Historical Accuracy

Several hundred feet, if you're lucky, probably worse.

A Naval Officer would know how to take star observations with a sextant at sea where the horizon is visible but the precision is fairly low, within a mile or so. It involves using a sextant to measure the angular altitude of navigational stars above the horizon the reducing the position on charts using tables. On land an artificial horizon can be used but typical nautical instruments don't have a level bubble because they use the sea horizon.

It would be more likely for him to take compass bearings to multiple landmarks such as hilltops or the church steeple. It's a tough problem if the union troops burn anything definite but building foundations typically survive.

He isn't going to be able to do it just from star positions. The best specialized scientific instruments of the day might a position on the ground within a hundred yards after averaging many repeated observations, and a sextant is lucky to get down to a fraction of a mile.

He needs either a) at least two reasonably permanent reference points, or b) at least one permanent point and a bearing angle relative to a landmark or the stars. Having more than the minimum number of measurements would be a check and insurance against one of the objects being destroyed.

By method a) he would measure distances with a surveyor's chain or something he had checked against a chain. He would measure from at least two objects such as the foundation corner of the house, the center of the well, the end of a stone wall, a recognizable big tree, or other object that stands a chance of remaining after a war.

By method b) he could measure from one or more such object in a direction determined by a landmark. Of course the church spire might burn. The bearing to a star at a particular time and date will work if he knows enough astronomy and trigonometry. The easiest star is Polaris, since it is only about a degree either side of true north depending on the time.

By 1862, surveyors' compasses were fairly common and early transits were available but expensive and not something most people would have unless they were using it regularly for surveying. If he had a sextant he might be able to use it for horizontal angles on the ground (I haven't tried that) but I don't think it wouldn't work for transferring a star position to a bearing on the ground. Maybe someone else can advise if that would work.

Mail me through the link on the little envelope by my name. I'll send you my fiction story that has something similar going on.

Why wouldn't he do what the pirates did? Find a landmark that will survive - foundation, rock, road or otherwise. Then pace along several compass courses to the desired location.

I would assume there are stone walls surrounding the farms. It did not take Morgan Freeman too long to find the obsidian in Shawshank Redemption.

Good luck.

Thanks, Dave and Bill, for the quick and informative replies. My immediate thoughts are these: a) artificial horizon: I'll look this up, but meanwhile, can I plausibly have Captain Beauregard know what the problem is and jigger his sextant with an add-on level bubble? b) Re permanent reference point: a to-be-ruined church would still work, wouldn't it, if upon his return he can figure out where the spire used to be? Does he have to know the altitude? Or, I guess I could have him plant an iron bar in a visible bluff and raise a flag over it that might stay there long enough for him to take a reading off it.

I was hoping for celestial reckoning, but I guess I'll have to have Cap'n B send one of his slaves out to do the legwork with the surveyor's chain. Bill, I'll contact you about your story-- looking forward to reading it.

LFM

Horizontal Resection by Sextant Angles

> How accurate a reckoning of the burial location can I get with the surveying/navigating equipment of the day? And how would I go about measuring it?

If you were a naval officer who knew how to use a sextant and owned one, you'd fix the position where you'd buried the gold by measuring the horizontal angles between prominent landmarks with it. You'd be familiar with the method from hydrographic surveying, as a way to locate where soundings were taken in a bay, for example.

You'd need at a minimum three such well-defined land marks such a church steeple, a chimney of a house, the visible trunks of large, long-lived trees, distance corners of field fences, or whatever. You'd also know that if the spot where you buried the goods lay on very nearly the same circle as those three landmarks, the position fix would be not very good at all, so you'd probably add horizontal angles to at least two or three other objects.

Depending upon how distant and how well-defined the objects were from the spot you were standing, you ought to be able to fix the location within better than a couple of feet using the sextant angles.

When someone finds your record, then the exercise would turn into one of surveying, particularly if less than three of the objects were no longer visible from the spot where the goods were buried.

Coast Guard Sextant Manual

Pacing or measuring along compass courses would be fine for starting at the well and finding the right big tree. The final leg needs to be a short distance from a recognizable object to use a compass bearing. If a simple compass was read 1 degree off, that's a foot sideways in a 57 ft leg. That's why two measured distances work better. A surveyor's compass would give maybe 1 in 500.

In the case of celestial navigation, altitude refers to the angular distance of a star (or moon or planet or sun) above the horizon. The sextant is used to measure the angle from the horizon up to the star. Through an arrangement of mirrors the observer aligns the horizon in one half with the star in the other half the reads the angle on the arc of the sextant (1/6th of a circle).

Then the observed angle has to be corrected for the line from the observer's eye to the horizon not being level but slightly down, and atmospheric refraction which makes stars appear higher than they really are. In the case of nearby objects such as the sun then parallax must be accounted for because the published tables assume the altitude from the center of the earth. Stars are so far away that the difference due to parallax is not measurable.

This website is a very good source of information and handy programs for reducing observations.

http://www.celnav.de/

> Several hundred feet, if you're lucky, probably worse.
>
> A Naval Officer would know how to take star observations with a sextant at sea where the horizon is visible but the precision is fairly low, within a mile or so.

Except a sextant can be used to measure *horizontal* angles, also. If you can measure horizontal angles between visible, distinct features that are unlikely to disappear completely, you can do a *resection*. I believe that was a standard 19th-century technique for plotting soundings made from a boat in sight of shore.

Well, I've definitely come to the right forum. Thanks to everyone for the suggestions and explanations. Given that the descendants don't get back for a hundred years, it looks like I'd better focus on creating "recoverable" landmarks.

Re pirates, all these complications would lead me to think that burying treasure must have been something done only as a temporary solution to a desperate situation, as in "we'd better off-load this stuff before the coming battle, and pick it up next week."

LFM

> Well, I've definitely come to the right forum. Thanks to everyone for the suggestions and explanations. Given that the descendants don't get back for a hundred years, it looks like I'd better focus on creating "recoverable" landmarks.

I'd think about trees, brick chimneys of buildings, high points of distant hills (if there are any), and cemetery markers.

The cemetery markers in particular should be a snap to find later to start the process of figuring out where the treasure was buried.

Kent's onto something

Burial in a cemetery would be super. There are so many reference stones that some would surely remain decades later. The trick would be to place the bootie directly above a used burial plot, not some empty space that might be excavated later.

Then the issue becomes far simpler---how to relocate the cemetery? Perhaps it could be defined by being a certain distance perpendicular to a straight stretch of railroad and from a somewhat definite starting point on that track being so many rods or chains from the center of a medium sized culvert. That size of watercourse would not move significantly over time.

Keep each element of the path to relocation as simple and repeatable as possible. For example, identify about a dozen or more stones in the cemetery and the relation of each to the proper burial site. Note natural objects at various points along the perpendicular traverse from the rairoad track and determine their perpendicular location from your traverse line and at what distance from the track. This provides repeatability. Use the sextant for determination of right angles. Also use the sextant at the point on the tracks where the perpendicular traverse is to begin and note as many enduring distant landmarks as possible at angles from the centerline of the track.

The track may be temporarily destroyed, but, will most likely be re-established. If so, the location of certain smaller watercourses crossing said track will most likely remain unchanged. They may be identified as being so many rods or chains from a specific large watercourse. You only have to get close enough with that dimension to know that you have found the proper watercourses. An established cemetery may be damaged or overgrown by negligence through the decades but will probably not disappear entirely. Instructions should designate that those eventually returning to find the bootie must use the now-ancient tools of the person laying out the instructions and thus insure that they are literally following in his footsteps, as all good surveyors do.

For your readers' amusement, you might have the slaves accumulate and construct the largest single pile of horse, cow and mule manure of all time. Provide clues to those searching for the bootie shortly after the family has relocated that suggest it is buried deep beneath the gigantic manure pile

By the way, Mr. Elefem

Are you related to my old buddy, Elef Eyeno?

Just as a matter of the philosophy of fiction writing, does it have to be precisely accurate?

It seems like a lot of fiction depends upon suspense of disbelief. I mean would Ishmael really be able to survive in a floating coffin? Would a whaling ship Captain really be able to waste the ship owner's money chasing a single whale on a vast ocean?

On the other hand, Patrick O'Brian is very precisely accurate in his Aubrey-Maturin stories.

> Just as a matter of the philosophy of fiction writing, does it have to be precisely accurate?

Well, some elements of it have to be entirely plausible. For example, the fellow who buried the treasure wouldn't want to involve other people in the process since the secret would be secure with him, but not with them.

Likewise, for the rediscovery of the treasure several generations later, you don't want to make it too easy or obvious. "Oh, it's sitting on the mantelpiece, hiding in plain sight," on page 50 would deprive the writer of at least 100 pages worth of sorting out the puzzle. Otherwise, about all you have is the plot twist that some of the slaves who helped the former naval officer bury the treasure later returned to dig it back up, as telegraphed in advance by the relative prosperity of their descendants who now own the land.

This is why I like the resection by sextant so well. It's something one person could have done, the record is not readily understood, and you have to actually find the objects to which the resection was made or reconstruct their positions by some means.

Kent's onto something

> Burial in a cemetery would be super. There are so many reference stones that some would surely remain decades later.

Here's the device: the record of where the officer leaves his booty is as follows:

0°00' Jasper Ball
95°35' Z. B. Lamar
139°15' Mariah S. Dixon

Those are, of course the clockwise angles, measured by sextant to the stones of those individuals. They actually identify the grave, new at the time, where the booty was buried. There may some other period-correct way of noting the angles, such as 0.00, 95.35, and 139.15 that would further obscure the answer.

Another variation would be to give bearings using the points of the mariner's compass. They would of course be in relation to magnetic North at the time and anyone trying to use those directions to find the treasure would have to allow for the change in the direction of magnetic North over about 150 years. (This would not be necessary in New Hampshire, of course. :>)

Kent's onto something

Does a sextant measure to the nearest minute?

Kent's onto something

> Does a sextant measure to the nearest minute?

Yes, I'm almost certain there were one-minute sextants. I'll have to check and see.

Edit: Yes, there were.

Broken glass....
A one foot diameter cylinder of broken glass buried above the gold...left one foot below the surface... In 40 years (or a hundred years)...just get close and do a little normal farm plowing...

There she be, mate...

DDSM

Dude, We don' t have much of a problem finding buried stones with the data from several hundred years ago. Whats a couple of decades?

Edit: I thought the post said "I'll be gone a couple of decades", and now we're talking generations?

But, seriously, thimk about it. We go out and fine buried rocks. How hard can it be?