Monday, January 3, 2011

Q&A - How did you derive the true North direction of The Tabernacle?

Technically speaking, the Tabernacle North was determined according to the so-called "true North" (defined by the celestial bodies such as the Sun, stars e.t.c), as opposed to the "magnetic North" that is defined by Earth's magnetic field lines.

Here are couple of excerpts to clarify the difference between "true North" and "magnetic North"...

This one is from the book called "Practical navigation" by Warren W. Sheppard, Publisher World Technical Institute, 1920:
"It was many years after the discovery of the compass before it was suspected that the magnetic needle did not point accurately to the north pole of the world, but about the middle of the sixteenth century, observations were made in England and France, which fully proved that the needle pointed to the eastward of the true north. This difference is called the variation of the compass and is named East when North point of the compass (magnetic North) is to the Eastward of the true North, but West, when the North point of the compass is to the Westward of the true North (see cut). The quantity of the variation may be found by observing with a compass the bearing of any celestial object, when it is in the horizon, or, as it is called, the magnetic amplitude, the difference between this and the true amplitude found by calculation will be the variation. The same may be obtained by observing the magnetic azimuth of any celestial object (that is, its bearing by a compass when elevated above the horizon). The difference between this and the azimuth found by calculation will be the variation.

Some years after the discovery of the variation of the compass it was found that it did not remain constant, for the Easterly variation observed in England gradually decreased until the needle pointed to the true North, and then increased to the Westward, and is now about 18 degrees West on the East coast of England.

The compass needle points to the magnetic poles of the earth, and as the magnetic poles do not coincede with the true poles of the earth, which are at the extremities of the exis of revolution and between which the true meridians are drawn, it may be seen that the magnetic meridian forms an angle with the true meridian and the difference as before explained is the variation of the compass. The magnetic North and South poles have been found. The magnetic North pole is in the latitude of 70° North and longitude 97° West. The South magnetic pole is situated in latitude 70° South and longitude 145° East.

The magnetic equator is not the same as the earth's equator, but an irregular line running around the earth, not very distant from the equator, which it crosses in two places. One near the West coast of Africa and the other in the middle of the Pacific Ocean. The variation differs greatly in different parts of the world, both in direction and in quantity, the needle inclines to the Eastward of the true North in some localities and to the Westward of the true North in others, and is called respectively Easterly and Westerly variation. Over the North Atlantic Ocean the greater part of the South Atlantic and Indian Ocean the variation is Westerly and over a part of the Atlantic and in the Pacific Ocean the variation is Easterly. There are places where there is no variation, the needle pointing to the true North. One of these so-called lines of no variation runs through Eastern Europe, Asia and Australia, another runs through North America, the Eastern part of South America near Rio Janeiro, Brazil and the (Southwestern part of the Atlantic Ocean. The annual changes of variation may always be found recorded on the compass diagrams on the Government charts."

As example, here is a map of Magnetic Intensity in Northern Hemisphere as of 2000. Today (2010) it would be different.



And here is another one from the book called "Aerial navigation" by United States. War Dept. Division of Military Aeronautics, Publisher Govt. Print. Off., 1918:
"One very common error made in orientation is that of comparing true north on the map with magnetic north on the ground, or vice versa. Care must be taken to compare true north with true north only, and magnetic north with magnetic north only, unless the proper correction has been made to work from one to the other. Maps which have no north line marked upon them may be assumed to be drawn with the direction of true north parallel the side of the map and painting toward the top."

............

"For example, if the compass needle allowing for variation and deviation points 10° to the west of true north, then true north bears 10° to the east of compass north; that is, the compass bearing of true north is .10°."

Here is a typical example of a modern nautical compass rose. The outer circle (true rose) is aligned with true north; the inner circle (magnetic rose) with magnetic north. Inside the magnetic rose there is also an older 32-point graduation.


 
You can also check out this article for more general and brief information of different techniques of identifying the "true North".

Now that I have explained the difference between the "true North" and the "magnetic North", I would like to touch on the reasons why the Tabernacle was using "true orientation" and not "magnetic orientation".

  1. Original text seems to imply "true orientation" by using specific expressions (words) that cannot be attributed to just any orientation or to magnetic orientation.
  2. It is much easier and much more reliable to use "true orientation" instead of "magnetic orientation", especially in the wilderness environment.
  3. Symbolically speaking, it would be also logical to assume that the divine Tabernacle would have been using celestial (cosmic) orientation (true orientation) based on the celestial bodies such as the Sun, stars, Earth-Sun orbit. This would, so to speak, symbolize an outreach to the Heavens (cosmos), instead of into the Earth (in case the magnetic orientation would've been used).
I would like to comment more on the first two points:

When original text speaks of the orientation of the Tabernacle, which is expressed in verses that describe Boards or sides of the Courtyard of the Tabernacle, it always uses very specific expressions (words) that are also utilized in other parts of the text to define specific "landmarks".

For example, in Exodus 27:13 (Exodus 38:13), when describing Eastern side of the Courtyard, an expression לִפְאַ֛ת קֵ֥דְמָה מִזְרָ֖חָה [lifə’aṯ qēḏəmâ mizərāḥâ] is used, that is literally translated as "for the eastward edge toward the sunrise".

Same goes for, say, Exodus 26:20 (Exodus 36:25), where expression לִפְאַ֣ת צָפ֑וֹן [lifə’aṯ ṣāfwōn ] which is literally translated as "for the edge of north" or "for the edge of seclusion".

The remaining directions are also identified according to the "true orientation". West is referred to as "sea ward" and South is referred to as "Negev(desert) ward".

Another reason why "true orientation" is implied by the original text, is that because it would be a reliable way to orient during the evening and night hours; conditions that wandering Israelites would encounter as per Numbers 9:21. So, if the Tabernacle would have to be put up during the evening or night hours, Israelites would have to have a reliable way to determine or check the correct orientation of the parts of the Tabernacle.

And last but not least, magnetic orientation can be unreliable due to natural or artificial magnetic interference that may be present in the particular area. I.e. large deposits of metals or magnetic fluxes can trow off (or even make impossible) use of the compas.

So in conclusion, even though the wandering Israelites most likely possesed compas technology and primarily relied upon the Pillar of Smoke and Fire to guide them through the desert, correctly orienting the Tabernacle was still their burden which was accomplished primarily with help of celestial navigation and knowledge of techniques to identify the "true North" direction.

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