Humboldt State University

Robert A. Paselk Scientific Instrument Museum

Humboldt's Latin American Expedition, 1799–1804

Richard Paselk, Curator

Leyden Jar

In his own words in his Personal Narrative of Travels…. Humboldt carried "... small Leyden phails, to be charged by rubbing." (Alexander von Humboldt. Personal narrative of travels to the equinoctial regions of the New continent, during the years 1799-1804, by A. von Humboldt and A. Bonpland. translated from the French by Helen Maria Williams, 1814, p 36.)

Selected on-line examples of early 18th and 19th-century leyden jars that may be similar to Humboldt's from the Department of the Histroy of Science at Harvard University include:

( 1750-1800)


leyden jar image  icon

Unknown maker

1st half 20th century; HSU Physics Dept.

leyden jar catalog scan icon

The Leyden jar (Leyden phial) is an early form of a capacitor used to store static electricity. The inner and outer walls of the lower part of the glass jar are coated with metal foil (commonly tin or lead) with the inner foil connected to a conducting rod in the center of the jar, often via a short length of chain.


The blown glass jar is approximately three and one quarter inches diameter by seven inches tall with a flared-in neck. The bottom two inches of the jar is covered inside and out with metal (tin?) foil. A turned oak "mushroom" cap is held in by cork wedges. The brass ball and rod secured in the center of the cap show traces of the original laquered brass finish. A length of brass chain hangs from an eyelet at the bottom of the brass rod with over an inch lying loosely on the bottom of the jar to ensure electrical contact as seen in the top-view of the jar. The catalog scan is from: W. M. Welch Scientific Co. Scientific Instruments Laboratory Apparatus and Supplies for High Schools. Chicago (1935). This was chosen because it has an oak top, most leyden jars found in the curator's catalog collection were of an open form (a version of which is also shown in the scan).

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HSTC (1921-34)
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HSC (1935-1953)
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HSC (1954-1973)

© R. Paselk

Last modified 13 August 2013