Horizontal levels were checked using a "chorobates", a flatbedded wooden frame fitted with a w and checked using a "groma", a relatively simple apparatus that was probably displaced by the more sophisticated dioptra, precursor of the modern theodolite.
Horizontal levels were checked using a "chorobates", a flatbedded wooden frame fitted with a water level. Courses and angles could be plotted and checked using a "groma", a relatively simple apparatus that was probably displaced by the more sophisticated dioptra, precursor of the modern theodolite.