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Astro*Dictionary by Michael Erlewine





2 articles for "Tables of Houses"

Table of Houses [Astro*Index]

Mathematical table which gives the longitudes of the house cusps (for a particular House System) for a set of sidereal times and for a set of geographical latitudes.

Modern tables usually allow the sidereal time to range from 0h to 24h, in equally spaced steps of 4m; latitudes range from about 22° to 66°, in steps of 1°. Older tables used unequal spacings for the sidereal time, in order to allow the longitude of the 10th house cusp (usually identical with the MC) to be an integral degree (whole number). Three of the most popular House Systems are: Placidus, Campanus, and Koch.

See also:
♦ Houses ♦ Placidus House System ♦ Sidereal Time ♦ Campanus House System ♦ Koch House System ♦ House System ♦ House Cusp ♦ Zodiacal Longitude
Tables of Houses [DeVore]

Tables showing the degrees of the Signs which occupy the cusps of the several Houses in different latitudes for every degree of Right Ascension, or for every 4 minutes of Sidereal Time. Generally available are those by Dalton (1913), Raphael (1920) and Hugh Rice (1935).

There is much argument anent the various systems of calculating the cusps of the intermediate Houses, until one wonders sometimes why not use a stop watch to locate the degree on the horizon every two hours. Of course it would have to be done over again in all latitudes, and besides it would not be very scientific. Nevertheless the general opinion is that none of the existing methods are correct for all latitudes, even though they may be near enough for practical purposes. The four best known systems are as follows:

The vertical circle from the zenith to the cast and west points of the horizon is trisected. Through these points are drawn great circles, the House circles, from the north and south points of the horizon. Thus the intersections will be at altitudes of 30° and 60° above the horizon, on both cast and west branches of the prime vertical. This divides the sky into six great sectors. Similarly divide the hemisphere below the horizon. The house cusps are the points at which the ecliptic at that moment intersects the horizon.

The celestial circle is trisected, instead of the prime vertical, and great circles extend from north and south points of the horizon to the points of trisection. The house cusps are at the points at which the ecliptic intersects the horizon. At the Equator the two systems give the same cusps, the disparity increasing as one approaches the Earth's poles.

Starting with great circles at the meridian and ante-meridian, the horizon and the prime vertical, add other great circles from Zenith to Nadir which trisect each quadrant of the horizon. The cusps will then be the points at which on a given moment the ecliptic intersects the vertical circles.

Instead of using great circles, the diurnal motion of the Earth causes a celestial object to intersect the cusp of the 12th House, after a sidereal-time interval equal to one-third of its semi-diurnal arc; to intersect the cusp of the 11th House after a sidereal-time interval equal to two-thirds of its semi-diurnal arc; and to culminate at the meridian after an interval of sidereal time that corresponds to the semi-diurnal arc. The semi-arc from the meridian that intersects the Eastern horizon gives the Ascendant; and the 2nd and 3rd house cusps are similarly extended below the horizon. The Placidian cusps are in almost universal use at the present time. Maurice Wemyss takes exception to the Placidus cusps on the grounds that the Ascendant is located according to one system and the intermediate cusps by another. He prefers what he terms the "Rational Method" of Riegiomontanus.

A set of Tables of Houses for Lat. 40° N., which is approximately the latitude of New York, in which can be seen a comparison of these four systems, is to be found in the American Astrology Ephemeris for the year 1941. The Tenth House is common to an four systems, and this is theoretically correct. The discrepancies show in the intermediate cusps between the IC and MC. The Ascendant is also the same for three of the four systems, but the Horizontal system has its own Ascendants. Different Latitudes require different sets of tables. Published volumes containing Tables of Houses for all Latitudes are available, most of them, however, confined to the Placidus system, which is the one most generally used. The one by Hugh Rice is the most recent and the most elaborate, with the cusps computed to several decimals. Unless you have a birth moment that is correct to the minute, and beyond doubt, detailed methods are futile and misleading, and one might well confine himself to whole degrees and ignore the decimals.

By means of these tables of houses computed for different latitudes, one is able to ascertain what degrees of the zodiac appeared upon the Ascendant and the various House cusps on any hour of any day, as calculated from the siderial time at noon of that day as indicated in the ephemeris. Actually the tables may be said to divide distance by time, showing how many degrees of the equator will pass the ASC or MC, as if the planet were there. It is to be understood, of course, that this is a rule-of-thumb short-cut for average use when one is not too certain of the reliability of his birth data, and is not to be used when seeking exactness.

See also:
♦ Houses ♦ Campanus House System ♦ Regiomontanus House System ♦ Horizontal ♦ Placidus House System


Astro*Index Copyright © 1997 Michael Erlewine