I use them fairly extensively relative to their usage today but still only under certain circumstances. The following is a quote from Kushyar Ibn Labban:

In this way the dodecatemorion of houses and of planets is obtained.
When a planet is in the dodecatemorion of <another> planet, it (the former) is in application with it (the latter). When it (a planet) is in the dodecatemorion of a house in the diagram of the horoscope, it is the same as when it is situated in this house. By the kindness and favour of God. (Introduction to Astrology, ch. 17)

I find the first part especially useful in connecting planets which have no traditional aspectual connection, and also in mitigating aversion when a planet is in its own dodekatemoiria (such as Mars in 27'30 to 29'59 of Sagittarius).

I don't use the 2nd part claiming a planet also being in the house of its dodekatemoiria so freely as I don't use houses very much in natal delineation, but I always note the dodekatemoiria of a planet falling on another planet or a lot, most especially in revolutions, but also, obviously, in the nativity.

@Lorenzo:

Thank you for the information!


@Johannes Susato:

(Your last name reminds me of a Japanese character...)

Let me answer your second question first. I have read about this method peripherally, but I'm not familiar with it. Ile from Beyond The Heaven gave a pretty clear explanation about this method (http://beyondtheheaven.wordpress.com/20 ... ascendant/).

Based on what he wrote, and from what I've gathered in Lorenzo's post, you do not multiply the degrees and minutes by 2.5, but rather divide by 2.5.

For example, Lorenzo wrote (italic part is likely a typing error):

"2) Like *d?dekat?morian* *d?dekat?moriou* indicates the 12th part of a sign, that is 2?20'. The first dodekatemorion of a sign is governed by the sign itself, the second by the successive sign and so on. This is put forth by Manilus in..."

Using the division method gives you the same sign as the multiplication method. If you know the sign, you know approximately where it is in the chart, but you won't know the exact degree. (This method is consistent with the whole sign house system.)

To illustrate, my Ascendant is at ~23 degrees Taurus. Dividing by 2.5, I get 9.2. Since 9.2>9, my Ascendant's duodecatemorion is in the 10th sign from Taurus. That would be Aquarius.

Using the multiplication method this time, 23*12=276. 276/30=9.2. 9.2>9, so again, this shows that the dodecatemorion is in the 10th sign from Taurus. (Note: the second step is an alternate step to the one I outlined earlier, where I asked you to count the number of degrees from the 0th degree.)



There are three additional things I want to talk about regarding this. I hope I'm not stating the obvious.


First, why 2.5 degrees? We are dividing a sign into twelve parts, giving each sign rulership over equal portions of that sign. There are 30 degrees within each sign. 30/12=2.5 degrees.

So Aries 0-2.5 degrees are ruled by Aries, Aries 2.5-5 degrees are ruled Taurus, Aries 5-7.5 degrees are ruled by Gemini, and so on. Taurus 0-2.5 degrees are ruled by Taurus, Taurus 2.5-5 degrees are ruled Gemini, Taurus 5-7.5 degrees are ruled by Cancer, etc.

Note how this method of sign division is very similar to the decanates.


Secondly, why do the two methods coincide? First let's look at the procedure of the multiplication method. Let D be the degrees and minutes of the planet/point. First, multiply by 12: D*12. Then, divide by 30: D*12/30.

As most of you probably know, if we want to change the formula so that it becomes "D divided by something" instead, we flip the numbers around.

So, D multiplied with 12/30 is the same as D divided by 30/12. Mathematically: D*12/30=D/(30/12).

30/12=2.5, so we get the formula D/2.5 degrees. This is the division method. Therefore, in essence, both methods are the same.


Finally, although I said that you cannot know the exact degrees of the sign the dodecatemorion is in using the division method, there's actually a way of finding the exact degree despite using it.

What I mean is that the result of the division alone will not tell you the exact degree, unlike when you use the multiplication method and then use the count step (instead of dividing by 30.)

To find the exact degree, after you have found the result of the division, subtract the whole number, then multiply by 30. That is the exact degree.

To demonstrate, when I've divided my Ascendant's degrees by 2.5, I got 9.2. 9.2-9=0.2. 0.2*30=6 degrees. Hence, my Ascendant's dodecatemorion is at ~6 degrees Aquarius.



To answer your first question, I have not read all the information about it in Maternus's and Valens's texts yet. I will refrain from giving an answer for now, so as to not confuse anyone. I will return to your question once I have completed my reading.

Good morning,

Aside from the linguistic questions, one might enquire if calculations of fixed and wandering stars' positions as well as of Asc, MC, Desc and IC were sufficiently accurate in Senator Julius Firmicus Maternus' time to warrant the interpretation of dodecatemoria, by 12 or by 13.

My humble opinion: probably not. Compared to contemporary measurement methods (Mr James Herschel Holden frequently mentions such problems in the footnotes of his translations and in his book on the history of horoscopic astrology), prior calculations including the Renaissance (example: Placido di Titi) were in error by an average of three degrees of ecliptic longitude, by six degrees or more in the case of Herm?s. This means on the average more than one entire dodecatemorion! Confines were as likely erroneous as not. Beginning with decans, the positions assigned were more likely than not correct.

With an adequately large randomly selected data base, one might today investigate to what extent, if any, significant correlations between events and dodecatemoria exist, bearing in mind that, even today, ephemerides differ.

Similar comments would apply to even smaller subdivisions, known for example in Indian astrology.

Best regards,

lihin

I remeber reading somewhere, I believe it was in an excerpt of Ben dyke's the search for the heart, that the 12th part of the ascendant was used in horary to ascertain the area of interest of the querent, that he sometimes would not tell the artist.
I've also noted many artist who have the 12th part of the ascendant on the 5th house nataly, so it is something I have been taking into account when delineating professions, or things that the person seeks/enjoys (when the birthtime can be trusted).

Using this logic I find it interesting that in George W. Bush's chart, that Stellarium posted the 12th part in conjunct the I.C. Seeing that this man has the same profession as his father.