Davison chart

Meaning

A Davison chart is a chart for a relationship cast for a real moment at a real place:

• the moment halfway in time between the two births, and
• the place halfway between the two birthplaces, found by averaging their latitudes and their longitudes [2].

It is then set up like any birth chart. The publisher's description of Davison's book calls it the relationship horoscope [1].

How it differs from the composite. A composite chart averages the two charts' positions planet by planet. A Davison chart averages the two birth times and looks up where the planets actually were at that time. Some consequences:

• The Davison chart is a sky that really happened. Mercury and Venus stay close to the Sun, the Moon has a real phase, and the angles and houses belong to one place at one moment. A composite can place Mercury or Venus opposite the Sun, which the sky never does [2].
• Davison planets have real motion, so they can be retrograde or stationary. Composite planets are averages and have no motion.
• For the slow outer planets the two charts come out close together, since those planets move little and fairly evenly between the two births. For the Sun, Moon and inner planets they can be far apart, because what happens halfway through the interval depends on how many whole cycles the planet completed between the births (see the example).

Variants. Astrodienst lists four versions [2]:

Astrodienst describes the corrected version as the original, classical method of the Davison chart [2]; whether Davison's own Synastry (1977) makes this adjustment could not be checked, as the book was not available for this article. When the birthplaces are far apart the spherical midpoint can lie close to the North Pole (Astrodienst's example is Hawaii and Switzerland), which makes houses hard to cast [2].

Origin and history

The chart is named after Ronald C. Davison (1914–1985), the English astrologer who was for many years president of the Astrological Lodge of London and editor of its journal Astrology. He set it out in Synastry: Understanding Human Relations Through Astrology, published in New York by ASI in 1977 and reissued by Aurora Press in 1983 [1]. The podcast notes date his first presentation of the chart to that book [3]. By the publisher's description, the book is a general guide to comparing charts, with twenty case studies, and the relationship horoscope is presented in it as the author's own new way of charting a relationship in a single horoscope [1].

The Davison chart appeared a few years after the midpoint composite had been introduced in English by John Townley (1973–74) and Robert Hand (1975), and the two have been compared ever since. Townley has argued that the Davison chart gets the outer planets roughly right, because they move evenly, but that its Sun and Moon tend to fall on or opposite the composite positions and its angles bear no clear relation to the two people, and that it is cast for a time and place where neither person was; he prefers the composite, and says Robert Hand reached a similar view (podcast, ep. 128) [3]. Supporters of the Davison chart value it precisely because it is a real sky that can be read, and progressed, like a birth chart.

How it is used

• Reading. It is read as a birth chart for the relationship: its Sun, Moon, angles, houses, aspects and dignities.
• Timing. Because it is a real moment, it can be progressed and directed like a birth chart, and transits to it are used to time events.
• Birth times matter twice over. An error in either birth time moves the Davison moment by half that error. An error of twelve hours in one birth time moves the Davison moment by six hours: the Moon shifts by about 3° and the Midheaven by about a quarter of the circle, so the Davison angles are only as good as both birth times.

On this site. The Synastry tool has three views: Synastry, Composite and Davison. The Davison view casts the chart for the midpoint in time of the two births (in Universal Time) at the average latitude and average longitude of the two birthplaces (taking the shorter way round if the birthplaces lie either side of the 180th meridian), without the Midheaven correction. It can be shown as a triwheel, with the Davison chart in the middle and both birth charts around it, or as a single wheel. Retrograde planets are marked. If either birth time is unknown, 12:00 is used, the Moon is marked approximate, and the chart is shown without angles or houses. The Transits tab gives the exact dates of the major transits to the Davison chart through a chosen year, and the contacts within about 1° today.

Examples

Albert Einstein (14 March 1879, 11:30 local mean time, Ulm, 48°24′N 9°59′E; 10:50:02 UT) and Mileva Marić (19 December 1875, Titel, about 45°12′N 20°18′E). Marić's birth time is not recorded, so 12:00 local mean time is assumed, which is 10:38:48 UT at 20°18′E.

• The moment. The births are about 1,181 days apart. The midpoint is 31 July 1877, 22:44:25 UT.
• The place. Average latitude 46°48′N, average longitude 15°08′30″E, in western Styria, Austria, in today's municipality of Bad Schwanberg. The local mean time there is 23:45.
• The planets (tropical): Sun 8°44′ Leo, Moon 21°31′ Aries (approximate), Mercury 21°02′ Leo, Venus 1°54′ Virgo, Mars 18°41′ Pisces (almost stationary, moving about 4′ a day), Jupiter 24°23′ Sagittarius retrograde, Saturn 19°36′ Pisces retrograde, Uranus 24°01′ Leo, Neptune 7°33′ Taurus, Pluto 25°26′ Taurus, True Node 1°45′ Pisces.
• A real sky. Mercury is 12°18′ and Venus 23°09′ from the Sun, as they must be; Jupiter and Saturn are retrograde.
• Compared with the composite. The slow planets agree fairly well with the composite (shorter-arc midpoints): Uranus is 1°29′ from the composite Uranus, Pluto 2°02′, Neptune 3°25′, Saturn 6°31′. The Sun does not: the Davison Sun at 8°44′ Leo is 178°24′ from the composite Sun at 10°20′ Aquarius. Between the two births the Sun went round the zodiac three times and a quarter; halfway through that journey it had gone round one and a half times and a little more, so it stands on the far side of the circle from the shorter-arc midpoint of the two Suns. Mercury and Venus, which travel with the Sun, are likewise nearly opposite their composite positions.
• The birth time. Had Marić been born at any other time that day, the Davison moment would lie between 16:44 UT on 31 July and 04:44 UT on 1 August 1877, and the Davison Moon between 18°26′ and 24°36′ Aries. The Davison Ascendant and Midheaven cannot be trusted at all, so none is given here.