Before creating his famed marine chronometers (1730–59) to determine longitude at sea, John Harrison focused on land-based timekeeping, striving to build pendulum clocks of the highest possible precision. In the years following the Scientific Revolution and on the cusp of the Industrial Revolution, pendulum clocks governed travel, work, and daily life. The United Kingdom’s variable climate posed a special challenge for clock precision: colder air contracted metal pendula while warmer air expanded them, shortening and lengthening the swing period, respectively. In 1726, Harrison invented the gridiron pendulum. By connecting alternating rods of metals such as brass and steel, each with different thermal expansion rates, Harrison’s gridiron compensated for temperature shifts and stabilized the pendulum’s length and period.

At the May 2025 lecture of the Horological Society of New York (HSNY), Eddie Landzberg will present his undergraduate research on John Harrison’s gridiron pendulum. In an independent study at Harvard University, Landzberg examined Harrison’s original manuscripts in London and constructed a brass and steel gridiron pendulum. In his lecture, Landzberg will discuss the scientific discoveries, climate conditions, and horological innovations that set the scene for Harrison’s work. He will further discuss how the gridiron pendulum functions, reflect on its early reception, and share insights from the reproduction process.

Time: 6:00-8:00 pm EST

Free!

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