Rasmus Bartholin anonyanya kuyeukwa nokuda kwekuwanikwa kwake (1669) kwekuputika kaviri kwechiedza chechiedza neIceland spar (calcite). Akabudisa tsanangudzo yakarurama yechiitiko chacho, asi sezvo chimiro chechiedza chakanga chisinganzwisisiki panguva iyoyo, aisagona kuchitsanangura. Yakanga iri chete pashure pokunge Thomas Young ataura dzidziso yechiedza, c. 1801 kuti tsanangudzo yakave inogoneka. Mubvunzo: Nei Rasmus aisagona kutsanangura chiitiko chacho?
chimiro chomuviri chechiedza chakanga chisinganzwisiswi zvakanaka panguva iyoyo