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A league is a unit of length. It was common in Europe and Latin America, but is no longer an official unit in any nation. Derived from an ancient Celtic unit and adopted by the Romans as the leuga, the league became a common unit of measurement throughout western Europe. Since the Middle Ages, many values have been specified in several ...
League: Length: Nautical mile: Length: Rhumb: Angle: The angle between two successive points of the thirty-two point compass (11 degrees 15 minutes) (rare) [1] Shackle: Length: Before 1949, 12.5 fathoms; later 15 fathoms. [2] Toise: Length: Toise was also used for measures of area and volume Twenty-foot equivalent unit or TEU: Volume
A sailor and a man on shore, both sounding the depth with a line. Depth sounding, often simply called sounding, is measuring the depth of a body of water.Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography.
Echo sounding or depth sounding is the use of sonar for ranging, normally to determine the depth of water . It involves transmitting acoustic waves into water and recording the time interval between emission and return of a pulse; the resulting time of flight , along with knowledge of the speed of sound in water, allows determining the distance ...
Bathymetric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. [3] Bathymetry has various uses including the production of bathymetric charts to guide vessels and identify underwater hazards, the study of marine life near the floor of water bodies , coastline analysis and ocean dynamics , including ...
This page was last edited on 26 April 2018, at 17:39 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
Audio-magnetotellurics (AMT) is a higher-frequency magnetotelluric technique for shallower investigations. While AMT has less depth penetration than MT, AMT measurements often take only about one hour to perform (but deep AMT measurements during low-signal strength periods may take up to 24 hours) and use smaller and lighter magnetic sensors.