The Visual Dictionary of Science & Energy

49telescopic sighterecting lensesLens system that returns the invertedimage formed on the objective lens.eyepieceOptical disk or system of disks throughwhich the eye sees the image producedby the lens.reticleOptical system made up of two fine crossed wires tocreate a precise point as a sighting reference.field lensLens placed between the objective andthe eyepiece to widen the field ofvision.elevation adjustmentButton for positioning the sight vertically to offset anydivergence of the target from the reticle.PHYSICS: OPTICSturret capPart covering and protecting anadjustment button.winding adjustmentButton for positioning the sight horizontally tooffset any divergence of the target from the reticle.dovetailDevice for mounting the telescopic sight onto a device or firearm.

50PHYSICS: OPTICSfinderscopeSmall low-magnification telescopewith a wide field of view; serves tolocate celestial bodies.eyepieceLens or system of lenses meant tomagnify the image when placed before Graduated disk indicating the right ascension ofthe eye.main tubeThe barrel of the telescopethrough which light rays travel;houses the optical system.focusing knobAdjusting device that makes it possible to obtain aclear image of the object.right ascension setting scalethe observed celestial body.azimuth clampClamp serving to lock the telescope along itshorizontal axis.altitude clampClamp serving to lock the telescope along its vertical axis.declination setting scaleGraduated disk indicating the declination of thecelestial body observed.azimuth fine adjustmentFine-tuning device that serves to position the telescope horizontally.altitude fine adjustmentFine-tuning device that serves to position the telescopevertically.reflecting telescopeOptical instrument that uses an objective mirror to observe celestial bodies.

51PHYSICS: OPTICSrefracting telescopeOptical instrument that uses an objective lens to observe celestial bodies.focusing knobAdjusting device that makes it possible toobtain a clear image of the object.altitude fine adjustmentFine-tuning device serving to position the telescope vertically.declination setting scaleGraduated disk indicating the declination of thecelestial body observed.azimuth clampClamp serving to lock the telescope along itshorizontal axis.altitude clampClamp serving to lock the telescope along its verticalaxis.right ascension setting scaleGraduated disk indicating the right ascension of theobserved celestial body.tripodStable three-legged stand of variableheight.azimuth fine adjustmentFine-tuning device serving to position the telescopehorizontally.main tubeThe barrel of a telescope housing the opticalsystem; light rays travel through the maintube.finderscopeSmall low-magnification telescopewith a wide field of view; serves tolocate celestial bodies.eyepieceLens or system of lenses meant tomagnify the image when placed beforethe eye.

52Celsius scaleTemperature scale that is based on a graduationfrom 0 (freezing point of water) to 100 (boiling pointof water); it was formerly called the centigrade scale.C degreesSymbol representing a unit of measurement on theCelsius scale (Celsius degree).Fahrenheit scaleTemperature scale that is used in some English-speaking countries, on which the freezing point ofwater is at 32 and the boiling point at 212.thermometerInstrument for measuring temperature by meansof a substance (usually a liquid or a gas)contained in a graduated tube.alcohol columnQuantity of alcohol that is contained in the glasstube; its height varies with the temperature.F degreesSymbol representing a unit of measurement onthe Fahrenheit scale (Fahrenheit degree).alcohol bulbGlass reservoir containing colored alcohol(methanol, ethanol) that expands and rises in thecapillary bore as the temperature rises.measure of temperatureTemperature: physical quantity corresponding to the level of heat or cold, which is measured by means of a thermometer.MEASURING DEVICES

53measure of temperaturemercury bulbGlass reservoir containing mercury (a liquid metal) thatexpands and rises in the capillary tube as the temperaturerises.constrictionNarrowing that prevents the mercury from spontaneouslydropping into the bulb as the temperature lowers (thethermometer must be shaken to make it go down).column of mercuryQuantity of mercury that is contained in the capillary bore; itsheight varies with the temperature.scaleDivisions of equal length (degrees) marked on thethermometer that constitute the units of measurement.capillary tubeEnd of the glass tube in which the mercury rises or falls with thetemperature; the mercury thermometer tube is filled with gas.stemGlass tube containing the capillary bore.expansion chamberSpace that is taken up by the gas in the capillary bore; it ispushed back as the mercury rises into it.clinical thermometerMore precise than the alcohol thermometer, it is used to take thetemperature of the human body; it is graduated from 94°F to 108°F.MEASURING DEVICES

54bimetallic thermometerThermometer that uses the difference inexpansion of two metals (usually iron and brass)to measure temperatures between 30°C or 86°Fand 300°C or 375F°; it is used especially inindustry.shaftRod that transmits the bimetallic helix’srotational motion to the pointer as a resultof warping caused by heat.bimetallic helixBand made by welding together twometals with different coefficients ofexpansion; it curves as the temperaturechanges.dialGraduated face with a pointer in front to indicate the temperature.pointerMetal needle connected to the shaft thatindicates the temperature on the dial.caseOuter covering that encloses andprotects the device’s mechanism.measure of temperaturedigital thermometerThermometer that indicates the temperature in digits on aliquid crystal display screen.MEASURING DEVICES

55measure of timeTime: physical quantity corresponding to a phenomenon or an event that is measured with devices such aswatches and stopwatches.start buttonKnob that is pushed to start the stopwatch and measure the duration ofa phenomenon or event.stop buttonKnob that is pushed to stop the hands,which then display the precise amount ofelapsed time.caseOuter covering that encloses andprotects the device’s mechanism.ringRound part for holding or hanging thestopwatch.1/10 second handMetal needle that indicates the 10 equal divisions of asecond on the dial.second handMetal needle that indicates the 60 equaldivisions (seconds) of a minute bymoving in small jumps.minute handMetal needle that indicates minutes on a dialgraduated from 0 to 30 minutes.stopwatchInstrument that precisely measurestime in minutes, seconds and fractionsof seconds.reset buttonButton that is pushed to return the stopwatch’shands to 0.MEASURING DEVICES

56mechanical watchSet of geared wheels that reduce theforce transmitted by a spiral spring tocause the watch’s hands to rotate.fourth wheelWheel that transmits energy to the third wheel.third wheelWheel that receives energy from the fourth wheel and drivesthe center wheel.winderPart that rewinds the mechanism, consistingof a series of wheels.clickSmall lever that is engaged betweenthe ratchet-wheel teeth and prevents itfrom rotating counter to its normaldirection.ratchet wheelToothed wheel having only onedirection of rotation; it is kept in placeby the click.center wheelWheel that is connected to the handsand causes them to rotate on the dial.hairspringFlat spiral spring that causes the wheelsof a watch to move over a certain periodof time.escape wheelLast wheel of the gear train with special teeththat causes the watch to operate regularlyand continuously; it controls the movementof the other wheels.jewelVery hard stone (formerly a ruby, today a rock crystal) that resists wear;the rotation axle of a wheel rests on it.measure of timeMEASURING DEVICES

57liquid crystal displayCrystal that illuminates when submitted to light anddisplays the shapes of letters and numbers.digital watchThe time is read from letters and numbers that appear on aclear background.strapLeather, fabric, plastic or metal bracelet with aclasp; it is used to hold a watch on the wrist.crownKnob with sprockets that is connected to thewinder; it is used to manually wind the watch andset its time.dialGraduated face over which the hands moveto indicate the time.sundialVertical or horizontal face with divisions thatcorrespond to the hours of the day, which areindicated by the shadow of a gnomon cast by theSun.dialFace marked with numbers over whichshadows are cast by the gnomon toindicate the approximate time of day.gnomonPart aligned with the Earth’s axis; its shadow indicatesthe time as it moves over the sundial.shadowDark area that results when thegnomon blocks the sunlight andindicates the time in accordance withthe position of the Sun.measure of timeanalog watchThe time is displayed by hands, which movearound the dial.MEASURING DEVICES

58Moon dialFace divided into 29 1/2 days that isrepresented by a moon whose movementindicates the phases of the Moon: first quarter,full moon, last quarter, new moon.grandfather clockClock with a pendulum that is operated byweights and housed in a tall (usually over 2 mhigh) straight body, which stands upright onthe floor.weightHeavy body that hangs from the main wheel; itsdescent provides the necessary energy for theclock’s mechanism.pendulumUnit whose regular swinging motion controlsthe workings of the clock’s mechanism.chainSeries of interlaced rings to which weights areattached.plinthBase that supports the clock and makes itstable.minute handMetal needle that points at the 60 minutes of anhour on the dial.pedimentSet of decorative moldings that surmount theclock.bodyUsually wooden box that houses and protectsthe clock’s mechanism.hour handMetal needle that points at the 24 hours of a dayon the dial.dialGraduated face over which the hands move toindicate the time.measure of timeMEASURING DEVICES

59weight-driven clock mechanismThis clock is operated by weights that, undergravity, drive the hands of the clock in theirrotational movement by means of a gear train.escape wheelLast wheel of the gear train with special teeththat causes the clock to operate regularlyand continuously and controls themovement of the other wheels.spindleCylindrical part that transfers therotational movement of one part toanother.third wheelWheel that receives energy from thecenter wheel and drives the escapewheel.minute handMetal needle that points at the60 minutes of an hour on the dial.hour handMetal needle that points at the24 hours of a day on the dial.winding mechanismDevice that raises the weights to start anewthe cycle of the clock’s mechanism.palletAnchor-shaped part that frees andconstrains the escape wheel’s teeth tomaintain the pendulum’s back-and-forth movement.suspension springSmall rigid plate from which thependulum hangs.pinionSmall wheel with teeth that is mounted on a shaft andtransmits the rotational movement of one wheel to another.forkPart that is operated by the escapewheel to cause the pendulum’smovement.center wheelWheel that is connected to the handsand causes them to rotate on the dial.pendulum rodRigid bar to which the pendulum bobis attached.clickSmall lever that is engaged betweenthe ratchet-wheel teeth and preventsit from rotating counter to its normaldirection.pendulum bobWeight attached to the end of thependulum rod.main wheelFirst wheel in the gear train thattransmits the driving force of theweights to the other wheels to turnthem.ratchet wheelToothed wheel having only onedirection of rotation; it is kept in placeby the click.weightHeavy body that hangs from the main wheel; its descent provides thenecessary energy for the clock’s mechanism.drumCylinder around which the weights’ cord or chainwinds when the clock is rewound.measure of timeMEASURING DEVICES

60measure of weightMass: physical quantity that characterizes an amount of matter (mass) that is measured by means of a scale.weightPiece of metal, such as copper or iron, ofknown mass that is placed on a pan tobalance the scale and thereby assess thecorresponding mass of a body.beam balanceCompares the mass of a body with that ofanother body of known mass (weight); when twopans hanging from a bar (beam) are in balance,the two weights are equal.beamHorizontal metal bar that balances on a verticalaxis and has pans hanging from each end.panFlat rigid support that holds eitherthe body to be weighed or theweights.Roberval’s balanceCommonly used scale that operates on thesame principle as the beam balance; thepans are stabilized by a shank and rest onthe beam.dialGraduated surface with a pointer infront that indicates the point ofequilibrium for the two pans.pointerMetal needle that indicates the point of equilibrium onthe dial when the beam is level.weightPiece of metal, such as copper or iron, ofknown mass that is placed on a pan tobalance the scale and thereby assess thecorresponding mass of a body.beamHorizontal metal bar that balances ona vertical axis and supports a pan oneach end.panFlat rigid support that holds either the body tobe weighed or the weights.baseSupport that provides stability to thescale.MEASURING DEVICES

61measure of weightsteelyardScale used for weighing loads that has a beam witharms of different lengths; the shorter arm supportsthe pan and the longer arm supports the weightsthat slide to attain a balance.sliding weightSliding part that is moved along thebeams until a balance between the twomasses is attained.notchGroove in which a sliding weight catches so that a precise reading on the graduatedscale can be taken.magnetic damping systemDevice made up of magnets that reduce the beams’oscillations when the weights are moved to providea quick reading of the mass.graduated scaleThe divisions of equal length marked onthe scale’s beam that constitute the unitsof measurement.vernierSmall graduated dial that slides alongthe beams and provides a very precisereading of the mass.pan hookCurved part from which the pan ishung by means of rods.baseSupport that provides stability to thescale.front beamRigid metal bar along which the slidingweight slides to provide a very precisereading of the mass.rear beamRigid metal bar along which the slidingweight slides to provide a relativelyprecise reading of the mass.panFlat rigid stand on which the body tobe weighed is placed.MEASURING DEVICES

62electronic scaleCommercial scale that weighs andcalculates the price of a quantity ofmerchandise and displays theseelements.platformFlat rigid surface on which the items tobe weighed are placed.function keysSet of keys that perform variousoperations (e.g., data entry,calculations and printing receipts).weightLiquid crystal display that shows theweight of the item.unit priceLiquid crystal display that shows the unitprice of an item.displayEach of the three liquid crystal displays thatshow various numeric information (e.g.,weight, unit price and total price).totalLiquid crystal display that shows the price ofeach weighed article and, at the end of thetransaction, the total price of all purchases.numeric keyboardSet of keys with numbers and symbolsthat are used especially to enter theunit prices or codes of items.product codeKey with a number that corresponds tothe code assigned to a product.printoutPaper on which various data areprinted (e.g., the weight, quantity andprice of the items weighed).measure of weightMEASURING DEVICES

63analytical balanceUsed especially in the laboratory fortaking very precise weightmeasurements.glass caseGlass box that protects the pan from aircurrents and dust that might cause a falsereading of the weight.door accessSliding doors that provide easy accessto the inside of the glass case.panFlat rigid support on which thespecimen is placed.leveling screwScrew for adjusting the level of thebalance’s base.measure of weightMEASURING DEVICES

ringRound part for holding or hanging the spring balance.pointerPointer connected to the spring that moves along a graduated scaleto indicate the weight of the body being weighed.graduated scaleThe divisions of equal length that are marked on the springbalance and constitute the units of measurement.hookCurved part on which the body to be weighed is hung.64bathroom scaleScale used for weighing a person; it hasa spring mechanism that compresses inproportion to the weight.digital displayLiquid crystal display that indicates the weight in numbers.weighing platformFlat base that a person stands upon to beweighed.measure of weightspring balanceScale made up of a hook attached to a springthat stretches in proportion to the weight ofthe object being weighed.MEASURING DEVICES

reset buttonKey used to reset the counter to 0.distance traveledNumber of steps taken by the walker orrunner converted into miles.step settingButton for adjusting the average length of astep in the walk or run.clipMetal fastener for attaching the pedometerto a belt or article of clothing.caseOuter covering that encloses and protectsthe device’s mechanism.65rulerInstrument for measuring length.pedometerDevice that counts the number of stepstaken by a walker or runner to measurethe distance traveled.scaleThe divisions of equal length that are marked on theruler and constitute the units of measurement.measure of lengthLength: the longer dimension of an object as opposed to its width.measure of distanceDistance: interval separating two points in space.MEASURING DEVICES

66measure of thicknessThickness: dimension corresponding to the distance between two surfaces of the same body.vernier caliperPrecision instrument for measuring the thickness anddiameter of mechanical parts.sliding jawTapered part attached to the end of thevernier that slides along the ruler to theobject to be measured.vernier scaleThe divisions of equal length that aremarked on the vernier and constitute theunits of measurement.clamping screwsScrews that lock the vernier and the clamping block intheir final positions in order to preserve the measurementobtained.fine adjustment wheelThumbwheel for making very fineadjustments to the sliding jaw’sposition.fixed jawTapered part at the end of the ruler thatsupports the object to be measured; theobject is place between the two jaws, whichare gently tightened.vernierSmall graduated rule that slides along the ruler and is used to read very precisemeasurements.rulerGraduated instrument ending in a fixed jaw that measures the thickness or diameter of an object.clamping blockPart that chocks the vernier against the part to bemeasured.main scaleThe divisions marked on the vernier toobtain fine measurements.MEASURING DEVICES

67measure of thicknessmicrometer caliperInstrument that measures the thickness or thediameter of relatively small parts; it producesfiner results than a vernier caliper.lock nutRing-shaped part that locks the finelythreaded screw in its final position topreserve the measurement obtained.spindleCylindrical end of the finely threaded screw.finely threaded screwScrew driven by the ratchet knob that moves thespindle against the object to be measured.thimbleGraduated cylindrical part that isactivated by the finely threaded screwand measures the thickness withprecision.anvilCylindrical part that is attached to the frame of the micrometer to support theobject to be measured; the object is placed between the anvil and the spindle.frameHorseshoe-shaped part that supportsthe anvil and a graduated device fromwhich the measurement is read.ratchet knobPart that stops the finely threaded screw whenthe pressure on the object being measured issufficient.MEASURING DEVICES

68theodoliteSighting instrument that is used especially inastronomy, geodesy and navigation formeasuring horizontal and vertical angles.alidadePart of the theodolite that rotates on avertical axle to measure angles bymeans of the telescope.adjustment for vertical-circle imageKnob that adjusts the sharpness of the image of the verticalcircle (graduated from 0° to 360°) in order to read theangles on the vertical axis.micrometer screwKnob that adjusts the micrometer to give a very precisereading of the circles’ measurements.adjustment for horizontal-circle imageKnob that adjusts the sharpness of the image of thehorizontal circle (graduated from 0° to 360°) in order toread the angles on the horizontal axis.optical sightDevice with an eyepiece that precisely aims thetelescope at the target whose angles are to bemeasured.leveling head levelTransparent tube that contains liquid and an air bubble; it serves as aguide for positioning the leveling head on the horizontal axis.leveling head locking knobKnob that locks the alidade to the leveling head.horizontal clampKnob that locks the alidade to prevent it from rotating.leveling headPlatform serving as a support for the theolodite.measure of anglesAngle: figure formed by two intersecting lines or planes; it is measured in degrees.MEASURING DEVICES

69telescopeOptical instrument composed of several lenses; it can beadjusted in the horizontal and vertical planes and is used toobserve distant objects.leveling screwScrew that adjusts the theodolite’sleveling head level on the horizontalplane.base platePlate to which the leveling head is attachedby means of three leveling screws.illumination mirrorAdjustable polished glass surface that reflects lightonto the circles so that the angles can be read.alidade levelTransparent tube that contains liquid and an air bubble; itserves as a guide for positioning the alidade on the verticalaxis.measure of anglesbevel squareInstrument whose movable arms areused for measuring or for marking anangle.protractorGraduated semicircular instrument formeasuring and drawing angles.MEASURING DEVICES

hertzFrequency of a periodic phenomenonwhose period is 1 second.measurement of frequency70SCIENTIFIC SYMBOLSinternational system of unitsDecimal system established by the 11th General Conference on Weights and Measures (GCWM) in 1960 andused by many countries.ampereConstant current of 1 joule per second in a conductor.wattEnergy transfer of 1 joule during 1 second.jouleAmount of energy released by the forceof 1 newton acting through a distanceof 1 meter.coulombAmount of electricity carried in1 second by a current of 1 ampere.newtonForce required to impart anacceleration of 1 m/s to a body having2a mass of 1 kg.measurement of electric chargemeasurement of electric currentmeasurement of forcemeasurement of energymeasurement of powermeasurement of electric potential differenceohmElectrical resistance between two points of a conductorcarrying a current of 1 ampere when the difference inpotential between them is 1 volt.voltDifference in potential between two points ofa conductor carrying a constant current of1 ampere when the power between thesepoints is 1 watt.measurement of electric resistance

71SCIENTIFIC SYMBOLSinternational system of unitsmeterDistance traveled by light in a vacuumin 1/299,792,458 of a second.kilogramMass of a platinum prototype that wasaccepted as the international reference in1889; it is stored at the International Bureau ofWeights and Measures.kelvinZero degrees Kelvin is equal to minus273.16°C.candelaUnit of light intensity equivalent to a radiant intensity of1/683 watts per steradian (solid angle).moleQuantity of matter equal to the numberof atoms in 0.012 kg of carbon 12.pascalUniform pressure exerted on a flat surface of 1 m with a force of 1 newton.2measurement of lengthmeasurement of massmeasurement of thermodynamic temperaturemeasurement of amount of substancemeasurement of pressuremeasurement of Celsius temperaturedegree CelsiusDivision into 100 parts of the differencebetween the freezing point of water (0°C) andits boiling point (100°C) at standardatmospheric pressure.measurement of luminous intensitybecquerelRadioactivity of a substance in which one atomdisintegrates per second.measurement of radioactivity

72divided bySign denoting a number (dividend) isto be divided by another (divisor); theresult is a quotient.is equivalent toSign denoting that the value on the leftis the same magnitude as the one onthe right.is approximately equal toSign denoting that the result of anoperation is close to the same value asthe one on the right.is not equal toSign denoting that the result of anoperation is not close to the samevalue as the one on the right.equalsSign denoting the result of anoperation.is not identical withBinary sign denoting that the result ofthe operation noted on the left does nothave the same value as the operationnoted on the right.is identical withBinary sign denoting that the result ofthe operation noted on the left has thesame value as the operation noted onthe right.empty setSign denoting that a set contains noelements.is included in/is a subset ofBinary sign denoting that a set A on theleft is part of the set B on the right.intersection of two setsBinary sign denoting that two sets M and Nhave elements in common.union of two setsBinary sign denoting that a set iscomposed of the sum of the elementsof two sets.mathematicsThe science that uses deductive reasoning to study the properties of abstract entities such as numbers, spaceand functions and the relations between them.plus/positiveSign denoting that a number is to beadded to another; the result is a sum.minus/negativeSign denoting that a number is to besubtracted from another; the result is adifference.multiplied bySign denoting that a number is to bemultiplied by another; the result is aproduct.SCIENTIFIC SYMBOLS

73mathematicsplus or minusSign denoting that the number thatfollows denotes an order of magnitude.is less than or equal toSign denoting that the result of anoperation is equal to or of smallermagnitude than the number thatfollows.is less thanSign denoting that the value on the leftis of smaller magnitude than thenumber that follows.is greater than or equal toSign denoting that the result of anoperation is equal to or of greatermagnitude than the number thatfollows.is greater thanSign denoting that the value on the leftis of greater magnitude than thenumber that follows.percentSign denoting that the numberpreceding it is a fraction of 100.is an element ofBinary sign denoting that the elementon the left is included in the set on theright.is not an element ofBinary sign denoting that the elementon the left is not included in the set onthe right.square root ofSign denoting that, when a number ismultiplied by itself, the result is thenumber that appears below the bar.sumSign indicating that several values areto be added together (their sum).fractionSign denoting that the number on theleft of the slash (numerator) is one partof the number on the right of the slash(denominator).infinitySymbol denoting that a value has noupper limit.integralResult of the integral calculation usedespecially to determine an area and to resolve adifferential equation.factorialProduct of all positive whole numbers less than andequal to a given number. For example, the factorial of4 is: 4! = 1x2x3x4 = 24.SCIENTIFIC SYMBOLS

74Roman numeralsUppercase letters that represented numbers in ancient Rome; they arestill seen today in uses such as clock and watch dials and pagination.birthSymbol placed before a date denoting aperson’s year of birth.blood factor positiveIndividuals are Rh positive when their redblood cells carry an Rh molecule (antigen); theRh factor is positive in about 85% of thepopulation.blood factor negativeIndividuals not carrying the Rh molecule (antigen)are Rh negative; the Rh factor plays an importantrole in pregnancy (the parents’ factors must becompatible).deathSymbol placed before a date denoting aperson’s year of death.femaleSymbol denoting that a being hasfemale reproductive organs.maleSymbol denoting that a being has malereproductive organs.biologyThe scientific study of living organisms (humans, animals and plants) from the point of view of their structureand how they function and reproduce.mathematicsSCIENTIFIC SYMBOLStenLetter whose value is 10 units.five hundredLetter whose value is 500 units.fiveLetter whose value is 5 units.oneLetter whose value is 1 unit.fiftyLetter whose value is 50 units.one hundredLetter whose value is 100 units.one thousandLetter whose value is 1,000 units.

75geometryMathematical discipline that studies the relations between points, straight lines, curves, surfaces and volumes.degreeSymbol placed in superscript after a number todenote the opening of an angle or the length ofan arc, or in front of an uppercase letter toidentify a scale of measurement.piConstant that represents the ratio of a circle’scircumference to its diameter; its value isapproximately 3.1416.secondSymbol placed in superscript after anumber that denotes degrees insixtieths of a minute.minuteSymbol placed in superscript after a numberthat denotes degrees in sixtieths of a measure.is parallel toSymbol denoting that two straight linesremain at a constant distance from oneanother.is not parallel toSymbol denoting that two straight lines do not remainat a constant distance from one other.perpendicularSymbol denoting that a straight linemeets another at a right angle.right angleAngle formed by two lines or twoperpendicular planes that measures90°.acute angleAngle that is smaller than a right angle(less than 90°).obtuse angleAngle between 90° and 180°.SCIENTIFIC SYMBOLS

76examples of anglesAngle: figure formed by twointersecting lines or planes; it ismeasured in degrees.0°90°130°240°360°acute angleAngle that is smaller than a right angle(less than 90°).right angleAngle formed by two lines or two perpendicularplanes that measures 90°.obtuse angleAngle between 90° and 180°.reentrant angleAngle between 180° and 360°.45°geometrical shapesDrawings that represent various geometric forms such as straight lines, circles and polygons.SCIENTIFIC SYMBOLS

77geometrical shapescircumferenceLength of a circle that corresponds tothe product of its diameter and pi.semicircleA half circle that is delimited by itsdiameter.diameterLine that connects two points on acircle’s circumference and passesthrough its center.sectorSurface bounded by two radii and anarc of a circle.radiusLine that joins a point on a circle’scircumference to its center; it is onehalf of the diameter.arcSection of a circle between two points onthe circle.centerPoint located at the same distance from every point onthe circle’s circumference.quadrantQuarter of a circle’s circumference; itcorresponds to an arc of 90°.parts of a circleCircle: closed plane curve; all itspoints are the same distance from afixed point (center).plane surfacesSet of points on a plane that describes an area ofspace.SCIENTIFIC SYMBOLS

78triangleThree-sided polygon; triangles arescalene (no side is equal to any other)isosceles (two sides equal) orequilateral (all sides equal).rhombusEquilateral parallelogram.squareEquilateral rectangle with four rightangles.parallelogramTrapezoid whose opposite sides are parallel and ofequal length; the sides do not meet at right angles.rectangleQuadrilateral whose opposite sides areequal in length; the sides meet at rightangles.quadrilateralAny plane figure with four sides and four angles.polygonsGeometric plane figures with severalsides and a number of equal angles.trapezoidQuadrilateral with two sides (bases) that areparallel. It is isosceles when it has two sides thatare not parallel and equal, and rectangle whentwo of its sides form a right angle.geometrical shapesSCIENTIFIC SYMBOLS

79regular hexagonPolygon with six (hexa = six) sides andequal angles.regular octagonPolygon with eight (octo = eight) sides andequal angles.regular pentagonPolygon with five (penta = five) sides andequal angles.regular heptagonPolygon with seven (hepta = seven) sides andequal angles.regular nonagonPolygon with nine (nona = nine) sidesand equal angles.regular decagonPolygon with 10 (deca = ten) sides and equalangles.regular dodecagonPolygon with 12 (dodeca = twelve) sides andequal angles.regular hendecagonPolygon with 11 (hendeca = eleven) sides andequal angles.geometrical shapesSCIENTIFIC SYMBOLS

80solidsGeometric shapes in three dimensionsthat are delimited by surfaces.hemisphereHalf sphere cut along its diameter.sphereVolume with all the points on its surface the samedistance from its center; the solid thus delimited is around ball.torusVolume or solid generated by therotation of a circle at an equal distancefrom its center of rotation.cubeVolume or solid with six square sides of equal areaand six equal edges; it has eight vertices.helixVolume or solid of spiral shape thatturns toward the left at a constantangle.geometrical shapesSCIENTIFIC SYMBOLS

81coneVolume or solid generated by therotation of a straight line (generatrix)along a circular line (directrix) from afixed point (vertex).pyramidVolume or solid generated by straightlines (edges) connecting the angles of apolygon (base) to the vertex and whosesides form triangles.parallelepipedVolume or solid with six sides (parallelograms) that areparallel in pairs.regular octahedronVolume or solid with eight triangular sides ofequal area; it has six vertices and 12 edges.cylinderVolume or solid generated by therotation of a straight line (generatrix)moving along a curved line (directrix).geometrical shapesSCIENTIFIC SYMBOLS

82condenserCircuit that cools the steam from theturbine and condenses it into water.water-steam mixHot water extracted from the aquifer; as it rises to the surface, it ispartially turned into steam.steamGaseous state of water; steam pressure operates the turbine.turbineSteam-powered machine whose wheel transmits mechanical energy tothe generator and causes it to rotate.separatorDevice that separates water from steam, which it recovers to operate theturbine; the water is reinjected into the aquifer.upper confining bedLayer of impermeable rock that covers the confined aquifer.confined aquiferLayer of porous sedimentary rock between two impermeable layers wherewater accumulates at a temperature between 300°F and 750°F.geothermal fieldArea of Earth’s crust where a pocket of hot confined water is closeenough to the surface to be exploited.production wellBorehole dug into the ground to allow the hot water contained in theaquifer to be pumped to produce electricity.generatorTurbine-powered rotating machine thatconverts mechanical energy into electricenergy to direct it toward a transmissionnetwork.GEOTHERMAL AND FOSSIL ENERGYproduction of electricity from geothermal energyHot water contained in the ground near a volcano, geyser or thermal source is piped to the surface by drilling toextract steam and produce electricity.

83cooling towerDevice that cools the condenser’s hot water oncontact with the air; some of the waterevaporates and the rest is reinjected into thecondenser and the aquifer.voltage increaseAt the outlet end of the power plant, thetransformer increases the voltage; this reducesenergy losses during transmission over longdistances.high-tension electricity transmissionUsing high-voltage lines to transmit electricity overlong distances reduces the strength of the current and,as a result, energy losses.waterLiquid made up of hydrogen and oxygen that becomes steam at 212°F; the watertransfers Earth’s internal heat.injection wellBorehole that is drilled into the ground toreturn water to the aquifer, where it isreheated after its heat has been extracted.magma chamberPocket of magma (molten rock emergingfrom Earth’s crust) that constitutes a heatsource; it transmits its thermal energy towater.lower confining bedLayer of impermeable rock that transmitsheat from the magma chamber to theaquifer.GEOTHERMAL AND FOSSIL ENERGYproduction of electricity from geothermal energy

84production of electricity from thermal energyThe heat that is given off by burning combustible fuels in the thermalpower plant converts water into steam; the steam turns a turbo-alternatorunit to produce electricity.thermal energyEnergy that is produced by turning water into steam through the burning of fuel (e.g., petroleum and coal) orthrough nuclear reaction.conveyorMaterials-handling device that consists ofa conveyor belt (sturdy belt on rollers) thatcarries coal to the crusher.belt loaderMovable materials-handling device that is fitted with an inclinedconveyor belt; it is used mainly to raise loads.coal storage yardArea where the coal extracted from a mine is stored to ensure acontinuous supply to the thermal power plant.crusherDevice that pulverizes the coal carried by the conveyor belt into relatively fine fragments.GEOTHERMAL AND FOSSIL ENERGY

85thermal energycooling towerDevice that cools the heated water in thecondenser through contact with the air; asmall amount of water evaporates and the restis reinjected into the condenser.turbo-alternator unitDevice with a turbine that transmits thewater’s mechanical energy to thealternator’s rotor to make it turn toproduce electricity.coal-fired thermal power plantPlant that produces electricity fromthermal energy by burning coal.pulverizerDevice that pulverizes coal into a very fine powder so that it burns more easily in the steamgenerator.steam generatorDevice that uses the heat produced fromburning coal to convert water into steam;the steam powers the turbo-alternator unit.voltage increaseAt the outlet end of the power plant, thetransformer increases the voltage; this reducesenergy losses during transmission over longdistances.high-tension electricity transmissionUsing high-voltage lines to transmit electricity overlong distances reduces the strength of the current and,as a result, energy losses.voltage decreaseThe transformer reduces the voltage in orderto increase the strength of the current; thisallows a greater number of consumers to beserved.transmission to consumersElectricity is carried to areas ofconsumption over low-voltagedistribution lines.condenserCircuit that cools the steam from theturbine and condenses it into water,which is reintroduced into the steamgenerator.stackPipe through which gases produced byburning coal are discharged; these gasesare first partially cleaned to reducepollution.GEOTHERMAL AND FOSSIL ENERGY

86coal mineThe underground or open-pit facilities that are set up around a coal deposit in order to extract it.open-pit mineType of mining that is used for shallow deposits; coal or ore is extractedby digging a succession of benches from the surface of the grounddownward.benchThe levels of a quarry that are arranged like steps of a staircaseand from which coal or ore is extracted.faceVertical surface created by dynamiting adeposit to extract its ore.haulage roadAccess road leading to the quarry; it isused to haul coal to the treatment plant.craterDepression that forms the bottom of thequarry; it is a result of the extraction ofdeposits.GEOTHERMAL AND FOSSIL ENERGY

87coal mineground surfaceThe land that covers the deposit.overburdenPart of the ground that covers the ore beds; it is removed to reach the deposit.rampRoadway between two benches; it isinclined so that motorized vehicles canremove the ore extracted from the variouslevels.bench heightVertical distance between the horizontalplanes of two benches.oreSolid fossil fuel that is black andcontains a large amount of carbon.GEOTHERMAL AND FOSSIL ENERGY

88strip mineType of mining that is used especially for large shallow deposits; coal or ore is extractedby digging a trench in the ground surface.conveyorMaterials-handling device that consists of aconveyor belt (sturdy belt on rollers) that is used totransport coal extracted from the mine.dumpPile that is made up of residue from mining operations.facePart of the quarry that is beingexcavated and from which ore isprogressively extracted.trenchLengthwise excavation that is made down to the top of the ore layer in order to extractits coal.roofGeologic stratum that covers the ore seam; it is of morerecent formation than the ore.GEOTHERMAL AND FOSSIL ENERGYcoal mine

89bucket wheel excavatorEarthmover that consists of a wheel fitted withbuckets (scoops); it is used to dig into rock toextract materials, which are then dumped onto aconveyor.mechanical shovelEarthmover that consists of a movable cab with an articulated arm fitted with a bucket(scoop); it is used for digging and handling loads.belt loaderMovable materials-handling device that isfitted with an inclined conveyor belt; it isused mainly to raise loads.overburdenPart of the ground that covers the ore beds; it is removedto reach the deposit.bulldozerExcavation machine for pushingmaterials; it is made up of a crawlertractor, a blade and often a ripper.GEOTHERMAL AND FOSSIL ENERGYcoal mine

90jackleg drillPercussive tool that is powered by compressed air; it is used to bore holes into hard rock. The airleg makes the job easier for the drill operator.hammer drillPercussive tool that is powered by compressed air; its piston (cylindricalpart) is pushed by the air leg and hits the drill rod, causing it to bore into therock.water hoseFlexible hose used to inject water under pressure toprevent wear on the drill rod and the bit and to dischargewaste.air legMovable cylindrical part that supports thehammer drill; it transmits air pressure to thedrill from the compressor to which it isattached.water separatorDevice that removes any trace ofhumidity from the compressor’s air toprevent damage to the hammer.bitCutting end of the drill rod that is usedto bore into the rock.drill rodUsually hollow, steel rod that isactivated by the hammer drill’s pistonto strike the rock and bore into it.air hoseFlexible hose through which oil is fed to thehammer.oilerDevice that allows oil to enter the hammer to prevent wear of its movingparts.GEOTHERMAL AND FOSSIL ENERGYcoal mine

exhaust portOpening through which compressed air isexpelled from the pneumatic hammer.flexible hose connectionFastening device with a metal part thataccepts the flexible hose so that compressedair can enter the hammer.flexible hoseFlexible hose through which compressed airfrom the compressor it is attached to entersthe hammer.retainerDevice that holds the tool in place in the chuck.91control leverGrip used to operate the hammer; the leveropens the throttle valve so that air can enter thehammer.handleThe two elements that allow a worker tomanipulate the hammer.lubricatorDevice that automatically oils the various parts of thehammer to prevent wear.silencerDevice that lessens the noise caused when air exitsthe hammer.throttle valveMovable part that is opened by the controllever to let compressed air into the hammer.pneumatic hammerPercussive tool that is powered by compressed air; with thehelp of a piston, it activates a tool, which breaks through veryhard matter such as rock and concrete.chuckPart of the hammer to which the tool is fastened.toolCylindrical rod that is set in motion by compressed airpressure from the hammer; it is used to break hard surfaces.GEOTHERMAL AND FOSSIL ENERGYcoal mine

92pitheadThe surface facilities needed for underground mining (including extraction machinery, storageareas and offices).maintenance shopWork area where machinery is maintained andrepaired.dumpPile that is made up of residue frommining operations.main fanDevice that ensures air exchange in the mine; air isdrawn through one shaft and exits through another.loading bunkerReservoir where processed coal is stored before being loaded onto freight cars to be transportedby rail to the power plant.GEOTHERMAL AND FOSSIL ENERGYcoal mine

93headframeOpening at the top of the shaft thatconnects the aboveground facilities(including ventilation fans and hoists)to the underground areas being mined. miners can go mainly to change their clothes.miners’ changing-roomArea with sanitary facilities (showers, toilets) wheretreatment plantPlace where all processing activities (includingcrushing and washing) are carried out to preparethe coal for market.conveyorMaterials-handling device that consists of aconveyor belt (sturdy belt on rollers); it is used tocarry coal to the treatment plant.winding towerBuilding that houses the shaft’s hoistingequipment (including motors and hoistingcables); it provides communication between thesurface and the mine galleries.hoist roomArea that houses the hoist (cylinder) on which thehoisting cables are wound; it controls movementof the elevators and skip hoists in the shaft.rail trackThe tracks formed of two parallel rails onwhich trains travel to transport coal.maritime transportMeans of transport that usesbarges to transport coal overwater.GEOTHERMAL AND FOSSIL ENERGYcoal mine

94underground mineProperty in which excavations are carriedout to extract deeply embedded (between30 and 11,500 ft) coal for industrialmining.headframeOpening at the top of the shaft thatconnects the aboveground facilities(including ventilation fans and hoists) tothe underground areas being mined.vertical shaftShaft that is dug perpendicular to the surface;it serves various levels and is used mainly totransport personnel, equipment and ore.pillarMass of ore that is left unmined atregular intervals in an excavation(chamber); it provides stability for theupper layers.manwayPassageway allowing workers to movearound in the mine.winzeVertical or inclined passageway thatconnects two levels; it is dugdownward from inside the mine andnot from the surface.chuteVertical or inclined passagewaythrough which ore, equipment,personnel and air move from one levelof the mine to the other.cross cutHorizontal passageway that cuts through theore bed perpendicularly; it providescommunication between the passageways andhelps to ventilate the mine.faceOpening that is dug laterally into therock as coal is extracted.driftPassageway dug horizontally along thegrade line of the ore seam; it can also bedug into the ore vertically.roomCavity that remains after the ore isextracted; pillars support its roof.elevatorPower lift fitted with a cab thattransports coal or miners between thevarious levels.GEOTHERMAL AND FOSSIL ENERGYcoal mine

95bottom roadHorizontal passageway that serves the base of a panel.winding shaftShaft that is dug vertically into the ground; coal is removedfrom the mine through it using hoisting machinery.winding towerBuilding that houses the shaft’s hoistingequipment (including motors and hoistingcables); it provides communication between thesurface and the mine galleries.top roadHorizontal passageway that serves the highest level of a panel.skipElevator consisting of a skip bucket that is activated by a hoist; it isused to bring coal and people to the surface.ore passInclined route that takes coal to a lower level; coal that falls on the minefloor is usually crushed before being brought to the surface.panelUnit of rock that is being mined; it is contained between vertical andhorizontal planes and is demarcated by various passageways.sumpBottom of the shaft in which waterrunoff accumulates inside the minebefore being pumped to the surface.levelThe horizontal passageways that branch offfrom the shaft at the same depth; they areusually at regular intervals.deckExtraction layer between two levels; mining is usually done in stagesand in descending order.landingLanding located around a shaft on each level; coal is collectedhere before being moved to the surface.GEOTHERMAL AND FOSSIL ENERGYcoal mine

96oilFlammable, relatively viscous oily liquid that is used as an energy source; it is made up of various hydrocarbonsresulting from the decomposition of plant life over millions of year.surface prospectingSearching for potential oil deposits by studying the structure of thesubsoil using a seismograph.shock waveThe shock wave spreads and sends back an echo, which varieswith the density and depth of the layers of subsoil; with thisinformation, the composition of the subsoil can be determined.petroleum trapAssemblage of porous rocks that contain recoverable oilreserves, which are produced from marine or land deposits.seismographic recordingA recording made using an apparatus called a seismograph; theanalysis of its shock wave echoes detects the presence of rocklayers that might contain pockets of petroleum or gas.GEOTHERMAL AND FOSSIL ENERGY

97oiloffshore prospectingVibrations from an exploding charge in the sea are used to locate oil deposits; prospecting offshore is more difficultthan on land.shock waveThe shock wave spreads and sends back anecho, which varies with the density and depth of discharging high-temperature gases over a very reserves, which are produced from marine or landthe layers of subsoil; with this information, thecomposition of the subsoil can be determined.seismographic recordingA recording made using an apparatus called a seismograph; the analysis of its shock wave echoes detects thepresence of rock layers that might contain pockets of petroleum or gas.blasting chargeQuantity of explosives (substances capable ofshort time period) that produce shock waveswhen detonated.petroleum trapAssemblage of porous rocks that contain recoverable oildeposits.GEOTHERMAL AND FOSSIL ENERGY

98drilling rigAll the drilling machinery and devices that are used toexcavate and extract oil from the ground.swivelPiece attached to the lifting hook and the kelly;it is used to introduce mud into the drill pipe tocool and lubricate the bit.drilling drawworksDevice that consists of a cylinder on which hoisting cables are wound; itis used to lower the drill pipes and bit into the well and to lift them out.derrickMetal structure erected over an oil well; tools for drillingthrough rock are raised and lowered through it.vibrating mudscreenPerforated vibrating tray that is used to filter mud as it exits the well toremove debris and recycle the mud.substructureMetal infrastructure that supports the derrick, engines and auxiliaryequipment.gasMixture of gaseous hydrocarbons (mainlymethane) that are found in undergrounddeposits, which sometimes also containcrude oil; it is used mainly as a fuel.oilFlammable, relatively viscous oily liquid that is used as an energy source; it ismade up of various hydrocarbons resulting from the decomposition of plant lifeover millions of year.bitRotating drill bit with toothed steel or diamond wheels;it bores into rock to break it up and drill a hole.drill collarHeavy steel tube immediately above the bit that appliesa certain weight to the bit to help it cut into the rock.drill pipeHollow steel rods that are joined together according tothe depth of the excavation; their rotation activates thebit.mud injection hoseFlexible hose that introduces the drilling mud into the swivel.oilGEOTHERMAL AND FOSSIL ENERGY