The round-shaped Râm Yantra (Altitude/Azimuth Instrument)
in the Delhi Observatory to read the altitude and direction of the sun.
The central round pillar (Gnomon) of 8.4 meters in diameter has 30 vertical
lines painted on its surface, the same number as the circumferential pillars,
while that of Jaipur is smaller with only 12 circumferential pillars.