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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. Soundings were traditionally shown on nautical charts in fathoms ...
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 ...
The depth was determined (rather inaccurately) by the time it took to surface. [3] Jacob Perkins (1766–1849) proposed a bathometer based on the compressibility of water. [ 4 ] In this instrument the movement of a piston compressing a body of water enclosed in its cylinder is dependent on the pressure of the water outside the cylinder, and ...
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 ...
A deep-sea lead, the heaviest of sounding leads, was used in water exceeding 100 fathoms in depth. [21] This technique has been superseded by sonic depth finders for measuring mechanically the depth of water beneath a ship, one version of which is the Fathometer (trademark). [22] The record made by such a device is a fathogram. [23]
Depth contour lines show the shape of underwater relief. Coloured areas of the sea emphasise shallow water and dangerous underwater obstructions. Depths are measured from the chart datum, which is related to the local sea level. The chart datum varies according to the standard used by each national Hydrographic Office.
If the leaves are wilted, the plant may need water. Feel the soil to a depth of about two inches. If the soil is moist, the plant may be wilted because the soil is too wet and the roots are ...
This instrument is used primarily for determining the depth of water by means of an acoustic echo. A pulse of sound sent from the ship is reflected from the sea bottom back to the ship, the interval of time between transmission and reception being proportional to the depth of the water.