The well known Fe I 6302 {A} spectral line has been measured by a special equatorial solar spectrograph designed at the Belgrade Astronomical Observatory. The first results showing the limb effect along the central meridian (for $0^{\circ}<\theta<52^{\circ}$) were obtained. The proposed theories for the limb effect have been analysed. A suggestion was made for the interpretation of the obtained results in the vicinity of the solar equator.