t waslyell who put everyone straight。 stephen jay gould； in time鈥檚 arrow； cites as a typicalexample this sentence from a popular book of the 1980s： 鈥渦ntil lyell published his book；most thinking people accepted the idea that the earth was young。鈥潯n fact； no。 as martin j。 s。
rudwick puts it； 鈥渘o geologist of any nationality whose work was taken seriously by othergeologists advocated a timescale confined within the limits of a literalistic exegesis ofgenesis。鈥潯ven the reverend buckland； as pious a soul as the nineteenth century produced；noted that nowhere did the bible suggest that god made heaven and earth on the first day；but merely 鈥渋n the beginning。鈥潯hat beginning； he reasoned； may have lasted 鈥渕illions uponmillions of years。鈥潯veryone agreed that the earth was ancient。 the question was simply howancient。
one of the better early attempts at dating the planet came from the ever…reliable edmondhalley； who in 1715 suggested that if you divided the total amount of salt in the world鈥檚 seasby the amount added each year； you would get the number of years that the oceans had beenin existence； which would give you a rough idea of earth鈥檚 age。 the logic was appealing； butunfortunately no one knew how much salt was in the sea or by how much it increased eachyear； which rendered the experiment impracticable。
the first attempt at measurement that could be called remotely scientific was made by thefrenchman georges…louis leclerc； te de buffon； in the 1770s。 it had long been knownthat the earth radiated appreciable amounts of heat鈥攖hat was apparent to anyone who wentdown a coal mine鈥攂ut there wasn鈥檛 any way of estimating the rate of dissipation。 buffon鈥檚experiment consisted of heating spheres until they glowed white hot and then estimating therate of heat loss by touching them （presumably very lightly at first） as they cooled。 from thishe guessed the earth鈥檚 age to be somewhere between 75；000 and 168；000 years old。 this wasof course a wild underestimate； but a radical notion nonetheless； and buffon found himselfthreatened with exmunication for expressing it。 a practical man； he apologized at oncefor his thoughtless heresy； then cheerfully repeated the assertions throughout his subsequentwritings。
by the middle of the nineteenth century most learned people thought the earth was at leasta few million years old； perhaps even some tens of millions of years old； but probably notmore than that。 so it came as a surprise when； in 1859 in on the origin of species ； charlesdarwin announced that the geological processes that created the weald； an area of southernengland stretching across kent； surrey； and sussex； had taken； by his calculations；306；662；400 years to plete。 the assertion was remarkable partly for being so arrestinglyspecific but even more for flying in the face of accepted wisdom about the age of the earth。
3itproved so contentious that darwin withdrew it from the third edition of the book。 the2although virtually all books find a space for him； there is a striking variability in the details associated withussher。 some books say he made his pronouncement in 1650； others in 1654； still others in 1664。 many cite thedate of earths reputed beginning as october 26。 at least one book of note spells his name 〃usher。〃 the matter isinterestingly surveyed in stephen jay goulds eight little piggies。
3darwin loved an exact number。 in a later work； he announced that the number of worms to be found in anaverage acre of english country soil was 53；767。
problem at its heart remained； however。 darwin and his geological friends needed the earth tobe old； but no one could figure out a way to make it so。
unfortunately for darwin； and for progress； the question came to the attention of the greatlord kelvin （who； though indubitably great； was then still just plain william thomson； hewouldn鈥檛 be elevated to the peerage until 1892； when he was sixty…eight years old and nearingthe end of his career； but i shall follow the convention here of using the name retroactively）。
kelvin was one of the most extraordinary figures of the nineteenth century鈥攊ndeed of anycentury。 the german scientist hermann von helmholtz； no intellectual slouch himself； wrotethat kelvin had by far the greatest 鈥渋ntelligence and lucidity； and mobility of thought鈥潯f anyman he had ever met。 鈥渋 felt quite wooden beside him sometimes；鈥潯e added； a bit dejectedly。
the sentiment is understandable； for kelvin really was a kind of victorian superman。 hewas born in 1824 in belfast； the son of a professor of mathematics at the royal academicalinstitution who soon after transferred to glasgow。 there kelvin proved himself such aprodigy that he was admitted to glasgow university at the exceedingly tender age of ten。 bythe time he had reached his early twenties； he had studied at institutions in london and paris；graduated from cambridge （where he won the university鈥檚 top prizes for rowing andmathematics； and somehow found time to launch a musical society as well）； been elected afellow of peterhouse； and written （in french and english） a dozen papers in pure and appliedmathematics of such dazzling originality that he had to publish them anonymously for fear ofembarrassing his superiors。 at the age of twenty…two he returned to glasgow university totake up a professorship in natural philosophy； a position he would hold for the next fifty…threeyears。
in the course of a long career （he lived till 1907 and the age of eighty…three）； he wrote 661papers； accumulated 69 patents （from which he grew abundantly wealthy）； and gained renownin nearly every branch of the physical sciences。 among much else； he suggested the methodthat led directly to the invention of refrigeration； devised the scale of absolute temperaturethat still bears his name； invented the boosting devices that allowed telegrams to be sentacross oceans； and made innumerable improvements to shipping and navigation； from theinvention of a popular marine pass to the creation of the first depth sounder。 and thosewere merely his practical achievements。
his theoretical work； in electromagnetism； thermodynamics； and the wave theory of light；was equally revolutionary。
4he had really only one flaw and that was an inability to calculatethe correct age of the earth。 the question occupied much of the second half of his career； buthe never came anywhere near getting it right。 his first effort； in 1862 for an article in apopular magazine called macmillan鈥檚 ； suggested that the earth was 98 million years old； butcautiously allowed that the figure could be as low as 20 million years or as high as 400million。 with remarkable prudence he acknowledged that his calculations could be wrong if4in particular he elaborated the second law of thermodynamics。 a discussion of these laws would be a book initself； but i offer here this crisp summation by the chemist p。 w atkins； just to provide a sense of them： 〃thereare four laws。 the third of them； the second law； was recognized first； the first； the zeroth law； wasformulated last； the first law was second； the third law might not even be a law in the same sense as theothers。〃 in briefest terms； the second la states that a little energy is always wasted。 you cant have a perpetualmotion device because no matter how efficient； it will always lose energy and eventually run down。 the first lawsays that you cant create energy and the third that you cant reduce temperatures to absolute zero； there willalways be some residual warmth。 as dennis overbye notes； the three principal laws are sometimes expressedjocularly as （1） you cant win； （2） you cant break even； and （3） you cant get out of the game。
鈥渟ources now unknown to us are prepared in the great storehouse of creation鈥濃�攂ut it wasclear that he thought that unlikely。
with the passage of time kelvin would bee more forthright in his assertions and lesscorrect。 he continually revised his estimates downward； from a maximum of 400 millionyears； to 100 million years； to 50 million years； and finally； in 1897； to a mere 24 millionyears。 kelvin wasn鈥檛 being willful。 it was simply that there was nothing in physics that couldexplain how a body the size of the sun could burn continuously for more th