‹‹‹ Vitr. 10.11.1 | Table of Contents | Vitr. 10.11.3 ›››
2For instance, holes are made in the capitals, and through them are brought the cords, made either of woman’s hair, or of gut, which are proportioned to the weight of the stone that the balista is to throw, as in the catapultæ the proportions are derived from the length of the arrow. But that those who are not masters of geometry and arithmetic, may be prepared against delay on the occasions of war, I shall here state the results of my own experience as well as what I have learnt from masters, and shall explain them, by reducing the Greek measures to their correspondent terms in our own.
2For the holes made in the capitals through the openings of which are stretched the strings made of twisted hair, generally women’s, or of sinew, are proportionate to the amount of weight in the stone which the ballista is intended to throw, and to the principle of mass, as in catapults the principle is that of the length of the arrow. Therefore, in order that those who do not understand geometry may be prepared beforehand, so as not to be delayed by having to think the matter out at a moment of peril in war, I will set forth what I myself know by experience can be depended upon, and what I have in part gathered from the rules of my teachers, and wherever Greek weights bear a relation to the measures, I shall reduce and explain them so that they will express the same corresponding relation in our weights.