The question I always have on my mind regarding the Morinus system is: why did he choose longitude circles and not hour circles in his design? Choosing longitude circles results in cusp 1 not being the Ascendant and cusp 10 not being the Midheaven, although they're always quite close.

I read somewhere that Morinus explained his choice in-depth in his book, but unfortunately I've not been able to find it. (I don't have access to AG.)

Can someone here paraphrase what Morin said about this subject? Thanks in advance.

I'm not actually sure that the AG is where Morin discussed his proposed system, but his reason for constructing it in the first place was for use in polar regions where there may not be an ascendant or a midheaven in the usual sense.