3I have briefly explained the principles of machines of draught, in which, as the powers and nature of the motion are different, so they generate two effects, one direct, which the Greeks call εὐθεῖα, the other circular, which they call κυκλωτὴ; but it must be confessed, that rectilinear without circular motion, and, on the other hand, circular without rectilinear motion can neither without the other be of much assistance in raising weights.
3I have briefly set forth what I thought necessary about the principles of hoisting machines. In them two different things, unlike each other, work together, as elements of their motion and power, to produce these effects. One of them is the right line, which the Greeks term εὑθεια; the other is the circle, which the Greeks call κυκλωτἡ; but in point of fact, neither rectilinear without circular motion, nor revolutions, without rectilinear motion, can accomplish the raising of loads. I will explain this, so that it may be understood.