Historical change in Magnetic Declination over time.

[kiddrock33]

im with stilldign on this one. if you use an angle system , to layout your symbols. this would have know problems with a shift.

 

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[Shortstack]

im with stilldign on this one. if you use an angle system , to layout your symbols. this would have know problems with a shift.

Isn't the "angle method" the way referred to in the book, De Re Metallica? I'll take a couple of aspirins an look it up. Everytime I try to read that book, I get a headace. I'm glad Mr. and Mrs. Hoover decided to translate it strictly into English, but it sure is a headache to read for very long................literally.

 

[Old Dog]

Bill,
Print out the part you are trying to read. Makes it easier.
I ended up with the whole thing in hard copy, Haven't regretted it for a second.
Takes a couple ink cartriges and a ream and 1/2 of paper ,,, but worth doing.

Easier to reference, and nice to have your own copy of.

 

[Shortstack]

OD,
That's the way I bought it several years ago; in print. I bought Wayne's last copy he had in his shop in OKC. He was real glad I wanted it. It had been on his shelf for several months. Guess the local "treasure hunters" were just wantabees" and didn't have a clue at the time. If I remember correctly, he sold his only copies of Kenworth's 3 books to me, too. Wayne's is where I found the Helms Associates book, too. I got one copy, went to my favorite Cafe for coffee; started reading it and went back to buy a 2nd copy which I've left in it's plastic packaging for archiving.

Anyway, when I started reading De Re........my eyes started watering, and a headache popped up BIG time. It's interesting enough, but a little reading goes a long way. Even though it's hard to read, I think everyone who is even remotely interested in Spanish mining and treasures should have a copy of this book on their shelf; right next to Kenworthy's 3. When you and Don Jose get YOUR books into print, they'll be on my shelf, too. So HURRY UP................................................please.

Your tip is an excellent one for anyone researching eBooks. Today, I'll print out any books bought on CDs and DVDs that I may want to have handy for reference.

 

[Curtis]

To answere part of the posed question above:

I know a lot of you already know this, but I am posting it for the newer guys…no one told me, I had to find it out for myself…didn’t find it on Tnet (bet it’s there someplace). One thing you might be interested in if you were a sailor (like Jonathan Swift who found silver mines in KY in 1760s) is the Prime Meridian in locating Longitude. A lot of maps use this. (haha) It has been changed several times in history…at least the English one has…the Spanish and French had different ones at different times. To make since out of an old map just because it has latitude and longitude, doesn’t mean you are on to it! The date of the Prime Meridian used makes a big difference just in that country. For instance England used something like three different ones in less than 100 years! If you are doing the treasure hunt in North America for something on a map dated before say, 1770, your Prime Meridian maybe in England or Philadelphia! Yes there were two of them used here then! It can make a mess of things! I would like to find a place that can calculate the differences between the accuracy in a given year and today…would have helped me immensely and save a week’s worth of research.
The really good cartographers and navigators used some really sophisticated calculation to arrive at where they were or were going. In Jonathan Swift’s journal he says that “By astronomical observations and calculation we found both veins to be just a little West of the longitude of 83 degrees” which shows he used the calculation method instead of the “clock” in 1765. Then just a few years later came the clock that could keep time at sea and longitudinal accuracy improved quite a bit.
So you can see those early explorers were not good at doing the longitude unless someone knew the methodology pertaining to the calculations. I imagine some of the Spanish were pretty good at it, especially the Jesuits. It would be interesting to know just how close they could calculate it back then. If we knew of the Longitude for a land mark in the 1760s and the same for it now what would the difference be?

 

[kiddrock33]

i have de re metallica also, but i found using the angles to locate carvings, because it is easier than using true north stuff. i map my carvings first, carvings dont shift over time. arrows still aim at their targets. drill holes still can be connected by lines.

 

[Clay Lindsey]

Kidd,

I'm half way with you and half on the other side of the fence on this one. Being fairly new at this I try to use every advantage I can get without over complicating things.

Using a more "line of sight" method has been the primary approach to my projects, but in instances where terrain interferes, I fall back to the good ol' topo map. This is where the re-calculation has it's greatest advantage; especially over more considerable distance.

I'm certainly glad the topic is getting responses. There are far too many ways previous cultures navigated the earth. You all are providing outstanding input. My eyes and ears are open as this discussion continues...

Clay

 

[kiddrock33]

i think the reason i stray away from true north stuff , is because i dont understand it enough to be able to confidantly use it. a compass works easily for me as far as shooting lines , but like you said lines through dips and hills where line of sight cant be done , or measured. so , i finally got a gps. it wont be anywhere as accurate as a tape measure and compass. surveyors are best at this, but the gps most definitely produced a geometric pattern when i landmarked my carvings. so what i found was a line east to west consisting of carvings. but it was off a few degrees. so possibly using this i might date the carvings, but i wont do this uless im confidant of my findings. i use a topo map to look around the site, many satelite images can be found online, heres an example of my pattern , i find a solitary drill hole, pull a tape measure 66 feet, walk that circle, map the carvings that fall on that circle. then shoot a compass line from the hole to carving. i think accurate mapping of everything ,i suspect , is key. but am unable to do yet. so hopefully ill learn something on this thread.

 

[Clay Lindsey]

We use the same method. I use both imagery and topo to verify what I see on the ground. I was hoping to gain more of a surveyor's point of view from this thread as well.

Clay

 

[kiddrock33]

i was just looking at your drill holes, i was wondering the compass bearings from hole to hole. is that partial drill hole the north. is there a 30 60 90 degree triangle ,when three drill holes are connected. i like the idea that yours may hold a rod for sighting through. depth of hole in inches convert to feet to get pole height. gun site from tips. just a thought.

 

[Springfield]

..... In Jonathan Swift’s journal he says that “By astronomical observations and calculation we found both veins to be just a little West of the longitude of 83 degrees” which shows he used the calculation method instead of the “clock” in 1765. Then just a few years later came the clock that could keep time at sea and longitudinal accuracy improved quite a bit.
So you can see those early explorers were not good at doing the longitude unless someone knew the methodology pertaining to the calculations. I imagine some of the Spanish were pretty good at it, especially the Jesuits. It would be interesting to know just how close they could calculate it back then. If we knew of the Longitude for a land mark in the 1760s and the same for it now what would the difference be?

There is no way to independently establish 'exact' longitude unless you know the 'exact' time in Greenwich, the zero meridian (or whatever other baseline you choose), when you make your observations at your new location. This is the definition of longitude. The best you can do otherwise is to traverse from a known longitudinal benchmark by conventional methods of field surveying. Until an accurate chronometer was developed, longitude was primarily an estimate, as can be seen on virtually all early maps. The telegraph vastly improved accuracy when it becan being used in the 19th Century, but before that, it was all an 'educated guess'.

As discussed earlier, latitude is another story. It's accurate determination has been used for millenia. Ever wonder why so many of the reputed caches are located at nearly 33.0 deg North latitude?

 

[okey dokey]

Springfield,
Here is one theory (I'm quoting)
"According to the Ethiopian Bible Book of Jubilees, the whole Earth was divided among Noah's 3 childranand 16 grandchildran, around the time of the fall of the Tower of Babel. The boundaries given in Jubilees specify that the line separating Ham's land to the South, from Yafet's land to the North, runs due West from "Gadir" i.e. Gibraltar. (The border line between the two also ran through the Meditteranean, so Ham received Africa and Yafet Europe.) Since Gibraltar is on the 36th parallel, a line running due West from there does not strike land until it hits Ablemarle Sound, North Carolina. Yet Jubilees clearly details how, the sub-portion within Ham's inheritance that is "on the sea" falls to Cana'an, while within Yafet's inheritance, the sub-portion "on the sea" is given to Moshakh. If you guessed that this line of the 36th parallel, separating Moshakh (son of Yafet) to the North, from Cana'an (son of Ham) to the South, crosses the Cimarron cliffs - where the word "whites" appears in both Canaanite and Celtic Ogham - you'd be 100% right. "

okey dokey

 

[Springfield]

Springfield,
Here is one theory (I'm quoting)
"According to the Ethiopian Bible Book of Jubilees, the whole Earth was divided among Noah's 3 childranand 16 grandchildran, around the time of the fall of the Tower of Babel. The boundaries given in Jubilees specify that the line separating Ham's land to the South, from Yafet's land to the North, runs due West from "Gadir" i.e. Gibraltar. (The border line between the two also ran through the Meditteranean, so Ham received Africa and Yafet Europe.) Since Gibraltar is on the 36th parallel, a line running due West from there does not strike land until it hits Ablemarle Sound, North Carolina. Yet Jubilees clearly details how, the sub-portion within Ham's inheritance that is "on the sea" falls to Cana'an, while within Yafet's inheritance, the sub-portion "on the sea" is given to Moshakh. If you guessed that this line of the 36th parallel, separating Moshakh (son of Yafet) to the North, from Cana'an (son of Ham) to the South, crosses the Cimarron cliffs - where the word "whites" appears in both Canaanite and Celtic Ogham - you'd be 100% right. "

okey dokey

Interesting stuff. It's my opinion that our modern world is somehow still controlled by agreements made millenia ago. Nothing new under the sun, as they say.

 

[Bum Luck]

With a weight and string, a nearby lake, and a rope, you can survey anything, find true north, lay out angles, and even find longitude.

Gotta be clever, though.

 

[Springfield]

With a weight and string, a nearby lake, and a rope, you can survey anything, find true north, lay out angles, and even find longitude.

Gotta be clever, though.

I'd be interested to know how you can establish longitude without knowing baseline clock time in Greenwich.

 

[Clay Lindsey]

I'll second that...

Admittedly, this is a subject I know little about and would like to expand my knowledge to match my interest.

Clay

 

[Bum Luck]

Well, it's Easter, so my time is not that long, but I just finished a project with my major Civil Engineering prof to find longitude by measuring the angular difference of the moon crossing a star, but the principle is basically:

(1) to locate north - this is easy in the northern latitudes - the north star has only a small wobble, less than a degree, and more importantly, can easily be "meaned out" to give a very accurate true north.

(2) the stars have an apparent uniform motion which of course defines the time since they are so far away. The variables in the sky are the planets and moon. The difference in the motions of them against the stars and each other are exploitable to give a longitudinal position on the earth's surface through a variety of means.

If this still seems complicated, a Google search will demonstrate that the ancients weren't dummies, but actually more highly sophisticated than we can understand. Someone designed and built the Antikythera mechanism, after all, BC, and it probably wasn't the first or only one.

Here's what Amerigo Vespucci said about this in 1502:
". . . I maintain that I learned [my longitude] . . . by the eclipses and conjunctions of the Moon with the planets; and I have lost many nights of sleep in reconciling my calculations with the precepts of those sages who have devised the manuals and written of the movements, conjunctions, aspects, and eclipses of the two luminaries and of the wandering stars, such as the wise King Don Alfonso in his Tables, Johannes Regiomontanus in his Almanac, and Blanchinus, and the Rabbi Zacuto in his almanac, which is perpetual; and these were composed in different meridians: King Don Alfonso's book in the meridian of Toledo, and Johannes Regiomontanus's in that of Ferrara, and the other two in that of Salamanca."

Happy Easter!

 

[Springfield]

Well, it's Easter, so my time is not that long, but I just finished a project with my major Civil Engineering prof to find longitude by measuring the angular difference of the moon crossing a star, but the principle is basically:

(1) to locate north - this is easy in the northern latitudes - the north star has only a small wobble, less than a degree, and more importantly, can easily be "meaned out" to give a very accurate true north.

(2) the stars have an apparent uniform motion which of course defines the time since they are so far away. The variables in the sky are the planets and moon. The difference in the motions of them against the stars and each other are exploitable to give a longitudinal position on the earth's surface through a variety of means.

If this still seems complicated, a Google search will demonstrate that the ancients weren't dummies, but actually more highly sophisticated than we can understand. Someone designed and built the Antikythera mechanism, after all, BC, and it probably wasn't the first or only one.

Here's what Amerigo Vespucci said about this in 1502:
". . . I maintain that I learned [my longitude] . . . by the eclipses and conjunctions of the Moon with the planets; and I have lost many nights of sleep in reconciling my calculations with the precepts of those sages who have devised the manuals and written of the movements, conjunctions, aspects, and eclipses of the two luminaries and of the wandering stars, such as the wise King Don Alfonso in his Tables, Johannes Regiomontanus in his Almanac, and Blanchinus, and the Rabbi Zacuto in his almanac, which is perpetual; and these were composed in different meridians: King Don Alfonso's book in the meridian of Toledo, and Johannes Regiomontanus's in that of Ferrara, and the other two in that of Salamanca."

Happy Easter!

As my good friend, who as first mate on the Third Sea, and its celestial navigator (using a sextant, a sailor's almanac and an accurate time fix), said, "You can't find longitude without knowing Greenwich and local time. Period. All else is guesswork."

Vespucci's method was extremely unreliable and was not widely used. This is why the early charts are so radically innacurate as to the positions of land masses, and more importantly, why the sailing hazards at sea were so poorly charted and so many vessels were lost. Since longitude is defined as the angular offset from an arbitrary baseline (currently the Greenwich prime meridian), and we're discussing its accurate determination in the field, then we are faced with the same dilemma as the mariners were until an accurate chronometer could be devised. Knowing the time offset from the baseline eliminates a typical 2 or 3 degree error, which is many, many miles depending on latitude.

 

[Bum Luck]

Yup, it's all Hocus - Pocus............

 

[Springfield]

Yup, it's all Hocus - Pocus............

No, just geometry, observation and a good clock.