The Astronomical Observatories of Jai Singh c6.s1.16

c6.s1.16

(iv) The alhidade or⁶ sighter revolves round the centre on the back of the mater. Each arm has a perforated libna⁷ or ‘tile,’ which is sometimes hinged on to the alhidade. European astrolabes sometimes had another marker or label⁸ without sights for use on the front of the instrument. (Figure 7.)