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[DPRG] Engineering angles vs. navigation angles

Subject: [DPRG] Engineering angles vs. navigation angles
From: Paul Bouchier bouchier at classicnet.net
Date: Thu Mar 17 18:21:42 CDT 2011

Erudite speculation from Rud & Randy. Just adding one more guess related to
"why clockwise on a compass", this article:
http://en.wikipedia.org/wiki/Clockwise
States that clock hands turn clockwise because they were originally built to
echo the movement of the shadow on a horizontally-mounted sundial (though
there were a few clocks built which run counter-clockwise). Compasses and
chronometers have a long association in navigation (though the first
nautical chronometers weren't invented until the 1760's), but it would be
odd to have a compass increase left when clocks (which were around from the
1500's) increased right. Also, screws increase right (clockwise) because the
human arm can pull harder than it can push (ref Clockwise article above), so
perhaps more imporantly than the sinister bias Randy refers to is a very
real human bias toward things that go clockwise that's based on physiology
as it relates to right-handed people.

Thanks for the interesting question John.

Paul

> -----Original Message-----
> From: dprglist-bounces at dprg.org 
> [mailto:dprglist-bounces at dprg.org] On Behalf Of Randy M. Dumse
> Sent: Thursday, March 17, 2011 4:00 PM
> To: 'John Swindle'; Dprglist at Dprg.Org
> Subject: RE: [DPRG] Engineering angles vs. navigation angles
> 
> 
> John Swindle said: Thursday, March 17, 2011 2:04 PM
> > Why do math/science/engineering angles start with 0 pointing
> > to the right and increasing counter-clockwise while 
> > navigation angles start with 0 pointing up and increasing 
> > clockwise? 
> 
> John, I once found a link that described "navigator 
> coordinates" but I can't find it now.
> 
> So let me take a stab at this off the top of my head.
> 
> I think DesCartes gave us the start with his name saked 
> Cartesian Coordinates. 
> http://en.wikipedia.org/wiki/Ren%C3%A9_Descartes
> http://en.wikipedia.org/wiki/Cartesian_coordinate_system
> 
> I believe our first introduction to a number line starts on 
> the horizontal. For instance a line across a paper. Because 
> of the sinister/dexter bias coming from the latin, right is 
> considered positive and left negative. Likewise, up is 
> considered positive, and down negative, as might be observed 
> in the heaven/hell bias. So when you orient a cartesian on a 
> page in front of you, you laydown the independent variable 
> first, right and left (usually x). Then you lay down the 
> dependent variable on the next most convenient axis, up and 
> down (usually y).
> 
> Now also remember, negative numbers are an advanced concept 
> too, and when you first deal with charts, you usually only show x
> (horizontal) and y (vertical) in the first quadrant. So there 
> you have the scientific or mathematical basis for a 2-axes 
> chart. Right X and Up Y are your positives. Angles wuld start 
> comparing something rising y as comared to x, which makes for 
> a counter-clockwise rotation.
> 
> Now navigation starts from an entirely different perspective. 
> Looking ahead is the primary independent axis, so advancing 
> ahead is positive, or backing up is negative. Veering to the 
> right would be positive, and left  would be negative from the 
> same (sinister/dexter) origins. So here looking straight 
> ahead is positive, and your angle is oriented clockwise. 
> 
> So you might say the math/science/engineering angles come 
> from looking at a surface, and the navigation orientation 
> comes from actually being on the surface.
> 
> Randy
> 
> 
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