NavList:

"I think it's well known that 1' of arc varies in length as a function
(cos)
of the latitude."

That is true for one minute of longitude because parallels of latitude are small circles.
This is not true for one minute latitude of for any 
other great circle. (Technically these also vary slightly due to the 
oblateness of the earth but these small variations are ignored for
 celestial navigation purposes.)

gl

From: Irv Haworth <irvhaworth@shaw.ca>
Subject: [NavList 7052] Re: FW: [NavList 6952] Re: Chronometer Suggestions
To: NavList@fer3.com
Date: Wednesday, January 14, 2009, 4:25 PM

Hello FER
Sorry for delay in responding to your comments.We have been snowed in and my
health (and perhaps mental..hi...hi) is not what it should be.

O.K. If I digest your message correctly it is unclear to you what I'm
trying
to say (most unfortunate as English is my first and really only
language..h.). I appreciate that my attempts at writing a good preacipe have
failed.
However before carrying forth , I would appreciate it if you would tell me ,
exactly what is not clear. (I find it hard to believe that you are
questioning the note about mass varying with latitude or that the  length of
1 NM (admittedly I had tongue in check when I presented it to several
decimal places) or that 1' of arc on a GC is = 1 NM or about Marc
St.Hilaire
and the intercept technique. 
I think it's well known that
 1' of arc varies in length as a function
(cos)
of the latitude on  say the earth so that to me leaves to believe the
problem lies  with how does one plot his position on (a) a sphere (globe)
(b) on a Mercator chart.
Given the above I would be most appreciative if you would spell out, in
specific / definitive terms where you believe my statements are without
foundation.
Kind regards;

Irvin Francis Haworth
L 49° 20.895' N
λ 123° 08.617 'W
 

-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf
Of frankreed@HistoricalAtlas.com
Sent: January 10, 2009 4:29 AM
To: NavList@fer3.com
Subject: [NavList 6973] Re: FW: [NavList 6952] Re: Chronometer Suggestions


Irv H., you wrote:
"I don't think this forum was intended to be used as a teaching
platform "

Who told you that?? There are plenty of opportunities to teach
 here.

That said... ahem.

Look, Irv, I've re-read this last post from you three times, and I have to
tell you, I can't figure out what you're trying to say. And of the few
claims you appear to be making, several seem flat-out wrong. I would invite
you to clarify your points. Don't mince words. Spell it out in detail so we
can make sense of what you're saying...

-FER