Over on the natal forum Deb picked me up for suggesting Alcabitius was the dominant house system in the time of Nostradamus. She pointed out that her research suggested he was relying on Regiomontanus houses and that this system was already widely used in his time.

This opens up the broader question of when the Alcabitius house system became eclipsed by the Regiomontanus house system?

The developer of the Regiomontanus house system Johannes M?ller von K?nigsberg (1436 -1476), known by his Latin pseudonym Regiomontanus, was a German mathematician, astronomer, astrologer and translator. The major astrological populariser of Regiomontanus house system in the German speaking world was Johannes Schoener-(1477 -1547).

In response to my question Tom came back with the following informative comment:

In 1490 after he died, of course. According to James Holden, Johann Mueller aka Regiomontanus published an ephemeris for the years 1474 - 1506 in the year 1474. The house tables he worked on were first published in 1490 and they became very popular possibly for the same reason Placidus houses are popular today: there were few if any other tables available to the astrologers of the day. More recently, and prior to the advent of the personal computer, it was difficult to find tables of houses for anything other than Placidus. Holden opines that if the Campanus system had tables published instead of Regio, they would have been the standard of the day. Regiomontanus believed he had recovered a system that Ptolemy had in mind, but he was wrong.

I think this sets us up for a better discussion. In particular do we know what house systems European astrologers were using during the 16th century? Was Nostradamus?s use of Regiomontanus houses already quite typical of European astrology in that period?

Mark

In his L' Introduction au Judgement des Astres of 1558 Dariot acknowledges that in that past there have been various methods and opts to follow Regiomontanus.

Thanks Kirk,

Here is the natal chart Johannes Kepler (1571?1630) cast in 1608 for the Bohemian Military commander Albrecht Von Wallenstein. Checking the house cusps they clearly seem to be Regiomontanus.
Mark

Dear Mark.

Thank you for his post. It was very helpful
since which house system to use was still my ongoing debate.
I have few questions though

in your quote, it argues that the scarcity of avaliable house tables
was what gave rise to regio. system. Well that is certanly
an interesting fact to know but does not say anything about
the reliability of using regio. system in practice.
"Regiomontanus believed he had recovered a system that Ptolemy had in mind, but he was wrong" Also, this statemen makes unwarrented claim
without any explanation or evidences to support why regiomontanus
failed to replicate Ptolemy's system.

If anyone could answer this, I will really appriciated it
so I can rule out regio. Actually in all of my practice, I use
alcabitus without any justification..
I think I must learn how to calculate houses according regio. system..
does anyone have any comprehensive sources for this?

You could read Mike Wackford's series of articles, starting with http://www.skyscript.co.uk/polar1.html. It doesn't go much into the historical aspects of various house systems, but does provide a sound analysis of many of the issues.

- Ed

Dear. Ed.

Thank you, this is very nice of you.
Starting my reading now! lol