heavy nucleus at terrific speeds so as to approxi- 

 mate shells. An atom In an electrically neutral 

 state has as many electrons as protons (ATOMIC NUM- 

 BER). Chemical changes (e.g., burning coal, gaso- 

 line, dynamite and etc.) affect the electrons of 

 an atom but not the nucleus. (39) 



ELECTROSTATIC (CAPACITOR) (CONDENSER) TRANSDUCER . 

 An electrostatic transducer is a transducer that 

 consists of a capacitor and depends upon interac- 

 tion between Its electric field and the change of 

 its electrostatic capacitance. (1) 



ELECTROSTRICTION . Electrostriction Is the phe- 

 nomenon wherein some dielectric materials ex- 

 perience an elastic strain when subjected to an 

 electric field, this strain being independent of 

 the polarity of the field. (1) 



ELECTROTAPE (MICRODIST) . A phase comparison base 

 line measuring system similar to TELLUROMETER and 

 GEODIMETER. It is similar to Tellurometer in 

 that radar frequencies are used whereas in the 

 Geodimeter light waves are employed. All three 

 systems use a 10 megacycle crystal as the basis 

 of their measurement so one period or lane width 

 is 15 meters in the electrotape and tellurometer 

 and is 7.5 meters in the geodimeter due to the 

 method of measuring. (29) 



ELEPHANTA . A strong southerly or southeasterly 

 wind which blows on the Malabar coast of India dur- 

 ing the months of September and October and marks 

 the end of the southwest monsoon. (17) 



ELLIPTICALLY POLARIZED SOUND WAVE . An elliptically 

 polarized sound wave is a transverse wave and hence 

 each particle in the medium is moving at right 

 angles to the direction of propagation of the wave. 

 There is the additional requirement, however, that 

 each point in the medium must be executing an el- 

 lipse, the plane of the ellipse being, of course, 

 at right angles to the direction of propagation of 

 the wave. (9) 



EL NINO . A warm ocean current setting south along 

 the coast of Ecuador, so called because it general- 

 ly develops just after Christmas. In exceptional 

 years, concurrently with a southerly shift in the 

 tropical rain belt, the current may extend along 

 the coast of Peru to 12°S. When this occurs, 

 plankton and fish are killed in the coastal waters 

 and a phenomenon somewhat like the RED TIDE of 

 Florida results. (24) 



ELONGATION . A term that is both general and speci- 

 fic. Generally, the extension of a material in the 

 Tension Test at any specified point (e.g. Yield 

 Point Elongation). Specifically, the extension of 

 a material at rupture in the Tension Test. General- 

 ly, Elongation (%) is calculated by dividing total 

 Increase in gage length by original gage length 

 and multiplying by 100. At rupture. Elongation 

 (%) Is usually calculated by dividing total per- 

 manent increase In gage length by original gage 

 length and multiplying by 100. Total permanent 

 strain can be measured by fitting the broken 

 specimen together after rupture or by subtracting 

 strain at the Elastic Limit from total strain 

 Indicated by a Stress-Strain Diagram. For any 

 material with high Modulus of Elasticity and an 

 Important degree of Elongation, the error intro- 

 duced by using total strain obtained from exten- 

 someter or Stress-Strain Diagram instead of total 

 permanent strain is insignificant. Elongation 

 of metals in short gage lengths is quite sensitive 

 specimen, and gage length must therefore be speci- 

 fied. Elongation cannot be used to predict other 

 mechanical properties but is considered an indi- 

 cator of Ductility in metals. As such it is used 

 to predict both formabillty and the extent to 



which a metal can deform in service without rup- 

 ture. However, Elongation may have little relation 

 to the highly localized extension occurring in 

 many forming operations, and Elongation specified 

 for structural materials often has little relation 

 to the much smaller extension actually permitted 

 by service conditions. Elongation cannot be used 

 to predict behavior of materials subjected to 

 to the effects of localized extension occurring 

 at the center of the "necked down" portion of the 

 sudden or repeated loading. (41) 



ELVEGUST (Also SNO) . A cold descending squall in 

 the upper parts of Norwegian fjords. (12) 



EMERY-DIETZ GRAVITY CORER . In this corer an at- 

 tempt was made to produce a cheap, sturdy and 

 reliable instrument capable of working even under 

 moderately adverse sea conditions. The corer 

 weighs about 650 lbs. in air and consists essen- 

 tially of a shaft, weights, and coring tube. The 

 shaft is a standard 8-ft. pipe 2 1/2 in. in dia- 

 meter with several small holes drilled in it to 

 allow water to run off as it is lifted on board. 

 On this shaft is mounted a set of removable lead 

 weights, roughly streamlined, and varying in number 

 depending upon the desired depth of penetration. 

 The weights rest on a shoulder which is part of 'the 

 valve housing. The valve is designed to prevent 

 loss of the core by suction during withdrawal from 

 the mud, to obviate any washing out of the relative- 

 ly fluid upper part of the core during hauling, and 

 to stop the weight of water in the shaft forcing 

 out a short core as the device is lifted out of the 

 sea. It consists of a rubber bung resting in 

 guides and fitting loosely in a brass seating. The 

 coring tube itself fits below this valve and con- 

 sists of a standard pipe, 2 or 2 1/2 in. In diameter, 

 thrust into a sleeve against a shoulder of the valve 

 housing and clamped there with a set-screw. A re- 

 movable plastic liner is fitted inside the coring 

 tube so that the core may be readily removed, in- 

 spected and stored. Screwed to the bottom end of 

 the tube is a nose-piece with a slightly smaller 

 diameter than the coring tube itself. A core re- 

 tainer is fitted in the nose-piece. This has strips 

 of plastic pressed into a thin rubber sleeve and 

 bent over towards the center. When the sample is 

 passing up the coring tube they are pushed back 

 against its wall, and if the core starts to slip, 

 they close the opening. In use, the instrument is 

 lowered on a 3/8-in. wire rope until about 300 ft. 

 above the bottom when it is allowed to run almost 

 free with only sufficient braking to Insure a ver- 

 tical descent. The device strikes the bottom with 

 a velocity of 12 to 21 ft/sec. (35) 



EMBATA . A local onshore southwest wind caused by 

 the reversal of the northeast TRADE WINDS in the 

 lee of the Canary Islands. (12) 



EMISSARY SKY . A sky of cirrus clouds which are 

 either isolated or in small, separated groups; so 

 called because this formation often is one of the 

 first indications of the approach of a cyclonic 

 storm. (12) 



EMIT . A Russiam electromagnetic current meter 

 which is similar to the American GEK. (35) 



EMPHYSEMA . Refers to a swelling or inflation due 

 to abnormal presence of air in the tissues. Sub- 

 cutaneous emphysema is the presence of air in the 

 tissues just under the skin. When seen in diving, 

 it usually Involves the skin of the neck and near- 

 by areas. Mediastinal emphysema is the presence 

 of air in the tissues in the vicinity of the heart 

 and large blood vessels in the middle of the chest. 

 Unless extreme, neither of these conditions is 

 likely to cause serious difficulty. If emphysema 

 is extreme, AIR EMBOLISM will usually be present 

 also. (37) 



1*1 



