by Jamie Longstreet
Interesting
to me always, is that Ebertin uses declination midpoints in his work.
To derive the midpoint via declination he applies basically the same rules
that are applied when calculating the midpoint in zodiacal longitude.
However, the longitude goes from 0 to 360 degrees and declination subdivides
itself into North and South declination. This complicates things for those
who are not visual. I'll try to provide an example.
If you look at a
planet - Say the Sun - and it is at 22N17 by declination and the Moon is at 18S08
degrees by declination, finding the midpoint could become
a matter for panic . . . don't despair. If you visualize a circle with
half of it South and the other half North and then place your points on it -
ah, remember in the tropical zodiac that the circle starts at 0 Aries reaches
apex and nadir at at 0 Capricorn and 0 Cancer and ends at 0 Libra -
this is the same in declination. On the apex and nadir the story is
just a little different. The zero Cap and Cancer points correspond to
23 degrees and 27.5 minutes North or South. Now, simply place the points
on the map and then visually locate the midpoint.