Edisto Island in Colleton County, South Carolina — The American South (South Atlantic)

Bache's Bar of Invariable Length

Photographed by Bernard Fisher, October 20, 2022

1. Bache's Bar of Invariable Length Marker

Inscription. In the 1840s, the U.S. Coast Survey finally began the first-ever accurate mapping of our coasts. The agency's superintendent, Professor Alexander D. Bache, great grandson of Benjamin Franklin and West Point roommate of Jefferson Davis, was a brilliant scientist. His innovations produced remarkably precise results.

Measuring tools had always expanded and contracted with temperature changes, but Bache's invention, the "bar of invariable length,” eliminated that longstanding obstacle to accuracy. He placed an iron rod beside a brass rod within a tin tube. Connecting the rods at one end with a compensating lever caused their different expansion rates to cancel each other out, yielding reliable measurements.

(caption) Prof. A. D. Bache, inventor of the measuring device called the "bar of invariable length,” later helped establish the Smithsonian Institution and the National Academy of Science. National Oceanic and Atmospheric Administration/Department of Commerce

Erected by South Carolina State Park Service.

Topics. This historical marker is listed in these topic lists: Exploration • Science & Medicine. A significant historical year for this entry is 1849.

Location. 32° 30.397′ N, 80° 19.483′ W. Marker is on

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Edisto Island, South Carolina, in Colleton County. It is on Oyster Row Lane half a mile south of Palmetto Road, on the right when traveling south. Located at the Edisto Environmental Learning Center. Touch for map. Marker is at or near this postal address: Oyster Row Ln, Edisto Island SC 29438, United States of America. Touch for directions.

Regionally, this marker is in South Carolina’s Lowcountry,

in the Ashepoo and Combahee and Edisto Basin.

It is also in the American South

and specifically in the Deep South.

Globally, it is in the North Atlantic Region,

North America,

the Western Hemisphere,

the Western World,

and the Anglosphere.

Historically, it finds itself in what was once New Spain,

the territory of the Mississippian Culture,

one of the original Thirteen Colonies,

one of the Confederate States of America,

and the Antebellum South.

Other nearby markers. At least 8 other markers are within 12 miles of this marker, measured as the crow flies: How to Measure the World, and Why (about 300 feet away, measured in a direct line); The Struggle for a Long Straight Line (about 500 feet away); Markers in the Woods (about 600 feet away); Lafayette's Tour (approx. 4.8 miles away); A Life-Saving Light Station (approx. 11.2 miles away); A Guiding Light (approx. 11.2 miles away); Fuel for the Flame (approx. 11.2 miles away); Charleston Tea Plantation (approx. 11.2 miles away). Touch for a list and map of all markers in Edisto Island.

Also see . . . Edisto Environmental Learning Center. (Submitted on October 20, 2022.)

Photographed by Bernard Fisher, October 20, 2022

2. Bache's Bar of Invariable Length Marker

Bache Monument image. Click for full size.

Photographed by Bernard Fisher, October 20, 2022

3. Bache Monument

Edisto Environmental Learning Center image. Click for full size.

Photographed by Bernard Fisher, October 20, 2022

4. Edisto Environmental Learning Center

Credits. This page was last revised on October 20, 2022. It was originally submitted on October 20, 2022, by Bernard Fisher of Richmond, Virginia. This page has been viewed 1,533 times since then and 104 times this year. Photos: 1, 2, 3, 4. submitted on October 20, 2022, by Bernard Fisher of Richmond, Virginia.