EMR . Electromagnetic Radiation. 



ENDOFHYTE . A plant living within another plant 

 but not necessarily parasitic upon it. (20) 



ENDOSKELETON . An internal supporting framework or 

 structure. (19) 



ENERGY. The capacity to perform work or the 

 ability to make a certain force act through a dis- 

 tance. Potential energy is stored energy such as 

 water behind a dam. Kinetic energy is energy which 

 is being released such as light, x-ray, etc. There 

 are various forms of kinetic energy, for instance 

 chemical, mechanical, nuclear, etc. (39) 



ENERGY ABSORPTION . A term that is both general 

 and specific. Generally, it refers to the energy 

 absorbed by any material subjected to loading. 

 Specifically it is a measure of Toughness or Im- 

 pact Strength of a material; the energy needed to 

 fracture a specimen in an Impact Test. It is the 

 difference in kinetic energy of the striker before 

 and after impact, expressed as total energy (ft-lb 

 or in-lb) for metals and ceramics, and energy per 

 inch of notch for plastics and electrical insulat- 

 ing materials. A higher Energy Absorption indicates 

 a greater Toughness. For notched specimens. Energy 

 Absorption is an indication of the effect of inter- 

 nal multiaxial stress distribution on fracture be- 

 havior of the material. It is merely a qualitative 

 index and cannot be used directly in design. Notch 

 behavior of most metals can be deduced from results 

 of the Tension Test, but notch behavior of ferritic 

 steels is not predictable. Transition Temperature, 

 derived from a series of Energy Absorption measure- 

 ments, is commonly specified for such materials. 

 Energy Absorption is quite sensitive to variations 

 in materials and in test conditions, especially 

 temperature, striking speed and energy, and speci- 

 men size and shape. Only results for identical 

 specimens and notches may safely be compared. If 

 a metal has reasonably high Energy Absorption at a 

 specified temperature, it is assumed that it will 

 exhibit ductile fracture at all higher temperatures. 



ENERGY COEFFICIENT . The ratio of the energy in a 

 wave per unit crest length transmitted forward with 

 the wave at a point in shallow water to the energy 

 in a wave per unit crest length transmitted for- 

 ward with the wave in deep water. On refraction 

 diagrams this is equal to the ratio of the dis- 

 tance between a pair of orthogonals at a selected 

 point to the distance between the same pair of 

 orthogonals in deep water. Also the square of the 

 REFRACTION COEFFICIENT. (11) 



ENTRANCE . The avenue of access or opening to a 

 navigable channel. (11) 



EOD . Explosive Ordnance Disposal. 



EPIBENTHIC DREDGE . This bottom sampler developed 

 by Scripps Institution consists of a pair of sheet- 

 metal skis attached to a light framework for a silk 

 or nylon net. A sheet of heavy canvas fastened 

 beneath the net protects it from tearing. Re- 

 movable rakers in front of the net stir up the bot- 

 tom as the dredge advances, permitting the net to 

 capture the creatures contained in the sediment. 

 A bottom-walking wheel connected to a small veeder- 

 root counter indicates the distance over the bottom 

 the device travels during a haul. The EBD is 

 lowered in the ocean with an ordinary hydrographic 

 winch, and will go as far down as 4500 m. Collect- 

 ing speed of the dredge is only 2 kt eliminating 

 wire angle problems . (30) 



EPICENTER . In Seismology, the point on the earth's 

 surface directly over the focus or theoretical 

 point of origin of an earthquake. (29) 



EPILIMNION . The layer of water above the THERMO- 

 CLINE in a fresh water lake or pool; the opposite 

 of HYPOLIMNION. In the ocean, the equivalent is 

 the MIXED LAYER. (24) 



EPIPHYTIC . A relationship in which one plant lives 

 attached to or supported by another plant, but ob- 

 tains food independently. (18) 



EPITHECA . (1) An external calcareous layer in- 

 vesting the lower portion of the theca of many 

 corals. (2) The outer or upper half or valve of 

 the diatom frustule. The inner or bottom half or 

 valve is called the HYPOTHECA. (20) 



EPIZOIC . Dwelling upon the body of an animal (or 

 plant) . (20) 



EPOC . Eastern Pacific Oceanic Conference. 



EPPLEY PYRHELIOMETER . This instrument is designed 

 to be used above water primarily for measurement 

 of the intensity of solar radiation upon a horizon- 

 tal plane and is calibrated at the Eppley Labora- 

 tory in sunshine against pyrheliometers which are 

 standardized every year at the Weather Bureau, 

 Washington, D. C. The probable error for the in- 

 strument, as compared with direct radiation inten- 

 sities ranging from 0.25 to 1.50 gm cal/ cm /min., 

 is +1.5 per cent. The instrument is sensitive to 

 the wavelength range between 3,000 and 50,000 A. 



EQUAIANT I & II . Tropical Atlantic Investigation. 



EQUAPAC . Equatorial Pacific (Project). 

 EQUATORIAL CALMS . See DOLDRUMS. 



EQUATORIAL COUNTERCURRENT . An ocean current flow- 

 ing eastward (counter to and between the westward- 

 flowing NORTH EQUATORIAL CURRENT and SOUTH EQUA- 

 TORIAL CURRENT) through all the oceans. 



In the Atlantic Ocean, it flows east across 

 the ocean between the north and south equatorial 

 currents across the full width of the ocean in 

 northern summer, and across the eastern half of the 

 ocean in northern winter. It eventually becomes 

 the GUINEA CURRENT. 



In the Pacific Ocean, it is one of the swiftest 

 of ocean currents; it flows east across the ocean 

 between the latitudes 3°N and 10°N. East of the 

 Philippines it is joined by the southern part of 

 the north equatorial current. 



In the Indian Ocean, it flows between the 

 north and south equatorial currents, to the east; 

 unlike the equatorial countercurrents of the Atlan- 

 tic and Pacific Oceans, it lies south of the equa- 

 tor. In northern summer, when the southwest mon- 

 soon forms a continuation of the southeast trade 

 winds, the countercurrent, along with the north 

 equatorial current, is replaced by an easterly 

 flowing monsoon current. (24) 



EQUATORIAL CONVERGENCE ZONE . 

 CONVERGENCE ZONE. 



See INTERTROPICAL 



EQUATORIAL CURRENTS . (1) Ocean currents flowing 

 westerly near the equator. There are two such 

 currents in both the Atlantic and Pacific Oceans. 

 The one to the north of the equator is called the 

 NORTH EQUATORIAL CURRENT, and the one to the south 

 of the equator is called the SOUTH EQUATORIAL CUR- 

 RENT. Between these two currents there is an 

 easterly flowing stream known as the EQUATORIAL 

 COUNTER CURRENT. (2) Tidal currents occurring 

 semimonthly as a result of the moon being over the 

 equator. At these times the tendency of the moon 

 to produce a DIURNAL INEQUALITY in the current is 

 at a minimum. See also DECLINATION. (24) 



EQUATORIAL EASTERLIES (DEEP TRADES. DEEP EASTERLIES) . 

 As used by some authors, the trade winds in the 



U2 



