2.1 The vertical cercle
This device enables the angular position of the Sun in the sky to be measured.
Do as Tycho-Brahé or Kepler did in the 16th century and note down its angular position: horizontally in comparison to the south and vertically above the horizon.
Note down the azimuth and the height of the star and then compare them.
Return later and take a new reading. Vou will notice the variation in the position of the Sun, which results from the rotation of the Earth.