The Brief And Curious Life Of Cincinnati’s First Astronomical Observatory

Did Jared Mansfield really establish the nation’s first astronomical lookout in Northside forty years before the founding of our magnificent Observatory? That depends.
1750

At the corner of Knowlton and Mad Anthony streets in Northside is a small and somewhat neglected monument cobbled together from the riot-wrecked detritus of the old Hamilton County Courthouse. The memorial marks the location of Ludlow Station, one of a line of fortifications maintaining a bulwark against attacks by Native American tribes as eastern settlers encroached on their territories. The monument was originally erected by the Daughters of the American Revolution in 1915. In 1976, an additional bronze plaque, now missing, was added by the DAR which read:

“First United States Observatory”

“First chartings of meridians and baselines of Northwest Territory by Jared Mansfield ordered 1803 by President Thomas Jefferson.”

Cincinnati is justly famous as “The Birthplace of American Astronomy” because of our magnificent Observatory in Mount Lookout, originally dedicated in 1843 on Mount Adams. That facility houses one of the oldest working telescopes in the world and was the first public observatory in the western hemisphere.

Pioneer surveyor Israel Ludlow built the large house occupied by United States Surveyor General Jared Mansfield while he was calculating accurate baselines for the Northwest Territory.

The Ludlow Mansion from “History of Cumminsville 1792-1914” Digitized by Public Library of Cincinnati & Hamilton County

Forty years earlier, Colonel Jared Mansfield arrived somewhat reluctantly in Cincinnati with his young family to await the arrival of a shipment of scientific instruments manufactured in England. Mansfield was the newly appointed Surveyor General of the United States and needed these devices to conduct his work. One of Mansfield’s sons, Edward, grew up to become an author and newspaper editor who left behind a detailed memoir of the family’s time in Cincinnati. He describes the scientific instruments required by his father:

“My father informed [President Thomas] Jefferson that the meridian line could not be run without certain astronomical instruments, and that these instruments could not be had in the United States. Mr. Jefferson said that Congress had made no appropriation for that object, but that he (the President) had a contingent fund out of which he would procure these instruments. Mr. Gallatio, then secretary of the treasury, wrote to Troughton, mathematical instrument maker, London, for the followingly instruments: First, a three-foot-long reflecting telescope, mounted in the best manner, with lever motion; secondly, a thirty-inch portable transit instrument, which answered the purpose of an equal altitude instrument and theodolite; thirdly, an astronomical pendulum clock; fourthly, several astronomical books. These instruments and books cost $1,054, but would cost four times that now, for they were very excellent of their kind.”

Portrait of Jared Mansfield from “Historical Collections of Ohio” By Henry Howe, Volume III Digitized by Internet Archive

Edward Mansfield’s recollections have been quoted by every historian ever since and they all repeat Mansfield’s initial error. Photographs of these valuable scientific instruments, now preserved in the museum at West Point, clearly show a refracting telescope, not a reflecting telescope—a warning to take Mansfield’s memoirs with a dash of salt.

“The astronomical instruments, whose purchase by Mr. Jefferson has been described, were set up in one room at our house, at Ludlow Station. Hence, as I have often said, the first real observatory was established in our house. There my father made such astronomical calculations as were necessary to his purpose.”

Jared Mansfield’s “purpose” was establishing accurate baselines from which land surveys could be calculated. In the young United States, accurate land surveys were critical. The new country had very little money, but it had lots of land. This land was rather inconveniently occupied by indigenous people but, as the Europeans saw it, the Native Americans had no surveyors to certify their land claims. As the United States settled its debts by awarding land grants, it wanted to guarantee clear title to the plots it awarded to veterans and other creditors.

Although Jared Mansfield’s accomplishments have been erased from the Northside monument, he left behind a significant memorial that you might see almost every day—the border between Indiana and Ohio. It took some years, many on-the-ground measurements and calibration with astronomical observations, but Mansfield plotted that interstate boundary line from the mouth of the Great Miami River northward. This is the “meridian line” that Jefferson assigned Mansfield to plot, and it is the starting point for almost every land survey in Western Ohio.

Let us now split a few hairs. Did Jared Mansfield really establish the first astronomical observatory in the United States in Northside in 1805? The answer to that question depends on how you define “observatory” and when.

I believe we can all agree that a portable telescope set up in somebody’s house does not actually constitute an “observatory.” True, observatories do have telescopes, but there is an implication that an observatory telescope will be permanently mounted, not something you might schlep into the closet when guests arrive.

Today we might also insist that an astronomical observatory be dedicated to, you know, astronomy—not some mundane task like land records. Our modern prejudice ignores the extremely practical origins of American astronomy. The Cincinnati Observatory was very much founded to help map the United States and to help regulate time in the days before standard time. Astronomy got a boost in early America precisely because it was so useful for marking time, guaranteeing precise deeds, creating accurate maps and other practical goals. According to W. Carl Rufus, writing in the “Publications of the Astronomical Society of the Pacific” [October 1944]:

“As late as 1816 a friend of [French philosopher Auguste] Comte wrote him from this country: If [mathematician and astronomer Joseph-Louis] Lagrange were to come to the United States, he could only earn his livelihood by turning surveyor.”

It must be noted that Mansfield also used his little telescope, in addition to routine observations related to land surveys, for actual astronomical work. Colonel Mansfield hauled out his Northside telescope to calculate the orbit of a large comet in 1807. His paper on that orbit was published in one of the prestigious scientific journals of the day.

Mansfield completed his work by 1812, packed up his little observatory and returned to the United States Military Academy at West Point as professor of mathematics and natural and experimental philosophy.

Weep not for the vanished Northside plaque. In addition to nailing the Indiana-Ohio border into perpetuity, Colonel Mansfield has another memorial, probably somewhat better known. The city of Mansfield, Ohio, was named in his honor.

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