How you would use an astrolabe to find the altitude of a star?

To find the altitude of a star using an astrolabe, first hold the instrument vertically and align the alidade (sighting arm) with the star. Once the star is in view through the sight, read the angle on the graduated scale, which indicates the star's altitude above the horizon. Ensure the astrolabe is level for accurate measurements by checking the orientation with the horizon. This method allows you to determine the star's position in the sky relative to your location.