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Along the Path

Updates as we learned about Lawson's journey and times -- and reports from the trail as we progressed along it. Plus tales of the process of publishing the result.

The Mathematical Devices

4/16/2015

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Today I fulfilled a dream that has been almost lifelong: I learned (in a sort of general way) to survey.

I did a newspaper story once about surveying, and though the trigonometry involved strained my brain's math app, I loved the idea: you are here. EXACTLY here, and once you know a few places you can find a way to connect every other place on the map. You can even make the map. (The trigonometry, by the way, is mostly involved in triangulation: you know various angles and lengths of sides of various triangles, and you use trig to fill in any lengths you'd like to know.)


So when I found out Lawson was a surveyor I was thrilled, and when I connected with Dale Loberger, a living history practitioner who reenacts seventeenth- and eighteenth-century surveying techniques, I realized: not only could I learn the basics of surveying, I could learn them in the simple way young men of Lawson's time would have learned them.

"Every educated man was taught surveying," Dale told me, dressed in his eighteenth-century garb and setting up the equipment of Lawson's time. "You're going to buy land, you've got to know whether you're getting what you're paying for.

"It was a practical skill that taught you all these concepts."

So naturally, the first thing I learned about surveying was, counterintuitively, what backbreaking work it was. Surveying, especially the newly divided land early colonial surveyors like Lawson would have surveyed, was usually covered with scrub, so just hacking your way through the brush took enormous effort. Then place yourself in Carolina, where it was nice and hot most of the year, to say nothing of bugs. Take a big honking knife, start whacking away, and there you are: surveying.
Picture
This hooky knife was a big part of surveying: you had to whack away enough underbrush so the surveyor and his crew could see each other. In the Carolinas, where Lawson surveyed? Not so easy.
Next, amazingly, was how much surveying was done by people who DIDN'T know the math. The surveyor would use complex equipment like the circumferentor, a surveyor's compass that enabled the surveyor to sight a distant object through slots called an alidade.

He would look through the sights and call to his assistant, who would stand where the surveyor told him and perhaps blaze a tree, stone, or other object while the surveyor noted on the circumferentor the exact angle to the object from his starting point. Then the surveyor would carry his equipment -- a tripod and his circumferentor -- to the spot, send his assistant to the next spot he wanted to sight, and begin again
Picture
Loberger here holds his circumferentor.
Meanwhile, the chain gang -- they were actually called that -- would take surveyor's chains and measure the distance from point to point. A surveyor's chain was 66 feet long and consisted of 100 links, and the chain gang measured to the nearest link. With the surveyor measuring angles to the nearest degree and the chain gang measuring distance to the nearest link there was plenty of wiggle room, but when your landmarks are inherently nonpermanent things like trees, close enough will do.
Picture
That's Loberger, showing about how far surveyors could get from one another. Those are arrows in the ground.
It only gets better. The chain gang measured by poking stakes -- called arrows, they were pieces of wood with a flutter of silk on the end, much like the stakes surveyors use even today -- in every time they reached the end of a chain. (Four rods per chain. The weird numbering comes because the surveyor's chain represents a genius-level metricization and combination of the ancient units of miles and acres. Long story; just trust me.)

Anyhow, the two assistants had quivers; the front one would have nine arrows, the back one none. The front one would stake an arrow into the ground at each chain, and when he ran out he would measure one more chain, then call "out," at which point the surveyor himself would note and track the out, whether on a special scorekeeper on his circumferentor or, lacking one of those, by moving a marker of some sort up the buttonholes of his waistcoat.

"An out was a unit of measure," Loberger told me. "You'd have one out and one arrow," he said, giving a possible measurement. So again: the chain gang did nothing more complex than count from one to nine (or ten, depending on whether you include "out"), and the design of the chains and links meant that simple multiplication yielded areas in acres. "The whole idea," he told me, "was to remove the mathematics." Being that the strong back was a bit more important than the strong mind. In places like Carolina, in fact, where brush was heavy, surveying crews often used half-chains instead of full chains so they could stay close enough to see and hear each other well enough to do their work. A half-chain is 33 feet, or a little more than ten yards. Which means it took a hooked machete, several pieces of equipment, and a crew of at least four to get a first down. Add in a guard and an instrument bearer and a couple guys to hold the staffs that were used for sighting to (and measuring smaller distances) and you can see that surveying took up a lot of energy of a lot of people.

An entire seized continent isn't going to carve up itself, right?
Picture
Boxes of surveying and drafting tools. Thank goodness for bearers!
But that's not even the cool part!

After demonstrating the use and lore of the circumferentor, Loberger pulled out the plane table and proceded to entirely blow my mind. With the plane table and a procedure called resection, a surveyor could map an entire area by taking sightings from two positions and end up with a perfect map of the area without leaving those two spots.

It's kind of insane, but let me explain. You take your plane table -- a flat surface on a tripod, basically -- and orient it towards the north. You may not need a compass -- you may just use a "needle box," a narrow box with 20 degrees of play or so for a compass needle. You orient the plane table, arbitrarily mark a spot on the paper on the table, and sight from there to several points, drawing a long pencil line along the straight edge of the alidade. Loberger demonstrated by sighting to the corners of the shelter in which we stood.

Then move the plane table, orient it exactly the same with the needlebox, and sight to the same spots, from a second arbitrarily chosen point on the paper. Your pair of pencil lines to each point will cross, and then you use a straightedge to connect the points where they cross.

Voila! You've mapped your site. Measure the distance between your two sighting spots, compare it to the distance between your sighting points on your map, and you've got your scale.

Mind blown.
Picture
It just doesn't seem right for something to be as intrinsically cool as the way a plane table can take points on the earth, place them on the plane in their exact proportional interrelationship, and result in a perfect map without your having to move beyond your two viewpoints. I mean, it's kind of crazy.
I could go on. Well, okay, I rather HAVE gone on, have I not.

Blame me, I dare you. Loberger also demonstrated the use of a sextant, with which observers on sea (or on land, with an artificial horizon, which I'd explain but your head might explode) could determine their position by measuring the height above the horizon of various celestial objects. (A predecessor to the sextant was the forestaff, which required you to squint directly into the sun as you measured its height above the horizon; ever wonder why pirates wore eyepatches? They were burning out their eyes. I am completely not kidding.)

The point is this: using technology available in 1700 and mathematics he would surely have known, Lawson was able to determine his position and, later, when he became the Surveyor-General of the Carolina Colony, parcel out land and design the towns of Bath and New Bern.

The point, really, is the do-ability of all this stuff. It wasn't magic -- it didn't require modern total stations and thousands of dollars of computing equipment. It required only the mathematics a young gentleman would know, a few pieces of equipment, and a little bit of want-to. You and I could do all of it with a pocket compass, a pencil, a pad, and a tape measure and come up with maps and measures that weren't all that ridiculous.

The world is amazing; the world Lawson wandered was perhaps even more so, because people hadn't yet forgotten that you could understand it so well by using mostly your brain, your hands, your feet, and your back.

Lawson's trail reminds me of all that. People like Dale Loberger stay reminded of that and try to remind the rest of us. You can still get the lay of the land.

Picture
Seriously: the pocket surveyor's kit. Loberger is sure Lawson had one just like it.
Picture
Dyes for colors, statistics on where celestial objects would be, and all kinds of scales and rulers, to say nothing of rudimentary mechanical pencils and pens you made yourself out of quills. Please -- may I go on a surveying trip in the early eighteenth century?
Picture
This is a reproduction, but Loberger is certain to the marrow of his bones that Lawson had one just like it: a little pocket globe, useful for pontificating in bars during discussions of matters political or geographical. I bet he's right. I mean, I'd have one. Wouldn't you?
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Finding the Old Road

9/11/2014

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One awesome thing about undertaking a project like retracing the route taken by someone like Lawson is that amazing people almost instantly begin flinging themselves at you out of the ether. Consider Dale Loberger. A geographic information system (GIS) specialist, Loberger works with Bradshaw Consulting in South Carolina, using GIS to improve people's lives and their understanding of their world -- through systems that connect information with maps (it's not just a fire hydrant; it's a fire hydrant last painted in 2007 and last maintained in 2012; it's not just an address, it's an address with a 17 percent likelihood of generating a 911 call within the next year). That U.S. map showing which NFL team each county prefers? That's a GIS map.
Picture
Dale Loberger in 19th-century surveyor garb, with a plane table. He has loads of cool stuff like that.
PictureThe Great Wagon Road drawn on a perfectly vague map from 1755
Anyhow, I've known Loberger on email for some time -- a mutual friend introduced us when he learned of our mutual interest in old maps and trails. And when I got interested in Lawson, Dale began telling me about his interest in uncovering the old roads in the Charlotte area where he lives: the Great Wagon Road, the Trading Path, and other ancient trails that lead through the area -- trails which Lawson almost surely trod. As someone skilled in GIS, he knew how to take the old maps he was familiar with and link them to modern maps, but he still wondered how he could find his way to the actual spots where the original roads lay.

In the seventeenth and eighteenth centuries, Loberger said, something like the Great Wagon Road "was less a name than a description." The Road referred to various ways leading, in general, from Philadelphia in the northeast down into Georgia, generally following the eastern edge of the Appalachians -- and, not coincidentally, the Trading Path, which existed before the Wagon Road, and the animal paths that probably existed before that. Roads were moving-around things in those days before significant paving -- they moved to accommodate new towns, to avoid swamps or ditches, to solve the needs of new kinds of wagons.

More, he says, the maps were meant to be nothing like we think of maps now, and returning to old maps trying to get specific pathways from them is a game of "teasing information from maps never designed to give that information." Speaking in an 18th century museum house in Raleigh, Loberger used a highly 21st-century ArcGIS Explorer* presentation while wearing his 19th-century surveying garb (don't worry, he assured me -- he has plenty of eighteenth-century gear more appropriate to Lawson's time). To understand those maps Loberger learned to survey. Most educated men of the 18th century would have learned surveying -- less as a job skill than as a way to truly learn math and computation. (Seriously, every educated man. Surveyor joke: What does a surveyor say when looking at Mt. Rushmore? "Well, there's three surveyors, but who's that other guy?" Teddy Roosevelt was the non-surveying president.) And surely Lawson knew surveying -- in 1708 he ended up as the Surveyor-General of the Carolina colony. Surveying in those days, Loberger has learned, often focused to a level of detail no greater than a single link in a surveyor's chain (7.92 inches) or even a single surveyor's pole (16.5 feet). Once you realize that the original surveyors figured that three person-lengths ("Smoots," to MIT students) was close enough, you're going to feel a little foolish trying to apply your phone's calculation of your position in degrees to 14 decimal points.

But not so fast. Loberger didn't give up. "These are not documents of truth," he says of old maps. But "they're documents full of secrets." He reasoned that the roads drawn on early maps were closer to legend images, like picnic tables for parks or big question marks for information centers, than actual representations of specific paths: all they did was say, "Charlotte and Salisbury are connected by road," not "the road from Charolotte to Salisbury looks like this." Just the same, the paths had to exist -- and if they did, they'd do what roads always did. They'd go the easiest way possible from point of interest to point of interest -- village, watering hole, mountain pass -- following the most sensible path: choosing solid places where you can easily ford a creek, following dry ridges where you can avoid insects and moisture plus not constantly climb and descend, traversing open land where you didn't have to wrestle through underbrush.

So Loberger turned to modern maps. The Natural Resources Conservation Service, he saw, rates soils for various purposes -- including limitations on utility for paths and trails. He realized that hydric soils -- those formed under conditions of wetness -- would make for bad roads, given that the wet conditions may remain. Soils indicative of thick undergrowth during formation would give the same hint: why would people -- or animals -- wrestle
Picture
From a 1972 USDA soil conservation study
PictureLoberger's composite suitability model
through the brush if they could easily avoid it? Same with hilly terrain -- horses and wagons are just as dangerous on slopes as an 18-wheeler, so Loberger included slope, soil type, proximity to landmarks, and other elements as he began to develop a sort of diagnostic tool for terrain. It ranks places on a 0-10 scale for road suitability. And as he's begun to apply it to old maps and old descriptions -- he hasn't published his results yet -- he's found, at least anecdotally, that his method works. 

Hoping to come within a mile of somewhere a road's original travelers would have walked, he describes a road he looked for near Charlotte. He found a road that he thought was likely the exact spot and felt certain that, given the uncertainties of old surveying methods and the assumptions of his model, he was probably in the ballpark, within 15 or 16 miles of Charlotte. After he once explained what he had done, someone approached him with a question. "Would you like to see one of the markers?" And took Loberger to a granite stone, marked "XV To C." Loberger wasn't sure whether a Roman "I" followed the "V," but the guy assured him. "That's 15," he said. "I know where 16 is" -- it had been used in a fence.

If I had to begin looking for Lawson's trail to bring me finally to Loberger? It's already worth it. Loberger will join us on the trail, probably around Charlotte, and he'll not only help us know exactly where Lawson would have gone but teach us to use the surveying tools that Lawson would have used. This one is called a Gunter scale, named after surveyor Edmund Gunter, who invented it as a sort of pre-slide rule, using logarithmic scales to simplify calculations.Of course Gunter had to become professor of astronomy at Gresham College, where Lawson took classes, because once you start looking for connections that's how it always happens. He was there long before Lawson was, but still.

Loberger has tons more cool stuff and ideas, and he'll tell us all about them when he joins us on the trek, probably sometime in the winter or spring.

*Oops. I originally called this a PowerPoint. My bad.
Picture
Dale Loberger's Gunter's scale. I suppose it's possible that stuff gets cooler than turn-of-the-eighteenth-century surveying equipment, but seriously: how?
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