A Dark Day in the Revolution

In the tumult of the military revolution that forms the backdrop of most study of the War of Independence, it’s easy to forget that the sciences were undergoing a parallel revolution. We’ve all heard about Benjamin Franklin’s experiments along the far frontiers of knowledge of electricity, even if the popular conception of them is somewhat skewed. “Natural philosophy,” as the pursuit of what we would today identify as science, consumed a great deal of attention and ink on both sides of the Atlantic. Right through the era of the Revolution every year brought important new discoveries and observations.

While many avenues of scientific exploration must be shifted to accommodate the vagaries of current events, astronomy, in some cases, cannot be delayed or displaced, lest the opportunity for important observations be missed completely. Eclipses fall into this latter category, presenting very different phenomena depending upon whether the observer is well-situated or placed less than ideally.

The total solar eclipse of June 24, 1778, which was seen in many parts of the nascent United States, excited the imagination of many natural philosophers. A Spanish sailor, Antonio de Ulloa, presented to the Royal Society of London a description of the Sun’s corona: “Out of this luminous circle there issued forth rays of light, which reached to the distance of a diameter of the Moon, sometimes more, sometimes less…”[i]

As the date of the next total solar eclipse neared, in October of 1780, Samuel Williams of Harvard University was determined to observe it. Inconveniently, his calculations showed that it would be best observed along the shores of modern-day Maine — at the time tenuously held by a British garrison. No matter how sweeping the events that might convulse human affairs, the orbits of the planets do not yield to our petty squabbles.

However, Williams convinced the Massachusetts Speaker of the House, John Hancock (of the famed signature on the Declaration of Independence) to send a letter to the British commanders in the area, asking for safe passage to the site, as a “Friend of Science.”[ii] The British Colonel Campbell at Penobscot gave the permission for a strictly limited stay at the chosen location. The location Williams had asked for was worrisomely nearby to his recently-besieged fortification there, and he did not want to take any chances with further American skullduggery.[iii]

After securing passage and wheedling precious supplies out of the Massachusetts government, Williams assembled a collection of the most advanced observational instruments available. All appeared to be in place for an American natural philosopher to make an important contribution to the advancement of astronomy, as well as the first detailed scientific observation of a total solar eclipse in North America.

The expedition arrived early and secured grudging permission to land and begin their preparations before the date originally specified by Campbell. He refused to let them onto the mainland, instead confining them to a small island off the shore where his garrison stood. Williams calculated that the location was within the area he’d planned to attempt, so they set up camp and arrayed their instruments to best take advantage of the natural spectacle to come.

Among other things, they brought a precision compass, astronomical octant, telescopes, and perhaps most critically, a high-quality clock[iv] to time the different events of the eclipse for refinement of the exact longitude of the site. This was a matter of wide usefulness to naval interests of all nations, and the chief practical objective of the expedition.

For readers who have experienced a total solar eclipse, Williams’ description of the event will doubtless bring a thrill of remembrance; the rest will have to imagine it from his words (and doubtless add it to their bucket lists):

Immediately after the last observation the sun’s limb became so small as to appear like a circular thread or rather like a very fine horn. Both the ends lost their acuteness and seemed to break off in the form of small drops or stars; some of which were round and others of an oblong figure They would separate to a small distance: Some would appear to run together again and others diminish until they wholly disappeared. Finding it very difficult to measure the lucid part any longer I observed again in the larger telescope looking out for the total immersion. After viewing the sun’s limb about a minute I found almost the whole of it thus broken or separated in drops a small part only in the middle remaining connected…

From the beginning of the eclipse unto the time of the greatest obscuration the colour and appearance of the sky was gradually changing from an azure blue to a more dark or dusky colour until it bore the appearance and gloom of night. The degree of darkness was greater than was to be expected considering the sun was not wholly obscured… Objects at a small distance appeared confused and we were obliged to make use of candles to count our clock. But as soon as the greatest obscuration was past it was universally remarked that the increase of the light was much more rapid than that of the darkness had been. As the darkness increased a chill and dampness were very sensibly felt… To this we may add so unusual a darkness dampness and chill in the midst of day seemed to spread a general amazement among all sorts of animals: Nor could we ourselves observe such unusual phenomena without some disagreeable feelings. [v]

Williams' diagram of the eclipse[vi]
Williams’ diagram of the eclipse[vi]
The event being over, the expedition packed up and left in accordance with Campbell’s orders, though Williams wrote later that he wished for the opportunity to amass additional observations to improve the accuracy of his calculations. Regardless, he prepared his triumphant report to the American Academy of Arts and Sciences. He exulted that they had the pleasure of “achieving their objectives,” recording sufficient data to very accurately calculate the exact longitude and latitude at which their observing site had been located.

However, even in the moment of observing this natural marvel, Williams’ excitement was tempered by the realization that their location, constrained as it had been by military considerations, had missed the area of actual totality by a mere handful of miles: “The longitude of the place of our observation agrees very well with what we had supposed in our calculations. But the latitude is near half a degree less than what the maps of that part of the country had led us to expect. On this account our situation, instead of falling within the limits of the total darkness, proved to be very near the southern extremity.”[vii]

Despite his disappointment, Williams’ contributions to the advancement of science could have been greater, had he recognized the phenomenon he described and sketched as being a new and original observation. The “small drops or stars” he described were recognized by a later (British) scientist, Francis Baily, as being the places where the sliver of the Sun’s light at its edge is being interrupted by the jagged peaks of mountains along the edge of the Moon. [viii] “Baily’s Beads,” as this phenomenon has become known, might have been called “Williams’ Drops” instead, had he pursued this observation more acutely.

It’s easy enough to overlook the broad and chaotic ferment of ideas outside of the field of political philosophy that formed the backdrop to the Revolution. It is remarkable to learn that even in the midst of the armed struggle, scientific advancement was considered by both sides important enough to take priority over the more ephemeral concerns of politics and military supremacy. Even as the course of history was being decided on the battlefields, this history of ideas and knowledge continued to unfold, only occasionally being hindered by mundane events.

[FEATURED IMAGE AT TOP: Total solar eclipse. Source: Wikimedia Commons]


[i] de Ulloa, Don Antonio, and S. Horsley. “Observations on the Total (with Duration) and Annular Eclipse of the Sun, Taken on the 24th of June, 1778, on Board the Espagne, Being the Admiral’s Ship of the Fleet of New Spain, in the Passage from the Azores towards Cape St. Vincent’s. By Don Antonio Ulloa, F. R. S. Commander of the Said Squadron; Communicated by Samuel Horsley, LL.D. F. R. S..” Philosophical Transactions of the Royal Society of London 69: 105-119. http://rstl.royalsocietypublishing.org/content/69/105.full.pdf+html (accessed May 17, 2014).

[ii] Baxter, James Phinney. The Baxter manuscripts,. Portland, Maine: Maine Historical Society, 1914. http://books.google.com/books?id=d8EMAAAAYAAJ (accessed May 17, 2014).

[iii] Rothschild, Robert Friend. Two brides for Apollo: the life of Samuel Williams (1743-1817). New York: IUniverse, 2009.

[iv] ibid.

[v] Memoirs of the American Academy of Arts and Sciences to the end of the year M, DCC, LXXXIII. Volume I. Boston: Printed by Adams and Nourse, in Court-Street, 1785. http://books.google.com/books?id=OrwAAAAAYAAJ (accessed May 17, 2014).

[vi] ibid, via Rothschild, Robert Friend. Two brides for Apollo: the life of Samuel Williams (1743-1817). New York: IUniverse, 2009.

[vii] ibid

[viii] Baily, Francis. “On a Remarkable Phenomenon that occurs in Total and Annular Eclipses of the Sun.” Memoirs of the Royal Astronomical Society 10: 1-42. http://books.google.com/books?id=I21aAAAAYAAJ (accessed May 17, 2014).

More from Lars D. H. Hedbor

From Pounds to Dollars

In all times and places, people have engaged in trade, and the...
Read More


  • Well done article on an obscure event taking place during the Revolution. Williams is an interesting character of note here in Vermont, generally recognized as the first state historian and publisher of a local paper. See, http://dssmhi1.fas.harvard.edu/emuseumdev/code/emuseum.asp?action=advsearch&newsearch=1&profile=people&rawsearch=constituentid/,/is/,/6656/,/false/,/true&style=single&searchdesc=Samuel+Williams

    It is also interesting to consider that at the very moment of the war, James Cook was traveling the Pacific making important scientific and geographical discoveries over the course of two voyages before his death in 1779.

  • Thank you, Gary! I’ve been planning for a while to write a novel based on this event, as part of my Tales From a Revolution series, and Williams is a fellow whose life story, as related in Two Brides for Apollo (cited above) is quite fascinating, as well.

    It’s all too easy for us to become provincial as historians of the Revolution, and forget that the late 18th century was a time when a *lot* of fields of human endeavor were undergoing exceptional changes.

  • Although in conflict with the author’s intent, this provincial historian of the Revolution could not pass on the opportunity to reference a quote about his hometown. From “John Peebles’ American War: The Diary of a Scottish Grenadier, 1776 -1782,” the following:

    “Wednesday 24th June…march’d to Allens Town [NJ], 4 miles and Encamp’d on a very fine extensive piece of clear ground & almost level, to the N:Ed: of the Village, fronting the West in two lines — or NW — a pretty Country — A Remarkable great Eclipse of the sun today, but being cloudy could not see it till near & at its height, near 10 A:M: when it was almost total…”

    It was at Allentown where the British reordered their march across New Jersey, placing the Jaegers and Light Horse in the rear, and turned east toward Monmouth Court House (Freehold). This movement provided Washington with knowledge of their eventual route to Sandy Hook, a prelude to the Battle of Monmouth four days later.

  • In response to the above, i have heard some accounts report that the 1778 eclipse was seen an as omen, as it was days before Monmouth. I wonder if there are not more primary accounts of that eclipse?

  • For the eclipse of Aug 21, 1914, Germans scientists set up in Russia to observe the eclipse to prove/disprove Einstein, but while there, Germany declares war on Russia…doh! The equipment was confiscated and they were arrested, although, thankfully, released later.

    Interesting side note : the equipment was financed by a weapons manufacturer from Crimea by the name of Gustav Krupp.

Leave a Reply

Your email address will not be published. Required fields are marked *