These are based solely upon the axial rotation of the Earth in relation to the circle of observation whereby planets arc carried clockwise through the Houses of the Figure, from east to west, forming aspects to the Ascendant, Midheaven, Sun and Moon. Aspects formed by the opposite or Converse Motion are also employed. The use of spherical trigonometry and of logarithms is necessary to reliable use of this so-called Primary System of Directing. Knowledge of the exact place, hour and minute is also essential.
ASTROLABE ENCYCLOPEDIA
