Heliotrope (instrument): Difference between revisions
Added drawing of Gauss' original heliotrope. |
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{{Other uses|Heliotrope (disambiguation)}} |
{{Other uses|Heliotrope (disambiguation)}} |
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[[File:Gauss'_Heliotrope.jpg|thumb|400 px |right|Gauss' Heliotrope ca.1822)]] |
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[[File:Heliotrope5.jpg|thumb|400 px |right|Wurdemann's Heliotrope]] |
[[File:Heliotrope5.jpg|thumb|400 px |right|Wurdemann's Heliotrope]] |
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The '''heliotrope''' is an instrument that uses a [[mirror]] to reflect [[sunlight]] over great distances to mark the positions of participants in a land [[Surveying|survey]]. The heliotrope was invented in 1821 by the [[Germany|German]] [[mathematics|mathematician]] [[Carl Friedrich Gauss]].<ref>[http://books.google.com/books?id=s93bifR6Fj0C&pg=RA1-PA358&lpg=RA1-PA358&dq=heliotrope+inventor&source=web&ots=b33mPoQ75X&sig=VctfyuoSbOpp4GrgVETKpl4hLFw&hl=en&sa=X&oi=book_result&resnum=4&ct=result#PRA1-PA358,M1 The Heliotrope, a New Instrument - Arts and Sciences - The Gentleman's Magazine (1822)]</ref><ref name=GaussTitan>{{cite book|last=Dunnington|first=G. Waldo|title=Carl Friedrich Gauss: Titan of Science|year=2004|publisher=The Mathematical Association of America|location=New York|isbn=0-88385-547-X|pages=122–127|url=http://books.google.com/books?id=_dce9Jaq7iQC&pg=PA123&dq=heliotrope}}</ref> |
The '''heliotrope''' is an instrument that uses a [[mirror]] to reflect [[sunlight]] over great distances to mark the positions of participants in a land [[Surveying|survey]]. The heliotrope was invented in 1821 by the [[Germany|German]] [[mathematics|mathematician]] [[Carl Friedrich Gauss]].<ref>[http://books.google.com/books?id=s93bifR6Fj0C&pg=RA1-PA358&lpg=RA1-PA358&dq=heliotrope+inventor&source=web&ots=b33mPoQ75X&sig=VctfyuoSbOpp4GrgVETKpl4hLFw&hl=en&sa=X&oi=book_result&resnum=4&ct=result#PRA1-PA358,M1 The Heliotrope, a New Instrument - Arts and Sciences - The Gentleman's Magazine (1822)]</ref><ref name=GaussTitan>{{cite book|last=Dunnington|first=G. Waldo|title=Carl Friedrich Gauss: Titan of Science|year=2004|publisher=The Mathematical Association of America|location=New York|isbn=0-88385-547-X|pages=122–127|url=http://books.google.com/books?id=_dce9Jaq7iQC&pg=PA123&dq=heliotrope}}</ref> |
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The heliotrope was utilized by [[Surveyor (surveying)|surveyors]] as a specialized form of 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 appear indistinct. Heliotropes have been used repeatedly 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 [[U.S. National Geodetic Survey|USCGS]] from [[Mount Shasta]], a distance of 192 miles (309 km).<ref>[http://celebrating200years.noaa.gov/theodolites/heliotrope.html NOAA 200th: Collections: Theodolites: heliotrope]</ref> |
The heliotrope was utilized by [[Surveyor (surveying)|surveyors]] as a specialized form of 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 appear indistinct. Heliotropes have been used repeatedly 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 [[U.S. National Geodetic Survey|USCGS]] from [[Mount Shasta]], a distance of 192 miles (309 km).<ref>[http://celebrating200years.noaa.gov/theodolites/heliotrope.html NOAA 200th: Collections: Theodolites: heliotrope]</ref> |
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[[File:Heliotrope2-2.jpg|thumb|400 px |left|Heliotrope (ca.1878): B.A. Colonna collection ([[NOAA]]). This may be the very one Colonna surveyed from 192 miles away.]] |
[[File:Heliotrope2-2.jpg|thumb|400 px |left|Heliotrope (ca.1878): B.A. Colonna collection ([[NOAA]]). This may be the very one Colonna surveyed from 192 miles away.]] |
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Revision as of 02:00, 8 March 2014
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 (Template:Lang-el), meaning "sun", and tropos (Template:Lang-el), meaning "turn". It is a fitting name for an instrument which can be turned to reflect the sun toward a given point.
The heliotrope was utilized by surveyors as a specialized form of 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 appear indistinct. Heliotropes have been used repeatedly 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).[3]
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.[4] 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
Notes
- ^ The Heliotrope, a New Instrument - Arts and Sciences - The Gentleman's Magazine (1822)
- ^ Dunnington, G. Waldo (2004). Carl Friedrich Gauss: Titan of Science. New York: The Mathematical Association of America. pp. 122–127. ISBN 0-88385-547-X.
- ^ NOAA 200th: Collections: Theodolites: heliotrope
- ^ Abbe, Cleveland (December 1900). "Meteorology and Geodesy". Monthly Weather Review. XXVIII (12): 545–547. Retrieved 10 July 2013.
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.