# Bilby tower

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Steel survey tower

Bilby tower under construction in 1927

Completed Bilby tower showing inner tower for instrument isolated from outer tower for surveyor access

A **Bilby tower** is a type of [survey](/source/Surveying) tower made from [steel](/source/Steel) and used by the [United States Coast and Geodetic Survey](/source/United_States_Coast_and_Geodetic_Survey) (USC&GS) from 1927 to 1984.[1] It is named after [Jasper S. Bilby](/source/Jasper_S._Bilby) who designed it in 1926.[2] In 1927, [Herbert Hoover](/source/Herbert_Hoover), then the [Secretary of Commerce](/source/Secretary_of_Commerce), commended Bilby's tower "for its cost and time efficiency" and cited the surveyor's service as "essential to the United States government".[3]

## History

[Jasper S. Bilby](/source/Jasper_S._Bilby) (1864–1949) was a [surveyor](/source/Surveyor) employed by the USC&GS from 1884 to 1937. He served as Chief Signalman of the USC&GS from 1930 to 1937. Born in [Rush County, Indiana](/source/Rush_County%2C_Indiana), he later moved to a homestead near [Osgood](/source/Osgood%2C_Indiana).[4]

### Design of the Bilby tower

Bilby began designing the first version of the Bilby tower in 1926 and worked with the [Aermotor Windmill Company](/source/Aermotor_Windmill_Company) to develop the first prototypes. The tower was designed to elevate surveyors high enough to look over obstructions and to account for the curvature of the Earth in their calculations.[5] The tower was tested with positive results and Bilby received a commendation from [Secretary of Commerce](/source/United_States_Secretary_of_Commerce) [Herbert Hoover](/source/Herbert_Hoover) for the invention.[6]

The Bilby Tower was a massive success, saving money compared to previous options and increasing the efficiency of the USC&GS surveyors. They could be constructed and deconstructed in less than a third of the time of previous towers, were lighter, and were easier to move.[7] In 1928 alone, use of the Bilby Tower cut costs by up to 35%, and over its first ten years of use it saved the government an estimated $3,000,000 (equivalent to $55,603,448 in 2025).[6][8] Its use also spread outside the United States, reaching as far as [Australia](/source/Australia) and [Denmark](/source/Denmark).[6] The towers were credited by *[The New York Times](/source/The_New_York_Times)* as being "one of the greatest aids to geodetic work."[9]

Prior to the introduction of Bilby towers, surveyors would try to build towers only to the minimum functional height to minimize the resourced expended to erect a tower. Bilby towers, with their low costs and ease of setting up, made this less of an issue. The last Bilby tower erected by the [National Geodetic Survey](/source/National_Geodetic_Survey) was in 1984, and it was placed near [Hartford, Connecticut](/source/Hartford%2C_Connecticut).[10]

### Bilby's legacy

In 1930, Bilby was promoted to the newly created position of "Chief Signalman" of the USC&GS.[6][11] In 1932 the federal retirement age was waived to allow him to continue serving. He retired in 1937.[6] Over the course of his 53-year career, Bilby traveled over 500,000 miles across the United States.[4] Bilby died on July 18, 1949, in [Batesville, Indiana](/source/Batesville%2C_Indiana).[6] The last remaining tower, at [St. Charles Parish](/source/St._Charles_Parish%2C_Louisiana) in [Louisiana](/source/Louisiana), was dismantled by the Surveyors Historical Society in 2012 and re-erected in 2013 at the Osgood Trails Park in [Osgood, Indiana](/source/Osgood%2C_Indiana), the home town of Bilby.[12]

## Features

The Bilby tower was designed to be used for [triangulation](/source/Triangulation_(surveying)).[13] The towers have two unconnected parts—an internal tower for mounting surveying instruments and an external tower for [surveyors](/source/Surveyor). This separation allowed for isolating the instruments from the vibrations induced by people, which increased the precision of measurements. It was portable, reusable and quick to assemble and dismantle.[14] Its quick erection made it possible to conduct surveying rapidly—a team of five men could assemble a steel Bilby tower in only five hours.[15]

## See also

- [Triangulation (surveying)](/source/Triangulation_(surveying))

- [Triangulation station](/source/Triangulation_station)

## References

1. **[^](#cite_ref-1)** ["Survey Towers: Bilby Tower"](https://web.archive.org/web/20170204230427/http://celebrating200years.noaa.gov/survey_towers/bilby.html). [NOAA](/source/NOAA). Archived from [the original](https://celebrating200years.noaa.gov/survey_towers/bilby.html) on February 4, 2017. Retrieved February 3, 2024.

1. **[^](#cite_ref-2)** ["Bilby Towers"](https://web.archive.org/web/20231110163751/http://celebrating200years.noaa.gov/magazine/bilby/welcome.html). [NOAA](/source/NOAA). Archived from [the original](https://celebrating200years.noaa.gov/magazine/bilby/welcome.html) on November 10, 2023. Retrieved February 3, 2024.

1. **[^](#cite_ref-3)** ["Bilby Steel Tower"](https://www.in.gov/history/state-historical-markers/find-a-marker/find-historical-markers-by-county/indiana-historical-markers-by-county/bilby-steel-tower/). [Indiana Historical Bureau](/source/Indiana_Historical_Bureau). Retrieved February 4, 2024.

1. ^ [***a***](#cite_ref-Clark-20162_4-0) [***b***](#cite_ref-Clark-20162_4-1) Clark, Justin (March 10, 2016). ["Jasper Sherman Bilby: To Map the Earth, Part I"](https://blog.history.in.gov/jasper-sherman-bilby-to-map-the-earth-part-one/). *The Indiana History Blog*. [Indiana Historical Bureau](/source/Indiana_Historical_Bureau). Retrieved February 3, 2024.

1. **[^](#cite_ref-5)** [Wilford, John Noble](/source/John_Noble_Wilford) (2000). [*The Mapmakers*](https://archive.org/details/mapmakers00wilf_0/) (Revised ed.). New York: [Alfred A. Knopf](/source/Alfred_A._Knopf). pp. 357–359. [ISBN](/source/ISBN_(identifier)) [978-0-375-40929-5](https://en.wikipedia.org/wiki/Special:BookSources/978-0-375-40929-5).

1. ^ [***a***](#cite_ref-Clark162_6-0) [***b***](#cite_ref-Clark162_6-1) [***c***](#cite_ref-Clark162_6-2) [***d***](#cite_ref-Clark162_6-3) [***e***](#cite_ref-Clark162_6-4) [***f***](#cite_ref-Clark162_6-5) Clark, Justin (March 14, 2016). ["Jasper Sherman Bilby: To Map the Earth, Part II"](https://blog.history.in.gov/jasper-sherman-bilby-to-map-the-earth-part-ii/). *The Indiana History Blog*. [Indiana Historical Bureau](/source/Indiana_Historical_Bureau). Retrieved February 4, 2024.

1. **[^](#cite_ref-7)** Ervin, Adrienne (1927). "Bilby Tower for Government Surveys". *[The Military Engineer](/source/The_Military_Engineer)*. **19** (107): 400–401. [JSTOR](/source/JSTOR_(identifier)) [44605260](https://www.jstor.org/stable/44605260).

1. **[^](#cite_ref-8)** [*Annual Report of the Director, United States Coast and Geodetic Survey to the Secretary of Commerce for the Fiscal Year Ended June 30, 1928*](https://web.archive.org/web/20170302074645/https://docs.lib.noaa.gov/rescue/cgs/005_pdf/CSC-0132.PDF) (PDF). Washington, D.C.: [Government Printing Office](/source/Government_Printing_Office). 1928. p. 24. Archived from [the original](https://docs.lib.noaa.gov/rescue/cgs/005_pdf/CSC-0132.PDF) (PDF) on March 2, 2017.

1. **[^](#cite_ref-9)** Durham, John (September 21, 1930). ["Nation's Vast Geodetic Survey to Give New Accuracy in Maps"](https://www.nytimes.com/1930/09/21/archives/nations-vast-geodetic-survey-to-give-new-accuracy-in-maps-work-now.html). *[The New York Times](/source/The_New_York_Times)*. pp. X14. [ProQuest](/source/ProQuest) [98916316](https://www.proquest.com/docview/98916316).

1. **[^](#cite_ref-10)** Dracup, Joseph F. ["Geodetic Surveying 1940–1990"](https://www.ngs.noaa.gov/PUBS_LIB/geodetic_surveying_1940.html). [National Geodetic Survey](/source/National_Geodetic_Survey).

1. **[^](#cite_ref-11)** Smith, Gretchen S. (May 16, 1930). ["J. S. Bilby Is Urged To Continue Work"](https://www.newspapers.com/article/evening-star-js-bilby-is-urged-to-cont/124860448/). *[The Evening Star](/source/The_Evening_Star_(Washington%2C_D.C.))*. p. B8. Retrieved May 31, 2023 – via [Newspapers.com](/source/Newspapers.com).

1. **[^](#cite_ref-12)** ["Bilby Tower Dedication Honoring Jasper Sherman Bilby - xyHt"](http://www.xyht.com/surveying/bilby-tower-dedication-honoring-jasper-sherman-bilby/). *xyHt*. August 21, 2014. Retrieved June 28, 2017.

1. **[^](#cite_ref-13)** Gossett, F. R. (1959). [*Manual of Geodetic Triangulation*](https://catalog.hathitrust.org/Record/102182069). [U.S. Government Printing Office](/source/U.S._Government_Printing_Office) for the [Coast and Geodetic Survey](/source/Coast_and_Geodetic_Survey).

1. **[^](#cite_ref-14)** ["Historic Traveling Bilby Tower 'Comes Home' to Osgood, Indiana"](https://web.archive.org/web/20170711025752/http://oceanservice.noaa.gov/news/features/nov13/last-bilby-tower.html). [National Ocean Service](/source/National_Ocean_Service). Archived from [the original](http://oceanservice.noaa.gov/news/features/nov13/last-bilby-tower.html) on July 11, 2017. Retrieved February 3, 2024.

1. **[^](#cite_ref-15)** [Bowie, William](/source/William_Bowie_(engineer)) (1931). ["Triangulation"](https://www.jstor.org/stable/24975698). *[Scientific American](/source/Scientific_American)*. **144** (6): 369–373. [JSTOR](/source/JSTOR_(identifier)) [24975698](https://www.jstor.org/stable/24975698).

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Adapted from the Wikipedia article [Bilby tower](https://en.wikipedia.org/wiki/Bilby_tower) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Bilby_tower?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.