In Christian Astrology Lilly gives an example about the missing brother (CA, p.197) in which Lilly tells the querent that he shall hear news of his missing brother “very suddenly” because the querent’s ruler Saturn Rx at 29 Aries 13 is mutually applying to a favorable TRINE with his brother’s significator Venus at 28 Sagittarius 53. According to Lilly, this trine will prefect about 4 pm the same day as the question, so Lilly advised the querent that he would receive news of his brother around 4 pm in London. The querent later confirmed that Lilly was correct.
The problem is that by modern calculations, this Venus/Saturn trine has already perfected at the time of the question, and Venus was separating from Saturn when Lilly cast the chart using what appears to be inaccurate data by modern standards. This raises the question posed by Geoffrey Cornelius in his book The Moment of Astrology of whether Horary Astrology is a system of omen interpretation in which the omen may or may not be the chart cast for the time of the horary question. In this example Lilly got the correct answer by interpreting a chart with inaccurate planetary positions, which happened to be an apt omen for the querent’s question despite the fact that the astronomical data were not correct.
Here is the chart with modern calculations. Capricorn rises, making Saturn the querent’s ruler. Taurus on the 3rd cusp makes Venus the significator of the missing brother. Saturn Rx at 28 Aries 55′ 17″ and Venus at 28 Sag 56′ 05″ are separated by 0 min 48 sec (0′ 48″) of arc. Lilly defined separation as “when two Planets are departed but six minutes distance from each other,” so in the modern chart Lilly would consider the Venus/Saturn trine to be in effect, but he would not have said that the trine would perfect at 4 pm since is it already past being exact by one minute of arc.
It’s also a bit puzzling why Lilly insists on a 6 minutes of arc distance between planets to consider them separating. Here is a diagram from wikipedia which shows the relative sizes of the planets to the human eye. Six minutes of arc is a large distance for all the planets other than the Moon and the Sun.
In the chart with modern calculations, the trine of Venus and Saturn occurs with the centers of the two planets having just 0′ 48″ of arc separation. In the diagram above, the average angular diameter of Venus is about 38″ of arc (range, 9.7″ – 66″), and the average angular diameter of Saturn is about 17″ of arc (range, 14.5″ – 20.1″). Thus 38″ + 17″ = 55″ of arc for the combined average diameters of the two planets. Since the centers of the planets are only 48″ of arc apart, the bodies of the planets are “touching” in their trine aspect, so Lilly is correct in saying that the querent will very soon hear from his missing brother.
A useful discussion of the greatest illuminated extent of Venus, which occurs about 36 days before and after its inferior conjunction with the Sun, can be found at http://earthsky.org/tonight/planet-venus-reaches-greatest-illuminated-extnet where this diagram can be found: