Rediscovering Thoreau the scientist

Henry David Thoreau famously went to Walden Pond to live deliberately. But for far longer, he pursued a lesser-known obsession: observing scientifically.

Besides penning a classic work of American literature, Thoreau was an assiduous collector of data who made prescient insights about the natural world. That dimension of his life — often obscured by his reputation as an iconic humanist and Transcendentalist — is recounted in the new book “The Walden Experiments: The Science of Henry David Thoreau” by Robert M. Thorson.

“Everybody calls it nature writing,” Thorson told an audience gathered at Zimmer Hall for a recent Harvard Science Book Talk. “And there’s good nature writing in it, but I think there’s more science writing.”

Thorson’s title illuminates Thoreau as a trailblazing empirical scientist who conducted experiments and recorded detailed observations in fields such as chemistry, astronomy, geology, archaeology, botany, climatology, and limnology (the study of lakes).

Thorson began his talk by showing an image of Thoreau’s handwritten chart of the depths of Walden Pond. In 1846, Thoreau triangulated some 150 survey points on the shore, used a compass and surveyor chain to lay out transect lines, drilled holes in the ice, and took soundings with a fishing line weighted by a rock. The deepest point he measured was 102 feet down.

“This is Thoreau obsessively surveying the bottom of Walden Pond — obsessively!” said Thorson, a professor in the department of Earth sciences at the University of Connecticut who also holds an affiliate appointment at Harvard Divinity School. “He’s doing a graphical version of calculus to do iterative lines to find the bottom. And you know why? Because he was so sick and tired of misinformation. … He found, without knowing it, the deepest lake in Massachusetts.”

His investigations in bathymetry, or studying the depths and bottom topography of bodies of water, represent just one example of Thoreau plumbing the mysteries of nature.

His first experiment was the most celebrated: living in a small house beside Walden Pond from 1845 to 1847. In famous lines, he explained: “I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.”

But the writer’s first attempts to document his experience were, as Thorson recounted, “a draft of social screed written over two years and put in a dustbin on the floor somewhere.” After returning to his family home in Concord, Thoreau put his manuscript aside and embarked on a second, longer phase of experimentation — living a conscientious life in society while making regular trips into the countryside as a “sojourning scientist.”

At first, Thoreau treated his subjects in the idealist tradition of his mentor, Ralph Waldo Emerson. In 1851, Thoreau read “The Voyage of the Beagle” (1839) by Charles Darwin and was inspired to take a more empirical approach.

While Darwin went global, Thoreau remained local. He was keen to document his own environs — not only Walden but the countryside around Concord, Cape Cod, the Maine woods, and the Concord and Merrimack rivers. Writer John Updike described Thoreau’s “Walden” (1854) as “exaltation of Nature as a chemical and molecular and mathematical construct — Nature seized in the tightening grip of science.”

The subsequent insights gave Thoreau a deeper appreciation for the natural world, elevated his work, and transformed his book into a classic of 19th-century American literature. Thorson described “Walden” as “a book resuscitated by science.”

Thoreau spent several years rewriting and polishing the manuscript, enriching the work with more science. In 1854, he went to the railroad station in Concord and took the train to Boston to settle a publishing agreement with Ticknor and Fields, the company which had printed works by other iconic writers of the era such as Emerson, Nathaniel Hawthorne, Harriet Beecher Stowe, and Henry Wadsworth Longfellow.

Afterward, Thoreau went to libraries at Boston Society of Natural History and at Harvard, his alma mater, and borrowed books on glaciers, gleaning new scientific details that he added to his final revision. With proceeds from the book sale, he bought an expensive brass telescope and enthused about the gadget in his journal.

“He’s just obsessed with his telescope and how it works,” Thorson said. “That sounds not like a literary don. It sounds like a scientist — and it is.”

But Thoreau’s work as a scientist has been obscured by the scholars who studied him. Thorson notes that the first seven presidents of the Thoreau Society were all English professors. As divisions within academia deepened, Thoreau was claimed by the humanists. Thoreau the scientist was eclipsed by Thoreau the Transcendentalist.

“We hear the name Thoreau, we think of his literary and philosophical works, and it’s hard for us to get past that,” Thorson said. “Well, we need to get past that, because he’s really going to help us with the sustainability movement if enough people read him.”

In working his bean field, for example, Thoreau extolled responsible land husbandry and condemned farmers who treated the soil “as a robber.” As writer Bill McKibben enthused in a blurb for Thorson’s new book, “Thoreau was not just ahead of his time but of our time too.”

Thoreau approached the natural world with a sense of wonder, humility, and desire to live in harmony — not the utilitarian impulse to conquer nature, extract resources, or engineer great works such as railroads or dams.

In a eulogy, Emerson lamented that Thoreau lacked personal ambition and did not turn his talents to more productive pursuits. “Instead of engineering for all America,” Emerson said, “he was the captain of a huckleberry party.”

Like his hero, Thorson — the author of five books on Thoreau and Walden — exhaustively collected data. He built a spreadsheet tracking Thoreau’s activities for 7,000 days and found that the naturalist spent more than 200 days annually venturing out of Concord to make observations. The records show he kept up this habit for 11 years.

Thoreau continued his scientific sojourning even as he became mortally ill with tuberculosis. His final diary entry, written on November 3, 1861, recorded his efforts to reconstruct the previous night’s windstorm by analyzing evidence on the ground. Today, this endeavor is known as paleocurrent analysis.

“That’s the last line of his 2-million-word journal,” Thorson said. “That sounds like a scientist to me.”