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    Re: Napier Diagram + north from Tassie
    From: Eddie C. Dost
    Date: 2006 Jan 29, 07:23 +0100

    Hi Bill,
    I have programmed this using "gnuplot" on Unix, I can output the diagram
    in hpgl or postscript. I could post the source (where you can see what
    lines to plot), the hpgl and the postscript to this "new place". Please
    tell me where this is, as I have lost the link to this place.
    On Sat, Jan 28, 2006 at 08:37:03PM -0500, Bill wrote:
    > > Bill, it wouldn't be too difficult for a bloke of your many talents to draw
    > > up a nice fresh one, would it?
    > Not difficult, just time consuming.  According to Chapman's the lines are
    > all at 60 degrees angles to the main vertical degree line.  What I am not
    > clear on is the spacing for a degree of deviation along those 60-degree
    > lines.  That would have to be retro-engineered. My first guess is that with
    > a 60/60/60 triangle the spacing will be identical to the vertical axis. The
    > curves of course are what one draws in after finding deviation.
    > In searching the internet for the Napier Diagram, I ran across a bit of a
    > history on him, and some of his other projects.  A very clever (brilliant)
    > fellow indeed.  I would hate to try second guessing him.
    > If push comes to shove, will indeed do my own.  Need to think about
    > copyright laws before posting.
    > Enjoyed your recounting of "men without boards in the companionway?"  How
    > the heck did they mange to fill the boat water!
    > "Always step *up* into a life raft."  LOL
    > ============================================================
    > Off topic, pulled out some more dusty Ansel books this AM.  He bemoans the
    > "K factor" (to HELP us) in most light meters that can cause 1/3 stop over
    > exposure, as well as the f-stops in many of his view camera lenses being off
    > for smaller openings (higher f-numbers).
    > Also tracked down his conversion of foot candles to shutter speed.  Foot
    > candles (incident light) once reflected yields foot Lamberts (for example
    > 100 foot candles reflected off a 50% reflective surface yields 50 foot
    > Lamberts. Foot Lamberts divided pi become candles/ft^2, then divided by the
    > square root of the f-stop gives the reciprocal of the shutter speed.   Pi
    > seems to be a kissing cousin of the conversion factor listed in "Pocket
    > Reference" of. 0.31831.  Wow, a long way to go.
    > Ansel also stated a Polaroid filter reduced light by about 1 1/3 stops.
    > Noticed in the Schneider PDF the number "2" popped up for their "superior"
    > filters, but I don't recall the context.  It would appear you have some nice
    > gear there.
    > Have a great trip.
    > Bill
    Christian Dost          brainaid GbR              Bluecher & Dost
    software                Monheimsallee 45          phone +49 241 5151 138
                            D-52062 Aachen            fax   +49 241 5151 139
    ecd@brainaid.de         Germany                   cell  +49 172 9312808

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