Babylonian and Italian hours measure the day

Babylonian and Italian hours on a sundial

This vertical dial has hour lines radiating from the top, as well as the criss-cross pattern of Babylonian and Italian hour lines, plus the lines for solstice and equinox. Looking at the shadow of the gnomon, the time of day is 9:30 am and the time of year is the equinox. The Babylonian time is 3½ hours from sunrise, and the Italian time is 8½ hours before sunset. Adding these together the length of day for the equinox is 12 hours.—Note, the figure has no numbers. Once you learn how to read the lines, it is not hard to learn how to count them!

Babylonian and Italian hours are wonderful. They measure out the day from the time of sunrise to the time of sunset. Add them together and they will give you the number of hours of daylight. A simple ancient type of sundial like this one can measure times for you that you will hardly ever find on a modern watch.

Of course we have lost the art of reading sundials. Nowadays we have so many other ways to read the time. Babylonian and Italian hours were popular for many centuries, especially on sundials in the countries of Europe, although less so in Britain.

The name ‘Italian’ comes from measuring 24 hours in the Roman church, running from sunset one day to sunset the next. The origin of ‘Babylonian’ is unclear but these hours start at sunrise. Clearly if you add together the time from sunrise and the time until sunset you have the hours of daylight or length of the day. A Babylonian and Italian sundial will keep track of the daytime, and measure how this changes in length with the seasons, and keep going from year to year. There is no need for adjusting the clocks, and no need to change the calendar. You look out for the shadow in sunshine on the sundial!