Before revision: He then traced the grid using an instrument known as a groma, tracing two road axes perpendicular to each other: the first, generally oriented east-west , was called decumanus maximus, which was traced taking as reference the place where the sun rose in order to know exactly where east was;Bell, Castra et urbs romana the second, with a north-south orientation, was called cardo maximus.
After revision: He then traced the grid using an instrument known as a groma, tracing two road axes perpendicular to each other: the first, generally oriented east–west , was called decumanus maximus, which was traced taking as reference the place where the sun rose in order to know exactly where east was;Bell, Castra et urbs romana the second, with a north–south orientation, was called cardo maximus.