!4C, your rule of thumb works where the conjunction is extremely close. If it's not, you start losing the aspect as you move up to higher harmonic numbers.
For example, an opposition (2-series) in a 9H chart suggests that the planets will be conjunct in the 18H chart, as well as the 36H chart, and so on up the 2x9 scale. In practice, however, you lose the conjunction (and hence the minor aspect) if the orb is too wide. This is why people who look at harmonics use very narrow orbs!
Apparently there is astrology software that can show the minor aspects in the radix (natal) chart, with or without the major aspects. I don't happen to own it and I'm not sure what it is, but am guessing it's Solar Fire. Anyone? Alternatively I think Astrodienst lets you construct a radix chart that doesn't show aspect lines. So you could print one and just pencil in the ones you want.
MJ, I know of two ways to read a harmonic chart. #1, as !4C suggests, is to look at minor aspects such as the novile within the radix chart. This is helpful, because you get functional signs and houses. Most western astrologers don't use houses in harmonic charts, and debate whether signs are meaningful.
If a novile is hard to eyeball in a radix chart, you can look at data tables indicating the degrees of separation for each planet pair. In the case of the novile, look for planets 40 degrees apart. Or you can run a 9H harmonic chart, note the noviles, and then bring that information back to the radix chart. Maybe print off the chart and draw in the novile aspects if that makes them easier to see.
The other way, which I indicated above, is to interpret the harmonic chart as such. But what is a novile? It might act like a weak trine. Or, as Alice Portman (
www.aliceportman.com ) observes, it might be an aspect of initiation. Transits or progressions making a novile aspect might be particularly interesting to watch. Harding and Harvey,
Working with Astrology, see it as an aspect showing what gives you delight. In this context, trines in the 9H chart would show how your happiness flows easily; and 2-series aspects would show where it is more difficult.
Similarly, if you look at an 18H chart, we have a sense of what makes you happy, but there is an edge to it; perhaps something requiring more struggle or tension to manifest it because of the 2-series.
Vedic astrologers work extensively with harmonic charts, but I can't speak about it from experience.