The clock painted by Paolo Uccello in the cathedral of Firenze has characteristics referring to the outlook of a vertical sundial. It has only one hand, it is divided in 24 hours, it indicates the hours in inverse sense compared wit modern clocks and it functions according to the 'hora italica', a measurement of time used in the past. The day began soon after sunset and ended at the following sunset.
But, according to the measurement of time used now, the hour of sunset is variabel according to the season. How the hand of the clock in Firenze is ajusted each day of the year so that it indicates the time passed since sunset? Is it done manually or with an ingenious mechanism? You can see an image of the clock at http://www.mega.it/ita/gui/monu/bus.htm Willy Leenders Hasselt, Flanders in Belgium -
