Engineering System in the Royal Ice Factory

The Extraction Wells and the Reservoir

The existence of two wells is justified by the abundance of water in this location. Both are «25 handspans deep», but the largest is «38 handspans in diameter» and the smallest «18 handspans in diameter». 
The pulley for extracting the water was in the smallest well. There may have been a third well, in the area of the largest one, but its dating is imprecise. 
The large adjacent rectangular tank was fed by water from the wells: it was stored here until it reached the limit marked on its walls by a red line (the water mark is still visible). 
When this mark was reached, there was enough water to supply the shallow tanks. 
Once the limit of the well was exceeded, the force of gravity caused the water to flow through a system of gutters dug into the limestone, successively filling the freezing tanks in a cascade process.