The Yantra-raja was designed to accurately measure the positions of stars and planets in the sky, enabling astronomers to study their movements and create precise astronomical tables.

The Chakra-yantra was primarily used to measure the altitude of celestial objects above the horizon, allowing astronomers to determine their positions in the sky.

The Gnomon, a vertical rod or pillar, was used to determine the time of day by measuring the angle of the Sun's rays at different times.

The Meru-yantra was an elaborate instrument that allowed astronomers to predict the occurrence of eclipses, calculate the time and duration of eclipses, and determine the positions of the Sun and Moon during eclipses.

The Navagraha-yantra was designed to determine the positions of the nine planets (Navagrahas) in the sky, enabling astronomers to study their movements and interactions.

The Shanku-yantra was a simple yet effective instrument used to measure the height of mountains by measuring the angle of elevation of the mountain's peak from a known distance.

The Kuttaka-yantra was a mechanical device used to solve complex mathematical equations, particularly those involving indeterminate equations and Diophantine equations.

The Yasti-yantra was a simple stick or rod used to determine the time of day by observing the shadow cast by the Sun.

The Gola-yantra was a spherical instrument used to determine the positions of stars in the sky, enabling astronomers to create star charts and study the movement of celestial bodies.

The Phala-yantra was an instrument used to predict the occurrence of eclipses, calculate the time and duration of eclipses, and determine the positions of the Sun and Moon during eclipses.

The Danda-yantra was a simple stick or rod used to determine the time of day by observing the shadow cast by the Sun.

The Chakravala-yantra was a mechanical device used to solve complex mathematical equations, particularly those involving indeterminate equations and Diophantine equations.

The Shanku-chakra-yantra was a complex instrument used to measure the Earth's circumference by measuring the angle of elevation of a star from two different locations.

The Kshipti-yantra was a complex instrument used to measure the Earth's radius by measuring the angle of elevation of a star from two different locations.

The Yantra-sarvasva, a comprehensive treatise on astronomical instruments, was written by Bhaskara II in the 12th century.