In 1702 Pope Clement XI inaugrated the meridian line he commissioned from the mathematician and astronomer, Francesco Bianchini.Its purpose was to verify the Gregorian calendar reforms of 1582, the date of the Vernal Equinox to which Easter is linked and other astronomical tasks.It was installed in the Church of Santa Maria degli Angeli in Rome, and is a horizontal brass strip, 44 metres long, aligned to the meridian of 12.29 degrees E. It shows the day of the year, not the time. The solar image on the meridian is created by an aperture of 6.6 mm diameter, at a height of 20.34 metres. The design also allowed observation of stellar transits. The left-hand scale is the zenith distance of the sun in degrees, also shown is one of the 22 stars Bianchini incorporates.