4I shall now explain the machines for raising water, and their various sorts. And first the tympanum, which, though it raise not the water to a great height, yet lifts a large quantity in a small period of time. An axis is prepared in the lathe, or at least made circular by hand, hooped with iron at the ends; round the middle whereof the tympanum, formed of planks fitted together, is adjusted. This axis rests on posts also cased with iron where the axis touches them. In the hollow part of the tympanum are distributed eight diagonal pieces, going from the axis to the circumference of the tympanum, which are equidistant.
4I shall now explain the making of the different kinds of engines which have been invented for raising water, and will first speak of the tympanum. Although it does not lift the water high, it raises a great quantity very quickly. An axle is fashioned on a lathe or with the compasses, its ends are shod with iron hoops, and it carries round its middle a tympanum made of boards joined together. It rests on posts which have pieces of iron on them under the ends of the axle. In the interior of this tympanum there are eight crosspieces set at intervals, extending from the axle to the circumference of the tympanum, and dividing the space in the tympanum into equal compartments.