Interesting link.
http://www.unc.edu/~rowlett/units/dictN.html#nautical_mile
It goes on about the various exact definitions of “nautical mile,” and then it says “There are exactly 60 nautical miles in a degree.” I think the mailbag used that one!
RM Mentock, you are responding to my earlier posting that has been superseded by later postings of mine in which i agree with some things you say.
While a dictionary can give you several definitions of a NM, the international definition used by navigators afloat and aloft is 1852 m as explained in the page I linked to: In 1929 an international conference in Monaco redefined the nautical mile to be exactly 1852 meters. I have no doubt there can be rule of thumb definitions, historical definitions etc but today the only recognised value of the NM is 1852m.
Regarding the definition of geographical latitude we do not need to go into it as I am fully aware of what it is and I am not disputing anything you have posted.
As I say, your post refered to an earlier post of mine. Right now my position is that the mailbag answer contains an error as explained in my last post before this one.
Just for the record I’ll state that I am quite knowledgeable about celestial navigation which I have studied, practiced and taught.
I started this thread on the subject but, unfortunately it hardly found any interest.
hehe, we are crossposting. that is why i said there is a contradiction in that definition. a NM cannot be both 1852m AND 1/60 of a degree.
Actually I have emailed the author in the past about some mistakes i detected and he corrected them and we had some pleasant exchanges. I think I’ll point this out to him
OK, sailor… I’ll let you and Monty hash this out, and if Monty wants to have a change made in the Mailbag Answer, he’ll let me know.
Thanks CKDextHavn, just trying to be accurate.
I emailed the authir of that page of definitions and now the phrase has been modified and reads:
Personally, I would have liked better (but it is my fault for not suggesting to him) something like:
The unit was originally designed to equal one minute of meridian arc at about 45 degrees of latitute, but the actual length of a minute of meridian arc varies from 1842.9 m at the equator to 1861.7 m at the poles.
I believe the term “meridian” is important. Note:
a minute of latitute at the equator: 1842.9 m
a minute of longitude at the equator: 1855.4 m