The Elevation of the Pole, or the Pole of the Descendant, is relative to the north or south latitude of the place for which a map is erected. Proceeding northward from the Equator the North Pole appears to rise up toward the zenith. The elevation of the Pole at London is 51° 30' - the latitude of the city. The Poles of the Houses increase as they recede from the Imum Coeli and the Mid-heaven, which have no polar elevation, toward the Ascendant and Descendant. The cusps of the intermediate Houses, have polar elevation proportional to the positions at which they cut the Prime Vertical or Circle of Observation - the circle in which a person stands when facing South.
The formula whereby to ascertain the Pole of a planet, is one-third of the planet's semi-arc: the difference of elevation of the two cusps:: the planet's cuspal distance: its proportional polar distance. To ascertain the cuspal distance of a planet from the Oblique Ascension of the cusp, subtract the planet's Oblique Ascension or Descension under the pole of that cusp.
To find the Oblique Ascension of a cusp - add 30° to the Right Ascension of the Mid-heaven for each successive House eastward.
To find the Oblique Descension, subtract 30° for every House westward from the Mid-heaven.
