…did the cord,1 since its motion was destined for the length of four hundred braccia, and the motion of the cord that drove that arrow was destined for one-third of a braccio

Pyramid of the power and motion of the motor.

Pyramid of the power and motion of the object moved.

If the crossbow's cord remained2 curved after the flight that this has given to an arrow, it is certain that its power, in every degree of motion, would acquire degrees of slowness and weakness, on to infinity.3 So this power, we shall say, is pyramidal, because it begins at a base and finishes at a point.

Further, when the arrow is propelled by the crossbow's cord, it is pyramidal, because at every degree of motion, it acquires degrees of slowness and weakness. But because this pyramid is longer than that of its motor, the arrow will have parted from the cord before the cord has stopped, indeed, when it its motor was at its greatest power.4

Ancora, essendo la saetta sospinta dalla corda della balestra, essa è piramidale, perché in ogni grado di moto acquista gradi di tardità e debolezza, ma perché tal piramide è più lunga che quella del suo motore, la saetta si partì dalla corda prima che tal corda si fermassi, anzi quand'era in potenzia maggiore il suo motore3.