Page:Aryabhatiya of Aryabhata, English translation.djvu/99

Rh decreased by the radius of the Earth is visible. The other half, plus the radius of the Earth, is cut off by the Earth.

16. The gods, who dwell in the north on Meru, see the northern half of the sphere of the asterisms moving from left to right. The Pretas, who dwell in the south at Vadavamukha, see the southern half of the sphere of the asterisms moving from right to left.

Quoted by Bhattotpala, page 324.

17. The gods and the Pretas see the Sun after it has risen for half a solar year. The Fathers who dwell in the Moon see it for half a lunar month. Here men see it for half a natural [civil] day.

Referred to by Alberuni, I, 330.

18. There is a circle east and west (the prime vertical) and another north and south (the meridian) both passing through zenith and nadir. There is a horizontal circle, the horizon, on which the heavenly bodies rise and set.

19. The circle which intersects the east and west points and two points on the meridian which are above and below the horizon by the amount of the observer's latitude is called the unmandala. On it the increase and decrease of day and night are measured.

The unmandala is the east and west hour-circle which passes through the poles. It is also called "the horizon of Lanka."