198 RISING, SETTING AND CONJUNCTION OF PLANETS longitude of the meridian-ecliptic point), subtract the resulting nadis from those corresponding to the inferred time; when greater, addition is prescribed. (For the time thus obtained calculate the longitudes of the Moon and the meridan-ecliptic point and find the nadis intervening between them with the help of the right ascensions of the signs as before; and then repeat the above process successively until the nearest approxi- mation to the time of meridian passage of the Moon is obtained). A rule for the determination of the Rsine of the Moon's meri- dian zenith distance: 41. By this process is obtained the Moon when she is on the meridian (lit. when her longitude is equal to that of the meridian-ecliptic point). From her celestial latitude and decli- nation, and from the (local) latitude is determined the Rsine of her meridian zenith distance. First obtain the Moon's true declination by rule 8 above; then apply the following formula: Moon's meridian zenith distance local latitude true declination, + or-sign being taken according as the Moon is to the south or to the north of the equator. A rule regarding the elevation of the horns of the half-risen or half-set Moon: 42. The determination of the elevation of the horns of the half-risen or half-set Moon is made with the help of the agra of the rising or setting point of the Moon's orbit.
When the Moon is rising or setting, its base is obviously equal 10 the agra of the rising or setting point of the Moon's orbit. The text does not say anything about the base and depth of the Sun lying below the horizon but these elements have to be calculated and made use of in the above-mentioned determination. Procedure to be adopted in the case of the planets : 43. This (above-mentioned) procedure should be adopted in the case of the nector-rayed Moon; the same process is pres- cribed for all the planets also.
