Sin autem ventus interpellaverit et motionibus lineae non potuerint certam significationem facere, tunc habeat in superiore parte canalem longum pedes v, latum digitum, altum sesquidigitum, eoque aqua infundatur, et si aequaliter aqua canalis summa labra tanget, scietur esse libratum.
But if the wind disturbs and, owing to their movements, the lines cannot give a certain indication, a channel is to be put on the top side of the plank, five feet long, an inch wide and an inch and a half deep. Let water be poured in. If the water evenly touches the lips of the channel, we shall know that the levelling is successful.
final_alignments\Vitruvius_Architecture_Book_8.json