1 Minute = 60 Seconds?

[StuM]

Originally Posted by El Pinguino

And you can show us a chart where the north pole is a horizontal line?

And you can show us a Mercator projection where the north pole is within the bounds of the chart.

[StuM]

Originally Posted by El Pinguino

Time to ask the experts on maps and stuff

NFOMCL!
Jay Foreman and Mark Cooper Jones? "experts on maps and stuff"?

A singer/comedian and an ex Geography teacher turned actor/comedian?

Really?

[billgewater]

Originally Posted by RaymondR

Comes back to the fact that the Sumarians were not very skillful with sharp knives and the zero had not yet been invented at that time.

Yes, early Sumerian stuff shows the absence of a zero as a numerical concept, but later, around the middle of the second millennium BC they used the symbol for two 10's laying on its side as an indicator of "nothing" in the appropriate space. Check it out pages 152, 153,154 in George Ifrah's "The Universal History of Numbers". They also developed a special indicator that looks like their 10 symbol with an extended leg, again on its side (British Museum 24581). Symbols for zero's as place value indicators first appear in Cambodia and Indonesia but the Indian zero appeared later then in Mohamed ibn Musa's book on Hindi numbers. (about 895 AD). The modern Arabic zero is not a circle - it's a blob. The word zero means "empty" as in a circle. However, zero on a number line as we learn in school was a much later development. A very handy concept.

[Lodesman]

I'm with Stu. If a TM was taken to the pole, the pole will be a straight line across the top or bottom of the chart. The distortion would be so great as to make the chart unusable; so polar azimuthal projections are used instead at high latitudes.

From this chart you can plainly see the "stretch" that happens towards the pole - just look at the latitude scale (that would be the right and left sides of the chart ).

[El Pinguino]

Originally Posted by StuM

NFOMCL!
Jay Foreman and Mark Cooper Jones? "experts on maps and stuff"?

A singer/comedian and an ex Geography teacher turned actor/comedian?

Really?

Its good to see your humourectomy was a resounding success.

[El Pinguino]

Originally Posted by StuM

And you can show us a Mercator projection where the north pole is within the bounds of the chart.

Nope, don't have a roll of paper of infinite length to print it on.

This section of an Admiralty chart of 'The World' shows the mercator concept quite well. Only goes to 81º North for two reasons.

[RaymondR]

Originally Posted by Lodesman

(My bold) this is not technically correct. The mercator projection in most of the nautical charts we use, need to "stretch" the latitude as you progress N or S from the equator, to conform to the distortion that results from stretching the meridians apart (so they are parallel rather than converging). At large scales this is not very apparent, but on small-scale charts it can be quite pronounced. A careful mariner will need to measure distance on the latitude scale at the same latitude that it is being applied.

Spot on mate.

If you look at the representation of Canada and the Russian Republic on a Mercator chart, good god they take up as much land as every other country on the planet.

[StuM]

Originally Posted by Lodesman

I'm with Stu. If a TM was taken to the pole, the pole will be a straight line across the top or bottom of the chart. The distortion would be so great as to make the chart unusable; so polar azimuthal projections are used instead at high latitudes.

As Ping implies (knowingly or not), the distortion would actually be infinite

[El Pinguino]

Originally Posted by StuM

As Ping implies (knowingly or not), the distortion would actually be infinite

It was knowingly, but thank you anyway.

[Alan Mighty]

Originally Posted by StuM

And you can show us a Mercator projection where the north pole is within the bounds of the chart.

In his 1569 map, Gerhard Kremer (Gerry the Merchant, hence the moniker "Gerardus Mercator") pictured the N Polar region in an inset, showing he did recognise the problem.

See one of the three or so versions of his 1569 map at: https://www.mapcompanion.org/map-47-...orld-map-1569/

And here's the inset of the N Polar region, located in the lower left corner of said map and overlapping part of the smear later called Antarctica (merged with what later was called New Holland). You'll recognise S America:

[El Pinguino]

I'm rather surprised that the condescending one amongst us hasn't mentioned the relationship between Lat and Long on a mercator chart.
In simple terms - if 1' of longitude is '1 mile' at the equator at reduces as the cosine from one to zero at the poles. This is what we use in our calculations.
On a mercator chart we maintain the 1' of longitude at unity throughout the change in latitude
Sadly this means that a minute of latitude varies as the Secant of the latitude - from unity at the equator ( 0º )to infinity at the poles ( 90º). Therefore the concept of a 'flat line pole' is a non sense. Unless you have figured out how to get to infinity...

[Lodesman]

Originally Posted by El Pinguino

I can only speak for the British system and having gone to sea in 1963 can not recall ever having worked with a 'seconds' chart. That doesn't mean that there weren't a few charts of remote areas out there that no-one saw the need to upgrade.
I think that french one I mentioned, which I inherited with my yacht, is one of the few I have ever seen.

Might be the Yanks were a bit more resistant to change, much like with the Metric system. Here's an Alaska chart from 1998:

[Lodesman]

Just so everyone doesn't think I'm down on Yanks - they do a lot of things right, especially making charts available for free. They also have some really fun sites for cartography nerds, like this one: https://historicalcharts.noaa.gov/#searchInput

[rooiedirk]

Time to adopt gradians in navigation. That would be 400 degrees in a full circle.
1g would have a distance of 100km
1 c(enti)g 1km,
and 1 mg 100m.
https://en.wikipedia.org/wiki/Gradian

[Nord Sal]

Originally Posted by rooiedirk

Time to adopt gradians in navigation. That would be 400 degrees in a full circle.
1g would have a distance of 100km
1 c(enti)g 1km,
and 1 mg 100m.
https://en.wikipedia.org/wiki/Gradian

Careful proposing gradians, someone will hear radians instead and then things get irrational.