4The inclination at which the screw is to be worked, is equal to that of the right angled triangle of Pythagoras: that is, if the length be divided into five parts, three of these will give the height that the head is to be raised; thus four parts will be the perpendicular to the lower mouth. The method of constructing it may be seen in the diagram at the end of the book. I have now described, as accurately as possible, the engines which are made of wood, for raising water, the manner of constructing them, and the powers that are applied to put them in motion, together with the great advantages to be derived from the use of them.
4It is to be set up at an inclination corresponding to that which is produced in drawing the Pythagorean right-angled triangle: that is, let its length be divided into five parts; let three of them denote the height of the head of the screw; thus the distance from the base of the perpendicular to the nozzle of the screw at the bottom will be equal to four of those parts. A figure showing how this ought to be, has been drawn at the end of the book, right on the back.
I have now described as clearly as I could, to make them better known, the principles on which wooden engines for raising water are constructed, and how they get their motion so that they may be of unlimited usefulness through their revolutions.