The cams caused trip-hammers to be raised and then released...

The cams caused trip-hammers to be raised and then released to fall on the material. Windmills Where waterpower was scarce, the Muslims had recourse to the wind. Indeed it was in river-less Seistan, now in the western part of Afghanistan, that windmills were invented, probably early in the seventh century A.D. The mills were supported by substructures built for the purpose of the towers of castles or the tops of hills.

They consisted of an upper chamber for the millstones and a lower one for the rotor. A vertical axle carried either 12 or six rotor blades, each covered with a double skin of fabric. Funnel-shaped ducts pierced the walls of the lower chamber, their narrower ends facing toward the interior in order to increase the speed of the wind when it flowed against the sails. This type of windmill spread throughout the Islamic world and thence China and India.

In medieval Egypt, it was used in the sugarcane industry, but its main application was to grist-milling. Fine Technology Now we turn to a type of engineering that is quite different from the utilitarian technology described so far. We may perhaps call it fine technology since its distinguishing features derive from the use of delicate mechanisms and controls.

Some of these devices had obvious practical uses: water clocks were used in astronomical observations and were also erected in public places; astronomical instruments aided both observation and computation. Others gave amusement and aesthetic pleasure to the members of courtly circles. Still, others undoubtedly had didactic purposes, for example, to demonstrate the principles of pneumatics as understood at the time.

Apart from astronomical instruments and the remains of two large water clocks in Fez, Morocco, none of these machines has survived. Our knowledge of them comes almost entirely from two Arabic treatises that have come down to us. The first is by the Bano (Arabic for sons of) Musa, three brothers who lived in Baghdad in the ninth century. They were patrons of scholars and translators as well as eminent scientists and engineers in their own right.

They undertook public works and geodetic surveys and wrote a number of books on mathematical and scientific subjects, only three of which have survived. The one that concerns us here is “The Book of Ingenious Devices”. It contains descriptions, each with an illustration, of 100 devices, some 80 of which are trick vessels of various kinds.