Archive for the Science, Technology & Math Category (3 posts)

Practicing Measurement with Historic Surveying

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This is a guest post by former Library geography and map specialist Kathy Hart and former Library intern Sandhya Rajan. 

For a summer enrichment project, we invite children and their adults to use the Library’s collections as inspiration for practicing skills of measurement using the methods of early surveyors. 

A metal chain and book with calculations for surveying

A 66 foot long Gunters Chain used for 18th century metes and bounds surveying in the colonies. Gunter, Edmund. [Gunters Chain], Library of Congress, Geography and Map Division. G9900 18– Vault

During the 18th century, land was measured by using a Gunter’s Chain. Named for Edmund Gunter who developed it, a Gunter’s Chain was 66 feet long with 100 links. Each link was .66 feet or 7.92 inches; eighty chains equaled one mile. To measure a section of land, a surveyor marked the starting point with a stake attached to one end of the chain, stretched the chain to its full length, then placed another stake at the end of the chain to mark the 66 feet. This continued until the desired amount of land was surveyed.

Map scale that reads "Scale in Chains"

Map of the Howland Place, Whitestone Avenue, Flushing, L.I. NY, circa 1845; Geography and Map Division

To begin, you can view the Map of Howland Place on Long Island in New York or the Plan of the Fairhaven Slate Quarry Estate in Vermont, both held in the Library’s Geography and Map Division, as examples of survey maps made using Gunter’s chain. Next, read about George Washington’s interest and expertise in surveying in this short essay  or one of these letters from a surveyor in 1882 to learn more about the experience of surveyors:

Letters from Uriah W. Oblinger to Laura I. Oblinger, 1882

  • June 8: I rec’d [received] your letter yesterday evening…we run our line within one half mile of town this forenoon, and this afternoon we ran through, & tomorrow I suppose we will have to locate every street, fence, building and privy, that comes near our line I tell you these towns are a big job. 
  • May 19: Rec’d your letter yesterday…I have had to carry chain…as one of the chain men…I was in water about all the time, sometimes 3 ft deep. 

To create your own Gunter’s Chain, measure 66 feet of rope, yarn, or string, and tie knots or make a mark every 7.92 inches. Then select a location to measure—it could be a room, the exterior of your house or apartment building, your yard, or a neighborhood park.

Make a map of your measured area, using the Map of Howland Place as an example. Add items like those on the map to illustrate it (trees, sidewalks, etc.), and include your scale in chains. 

Then, have a conversation about it. What was the result? You might discuss what it might have been like to survey a town or county or other larger area in this way, what would life might have been like for a surveyor in the 18th century, or how surveying is done today. 

To explore more, you can: