He uses a paragraph of iron chain and a pair of bases only, measure the circumference that gave the

Face the world below the foot, a lot of people want to know, does it have after all how old? For convenient computation, the scientist differentiated to the earth a lot of warp, join namely the half circular arc with polar north and south, say normally, if know for a time the length of longitudinal correspondence, can the circuit of cipher out earth has how long. ? ? The bosom is putting such dream, june 1633, do one call Richard? The British male youth of Nuo five heart, carried recumbent London tower on the back to begin pedestrian. He used two years of time, walk along York county from London tower, in this process, keep be being measured with chain ah measure. ? ? Friends, this road can not be an even highway, however bank of channel of channel of a lot of bumpy pits. Measure wrong little, that length can be differred old far. Where is result? Nuo five heart finished the job outstandingly, be in repeatedly correctional and after planning to close, he is calculated finally the length that gives every degrees of warp is less than 550 meters difference only with true length, calculate come down the error is less than 1% , we must plaint he exceeds strong measurement ability. ? ? Nevertheless, after brother of Nuo five heart measures computation to give earthly circumference, newton turns cipher out world is not a perfectly round sphere actually, however ellipsoid -- polar a few flatter, equatorial beat a few. Even if is such, the data of Nuo five heart is particularly fierce still, old ox is published later " principle " this book when, mentioned his job technically still. ? ? In one part person busy move measures meridian when, another part person is in the problem of kink is, does the earth have after all multiple? Newton is in " principle " in put forward, one is hanged in the plumb line near big hill, can get the joint action of big hill and earthly gravitation, so a bit deflective. If know this deflective angle, according to the quality of gravitation constant and big hill, with respect to the quality that can promote itself of cipher out earth. Measuring earthly quality on this thing, is we want benedictory Er of the dimension inside British astronomer? Masijilin. ? ? 1761, appeared infrequent Venus transit, but this gauges the rare the main chance that Venus is apart from, a lot of countries send his scientist to world each district to have observation. Masijilin regards England as the member of royal society, was gone to by the clique the Shenghele on Atlantic takes an island. Hereat at the same time, does British land measure a Charles? Mei Sen is gone to by the clique Sumatra island observation, result boat just left port before long, one when sufferred French frigate cruel dozen. This can frighten Mei Sen jump, he hastens British government writes a letter, say to be no good ah the old, we took a beating, cannot see Venus. British government looks, hey leveret whelp, you this was to take Qianbugan thing ah, be no good, you must go! ? ? The home is not answered, sumatra is done not have again by French control the law goes, how to do? Mei Sen is act on one's own, it is good to run hope horn goes seeing Venus transit. But did not think of, good the observation effect how terrible that looks at horn was appeared, he can leave again only go back to the motherland. Artful is, he takes an island through Shenghele during transit, met Masijilin, two people became a good friend very quickly. ? ? Masijilin cooperated for some time with Mei Sen, caught up with the task that measures earthly quality. Masijilin's tentative idea is, look for the hill with an even quality to regard the measurement of gravitation deviation as the object. As a result appropriate hill has not been found, he is troubled by with respect to He Meisen broke, be forced oneself continue to measure. ? ? Final, pitch on of equestrian Si Jilin be located in the Si Xi with Scotland mid upland to breath out Lin Shan. He is heading surveyor spot operation, the basis measures result computation, earthly quality is nine hundred and thirty-seven million four hundred and fifty-nine thousand seven hundred and twelve tons about. Not only such, masijilin still has an additional results: When mapping group is circling hill to be measured everywhere, do one call Charles? He Du's gauger is written the map of full altitude number is so irritated that the map of full altitude number want dead, flat conveniently links the drop of same height into the line, this is today commonly used contour line. ? ? Had earthly quality, had contour line again, studying it seems that is successful, but a person does not think so, does the agreement of Cantabrigian university writing brush? Michelle. Michelle feels, although be in calculative moment, can regard the density of hill as with common stone about the same, reoccupy bulk comes the quality of estimation hill. But the fact is, this quality follows actual number error very big, it comes to reoccupy computational earth quality, final error is bigger. Then, this big ideologist decides to move personally, designed an instrument that measures earthly quality. Regrettablly is, he himself did not live to be the experiment finishs that day, did all his train of thought send another England scientist -- henry? Ka Wendi is made. ? ? A what person is blocking Wen Di to make? Two keywords can generalize: Rich, dissocial, this can say the optimal recipe that is past scientist. In fact, ka Wendi makes the science of lifetime contribute without number: He departed the first times hydrogen, it is hydrogen and oxygen synthesis again water, he also exceeds a person of the same trade on the research of conductivity one big chunk. Nevertheless most the contribution that lets his leave a good name forever, still be the Kawendi that he consults Michelle is designed makes torsion balance, measure the quality that gave the world accurately. Ka Wendi is allowable one year time completes a test, measure an outcome according to his, the earth should have -69312512 tons to weigh. This number follows up to now people uses all sorts of advanced instruments to measure the result look that give to compare, have the error of about 1% only. ? ? Knew earthly size and weight, people had more knowledge to the heavenly body below the foot eventually. Very fast, our scientist begins to be satisfied at no longer " appearance of earthly long what " level, think thorough underground however, clear up " what is the earth " . A new science -- geological, emerge as the times require. Is thinking the face that knows the world and interior what after all? Why to want to know this heavenly body can become today's model? Issueing one concentration, we can follow rocksy one case, know our world further. ? ? Read on the road, your frequency library. Below period program good-bye!