Paolo Uccello's Clock

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Clock by Angelo Niccolai, fresco by Paolo Uccello, 1443
Santa Maria del Fiore (Saint Mary of the Flower)
Piazza del Duomo
Florence, April 2014

“The first public clock in the city of Florence was installed on the tower of Palazzo Vecchio on March 25, 1353, the work of Niccolò di Bernardo. A little less than a century later, a grandson of his, Angelo Niccolai degli Orologi, was commissioned to construct the mechanical clock of Santa Maria del Fiore, installed on the cathedral's inner façade in 1443. The dial was painted in fresco by Paolo Uccello (1397-1475), inscribing in a square a circle divided into 24 hours running counter-clockwise, according to a conventional representation of the time, emulating the movement of the gnomon's shadow on a vertical sundial. The hours are given in the so-called ‘Italian style’, which marked the duration of the day starting from sunset. They are indicated by an elliptical star with one ray longer than the others, an element recurrently used by the artist in his paintings to depict the comet of the Nativity. This is probably an allusion to Christ, ‘light of the world’, as is further confirmed by the presence of the four Evangelists portrayed in the false oculi at the corners of the great square.” (Ancient mechanical ‘oriuoli’, Museo Galileo)