Henry David Thoreau
Presented by The Thoreau Project, a nonprofit initiative of Calliope, Inc.
Phone: 781.674.2926 - e-mail: [email protected]
Visit all our subject areas in American history and culture:
Harlem Renaissance Links | The Classic Blues| Shays' Rebellion & the Constitution | The Gold Rushes

Green Thoreau: Global Warming

Nature & Science

2010 Annual Gathering


Postmodern Thoreau


A Thoreau Time Line
A Page in Thoreau's Journal
Reading Thoreau
Teaching Thoreau
Best Thoreau Web Sites
Thoreau & the Underground Railroad
Books About Thoreau & His Times;
Book Reviews
Advanced Thoreau Studies


Devices of David Henry

The Machine in the Wetland:
Re-imagining Thoreau's Plumbago-Grinder

By Randall Conrad  

Summer and winter, a pair of up-ended, rusty, criss-crossing shafts crowned with reddish-colored gears sprouts from the mud of a conservation site in Acton known as the Pencil Factory Dam. These iron perennials mark the site of a mill that once thrived on steady custom from the Thoreau pencil business in neighboring Concord.

The mill belonged to Ebenezer (Eben) Wood (1792-1880), remembered as a "cabinet maker, inventor, Mason, veteran of the War of 1812, and a gentleman." For many years beginning in the 1830s, Wood ground plumbago (now called graphite or black lead – the essence of pencil "lead") exclusively for the successful Thoreau company, manufacturers of industry-leading writing and drawing implements.

Wood, a pioneering pencil-maker and inventor himself, is credited with "using the first circular saw in the pencil business, inventing a grooving machine, a molding and trimming machine, a wedge glue press, [and] creating the hexagonal and octagonal [rather than round] pencil – and patenting none of them." [NOTE 1.]

All these inventions support the manufacture of the pencil's cedar "case," the familiar wooden cylinder that encases the shaft of "lead" (powdered graphite mixed with clay). Assuming Wood brought in cedar and used his novel machinery on site, his mill served as a complete pencil factory. Nineteenth-century Acton counted at least three such pencil factories among its various mills.

In neighboring Concord, Henry Thoreau put the family concern on the road to success by contributing ingenious engineering solutions as well as physical labor. The leading historian of pencil manufacturing, Henry Petroski, devotes an entire chapter of his definitive history, The Pencil, to Henry, his father John Thoreau, Sr., and their innovative collaborations. Most famously, Henry discovered and implemented a groundbreaking improvement in the lead-making process by substituting clay for traditional fillers. As a result, high-quality Thoreau pencils were soon in wide demand and won Mechanic Association awards in 1847 and 1849 (Petroski 110-20.)


A Chamber Seven Feet High

One intriguing contrivance designed and constructed by father and son in the 1830s, the subject of these notes, was the very thing which "at once put their black lead for fineness at the head of all manufactured in America," according to Edward W. Emerson.

…the narrow churn-like chamber around the mill-stones [was] prolonged some seven feet high, opening into a broad, close, flat box, a sort of shelf. Only lead-dust that was fine enough to rise to that height, carried by an upward draught of air, and lodge in the box was used, and the rest ground over (Emerson, Young Friend 14).

Dr. Emerson's description – the only one that has come down to us – clearly portrays Thoreau's device as a fixture within the mill itself, extending the walls surrounding the millstones.

The Problem: Imagination

But men of letters, alas, blithely stringing sentences together in the all-verbal universe they inhabit, cannot be trusted to picture to themselves the material thing they are writing about, if they have never seen it. I re-learned this unhappy truth while trying to interpret a baffling second-generation "description" of the same device. If this sort of rumination interests you, read on.

When Walter Harding borrowed Dr. Emerson's description almost verbatim in his 1965 biography of Thoreau, he added an element found in some other source I have not identified: "The machine spun around inside a box set on a table and could be wound up to run itself so it could easily be operated by his sisters." [Days 56]

A box set on a table? Both Thoreau sisters? Now it seemed I must visualize the Thoreaus' invention as a home-based or portable contrivance, rather than a mill-based fixture.

For a time, I tried to visualize this hybrid rig standing in one of the work-sheds annexed to the Parkman House (the Thoreau residence since 1844). I wondered how a table, itself more than two feet high, could anywhere indoors accommodate a seven-foot tower with a receptacle on top. Even the high-ceilinged parlors in the Yellow House reached only nine feet, and the Thoreaus didn't move there until 1850. [Days 263]

Petroski takes note of the additional sentence, yet his book offers no comment as to how these two descriptors can apply to the same machine. [Petroski, 114]  I supposed the flat, shelf-like "box" at the top of the extension could have been detachable, in order for someone to collect the powder easily, but was it roomy enough to accommodate a spinning "machine"? And if so, what action did the machine perform? If located inside a seven-foot tower, the whirligig was probably an air-circulator that pulled a draft upward. If located inside a flat, elongated table-top box, what was it then? Whatever it was, wouldn't any mechanism hamper the accumulation of ultra-light powder inside these narrow confines?

At this point, a phone conversation with Petroski, professor of both civil engineering and history at Duke University, tended to support the original idea of the mill-based tower. Harding's "table," after all, could refer to a platform erected over the millstones that were doing the grinding. The "spinning" machine, Petroski confirmed, was surely a rotary fan located inside the tower and creating the upward draft of air needed to carry the finest powder to the top.

Harding's extra sentence, it now seems to me, could refer to some different machine – smaller, portable, and spring-wound – that functioned inside a portable "box" or case. In this form, the machine might have been an altogether different invention, designed to continue the refining process in the privacy of the Thoreaus' home-based manufactory. Inside the box, I could suppose that the mysterious spinning mechanism, perhaps a centrifugal separator, reduced ground graphite to a finer and more uniform grade, with or without a current of air to assist. 

But at this point, I am only imagining, until I can identify the source of Harding's second sentence.

An Upward Draft

The upward draft of air was created by a rotary fan located inside the tower to carry the finest powder to the top. (The fan was apparently spring-wound by hand.) Our site in Acton, known as the Pencil Factory Dam, is the likely location of the Thoreau mill-extension (although it may have been used in Concord later). The device was seemingly in use as early as the 1830s or 1840s.

One explanation why the Thoreau mill extension provided an edge in the pencil marketplace is this. Dr. Emerson notes that the grinding of Thoreau’s graphite was done with mill-stones instead of traditional means, and that “the grit of the stones would have spoiled their product” if they had not invented the high column with its upward draft of air.

Clearly, the mill-extension provided superior quality to Thoreau’s pencil-lead overall, not just to the finer grades. As we learned above, the different hardnesses in Thoreau’s “polygrade” pencils were achieved by varying the proportion of clay in the mixture, not the grade of the graphite powder.

It is fortunate that the Thoreaus discovered this fine-grinding technique when they did, for it gave their product a leading edge in the marketplace when the demand for graphite surged later, due to a major innovation in the printing industry.

Electrotype, the revolutionary industry that would require a quantum leap in milling technique, emerged in 1849. (And John Thoreau may have experienced an early need to produce a more consistent grade of powder for specialized products, such as his “Plumbago Plates for Galvanic Batteries,” advertised in a circular around 1844.)

So probably none of my speculations about plumbago plates, etc., was relevant. The Thoreau mill extension may or may not have expedited volume production of uniform fine-grade graphite that the company required in later years. All it had to do was provide an edge in the pencil marketplace of the 1830s.

Arriving Where I Started

My rambling researches, like a Thoreau excursion, brought me back to where I started –  the Pencil Factory Dam site. It had sprouted an informative visitors' kiosk in the years since my first visit, created by Eagle Scout Jeff LeBlanc and members of the Acton Land Stewardship Committee with state funding. Full story and credits at www.town.acton.ma.us/LSCOM/News010614.htm).

One fact for certain, I supposed – the Thoreau mill-extension was located in Acton.

Or, wait, maybe it was in Concord. The visitors' kiosk is silent on the issue.

The case for Acton

Eben Wood's Acton mill was still working for the Thoreau company as late as 1853, the point when John Thoreau shifted the family pencil-manufacturing firm to the more lucrative (and secretive) business of producing fine graphite powder in volume. It was Henry who would drive to Acton to bring the ground graphite home in bulk, where the Thoreaus secretly boxed orders that would be shipped to customers in other cities. (Young Friend 15; Days 261).

Horace Hosmer (1830-1894), an alumnus of the Thoreau brothers' Concord Academy who became a pencil-finisher in Acton (and occasionally a salesman or business representative for John Thoreau's company), leased Wood's mill for five years "for Pencil Work," presumably during the 1850s. There Hosmer observed, and very possibly lent a hand to, Wood's graphite-grinding for John Thoreau. He later recalled "how particular Mrs. Thoreau was to have it fine and of uniform quality" (Hosmer 32; author's emphasis. Henry’s mother was as active in the business as his father, and continued it following the latter’s death in 1859).

Henry’s round trips between Acton and home suggest that the pencil factory's mill may have been dedicated to the specialized function of producing the uniform fine-grade powder required by electrotyping, while "the coarse [preliminary?] grinding was now done at the mill at Loring's Lead Works in Concord Junction" (Days 263). If so, this would tend to confirm that Henry Thoreau's fine-grinding mill-extension was located in Acton, in Wood’s mill. Its usefulness extended from the heyday of pencil manufacture right through the electrotype revolution in printing.

An additional argument for the Acton location of Henry's device comes from an undated (circa 1890s) photograph owned by the Acton Historical Society. (Klauer 18, shown below) Davis Road in those days extended along the dam, as shown in the photo. (You're standing on it.) The same railroad tracks that are overgrown today can be seen in this picture – it's that horizontal roadway intersecting Davis Road's vertical path, bisecting the middle distance.

The photo shows an active railroad – the bar-shaped sign above the intersection in the photo, not legible at this resolution, reads "Watch Out for the Engine." On the left, where only foundations gape today, are two buildings – a three-story structure with windows, and in front of it a much smaller house with no visible windows, possibly a single-story studio. According to the caption by local historian William A. Klauer, "The graphite grading equipment may have been in the small structure… It appears that this building had some kind of heating equipment (since it also has a chimney), and the pencils were manufactured in the larger building." (Klauer 18.)

The case for Concord

On the other hand, when Dr. Emerson saw the thing at work, it was apparently in Concord: "Mr. Miles took me to his mill to see the perfection and simplicity of the operation" (Young Friend 56). Warren Miles was the owner of a sawmill in Concord on Nut Meadow Brook, housed in slabs of old sapwood on an existing mill-dam, about two miles from the Thoreau family's Yellow House. Miles also ground graphite for the Thoreaus. (Most mills served a range of customers and industries.)

In his journal, Thoreau recorded several visits to Miles in 1856, noting that Miles "at his mill near the factory ... used a small undershot wheel, eighteen inches in diameter, for grinding lead." (24 April 1856 – VIII.303.) Note, however, Thoreau's use of the past tense. It confirms that the "mill near the factory" was an older facility, distinct from Miles's "new mill" at Nut Meadow which Thoreau was currently visiting. [NOTE 2]

Warren Miles, by his own account, was the first to suggest that Henry begin using stone instead of traditional "iron pots and balls" to grind graphite. [NOTE 3] He and Henry collaborated in 1858 on a "crushing method" that was an improvement. Miles purchased the Thoreau business from Cynthia Thoreau after Henry's death in 1862. (Emerson, Notes of Interviews.) [NOTE 4]

Simple Machinery, Rude Appliances

So was the Thoreau mill-extension in Acton or Concord? It seems most likely that it was used for years in Wood's mill at Acton, and later was moved to, or replicated at, the Miles mill in Concord, when Miles acquired the Thoreau business. And since the Thoreaus (like Eben Wood) never patented their inventions, this profitable device may even have been widely replicated.

The mill pond at Nut Meadow inspired eloquent journal pages in which Thoreau exults in its wildlife, human visitors and ecology. (See 28 Feb. 1856 – VIII.190-91.) And although Thoreau never left us a description of his own mill extension, Nut Meadow did inspire a clear-eyed description of sawmill construction: "How simple the machinery of the mill! Miles has dammed a stream, raised a pond or head of water, and placed an old horizontal mill-wheel in position to receive a jet of water on its buckets, transferred the motion to a horizontal shaft and saw by a few cog-wheels and simple gearing, and, throwing a roof of slabs over all, at the outlet of the pond, you have a mill."

Thoreau, who knew a thing or two about mills, added one caveat. Miles should have constructed a new dam, he thought, rather than using a century-old dam that had already given way once, necessitating troublesome repairs. "Rude forces, rude men, and rude appliances," he concluded. (28 Feb. 1856 – VIII.193.)

Works Cited

Conant, Elizabeth S., "Pencils and 'the Goat of Acton,'" Acton Historical Society Newsletter, March 1992.

Emerson, Edward Waldo, M.D., MS and typescript of "H. D. Thoreau" in: Notes on Thoreau, Edward W. Emerson Collection, Concord (Mass.) Free Public Library, Rare Books and Manuscripts Division.

______, Notes of Interviews with Warren Miles, 29 Oct. and 3 Nov. 1890, in: Notes on Thoreau.

______, Thoreau as Remembered by a Young Friend [1917], Dover, 1999.

Charles Hammond, "Concord's 'Factory Village': 1776-1862," Historic New England, 66:241 [summer-fall 1975], 32-38. Online at www.spnea.org/resources/list.asp?Number=241

Harding, Walter. The Days of Henry Thoreau [1965], Princeton UP, 1993.

Hosmer, Horace, Remembrances of Concord and the Thoreaus, ed. George Hendrick, U IL P, 1977.

Klauer, William A., Images of America: Acton, Arcadia, 2001.

Meltzer, Milton and Walter Harding, A Thoreau Profile, Thoreau Foundation, 1962.

Petroski, Henry, The Pencil: A History of Design and Circumstance, Knopf, 1999.

Thoreau, Henry D., Journal of Henry David Thoreau [1906], ed. B. Torrey and F. Allen, Dover, 1962.



An earlier version of this article appeared in the Thoreau Society Bulletin, no. 253, fall 2005.  Special thanks to Betsy Conant at the Acton Historical Society, Bill Klauer, Richard Lenat, and Henry Petroski.

1. Eben Wood remembered: Acton Land Stewardship Committee web site (http://town.acton.ma.us/LSCOM/EAPencils.htm). Exclusively for Thoreaus: Harding, Days 17. Credited: by Conant. Henry Petroski, however, disputes the attribution of primacy in respect to creating more comfortable cylinders: octagonal cases were made as early as the seventeenth century (e-mail to author, 30 Oct 2002.) Back to Text

2. "When Miles first worked for them [the Thoreaus] it was at Hayward's Mill at Factory Village." The Nut Meadow mill was used subsequently: "Warren Miles said, I think, that later he ground it for them in [name left blank] Brook near Marshall Miles's house." (Notes of Interviews with Warren Miles.) Dr. Emerson interviewed Warren Miles on two or three occasions in the fall of 1890. The essential material found its way into Thoreau as Remembered by a Young Friend, but there is more detail in the manuscript notes. "Factory Village," a place which Thoreau would survey in 1859, was a small-industrial section of Concord on the Assabet River that had its heyday in the 1840s and 1850s. (Hammond). Back to Text

3. "Presumably," Dr. Emerson supposed, "this was after the Thoreaus' invention of the air-blast which gave the wonderfully fine powder to which they owed their success, for, before that, the grit of the stones would have spoiled their product" (Young Friend 56). Back to Text

4. "When Henry died, W. Miles bought of Mrs. Thoreau the odds and ends of stock and the right to manufacture the so-called fire proof lead. This lead of theirs was mixed with clay ground exceedingly fine and baked."  .Besides black pencil lead, the Thoreaus also made a "rich blue" pencil. "Miles doesn't know how the blue was got, as he did not buy this right." (Emerson, Notes of Interviews with Warren Miles.) Back to Text

Randall Conrad is an independent scholar based in Lexington, Mass., and the director of the nonprofit Thoreau Project on these pages. He has contributed essays and reviews to the Concord Saunterer, ATQ, Thoreau Society Bulletin and other journals. Back to Top

Visit all our subject areas in American history and culture:
Harlem Renaissance | Classic Blues| Shays' Rebellion & the Constitution | Gold Rushes
Calliope Home
| Comments? e-mail the Webkeeper

Updated Feb. 20, 2010