Sun Dial, a historical instrument shown in photo is the 1,400-year-old sun clock mounted on the 35-feet-high inner wall of Sivayoginathar temple at Thiruvisainallur, some 12 km from Kumbakonamin Thanjavur district. It is the only ‘wall clock’ in Tamil Nadu in the real sense of the term.The temple authorities have decided to refurbish the historic legacy which stands testimony to the infinite wisdom and scientific temper of the Chola kings.
The wall clock built during Parantaka Cholan’s rule does not require battery or electricity. Carved out of granite and shaped like a semi-circle, all it has is a three inch-long brass needle permanently fixed at the centre of a horizontal line. As the sun casts its rays on the needle, the shadow of the needle indicates the right time. The people, mostly the devotees coming to the temple, deciphered the time of the day by watching the silhouette cast by the needle of the sun clock from six am to six pm, and perhaps planned their day accordingly.British have added numerals while repainting the centuries old sun clock for easy reference.
Expectedly,time has taken its toll on the sun clock at the sixth-century temple. The clock will work as long as the sun shines because of its unique working principle. But due to brass discoloration, the needle is getting blurred on the granite surface.