Thirdly, twonervesalsoorappendagesofthebrain, fortheydonotgobeyondthelimitsoftheskull, aremovedbytheparticlesofterrestrialbodies, separatedandflyingintheair, notindeedbyallparticlesindifferently, butbythoseonlythataresufficientlysubtleandpenetratingtoentertheporesofthebonewecallthespongy, whendrawnintothenostrils, .
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Fourthly, therearetwonerveswithintheears, soattachedtothreesmallbonesthataremutuallysustaining, andthefirstofwhichrestsonthesmallmembranethatcoversthecavitywecallthetympanumoftheear, thatallthediversevibrationswhichthesurroundingaircommunicatestothismembranearetransmittedtothemindbythesenerves, andthesevibrationsgiverise, accordingtotheirdiversity, tothesensationsofthedifferentsounds.
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Finally, theextremitiesoftheopticnerves, composingthecoatintheeyescalledtheretina, arenotmovedbytheairnorbyanyterrestrialobject, butonlybytheglobulesofthesecondelement, whencewehavethesenseoflightandcolours: asIhavealreadyatsufficientlengthexplainedintheDioptricsandtreatiseofMeteors.[21]
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