James: it's on p. 75. You could have found it under 'keys' in the index. Or by just reading the book.

thanks margherita and martin,

well it definitely wasn't under placidian keys, and the index includes a lot of reference to placidius and i didn't look at them all! i did read the book about 6-8 months ago, but unfortunately i didn't ''remember'' everything in the book.. there is a difference between reading a book and remembering the book.

martin, does your conclusion on page 102 regarding placidus methods also include his use of this key? you mention on page 79 the key of placidus will be less predictable..

with so many keys to choose from, one is bound to find a 'key' to open the door of prediction, in hindsight at least..

thanks james

james_m wrote:
martin, does your conclusion on page 102 regarding placidus methods also include his use of this key? you mention on page 79 the key of placidus will be less predictable..

with so many keys to choose from, one is bound to find a 'key' to open the door of prediction, in hindsight at least..

thanks james

I believe the use of the key and of the method is very personal. In Cieloeterra for example they use only Placidian directions and key since many years. Others would say differently.

Maybe you should find your way,

margherita

thanks margherita,

that is indeed just what i am doing. i have gotten a different response from every person i ask who is supposed to be knowledgeable on this. one can't make predictions into the future without a better certainty on the tools they use, or the options that go with these tools beforehand.

james

james_m wrote:well it definitely wasn't under placidian keys

No, as I said, it could be found under keys. Or under Placidus. The pages listed against both these entries would have been my first choice.

martin, does your conclusion on page 102 regarding placidus methods also include his use of this key?

Which conclusion do you mean?

As I wrote on another thread some time ago, directions are a highly technical subject that requires systematic study -- not necessarily under a teacher, though that can help. The chances of picking it up piecemeal are very poor.

hi martin,

thanks for getting back to me here. it appears i am not the only one who can be accused of not reading! the quote i mention is the one i gave in an earlier post directed to you. thanks for your feedback. fwiw,there are 35 different page references for placidus in your 193 page book. i suppose i could have just read the book again too which i plan on doing at some point in time! if one searches in the index for 'true solar equatorial arc' which is the first thing i did, a person would be out of luck as well.
cheers james

james_m wrote:
i did happen to note on page 102 in the summary for chapter 8 'modern innovations' - "Placidus further invented a directional method based on planetary poles and circles of position, meant to approximate the Ptolemaic method. Many later authors mistakenly accepted this approximation as the preferred method of Placidus." would this include this placidus key 'true solar equatorial arc' that you are referring to here? it would seem chapter 8 of ganstens book covers placidus approach in many respects.

james

It's still not clear to me what you mean, James. Placidus' equation of time (his 'key') has nothing to do with his method of directing under the pole.

thanks martin,

you've clarified the fact his key is not the same as one of his methods of directing (under the pole) for me. i will have to re-read your book to get a better understanding of your views on what you think placidus preferred methods actually were.

what are your thoughts on the large differential in time that comes with one's choice of the primary key they use? in this example that margherita has given there is a difference of 4 years for the particular direction of mars to the opposition of the sun which makes one realize the use of this key is going to give very different primary directions then the use of the ptolemy key. trying to ascertain the relevant primary directions in an event is difficult enough as it is without also realizing depending on which one a person uses the gap in time can be very great as in this example.

james_m wrote:i will have to re-read your book to get a better understanding of your views on what you think placidus preferred methods actually were.

My views on what I think they were? Goodness. I hope my account of Placidus' preferences is more objective than that sounds. I do give my own views occasionally, but first and foremost, I try to give the facts.

Yes, the choice of time key can make a big difference. It's only one of the factors involved, though -- as I said, directions are a technical subject. Personally, I prefer to keep things both simple and traditional, with 1 degree of ascensions equalling 1 year (or something very close).

martin thanks for the feedback.

Martin Gansten wrote:

james_m wrote:i will have to re-read your book to get a better understanding of your views on what you think placidus preferred methods actually were.

My views on what I think they were? Goodness. I hope my account of Placidus' preferences is more objective than that sounds.

martin that was in response and reference to what you specifically said on page 102 in your book!

james_m wrote:
i did happen to note on page 102 in the summary for chapter 8 'modern innovations' - "Placidus further invented a directional method based on planetary poles and circles of position, meant to approximate the Ptolemaic method. Many later authors mistakenly accepted this approximation as the preferred method of Placidus."

james

Many later authors mistakenly accepted this approximation as the preferred method of Placidus.

They did; but the fact that Placidus really advocated the semi-arc method is just that: a fact, obvious from his writings, and not a mere view or opinion.