Dreamhouse: Attic: Roof: Astro: Lots: Calculation

Arabic Parts or Lots

How to Calculate the Formulas

There are two primary methods: numerical, and spatial. The numerical method is based on inserting the degree of the mentioned planet/point into the formula in the proper place, and completing the calculations. In the numerical method, there are two ways to convert the degrees for calculation. The simplest way is to use the following table to convert the degree to a proper numeral. To do this, use the number given for the relevant sign, then add the actual degree within the sign. This, of course, is based on the 360 degree circle. No number is allowed to go over 360 or below 0. Any number which does, must either have 360 added or subtracted to give a working number which falls within the specified range (0-360).

Aries = 0
Taurus = 30
Gemini = 60
Cancer = 90
Leo = 120
Virgo = 150
Libra = 180
Scorpio = 210
Sagittarius = 240
Capricorn = 270
Aquarius = 300
Pisces = 330

The traditional way to convert the degrees, and the way I actually learned, is somewhat more cumbersome and confusing for students, given that a single "number" is comprised of portions in several difference bases. I will give a brief example, and leave the details to those who really want to explore the subject.

For example, to calculate the Part of Marriage in my chart using the formula Asc + H7 - Venus.

Asc = 6 Aries 40

H7 = 6 Libra 40

Venus = 17 Virgo 06
This could be written as:

6 Aries 40

+ 6 Libra 40

- 17 Virgo 06.
Using the traditional method of calulation, sign is assigned a number of 0-11 on a scale of 12. The degrees remain in a base of 30 (30 degrees per sign), and the seconds of arc are of course 60 per degree. Thus, this could also be written as:

0.06.40

+ 6.06.40

- 5.17.06.
The trick with this is to remember when moving between signs, degrees, and seconds, to carry and subtract in the appropriate base for that portion of the "number." So, if you add the first two "numbers," the seconds add up to 80; you must subtract 60, leaving 20, and carry the number 1 over to the degree column. The advantage of this method is that you can, without performing the calculations, rapidly get a good idea of the sign and house location of the final result, simply by performing a rough calculation based on the houses, and a bit of the degrees. Naturally, to use in a proper delineation, one must have the accurate result to use with transits, directions, and progressions. (NOTE: Trying to calculate arabic parts is basically useless unless one has a rectified chart for the native.)

To perform the same calculation with the simplified approach mentioned above, you would convert the degrees and write the formula like this:

06.40

+186.40

-167.06
No matter, how you write it, any of the numerical approaches to calculation will give the same result:

26.14

0.26.14

26 Aries 14

To calculate a formula using a spatial method, also known as the method of the ancients, is very different, and will give different results based on your preferred house system. Be forewarned. A simplistic approach would be to overlay a transparent copy of your chart, with the subtracted planet/point on the natal Asc, and then mark the location of the added planet/point. This is for working purposes only. Since I do not feel secure in my ability to accuractely describe how to properly calculate a part using the spatial method, I gladly refer you to the instruction in Chapter Four, "The Methods," of Granite's book, specifically pages 43-59. Good luck in your explorations!

Last modified August 23, 1997.
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