This is an old revision of this page, as edited by Lightbot (talk | contribs) at 17:12, 13 August 2011 (mostly units). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 17:12, 13 August 2011 by Lightbot (talk | contribs) (mostly units)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff) | This article may require cleanup to meet Misplaced Pages's quality standards. No cleanup reason has been specified. Please help improve this article if you can. (December 2008) (Learn how and when to remove this message) |
Depth sounding refers to a historical nautical term for measuring depth; it is often referred to simply as sounding. Sounding is finding the depth of a given point in a body of water. Sounding data is used in bathymetry to make maps of the floor of a body of water. Soundings were traditionally given on nautical charts in fathoms. The National Oceanographic and Atmospheric Administration (NOAA), the agency responsible for bathymetric data in the United States still uses feet on charts, but metres have become the international standard for measuring depth. Sounding was originally done by hand with sounding poles or a weighted sounding line for greater depths.
Sometimes soundings were taken to establish position, a navigation function then, rather than safety alone. Soundings of this type were usually taken using tallow coated leads with a big wad of tallow in the bottom concavity. The tallow would bring up part of the bottom sediment (sand, pebbles, clay, shells, etc.) and allow the ship's officers to better estimate their position.
Traditional terms for soundings are a source for several important common expressions in the English language, notably "deep six" (a sounding of 6 fathoms) and Mark Twain (from "by the mark, twain", for a 2 fathoms). The term lives on in today's world in echo sounding, the technique of using sonar to measure depth. See Fishfinder (fathometer).
References
- Sounding Pole to Sea Beam, NOAA, http://www.history.noaa.gov/stories_tales/poletobeam.html