This is the text in which Ronald Davidson introduces his "Relationship Chart." This chart, which is similar to a Composite Chart, uses the theory of midpoints to mathematically create a chart that will be symbolic of a relationship between individuals. Unlike the Composite chart, which uses degree midpoints between the same planets in the two individuals' charts (i.e. the midpoint between the individuals' Suns, Moons, Venus etc) this Relationship chart uses time to create a midpoint structure. A basic and not an all inclusive example to present this theory is, say one partner is born on June 4, 1963 and the other partner is born on December 5, 1963, then their relationship chart would be created for the date September 4, 1963, which is the midpoint between the two dates. I'm using a crude example and there other considerations to take into account, but basically you look up the planetary configurations for the midpoint date and that would symbolize the relationship.
A composite chart uses the midpoints between planetary degrees. Hence, Sun in Sagittarius at 13 degrees, and the partner's sun in Gemini at 13 degrees would produces a composite Sun of 13 degrees along the Virgo/Pisces axis, and likewise you'd do this for all the other planets and sensitive points and place those degrees in the chart; which symbolizes the couple's relationship. Again, I'm using a crude example and there are other considerations to take into account. Astrologer John Townley introduced the Composite chart into America back in the early 1970s. Robert Hand then elaborated on Townley's work and their methods were the leading technique for analyzing relationships, until Davidson came up with his Relationship Chart. Many astrologers, including Townley and Hand, have criticized Davidson's work and have called it scientifically challenged. On the other hand, there are other astrologers who have tried the Davidson technique and they find it superior to the Composite chart. Unfortunately, the reasons for the debate are too lengthy for me to present in this review. I just want those of you who are unfamiliar with this chart to know about the debate so that you can test the two approaches and objectively arrive at your own conclusions.
For me, I have been using both techniques for a number of years now and I have tested both methods extensively. My own conclusion is that the Relationship Chart cannot be easily dismissed. Although there may be scientific reasons working against it, namely it doesn't take into account the motion of retrograde planets, the relationship chart has on many occasions described a relationship quite accurately that I had to evaluate. Others have claimed it failed them, I have not found this to be the case. I think that those of you interested in relationship analysis might want to take a look at Davidson's theory and see what your results prove. But I would not recommend discarding this method until you have given it a fair trial.
Although this book introduces the Relationship chart, it is primarily dedicated to analyzing relationship synastry, and here, Davidson's insights are frequently good. However, Davidson omits Ascendant and Midheaven cross aspects, and I wish he would have expanded his cookbook approach to include more depth and analysis of the various kinds of cross aspects between planets. It seems that few astrologers have taken up the challenge to write a comprehensive and in depth synastry text, and for this reason Davidson follows suit with many other authors by using condensed evaluations. All in all, this book is a good addition for your astrology library. However, you might want to also look at other authors such as Steven and Jodie Forrest, E. W. Neville, Derek and Julia Parker, Jeffrey Wolf Green, and Liz Greene, to name a few, so that you'll get a nicely rounded view of relationships analysis through such various approaches as spiritual, psychoanalytic and evolutionary methods of interpretation. Davidson's text stands out as a unique and thoughtful approach to relationship analysis, and it is particularly useful if you want to learn and explore the Relationship Chart.
One final note, and I hope this helps. Casting a chart by hand can be troublesome because of the math involved. Astrologer Allen Edwall created software that generates composite and relationship charts that you can download for free. The program is called MatchMkr. It might be helpful to you, if you don't want to erect a chart by hand. Good luck!
I am a novice at understanding astrology, let alone synastry. However, I have looked at and studied composite charts as well as helping to interpret aspects to natal charts. I found this book very helpful for an overlay. It gives a description of what one might typically expect. The author suggests that when reading the interpretations that we can change the written language from he to she. I found this a bit troublesome. I think it would have been better expressed in gender neutral language.
Though I am a novice to the data he refers to, I do believe, based on my many conversations with people asking questions about synastry, that he is fairly accurate. The book is basically easy to read and understand.