An enumeration district is a geographic area determined for purposes of taking the census. In one city there may be many enumeration districts, so once you enter a city, county, or state, you can narrow your results by entering street level information, or investigate enumeration district maps, or descriptions.
P wave. 1. a longitudinal earthquake wave that travels through the interior of the earth and is usually the first conspicuous wave to be recorded by a seismograph. Also called primary wave. Compare L wave, S wave. The P wave is admitted to be the wave of auricular contraction. p wave.
Another example of a longitudinal wave is a P wave or primary wave during an earthquake. P waves are also known as compressional waves, because of the pushing and pulling they do. A transverse wave is a wave in which the motion of the medium is a right angles to the direction of the wave. A wave on a rope is a transverse wave. Light and other electromagnetic waves are also transverse waves.