Plane table

Plane table

A plane table is a device used in surveying and related disciplines to provide a solid and level surface on which to make field drawings, charts and maps.

History

The first known instrument for directly producing a drawing of a site was developed by Johann Richter, also known as Johannes Praetorius [ [http://books.google.com/books?id=rmrGS9s-KewC&pg=PA200&lpg=PA200&dq=johannes+%22plane+table%22&source=web&ots=BM1Ad8syAu&sig=XHgQ7YZ8GZY___o6hqfhuTvD_pQ Vai, Gian Battista, Caldwell, W. G. E. "The Origins of Geology in Italy"] Google books online copy] , a Nuremberg mathematician, in 1610.Laussedat, Amié, "Recherches sur les instruments, les méthodes et le dessin topographiques", Paris, 1898-1902, two volumes] dubious This circular table, called a "tabula praetoriana", "mensula praetoriana" or "Pretorian table", used a simple alidade and allowed a piece of paper to be slipped under the alidade for drawing.

Later devices adopted a rectangular table and enhanced the type and features of the alidade.

Plane table construction

s, in a horizontal plane. The base, often a tripod, is designed to support the table over a specific point on land. By adjusting the length of the legs, one can bring the table to being approximately level regardless of the roughness of the terrain.

Use of a plane table

In use, a plane table is set over a point and brought to precise horizontal level. A drawing sheet is attached to the surface and an alidade is used to sight objects of interest. The alidade, in modern examples of the instrument a rule with a telescopic sight, can then be used to construct a line on the drawing that is in the direction of the object of interest.

By using the alidade as a surveying level, information on the topography of the site can be directly recorded on the drawing as elevations. Distances to the objects can be measured directly or by the use of stadia marks in the telescope of the alidade.

References

*Raymond Davis, Francis Foote, Joe Kelly, "Surveying, Theory and Practice", McGraw-Hill Book Company, 1966 LC 64-66263

External links

* [http://americanhistory.si.edu/collections/surveying/enlarge.cfm?recordnumber=764357 Telescopic Plane Table Alidade] in the collection of the Smithsonian National Museum of American History. This image shows the bubble levels on the base.


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Look at other dictionaries:

  • Plane table — Plane Plane, a. [L. planus: cf. F. plan. See {Plan}, a.] Without elevations or depressions; even; level; flat; lying in, or constituting, a plane; as, a plane surface. [1913 Webster] Note: In science, this word (instead of plain) is almost… …   The Collaborative International Dictionary of English

  • Plane table — Plane ta ble See under {Plane}, a. [1913 Webster] …   The Collaborative International Dictionary of English

  • plane table — n. a surveying device for plotting maps in the field: it consists of a drawing board mounted on a tripod with an alidade that can be moved about over the table to establish a reference point …   English World dictionary

  • plane-table — ˈ ̷ ̷ˌ ̷ ̷ ̷ ̷ verb Etymology: plane table intransitive verb : to make use of a plane table transitive verb : to plot with a plane table …   Useful english dictionary

  • plane-table — [c]/ˈpleɪn teɪbəl/ (say playn taybuhl) verb (plane tabled, plane tabling) –verb (t) 1. to survey (a tract of land) with a plane table. –verb (i) 2. to carry out surveying using a plane table …  

  • plane-table — /playn tay beuhl/, v.t., v.i., plane tabled, plane tabling. to survey with a plane table. [1870 75] * * * …   Universalium

  • plane table — plane′ ta ble n. sur a drawing board mounted on a tripod, used in the field, with an alidade, for surveying tracts of land • Etymology: 1600–10 …   From formal English to slang

  • plane table — drafting table, table used for drawing blueprints …   English contemporary dictionary

  • plane table — Survey. a drawing board mounted on a tripod, used in the field, with an alidade, for surveying tracts of land. Also, plain table. [1600 10] * * * …   Universalium

  • plane table — noun Date: 1607 an instrument consisting essentially of a drawing board on a tripod with a ruler pointed at the object observed and used for plotting the lines of a survey directly from observation …   New Collegiate Dictionary

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