Galileo Pendulum Clock Model, Replica

After decades of experiments with the pendulum, Galileo Galilei (1564-1642) conceived of a pendulum clock that could be used to determine longitude at sea. Near the end of his life, blind and in failing health, he discussed the design with his son Vincenzio and his biographer Vincenzo Viviani. His son made a partial model and his biographer made or commissioned a drawing of the incomplete model after Galileo’s death.
The model in the Museum’s collection, made by New Jersey instrument maker Laurits Christian Eichner in 1958, is based on the seventeenth-century drawing preserved in the Biblioteca Nazionale Centrale, Florence, Italy. It is made of iron and features a pinwheel escapement and a pendulum.
During the seventeenth century, the problem of finding longitude at sea was among the leading topics in scientific research. The idea of using a precise clock to find longitude dated from the century before, but no such clock existed. Clocks in Galileo’s era told time only to the nearest quarter hour and allowed only crude rate regulation. The pendulum-regulated clock, first conceived by Galileo and then realized by Christian Huygens of the Netherlands in 1656, proved unsuitable for finding longitude on a rocking ship, and a good solution to the longitude problem would not appear until the marine chronometer at the end of the 18th century. But the pendulum clock revolutionized precise time for astronomy and other research by measuring time accurately to the second.
1. Bedini, Silvio A. The Pulse of Time: Galileo Galilei, the Determination of Longitude, and the Pendulum Clock. Florence: Olschki, 1991.
2. Multhauf, Robert. Laurits Christian Eichner: Craftsman 1894-1967. Washington, D.C.: N. P., 1971.
3. Vanpaemel, G. “Science Distained: Galileo and the Problem of Longitude,” Italian Scientists in the Low Countries in the XVIIth and XVIIIth Centuries. Edited by C. S. Maffioli and L. C. Palm, 111-130. Amsterdam and Atlanta: Rodopi, 1989.
Object Name
pendulum clock
clock, model
date made
Eichner, L. C.
Physical Description
iron (overall material)
brass (overall material)
overall: 14 in x 5 in x 5 7/8 in; 35.56 cm x 12.7 cm x 14.9225 cm
ID Number
catalog number
accession number
See more items in
Work and Industry: Mechanisms
Measuring & Mapping
Time and Navigation
Time and Navigation, National Air and Space Museum
Data Source
National Museum of American History, Kenneth E. Behring Center


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