A timely trip of observation

Nutting, B.F.; Sonrel, A., “The Cambridge U.S. Equatoreal,” Lithography, 1848, In Memoirs of the American Academy of Arts and Sciences, 187, United States: The Academy, 1849.

On a clear January afternoon, I stroll around the Harvard College Observatory. The unimposing main building, an amalgam of different extensions, sits on an almost perfect East-West axis atop the hill [1]. A few cumulus clouds blow past the copper dome of the Sears tower, the only remnant of the original observatory building. This Greek revivalist centerpiece was designed by architect Isaiah Rogers in 1843, noted for his role as supervising architect of the United States from 1863 to 1865 [2]. The tower’s primary granite entrance is rendered secondary today. It serves as a hangout area with wooden benches and a compost bin. The main doors are locked, but the mind wanders on its own.

Looming through the vestibule, a floor to ceiling granite pier fills the center of the room. I move up the stairs and find myself inside the once pivoting rotunda. The sculpted tip of the pier perforates the floor. It carries the Great Refractor, an equatorial telescope constructed in 1847, the largest of its kind then present in the United States. Its long wooden tube veneered with mahogany incorporates a 15-inch lens by German lens makers Merz and Mahler. To its side, a puffy observing chair with rolling legs sits on two rails circling the room. The observers would sit here and take daguerreotype images of the sky [3]. But the Great Refractor was not simply an observation device, peeking through the crevice of the roof and onto the gleams of distant stars; it was used to measure celestial movements and tell time.

Sears tower is but a fragment of the original complex. Throughout time, pieces were demolished and new extensions planned. On the imprint of the former two wings now stand brick buildings of the same proportions. Large glass openings structure their facades, protected by shabby sun panels. I descend two flights of stairs to find myself in the west wing of the original building. A large heavy door sealed with felt packing hinders the way. Completed on March 2, 1873, the clock room encapsulates the three delicate timepieces of the observatory, placed on marble slabs with brick piers. Their faces can be viewed through the thick glass panes mounted in the walls: Human vicinity, so it was believed, could alter the delicate settings of the clocks [4]. But the construction also protects the devices from the environment. The double-walled room seals time from the elements and temperature variations.

Between dome and clock room, an electro-recording apparatus wires the refractor with the timepieces. On the occasion that the observer would see a star transit the meridian, he would press a switch, electronically recording the event in reference to the time set by the clock. These two measurements together provided the basis for precise latitude measurement on Earth by the team of female “computers” sitting in the neighboring room [5]. For the age of colonial trade and cosmopolitanism, the importance of these measurement and their accuracy is difficult to overestimate.

The Harvard Observatory was not simply a research center but actively serviced its community. Its timepieces –accurate to a few milliseconds– were admired by the train supervisors, fire departments, city officials, and watchmakers, all looking to acquire precise time. All day, in two-seconds intervals, Harvard’s telegraphs sent out electronic signals to subscribers all around New England so they could match their clocks to the one at the observatory. Over the years, public clocks were synchronized and train schedules were adapted. Effectively, the scientists were producing live experiments on simultaneity and relativity [6].

Back on my feet, I peer through one of the windows of the recent brick additions. Before me is a small office with an Apollo mission illustration poster, a wall clock, and the newest edition of “An introduction to modern Astrophysics” standing fore on the shelf.

[1] The South-West Axis, as well as the orientation on the Meridian, are given particular emphasis in the site plan of 1856: Anonymous, “Plan of the Grounds of Harvard College Observatory,” 1856, In History and Description of the Astronomical Observatory of Harvard College by William Cranch Bond, 139, United Kingdom: Metcalf, 1856.

[2] "Massachusetts Cultural Resource Information System CAM.161", Mhc-Macris.Net, accessed 13 March 2021, https://mhc-macris.net/Details.aspx?MhcId=CAM.161.

[3] Memoirs of the American Academy of Arts and Sciences (United States: The Academy, 1849), 146. And "The Great Refractor", Harvard Magazine, 2004, https://harvardmagazine.com/2004/05/the-great-refractor.html.

[4] Peter Galison, Einstein's Clocks, Poincaré's Maps (New York: W.W. Norton & Company, 2003). No primary source of the description of the clock room could be found.

[5] See Dava Sobel’s The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars (2016) for an extensive history of the imperative work of female astronomers and mathematicians (historically referred to as “computers”) at the Harvard Observatory.

[6] Peter Galison, 2003.