Sundials are very interesting scientific instruments in the history but they are forgotten during recent centuries and especially in orient.
For more than 5000 years human kind are using a simple instrument to determine time. The shadow of simple vertical gnomon show the time for human and step by step sundials technology grow up and mathematicians and engineers use advance concepts of science, art and architecture to build these sun clocks.
After Hellenic period of sundials these clocks reach to Islamic empires although before Islamic period we have some evidences about ancient sundials in the east. Somewhere like India, Egypt and Iran but during the golden time of Islamic scientific civilization we were witnessed the great growing about making sundials.
Because of Islamic daily prays times (Namaz) directly related to astronomical events, Islamic astronomer use advance mathematics to help people to determine these times and because of it knowledge of sundials are growing rapidly.
According to new sundials that found in Egypt using multi gnomon sundials in this time were very common. The sundials that show prays time more than local time to people and even time of morning or ISHA pray.
By definition ISHA pray is holding when sun reach few degree under the horizon. So in this time or morning pray that sun doesn’t rise yet, we don’t have any shadow. So mathematicians use shadow of gnomon during sun set to determine when sun rise in that day or when sun reach to morning pray time. If you see the shadow in the evening that point to the sign on the curves of sundials you find how much time remain to morning.
Unfortunately in next centuries sundials forgot in eastern lands – like other branch of science- in 21 century you can find more than 30 000 sundials in France but only about 50 sundials in Iran. Today sundials played a role more than some instruments for timing as conjunction of Art, Literature, Science and Architecture.
So in recent yeas new movement grows in eastern country to introduce again these cultural and scientific heritages to the people.
In this year and in summer solstice day, Iran Astronomy Society hold first national sundials festivals and many people gathered in many cities to make and introduce sundials to people and ask them try to find some forgotten sundials in all around the country.
Some activity like this can help people to better know the importance of history of science and keep them in tough with their history.
Unfortunately know, man country are forgetting these heritages and in the long time it can damage the process of science devolpment.