A sundial is a device that tells the time of day by the sun's position. In olden days when no watches were available, the people used the sundial to calculate the time of the day. The position of the sun puts the shadow on the surface marked with the lines indicating the hours of the day. In general, sundials indicate the time by casting a shadow or throwing light onto a surface is known as a dial face or dial plate.
Some history of sundial
Ancient Indians used the sundial to estimate the daytime. One of the best sundial examples is in Jantar Mantar.It was built by Raja Jai Singh 2 somewhere in 1725. Mainly on display there are three yantras 1)Samart Yantra ( image 3)
There is a total of 13 instruments for various studies.
The name Jantar Mantar has been derived from the Sanskrit language. Yantra (Jantar) means instruments and mantra mean formula. As the name indicates it was used for scientific purposes.
Samart Yantra is It is 70 feet high, 114 feet long at the base, and 10 feet thick.
The Samart Yantra is popular because it can accurately predict the days, hours, minutes so and so it shows accuracy down to seconds.
Small Sundials as shown in picture are available in the market.
How to position a sundial?
The sundial should be positioned in the North, South direction. You have to make sure it points to the true north, not the magnetic north. The north pointed by compass is magnetic north. The true north is approximately about 6 degree of magnetic north.
Try to see how accurate this tiny looking sundial is.
The sun shadow is on numerical one slightly on the other side of it. My wristwatch shows the time of 1:10.
Small dots on the side of numerical indicates 5 minutes each. So by looking at the sundial, you can estimate the time to be 1:15 which is very close to the watch showing 1:10.
In this case, I give the credit to the Sundial and our ancestors who devised this machine.
As you know some days are long and some days are short. But our watch shows the same time for long and short days. There is no daylight shift in Asian countries.
But the Sundial time is based on how long the sunlight is present. In this case, Sundial is more accurate.
But what happens on rainy days or at night. How would our ancestors know time then?
Well in olden days there was no electricity. So it did not matter for them if it was day or night, or what time it was if there was no sunlight.