1 , ▁Mason ▁was ▁assigned ▁to ▁travel ▁to ▁the ▁island ▁of ▁Sum atra ▁to ▁observe ▁the ▁trans it ▁of ▁Ven us ▁as ▁part ▁of ▁an ▁international ▁effort ▁to ▁record ▁data ▁that ▁would ▁enable ▁scient ists ▁to ▁determine ▁the ▁distance ▁from ▁the ▁Earth ▁to ▁the ▁Sun . ▁ ▁Mason ▁was ▁joined ▁by ▁Jer em iah ▁D ixon , ▁a ▁survey or ▁and ▁amateur ▁astronom er ▁from ▁C ock field ▁in ▁the ▁County ▁of ▁Dur ham . ▁ ▁O wing ▁to ▁an ▁attack ▁by ▁a ▁French ▁man - of - war , ▁they ▁did ▁not ▁reach ▁their ▁destination ▁in ▁time ▁for ▁the ▁trans it ▁and ▁were ▁forced ▁to ▁record ▁their ▁observations ▁from ▁the ▁Cape ▁of ▁Good ▁Hope . ▁On ▁the ▁way ▁back ▁from ▁the ▁Cape ▁they ▁visited ▁St ▁Hel ena ▁where ▁they ▁made ▁a ▁series ▁of ▁observations ▁with ▁the ▁astronom er ▁Ne vil ▁M ask ely ne . ▁ ▁The ▁Mason – D ixon ▁line ▁survey ▁ ▁From ▁November ▁ 1 7 6 3 ▁to ▁ 1 7 6 8 , ▁Mason ▁and ▁Jer em iah ▁D ixon ▁established ▁the ▁boundary ▁line ▁between ▁the ▁American ▁provinces ▁of ▁Pennsylvania ▁and ▁Maryland . ▁Col onial ▁survey ors ▁had ▁been ▁unable ▁to ▁accur ately ▁establish ▁the ▁boundary ▁due ▁to ▁their ▁poor ▁training ▁and ▁in ade qu ate ▁scientific ▁instruments . ▁ ▁Mason ▁and ▁D ixon , ▁accompanied ▁by ▁a ▁large ▁party ▁of ▁assist ants , ▁established