How one can weigh water with convenient instruments, and bring them fittingly to the place and end where one desires them.

Now we want to give instruction first on how water may be fittingly led from the springs to the cities and inhabited places. Such leading, however, has its foundation in the leveling, which leveling is done primarily through the dioptra an ancient surveying instrument, the water-level, or the corobates a long leveling bench/instrument. Yet the corobates is the most certain, for the reason that the water-level and dioptra sometimes fail and err. But the corobates is a long leveling board 20 feet long, which has its anconen supporting legs or little arms at both ends set up in equal measure, and well-fitted and joined to one another, according to the square, together with the cross-beams between such leveling board and the legs, which have their