βορβόρῳ δ' ὕδωρ λαμπρὸν μιαίνων οὔποθ' εὑρήσεις ποτόν → once limpid waters are stained with mud, you'll never find a drink
transtillum: i, n. dim. transtrum,I a little cross-beam, Vitr. 5, 12.