NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Napier Diagram + north from Tassie
From: Eddie C. Dost
Date: 2006 Jan 29, 07:23 +0100
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. Thanks, Eddie 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 -- __________________________________________________brainaid______________ 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