World Library  
Flag as Inappropriate
Email this Article

Heliotrope (instrument)

Article Id: WHEBN0002104341
Reproduction Date:

Title: Heliotrope (instrument)  
Author: World Heritage Encyclopedia
Language: English
Subject: Carl Friedrich Gauss, Mirror
Publisher: World Heritage Encyclopedia

Heliotrope (instrument)

Heliotrope (ca.1878): B.A. Colonna collection (NOAA). This may be the very one Colonna surveyed from 192 miles away.
Gauss's Heliotrope (ca.1822)
Wurdemann's Heliotrope (1866)

The heliotrope is an instrument that uses a mirror to reflect sunlight over great distances to mark the positions of participants in a land survey. The heliotrope was invented in 1821 by the German mathematician Carl Friedrich Gauss.[1][2] The word "heliotrope" is taken from the Greek: helios (Greek: Ἥλιος), meaning "sun", and tropos (Greek: τρόπος), meaning "turn". It is a fitting name for an instrument which can be turned to reflect the sun toward a given point.

Heliotropes were used in surveys from Gauss's survey in Germany in 1822 through the late 1980s, when GPS measurements replaced the use of the heliotrope in long distance surveys. Great Trigonometric Survey in India around 1831,[3] and the US Coast and Geographic Survey used heliotropes to survey the United States. The Indian specification for heliotropes was updated in 1981,[4] and the American military specification for heliotropes (MIL-H-20194E) was retired on 8-Dec-1995.[5]

Surveyors used the heliotrope as a specialized form of survey target; it was employed during large triangulation surveys where, because of the great distance between stations (usually twenty miles or more), a regular target would be indistinct or invisible. Heliotropes were often used as survey targets at ranges of over 100 miles. In California, in 1878, a heliotrope on Mount Saint Helena was surveyed by B.A. Colonna of the USCGS from Mount Shasta, a distance of 192 miles (309 km).[6]

The heliotrope was limited to use on sunny days and was further limited (in regions of high temperatures) to mornings and afternoons when atmospheric aberration least affected the instrument-man's line of sight.[7] The heliotrope operator was called a "heliotroper" or "flasher" and would sometimes employ a second mirror for communicating with the instrument station through heliography, a signalling system using impulsed reflecting surfaces. The inventor of the Heliograph, a similar instrument specialized for signaling, was inspired by observing the use of heliotropes in the survey of India.

See also

  • Heliograph, a similar instrument, used in communication


  1. ^ The Heliotrope, a New Instrument - Arts and Sciences - The Gentleman's Magazine (1822)
  2. ^ Dunnington, G. Waldo (1955). Carl Friedrich Gauss: Titan of Science. New York: Exposition Press. pp. 122–127,119,221.  
  3. ^ Gleanings in science, Volume 3. Baptist Mission Press. 1831. p. 344. 
  4. ^ Specification for Heliotrope, Surveying. Indian Standards Institution. 1981. 
  5. ^ "MIL-H-20194E Note 1". 
  6. ^ NOAA 200th: Collections: Theodolites: heliotrope
  7. ^ Abbe, Cleveland (December 1900). "Meteorology and Geodesy". Monthly Weather Review. XXVIII (12): 545–547.  

External links

  • The Surveyor's Heliotrope
  • Topographic, Trigonometric and Geodetic Surveying, by Herbert Michael Wilson (1912) pp. 566–574 are devoted to heliotropes
  • Elemente der Vermessungskunde, (in German) by Karl Maximilian von Bauernfeind (1862) pp. 115–122 are devoted to Gauss's heliotrope, and the Stierlin and Steinheil heliotropes are described as well.
  • The Heliotrope A short history.
  • Transits of Venus Page with photographs of three heliotropes from 1873.
  • Improvised Heliotrope this 1969 article also provides the US Army part number for a heliotrope.
  • Heliotrope Heliotrope photo, description of a 192-mile record.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.