"Annenberg Media" "¶" "EVERYBODY LIKES TO TALK ABOUT THE WEATHER." "USUALLY THAT MEANS THE TEMPERATURE." "WHETHER IT'S FRIGID IN FEBRUARY" "OR TORRID IN AUGUST," "TEMPERATURE IS AN INESCAPABLE PART OF OUR LIVES." "THAT BEAUTIFUL PHYSICS THAT NEWTON TAUGHT US" "SAYS VERY LITTLE ABOUT TEMPERATURE." "BUT THERE IS A CONNECTION." "IF I LIFT THIS BLOCK, I'M WORKING AGAINST GRAVITY." "NOW THE BLOCK HAS POTENTIAL ENERGY." "IF I RELEASE IT," "THE POTENTIAL ENERGY TURNS INTO KINETIC ENERGY." "LOOK WHAT'S HAPPENED NOW." "THE KINETIC ENERGY IS GONE." "THE POTENTIAL ENERGY IS GONE." "MY WORK IS GONE." "NOW, I DON'T THINK NOBODY APPRECIATES MY WORK," "BUT WHAT HAPPENED TO IT?" "THE ANSWER IS IT TURNED INTO HEAT," "THE RANDOM MOTIONS OF ATOMS AND MOLECULES." "THE EVIDENCE FOR THAT" "IS THAT THE TABLE IS JUST A LITTLE BIT WARMER NOW." "SO THERE IS SOME CONNECTION BETWEEN TEMPERATURE" "AND THE MOTION OF ATOMS AND MOLECULES." "THAT CONNECTION IS OUR STORY FOR TODAY." "A LONG TIME AGO, SCIENTISTS CONCLUDED" "THAT HEAT IS THE RANDOM MOTION OF ATOMS AND MOLECULES." "YOU'RELISTENINGTO KNT," "RADIOKNT,HOTSPRINGS." "THE AVERAGE PERSON DOESN'T NEED SCIENCE" "TO TELL WHEN IT'S HOT OR COOL." "AT25BEFORETHE HOUR, THE MERCURY HAS PASSED 112," "ANDWHERESHESTOPS, NOBODYKNOWS." "BUTLET'SGETBACK TOTHEMELLOWSOUNDS," "BROUGHT TO YOU BY PACKARD, THE MOTORCAR OF DISTINCTION." "ONE WAY OR ANOTHER," "TEMPERATURE AFFECTS EVERYTHING ON EARTH." "PRACTICE AND MEMORY," "INTUITION AND EXPERIENCE," "TASTE AND TOUCH" "THEY ALL PROVIDE A VERY PRACTICAL SENSE OF TEMPERATURE." "BUT KNOWING RATHER THAN FEELING" "HOW HOT OR COLD IT REALLY IS" "CALLS FOR SOME SORT OF OBJECTIVITY" "AND SOME FORM OF QUANTIFICATION." "THAT CALLS FOR SOME TOOLS OF SCIENCE," "A THERMOMETER, FOR EXAMPLE, OF ALMOST ANY VARIETY." "THE STYLE DOESN'T MATTER MUCH AS LONG AS IT WORKS." "OH, MERCY." "FINDING AN ACCURATE MEANS OF MEASURING TEMPERATURE" "CAN BE A CHALLENGE." "SOMETIMES IT'S HARD TO GET A HANDLE ON TEMPERATURE." "SINCE IT LACKS PHYSICAL DIMENSIONS," "THERE'S NO WAY TO MEASURE TEMPERATURE DIRECTLY." "WHILE AN OBJECT'S LENGTH CAN BE EXPRESSED IN METERS" "AND ITS MASS IN KILOGRAMS," "TEMPERATURE CAN BE MEASURED ONLY IN TERMS OF ITS EFFECTS," "AND TEMPERATURE CAN BE MEASURED EFFECTIVELY" "ONLY WHEN THERE'S AN ACCEPTED SCALE." "[ENGINE WON'T START]" "WHETHER SEEN ON A FAHRENHEIT SCALE," "WHICH IS STILL PREDOMINANT IN THE UNITED STATES," "OR ON A CELSIUS SCALE," "TEMPERATURE SCALES ARE EFFECTIVE SCIENTIFIC SCALES" "BECAUSE THEY OFFER STANDARDS FOR COMPARISON." "ONE USEFUL CALIBRATION POINT IS THE FREEZING POINT OF WATER." "ON THE CELSIUS SCALE," "WATER FREEZES AT ZERO DEGREES." "ON THE FAHRENHEIT SCALE," "IT FREEZES AT 32 DEGREES." "ANOTHER RELIABLE CALIBRATION POINT" "IS THE BOILING POINT OF WATER." "IT BOILS AT 212 DEGREES FAHRENHEIT." "IT BOILS AT 100 DEGREES CELSIUS." "BUT WATER AND PEOPLE" "AREN'T THE ONLY THINGS AFFECTED BY TEMPERATURE," "NO MATTER HOW IT'S MEASURED." "TEMPERATURE CAN ALSO AFFECT PRESSURE." "PRESSURE IS THE FORCE-PER-UNIT-AREA EXERTED," "IN THIS CASE, ON THE FABRIC OF A BALLOON." "OBVIOUSLY, PRESSURE IS AFFECTED BY HEAT." "BUT THAT'S NOT THE ONLY WAY TO BLOW UP A BALLOON." "HOW DOES GAS BLOW UP A BALLOON?" "OR, FOR THAT MATTER," "HOW DOES IT EXERT PRESSURE AGAINST A SOLID WALL?" "EACH TIME A GAS MOLECULE HITS A WALL," "IT GIVES THE SURFACE A TINY PUSH." "BY BOUNCING OFF THE WALL," "THE MOLECULE CHANGES ITS MOMENTUM." "THE CHANGE IN MOMENTUM" "MEANS A FORCE ACTED ON THE MOLECULE." "THAT MEANS THE REVERSE FORCE" "ACTED ON THE WALL." "AS MORE AND MORE MOLECULES STRIKE THE WALL," "THE INDIVIDUAL PUSHES BEGIN TO MERGE." "AT AN ALMOST UNIMAGINABLE RATE," "EVEN WITHIN AN ORDINARY GAS SUCH AS AIR," "THERE'S A STEADY DRUMBEAT OF MOLECULES," "CONSTANT, UNIFORM PRESSURE AGAINST THE WALL." "THISPHENOMENONIS ILLUSTRATED BYA COMPUTERCALCULATION" "OF A KIND OFTEN USED TODAY BYSCIENTISTS" "TOHELPTHEMDORESEARCH." "THEPISTONANDEACHATOM" "AREPROGRAMMED TOOBEYNEWTON'SLAWS" "ANDTHENARESET FREE." "THEPISTONIS FALLING" "ASIFUNDERTHE FORCE OFGRAVITY," "BUTIT'SHELDUP BY THE ATOMS COLLIDING WITH IT." "THE MASS ON TOP OF THE PISTON" "SHOWSHOWBIGTHE PRESSUREIS." "THISKINDOF CALCULATION" "ISCALLEDAMOLECULAR DYNAMICSSIMULATION." "SUCH A SIMULATION CAN HELP EXPLAIN" "WHY FUEL IS NEEDED TO KEEP A HOT AIR BALLOON ALOFT." "HEAT IS THE ENERGY" "OF RANDOM MOTIONS OF ATOMS AND MOLECULES." "HEATING A GAS" "INCREASES THE KINETIC ENERGY OF ALL THE MOLECULES." "EACH COLLISION EXERTS GREATER PRESSURE ON THE WALL." "THAT'S WHY HEATING A GAS INCREASES ITS PRESSURE." "CONVERSELY, THAT'S WHY IT TAKES LESS GAS" "TO MAINTAIN THE SAME PRESSURE." "BECAUSE OF THE HEATER, FEWER MOLECULES ARE NEEDED" "TO PROVIDE THE BALANCE OF PRESSURE" "FROM INSIDE THE BALLOON." "IT WEIGHS LESS THAN THE SAME VOLUME OF AIR." "THAT'S WHAT GIVES THE BALLOON ITS BUOYANCY." "REDUCED TO ITS ESSENCE," "IT ALL COMES DOWN TO FORCE AND MOMENTUM," "ACTION AND REACTION." "ISAAC NEWTON WROTE THE BOOK" "ON FORCE, MOMENTUM, ACTION, AND REACTION." "THE BOOK HAD SOMETHING TO SAY" "ABOUT THE PRESSURE AND VOLUME OF A GAS." "WHAT IT SAID PROVED TO BE SURPRISING." "IT PROVED THAT EVEN THE GREAT SIR ISAAC COULD BE WRONG." "THE CORRECT EXPLANATION," "FIRMLY BASED ON NEWTON'S LAWS OF MECHANICS" "BUT NOT ON NEWTON'S THEORY OF GASES," "WAS PROVIDED BY 19th-CENTURY SCIENTISTS" "NAMED JOULE, MAXWELL, AND BOLTZMANN." "EXPRESSED IN MODERN TERMS," "THEYFOUND THAT THE PRESSURE IN A GAS" "ISPROPORTIONAL TO THE NUMBER OF MOLECULES" "AND INVERSELY PROPORTIONAL TOTHEVOLUME." "IT'SALSOPROPORTIONAL" "TO THE AVERAGE KINETIC ENERGY OFA MOLECULE." "BYAPPLYING NEWTON'SLAWSOF MOTION" "TOINDIVIDUAL GASMOLECULES," "THEY FOUND THAT THE CONSTANT OFPROPORTIONALITY" "ISSIMPLY2/ 3." "THIS GREAT THEORETICAL INSIGHT CAME IN RESPONSE" "TO EVER-EXPANDING EXPERIMENTAL KNOWLEDGE" "ABOUT THE NATURE OF GASES." "IN THE 1600s, WHEN THE DIVIDING LINE WAS THIN" "BETWEEN SCIENCE AND WITCHCRAFT," "IT TOOK AN UNUSUAL RESEARCHER" "TO RISE TO THE CHALLENGE OF INVISIBLE GASES." "HE WAS A CHEMIST AS WELL AS A PHYSICIST," "OFTEN ACCUSED OF PUTTING TOO MUCH PHYSICS" "INTO HIS CHEMISTRY." "HIS NAME WAS ROBERT BOYLE." "FOR 15 YEARS, HE WORKED IN HIS LABORATORY AT OXFORD." "MORE THAN HIS CONTEMPORARY, ISAAC NEWTON," "BOYLE'S APPROACH WAS AHEAD OF HIS TIME." "HE HIRED ASSISTANTS" "AND EMPHASIZED THE SCIENTIFIC METHOD," "BUT UNLIKE NEWTON," "BOYLE WAS ACCESSIBLE TO THE PUBLIC." "UNTIL HIS DEATH IN 1691," "LONDON SOCIETY VIEWED ROBERT BOYLE" "AS ONE OF THE MORE POPULAR SCIENTISTS" "OF THE DAY." "BOYLE WAS AN EARLY PRACTITIONER OF THE QUANTITATIVE APPROACH." "HE NOTED EVERYTHING IN DETAIL," "SO OTHERS COULD REPEAT, VERIFY, AND ADVANCE HIS RESEARCH." "BOYLE'S PRACTICE BECAME UNIVERSAL" "AND UNIVERSALLY PRACTICED" "AS THE SCIENTIFIC METHOD." "FOR THE MOST PART," "ROBERT BOYLE WENT ABOUT HIS SCIENTIFIC BUSINESS" "WITH THE GREATEST CARE." "HE DISCOVERED THAT AT A FIXED TEMPERATURE," "THE PRODUCT OF THE PRESSURE AND THE VOLUME OF A GAS" "IS NEARLY CONSTANT." "IF THE TEMPERATURE OF A GAS REMAINS UNCHANGED," "THE PRESSURE IS INVERSELY PROPORTIONAL TO THE VOLUME." "THEEXPERIMENTALEQUATION PV=CONSTANT" "ISKNOWNAS BOYLE'SLAW ." "THE APPLICATION OF MECHANICS TO THE PROPERTIES OF A GAS" "EXPLAINTHEINNERMEANING OFTHATLAW." "THE CONSTANT IN BOYLE'S LAW" "ISEQUALTO 2/ 3 THENUMBEROF MOLECULES" "TIMESTHEAVERAGE KINETIC ENERGY PER MOLECULE." "PVISPROPORTIONAL TO THE TOTAL KINETIC ENERGY" "OFALLTHEMOLECULES OFTHEGAS." "THATKINETICENERGY ISA FORMOF HEAT." "HEATING A GAS EITHER CAUSES ITS PRESSURE TO RISE" "OR ITS VOLUME TO EXPAND." "HEATING A GAS CAN ALSO CAUSE ITS TEMPERATURE TO RISE." "SO TEMPERATURE IS RELATED TO PRESSURE AND VOLUME." "BUT HOW?" ""HOW INDEED?" WONDERED JACQUES ALEXANDRE CESAR CHARLES." "CHARLES WAS INTRIGUED BY THE HOT AIR BALLOON FLIGHTS" "OF THE FAMOUS MONTGOLFIER BROTHERS," "THE PIONEERS OF HOT AIR BALLOONING." "ON DECEMBER 1, 1783," "CHARLES TOOK THE SECOND BALLOON FLIGHT IN HISTORY." "A PIONEER IN SCIENCE AS WELL AS SPACE," "HE BEGAN EXPERIMENTS TO EXPLORE THE NATURE OF GASES." "CHARLES' CURIOSITY LED HIM TO THE DISCOVERY" "THAT ALL GASES EXPAND BY THE SAME AMOUNT" "WITH A GIVEN RISE IN TEMPERATURE." "CHARLES DISCUSSED HIS LOFTY BUT UNPUBLISHED DISCOVERIES" "WITH JOSEPH LOUIS GAY-LUSSAC," "ANOTHER FRENCH SCIENTIST AND BALLOON ENTHUSIAST" "WHO WAS ABLE TO SOAR TO NEW HEIGHTS," "AN ALTITUDE OF FOUR MILES." "PUBLISHING HIS OWN WORK," "GAY-LUSSAC DESCRIBED, CRITICIZED," "AND CONSIDERABLY IMPROVED UPON CHARLES' DISCOVERY." "AT A GIVEN PRESSURE," "THE VOLUME OF ANY GAS CHANGES BY THE SAME FRACTION" "FOR EACH DEGREE RISE IN TEMPERATURE." "IF THAT BEHAVIOR REMAINED TRUE," "THERE COULD BE A TEMPERATURE SO LOW" "THAT A GAS WOULD OCCUPY NO VOLUME AT ALL." "AS THE GAS WARMED, ITS VOLUME WOULD INCREASE" "IN PROPORTION TO THE TEMPERATURE." "OF COURSE, THE REASON THE VOLUME INCREASES" "IS THE INCREASE IN HEAT OR KINETIC ENERGY" "OF THE MOLECULES." "THIS IDEA LED TO A NEW CONCEPT" "OF TEMPERATURE ITSELF." "IT WOULD HAVE AN ABSOLUTE MEANING" "BASED ON THE UNIVERSAL PROPERTIES OF GASES." "AN ABSOLUTE ZERO," "THE LOWEST POSSIBLE TEMPERATURE," "WOULD BE THE TEMPERATURE AT WHICH A GAS" "WOULD BE ENTIRELY WITHOUT HEAT." "ACCORDING TO CHARLES AND GAY-LUSSAC," "ABSOLUTE ZERO WOULD OCCUR" "AT 273 DEGREES BELOW ZERO CELSIUS" "OR 459 DEGREES BELOW ZERO FAHRENHEIT." "THE IDEA OF AN ABSOLUTE TEMPERATURE" "WAS GIVEN ITS FINAL FORM BY LORD KELVIN," "FOR WHOM THE ABSOLUTE OR KELVIN TEMPERATURE SCALE" "IS NAMED." "ON THE KELVIN SCALE," "THE TEMPERATURE IS DIRECTLY PROPORTIONAL" "TO THE VOLUME OF A GAS," "AS CHARLES AND GAY-LUSSAC SAID IT SHOULD BE." "BUT TWICE AS MUCH GAS MUST OCCUPY TWICE THE VOLUME." "IN OTHER WORDS," "VOLUME MUST ALSO BE PROPORTIONAL" "TO THE NUMBER OF MOLECULES OF GAS." "BOYLE'S LAW STATES THAT AT ANY CONSTANT TEMPERATURE," "PV IS CONSTANT." "BUT IF T CHANGES," "THAT CONSTANT MUST ALSO CHANGE." "SO, PV IS PROPORTIONAL TO NT," "WHETHER N AND T ARE CONSTANT OR NOT." "THE CONSTANT OF PROPORTIONALITY, k," "IS DEFINED TO BE EQUAL" "TO 1.38 TIMES 10 TO THE -23 JOULES PER KELVIN." "THIS DEFINITION DETERMINES THE SIZE OF ONE KELVIN," "AND WITH IT, FIXES THE WHOLE KELVIN TEMPERATURE SCALE." "FOR EXAMPLE, ICE MELTS AT 273 KELVINS." "AND THE BOILING POINT OF WATER..." "IS 373 KELVINS." "WELL, I'M HERE." "I WASN'T SURE SHE'D EVEN MAKE IT." "LOOK AT THAT." "I TRIED DRIVING SLOWER," "AND THAT MADE IT WORSE." "DRIVING FASTER MADE IT WORSE." "SO I'M GLAD I FOUND A STATION" "WITH A MECHANIC." "TELL YOU WHAT." "I'LL BRING IT UP FRONT." "ROOM TEMPERATURE IS ABOUT 300 KELVINS." "OH, MERCY." "I WAS AFRAID OF THIS." "I THINK IT MUST BE OVERHEATING." "THE SURFACE OF THE SUN, 6,000 KELVINS." "I THREW SOME ENCYCLOPEDIAS OFF" "JUST TO LIGHTEN THE LOAD." "I'M SO HAPPY I FOUND THIS HERE." "THE TEMPERATURE WITHIN THE SUN'S CORE" "IS 15 MILLION KELVINS." "BOY, YOU LOOK LIKE YOU FIXED" "ABOUT 100 CARS ALREADY TODAY." "WHY DON'T YOU CHECK IT OUT?" "I'VE BEEN WORKING IN TOWN." "THE HOUSES ARE SO FAR APART." "IT'S A LOT WORSE THAN I THOUGHT." "LITTLE BOY, PLEASE DON'T." "THIS CAR IS HAVING A HARD TIME." "THANK YOU SO MUCH." "YOU CAN GO AHEAD." "I HAVE TO CALL MY BOSS." "CLOSER TO EARTH," "THE EXPERIMENTS OF CHARLES AND GAY-LUSSAC" "SUGGESTED THAT SINCE GAS CAN BE COMPRESSED," "GASES MUST BE COMPOSED OF DISCRETE PARTICLES" "SEPARATED BY A VOID." "APPLYING THE LAWS OF MECHANICS TO THOSE INVISIBLE MOLECULES" "LEADS TO THE KINETIC THEORY OF GASES" "WHICH SAYS THAT THE KINETIC ENERGY OF THE GAS," "THE COLLECTIVE EFFECT OF MOLECULAR COLLISIONS," "IS WHAT GIVES A GAS ITS PRESSURE AND VOLUME." "BUT PRESSURE TIMES VOLUME" "IS ALSO RELATED TO THE ABSOLUTE TEMPERATURE." "SO THERE IS A DIRECT AND SIMPLE RELATIONSHIP" "BETWEEN TEMPERATURE AND HEAT." "THE ABSOLUTE TEMPERATURE IS GIVEN" "BY 2/3 THE MEAN AVERAGE KINETIC ENERGY" "OF ONE MOLECULE OF GAS." "AND OF COURSE, HEAT IN A GAS" "IS JUST THE AVERAGE KINETIC ENERGY" "OF ITS MOLECULES." "IN OTHER WORDS, HEAT AND TEMPERATURE" "CAN BE RELATED TO A MECHANICAL PROPERTY," "THE KINETIC ENERGY OF INDIVIDUAL MOLECULES OF GAS." "AGAIN, NO MATTER WHERE THEY RISE OR FALL," "ALL TEMPERATURES ARE RELATED TO THE PRESSURE OF THE GAS" "BY THE EQUATION PV = NkT." "THIS EQUATION," "VITAL IN BOTH PHYSICS AND CHEMISTRY," "IS CALLED THE IDEAL GAS LAW." "NOT ALL GASES ARE IDEAL," "BUT THE IDEAL GAS LAW" "NONETHELESS ACCURATELY DESCRIBES" "HOW NUMEROUS REAL GASES BEHAVE." "MORE THAN A DEFINITION" "OF THE ABSOLUTE TEMPERATURE SCALE," "IT EXPRESSES BOTH BOYLE'S LAW AND CHARLES' LAW," "AND IT LEADS TO A KINETIC THEORY OF TEMPERATURE." "I DON'T SUPPOSE YOU KNOW ABOUT CARS," "BUT IF YOU DO, YOU SPEAK UP." "THERE'S TROUBLE HERE FOR SURE." "I'M AN ENCYCLOPEDIA SALESMAN." "I'D SHOW YOU SOME OF THE STUFF I CARRY, BUT..." "ANDTHOSESWEETSOUNDS" "BRINGUSRIGHTUP TOTHEHOURHEREATKNT." "THAT'SRADIOKNT." "ANDNOWAWORD FROMOURSPONSOR." "IN THE UNITED STATES," "WE USE THE FAHRENHEIT TEMPERATURE SCALE." "I'VE HEARD SILLY STORIES" "ABOUT HOW THAT SCALE CAME INTO BEING." "I'LL TELL YOU HOW IT REALLY HAPPENED." "DANIEL FAHRENHEIT WAS NOT A SCIENTIST AT ALL." "HE WAS A POLISH MERCHANT WHO, DURING THE 1700s," "DECIDED TO TRAIN HIMSELF IN THE NEWLY EMERGING CRAFT" "OF SCIENTIFIC INSTRUMENT MAKING." "HE SAW A FUTURE IN CALIBRATED THERMOMETERS." "HE HEARD THAT A DANISH ASTRONOMER" "NAMED OLAUS ROEMER KNEW HOW TO DO THE JOB," "AND SO HE TRAVELED TO DENMARK" "TO SEE HOW ROEMER CALIBRATED HIS THERMOMETERS." "ROEMER HAD INVENTED HIS OWN TEMPERATURE SCALE," "WHICH LIKE CELSIUS," "WAS BASED ON THE FREEZING POINT" "AND THE BOILING POINT OF WATER," "BUT THE SCALE WAS DIFFERENT FROM CELSIUS." "FIRST OF ALL, ROEMER BASED HIS SCALE" "ON ZERO TO 60 DEGREES, RATHER THAN ZERO TO 100." "THE ZERO TO 60 DEGREES" "PROBABLY CORRESPONDED TO THE DEGREES IN A CIRCLE." "THE SECOND DIFFERENCE WAS THAT ROEMER" "DIDN'T LIKE NEGATIVE NUMBERS," "SO WHEN HE DIPPED HIS THERMOMETER" "IN FREEZING WATER AND MARKED IT," "HE DIDN'T MARK THAT AS ZERO DEGREES," "BUT RATHER AS 7 1/2 DEGREES," "LEAVING 1/8 OF HIS SCALE BELOW THAT." "ON THE DAY THAT FAHRENHEIT CAME" "TO WATCH ROEMER CALIBRATE HIS THERMOMETER," "ROEMER WAS MAKING THERMOMETERS TO BE USED" "FOR METEOROLOGICAL PURPOSES." "A THERMOMETER FOR METEOROLOGICAL PURPOSES" "SHOULDN'T READ FROM THE FREEZING POINT OF WATER" "TO THE BOILING POINT OF WATER" "BECAUSE THE WEATHER SELDOM GETS THIS HOT." "ROEMER MADE ONE MARK AT THE FREEZING POINT," "FOR THE OTHER MARK," "HE MEASURED HUMAN BODY TEMPERATURE." "WHEN HE HAD FOUND THAT MARK," "HE CALLED THAT 22 1/2 DEGREES." "THAT WAS THE BASIC SCALE THAT FAHRENHEIT ADOPTED." "BUT FAHRENHEIT DIDN'T LIKE FRACTIONS," "SO WHEN HE MADE HIS OWN THERMOMETERS," "HE MULTIPLIED EVERYTHING BY FOUR." "AND NOW THE SCALE WAS 30 DEGREES TO 90 DEGREES." "FROM THE FREEZING POINT TO BLOOD TEMPERATURE." "THEN HE DECIDED THAT IT WOULD BE MORE CONVENIENT TO HAVE 64 DEGREES BETWEEN THESE TWO POINTS, NOT 60." "THE REASON IS HE HAD TO ENGRAVE" "SINGLE-DEGREE MARKS ON HIS THERMOMETER." "IF IT WERE 64 DEGREES" "BETWEEN HIS TWO CALIBRATION POINTS," "THEN HE WOULD DIVIDE IT" "IN HALF AND IN HALF AGAIN SIX TIMES." "SO HE SHIFTED HIS TEMPERATURE SCALE ONCE MORE" "TO MAKE IT 32 DEGREES AND 96," "A DIFFERENCE OF 64." "THEN, USING THAT THERMOMETER," "HE MEASURED THE TEMPERATURE OF BOILING WATER" "SOMEWHAT INACCURATELY" "AND DECIDED THAT IT WAS 212 DEGREES." "AFTER HE DIED, 212 DEGREES WAS DEFINED" "TO BE THE TEMPERATURE OF BOILING WATER." "THAT SHIFTED THE TEMPERATURE OF THE BODY TO 98.6 DEGREES." "THAT'S HOW THE FAHRENHEIT SCALE CAME ABOUT." "NOW YOU MIGHT ASK" "WHICH TEMPERATURE SCALE IS THE BEST ONE." "THE KELVIN SCALE, OR ABSOLUTE SCALE," "IS THE ONE USED BY SCIENTISTS.," "THE CELSIUS SCALE IS ALMOST IDEAL FOR COOKING" "BECAUSE IT'S BASED ON THE TEMPERATURE" "OF BOILING WATER IN AN OPEN POT." "THE FAHRENHEIT SCALE," "WITH ZERO TO 100 DEGREES AS THE RANGE OF NORMAL WEATHER," "IS ALMOST PERFECT FOR WEATHER." "WELL, THAT'S IT." "I'LL SEE YOU NEXT TIME." "CAPTIONING PERFORMED BY THE NATIONAL CAPTIONING INSTITUTE, INC." "CAPTIONS COPYRIGHT 1985 CALIFORNIA INSTITUTE OF TECHNOLOGY" "THE CORPORATION FOR COMMUNITY COLLEGE TELEVISION AND THE ANNENBERG/CPB PROJECT" "Annenberg Media" "¶"