Such a brilliant work, for that time. Clearly, the hydraulics know-how played a prominent role in conceiving such a system. The operating principle of the mills arranged in series was incredibly efficient: the water output of the uppermost mill served as a geodetic head for the next one, and similarly for each of them further downstream. Within this framework, the sum of the potential energy of the many geodetic heads shall be equal to the amount of energy available from all the mills. The global production of  ground wheat actually corresponded to the sum of the work always done by the same amount of water.

As for the Valley’s water system, it must be pointed out that everything worked thanks to the water sources of the Vernotico’s creek placed on an optimal slope. With few technical measures, the force of the water falling from huge tanks - which were integral part of the system - would power the mills.

Slope of the Valley
This natural slope was the pivotal point of the entire water system of the Valley of the Mills. After triggering the millstone, water flowed from a mill to another thanks to gravity. The latter, however, wouldn’t be enough to fill the Towers. Help would come from the construction of an aqueduct connecting the mills. The aqueduct would drain water from the Towers and carry it to the next mill further downstream. Within this framework, it must be highlighted that the mills were built taking into account the height difference between the two of them, and not their distance.

What might at first sight appear to be something superfluous is actually the most significant work of the entire Valley.

The way the aqueduct was built and spaces were optimised leads us to believe that the mills of the Valley were all part of a single project: a waterfall interspersed with geodetic heads of the same size, which would give rise to several mills of the same productive capacity.

 
 
Valle water system
Aqueducts
Unknown Track - Unknown Artist
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A graphical representation of Gragnano drawn with contour lines along the Vernotico river using Indian ink. Thesis presented by architect Antonio Giordano and architect Antonio Sbrizzi 35 years ago

© 2017 by Ingenito Pietro - www.valledeimulinigragnano.it