Tables
of Houses.
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:
Campanus.
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.
Regiomontanus.
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.
Horizontal.
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.
Placidus
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 Regiomontanus.
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.
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