The towers were huge tanks always full of water to keep constant the outlet pressure so as to make the mill turn without interruption or slowing down. In the valley are visible smaller circular towers and larger ones with a trapezoidal shape. In reality, the inside Towers are all cylindrical, the trapezoidal appearance is due to the buttresses built to contain the water pressure on the internal walls which, having been built in incoherent material, had little resistance. All cylindrical towers are actually funnel-shaped, have a slight internal inclination and this always to increase the outlet pressure.
The prison is the side room at the base of the tower where the water wheel was placed, which in practice was the driving motor of the mill placed in the mill at the upper level. The dimensions were those strictly necessary for the functioning of the mechanism. A narrow room, with a low ceiling and obviously very humid due to the huge amount of water that passed through it. For these characteristics it was called "prison" and certainly was not a flattering reference to the living conditions of the prisoners of that period.
The mills were marvelous machines that in the dark centuries of the Middle Ages represented an element of technological innovation, compared to the primitive methods of grinding. They were simple but perfect systems, the result of a long process of improvement. They replaced animal work and helped man perform heavy and repetitive work.
Mills
elementi costruttivi di un mulino a ruota orizzontale
disegno
schema a blocchi
The mills were built on the aqueduct route and all used the same vertical axis milling system (on a horizontal wheel).
From a technical point of view, a Mill consisted of three main elements:
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The Tower was basically a well above ground, always kept full of water;
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From a small room adjacent to the base (called the prison) where it was placed a wheel that turned because struck by the power of water;
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The mill on the upper floor, driven by the wheel on the floor below
Mills on loan for use by the Alfonso Maria Di Nola Association
Horizontal wheel:
The movement of the wheel was due to the impact force of the outlet water at the base of the tank against the fins. For this reason the mills had a tower / tank that was actually a huge cylinder, always kept full of water in order to guarantee a constant pressure at its base. From the center of the wheel a pole (vertical axis) was used to transfer the rotary motion to the mill of the upper floor
The Hopper: it was a wooden box shaped like an inverted pyramid, in which the cereal was poured through a hole going to the mill. This shape allowed an easy loading with the wide opening, and with the slight inclination of the walls a slow descent of the seeds towards the lower discharge mouth.
Millstones:
The millstones were on average 1.30 meters in diameter and made of hard and homogeneous stone because during the operation they did not lose dust that was mixed with flour. They were two superimposed wheels in a horizontal position, the upper one in motion. The flour thus obtained, by means of grooves, fell into a sieve crivo where it was separated from the pulp to then
be put in the bags. In this the good quality of the product was guaranteed keeping unchanged all the organoleptic properties, thanks to the low speed of the movement of the millstones.
Only 13 mills are currently visible in the Valley. Unfortunately, all now in very bad condition.
© 2017 by Ingenito Pietro - www.valledeimulinigragnano.it