The very first mills for grinding grain were querns or manual ones - a cylindrical stone rolled back
and forth inside a concave one. In the higher echelons of society, these were eventually superseded
by mills known in Spain and, therefore in Mallorca, as molinos de sangre, literally blood mills;
less graphically sweat mills in English. They owe their name to the fact that they were originally
moved by slaves. The spread of more liberal ideas led to a dearth of manpower and the impossibility
of replacing slave labour by freemen.
Donkeys or mules were then used as an alternate source of power. The mill properly speaking was on
the first floor and the axle that moved the grindstone continued to the ground floor where it was
crossed by pieces of wood harnessing either the donkey or mule that walked constantly in a circle
to move the stone. Their eyes were covered to prevent them from becoming dizzy.
Known to date back to 3000 BC, these horizontal corn grinding mills were gradually
replaced by vertical mills at the beginning of the first century AD.