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George

I believe you have put your finger on precisely why there is misuse and
misunderstanding of the term 'Assumed' Position:  and clarified for me why
some of my students don't instantly latch on to what I am saying to them
about sight reduction.

The original meaning of the word 'to assume' meant to take up a position or
office;  "he assumed the position of first mate".  Only later did 'to
assume' acquire the meaning in popular usage of making use of a convenient
value or fact.

For some reason (probably due to receiving an 'old-fashioned' education from
literate teachers) I have always understood 'Assumed Position' to mean what
would have been the understanding when inspection tables were first produced
(eg Revd Ball, 1907) - namely, that one imagined physically relocating to
the AP and used the tables to find what would be seen from that position.

'Assumed' means 'going to a location' not 'taking up a convenient value'.

Geoff Butt

----- Part of Original Message -----
From: "George Huxtable"
:
: And (reluctantly) he accepts the name Assumed Position, or AP to refer to
: "any preselected point defining the region of interest", quibbling
somewhat
: about that name by saying "... that's misleading; we are not assuming the
: ship is there- on the contrary, we usually expect that it is not". But (to
: quibble back) isn't that what the word "assuming" implies? You "assume"
: something to be the case, whether or not it actually IS the case. Usually,
: "assumed position" has been used for a position which is deliberately
: displaced from the DR, to allow whole-degree entries in the alt-az tables
: (and an unnecessary distraction when using a calculator, as John Karl
: recommends). Later in the book, he uses AP in that special context.
:
: What I'm saying, really, that his use of DR, AP, EP can be different from
: the usage you may find elsewhere, which is fair enough, when those
meanings
: have been carefully defined. Indeed, you may find in other works the terms
: chosen position, trial position, just to add to the complicated mix.
:
: George.
:


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