# Why is North considered the reference direction in Surveying?

While Surveying, the North is always considered the reference direction, for the purposes of mapping. I have specifically the following issues:

1. The magnetic compass, has a least count of 30 minutes, and it deeply affected by local disturbances.
2. The pole star, which denotes the astronomical north, is not visible during the day time, while it is the best time to conduct the surveying process.
3. The sun, definitely cannot be taken as the reference object, as it is not fixed during the day, and also suffers from the sun moving from the north to south and backwards during various parts of the year.

Therefore, I would like to know, as to why the North was chosen as the reference direction for Surveying and Mapping.

• Because it was better than just saying left or the “big tree” - it may have its issues, but does have the advantage that everybody uses it. Nov 25, 2017 at 6:21
• Then what was the problem with South? "Everybody uses it" has the "crowd-is-right" logical fallacy attached with it. Nov 25, 2017 at 14:02
• some did use South, but they followed with the others when some chose North : it is much easier to have one system that all follow that different ones look at the number of styles of plugs for household use around the world which means a huge amount of travel adaptors sold .... Good for those who make travel adaptors though... Nov 25, 2017 at 16:56

Firstly True North is a well defined point which can be determined fairly easily by the pole star and indirectly (but still fairly easily) by a compass. Even if there was no pole star or compass this is still a fairly logical way to define direction on a rotating globe.

This also relates to the most sensible way to draw a grid on a globe. Having parallel lines of latitude and converging lines of longitude is as sensible as anything else, allowing for a simple global coordinate system which can easily be translated to a flat local map. If you define true north as the axis of rotation then from that simple definition you can work out the precise point as accurately as you want.

To put it another way if you draw an arrow on your map which points north it is then very easy for anyone else to determine exactly what direction that is supposed to be.

Also once you have established the direction of true north on a particular site you don't need to make every measurement from it directly. You can set up a physical marker or calibrate a magnetic compass.

Also you absolutely can use the sun as a reference point as long as you know the accurate local time relative to a reference time (noon at Greenwich being the traditional reference) in fact with the right instruments this can tell you absolute position as well as the direction of north.

As to why you use north rather than south, west or east, it doesn't makes any fundamental difference as they are all still defined relative to each other and historically north is the most convenient direction to find by the pole star, a magnetic compass or by observing the track of shadows. Plus if you have a universal convention that the top of a map is north it makes it easier for everyone to use and prevents confusion.

Finally I'm not sure what else you would use, you can pick any arbitrary direction you want but you still have to define it in terms of something and the same limits of accuracy of direction finding equipment still apply.

The Chinese invented the compass & ancient Chinese compasses pointed south, not north. Because of this, the Chinese used to draw their maps with south at the top. Arab map makers did the same, possibly because the Chinese did it that way.

Having North at the top became the dominant situation by the beginning of the 16th Century, when Europeans were in a world exploration phase. Map makers of the era, took note of what Ptolemy did in the second century AD/CE.

Based on the knowledge of the ancient Greeks, Ptolemy, who lived in Alexandria, in Egypt, realized

he was in the northern half of a very large globe

Previously though, there was a tradition among some Europeans to put East at the top of maps.

The Northern Hemisphere is home to approximately 6.57 billion people which is around 90% of the earth's total human population of 7.3 billion people.

From ancient times, it is logical that navigation over land and later across the sea would be conducted based upon the so-called North Star and magnetic north. A northerly reference point would therefore become a conventional orientation for the larger population of the planet.

I suspect that it is more a matter of culture and demographics rather than purely functional or technical origins.