Point of Beginning

Surveying Walden Pond

August 2, 2010

A surveyor’s son and English professor delves into the lost bounds and measures of Henry David Thoreau. ...

Patrick Chura accompanied his father, a land surveyor, on many surveying outings in the 1970s and 80s. It was this fieldwork that generated his initial interest in Thoreau's land-based profession. Later, as assistant professor of English at the University of Akron, Chura studied Thoreau's field notebook and then retraced Thoreau's footsteps along the western edge of Walden Pond using borrowed nineteenth-century surveying tools. In this excerpt from his new book, Chura gives us a window into Thoreau's drafting work.

Figure 1. “Walden Pond. A Reduced Plan.” This image appeared opposite page 307 in the first edition of Walden.

In the book for which he is famous, Henry Thoreau writes, “Desirous to recover the long lost bottom of Walden Pond, I surveyed it carefully, before the ice broke up, early in ‘46, with compass and chain and sounding line.” But the sole reason Thoreau gives for his survey--that he wanted to make sure the pond had a bottom--is intentionally misleading. Sounding the depths of the pond was only a part, perhaps the simplest part, of an ambitious task with profound justifications. This task, along with almost everything about the extensive surveying work Thoreau did in his lifetime, deserves a closer look.

For starters, it seems essential to know how Thoreau actually made the Walden survey, a three-dimensional pond map that is now one of the most important images in American literary history. Surveying the sixty-one-acre pond presented significant technical challenges, but it was also a physically arduous process requiring days, perhaps weeks of toil. Chopping more than a hundred sounding holes through ice that was sixteen inches thick was in itself a substantial feat, requiring of Thoreau’s relatively small frame considerable stamina and physical power. Amazingly, the hard work did not blunt Thoreau’s perceptions but stimulated his interpretive faculties.

To measure and map the pond, Thoreau used a method of angle intersection, a procedure that enabled satisfactory accuracy but required a minimum of actual measuring with the Gunter’s chain. He began at the southernmost tip of Walden and measured almost due north for about 1,300 feet, bisecting the pond with the line BCD. This was his baseline, the verification base of all adjoining measurements, the first line he would draw in transforming his data to visual form, and one of the few distances he had to measure with extreme precision. As the notes on his draft survey indicate, line BCD was “accurately measured,” while other distances were “carefully paced”--walked off rather than measured with the chain.  

Figure 2. Schematic of the Walden survey, showing Thoreau’s method of angle intersection. Lines of bearing originate from stations B, D and midpoint C on the baseline, with secondary stations along the pond edge. The Fitchburg Railroad is shown with parallel lines at lower left.

Next Thoreau established his stations, points on the pond surface from which all or nearly all of its perimeter could be seen. Points B and D--at opposite ends of the baseline and providing a full panorama of the pond--became the primary stations or hubs. After setting up the tripod and leveling the compass at station B, Thoreau recorded a series of bearings to significant points along the edge of the pond where the shoreline changed direction or formed coves.

Interestingly, Thoreau labeled the bearings with letters of the alphabet. His first piece of data was the angle from station B to point A1, where the pond met the south edge of the railroad embankment. This field note would have read “B-A1 S 76 1/4 W,” meaning that the line from station B to point A1 had a bearing of seventy-six and one-quarter degrees west of south. Remaining at station B, Thoreau then turned his compass sight to the next significant shift in the pond’s outline at the north extremity of the railroad embankment. To this point, labeled B1, he recorded a bearing of about N 89 W, or eighty-nine degrees west of north.

And so on. Thoreau took at least twenty-eight readings from station B, filling out his data by locating four objects in the surrounding topography--a tall tree at the pond’s eastern edge, a tree in the distance to the northeast, and the “wooded peak” and “bare peak” on the north side of the pond. In the process of gathering data from this initial hub, Thoreau turned his compass in a complete circle. His last bearing, labeled Z on the draft, was within a degree of his first. The final degree of the horizon was the final letter of the alphabet. The coupling of numbers and letters was strangely appropriate in this survey, for in gathering mathematical data about the pond Thoreau was also producing the literary text of Walden.

As most nineteenth-century surveyors did in projects of this type, Thoreau compensated for not measuring each radial line by taking a large number of bearings, including some to landscape features outside the immediate area. These reference azimuths helped establish the accuracy of angles read with the compass and orient the primary object of the survey in relation to features of local topography.

As an azimuth mark crucial to his Walden survey, Thoreau chose an intriguing object: the front door of the cabin he was living in to the north of the pond. With his tripod and compass at point C, the center of the pond, Thoreau sighted his cabin and recorded a bearing probably in the neighborhood of N 16 3/4 W. He then turned his compass about ninety-seven degrees to the point where the railroad runs nearest to the pond, and took a bearing of S 66 W. The draft survey shows that he later set up his tripod at the base of the railroad embankment on the pond’s western extremity and took a bearing from here to his cabin that read about N 24 E. This final piece of data created a triangle within Thoreau’s survey that enabled him to check for closure. If the sum of the internal angles of the three-sided figure was near to 180 degrees, Thoreau knew that the bearings he had taken could be trusted. He also knew exactly where to draw on the Walden map the tiny dot that represented the house he had built the previous summer. 

The pragmatic purposes of using his cabin as a reference point are interesting, but so are the philosophical inferences that may be drawn from it. By sighting his cabin from the center of the pond and the railroad embankment, Thoreau created a three-sided figure that brought key locations into contact with each other. As all good readers of Walden know, the deepest part of the pond provides Thoreau with his “rule of the two diameters,” a metaphysical axiom suggesting that the “height or depth” of a person’s character is located, as with the pond, at the intersection of length and breadth. That the pond’s greatest length, width and depth were concentric was in Thoreau’s view a remarkable coincidence, enabled by a surveying chain and sounding line and of substantive importance in Walden.

Creating the pond-cabin-railroad triangle at the core of the Walden survey has similar implications. Obviously it confirms Thoreau’s awareness that station C, the nucleus of Walden, bore a relation worth discerning to the point where the pond met the railroad. Thoreau’s statement in Walden that the railroad “touches” the pond is only true once an association between the two objects has been made. As the draft survey suggests, the symbolic pond-to-railroad linkage was established in survey form before it was established in literary form.

The numerical data or field notes for the Walden survey no longer survive, but they may be reconstructed with fair precision using documents Thoreau did leave behind. It is likely that the production of the literary text of Walden actually began with surveying notes--that before Thoreau wrote a line of his book, he measured lines across the pond. If the notes are the earliest recoverable fragment of the book, it should be acknowledged that this text originated in an unusual way. The field notes, after all, were authored as much by the compass needle as by Thoreau. They, and therefore the first component part of Walden, were a materialization of the earth’s magnetic field, transcribed in contact with the frozen surface of the pond itself. Prompted by a desire to know and shape reality for visual rather than verbal representation, Thoreau began the book not with words of his own making but with symbols for which he was merely a conduit, not with the drafting of sentences but with the drafting of a landscape.

Figure 2 shows the meshlike network of facts with which the surveyor blanketed his environment. Engineering software and the reconstructed field notes were used to create this image, but anyone with a protractor and a straightedge could apply the same field notes to establish Thoreau’s baseline, determine his angles, and in essence redraw the Walden map. Thoreau wanted his readers to know that drawing a pond for its own sake, with no reason other than love for it, could be a worthwhile endeavor. Having sketched Walden in the same manner, and with the same motivations, I can argue that he was right. Drawing the pond could not reproduce the sensations of wintry afternoons spent chaining and chopping on a vast sheet of ice, but it offered a compelling kind of access to the writer-surveyor who performed such work, and to the origins of his great book.



Thoreau the Land Surveyor, copyright © 2010 by Patrick Chura, is published at $34.95 by University Press of Florida, and will be available in September at www.upf.com. The book can also be purchased through the AEC Store at www.aecstore.com.