HisÂtoÂriÂans have long thought that the decÂiÂmal point first came into use in 1593, when the GerÂman mathÂeÂmatiÂcian ChristoÂpher ClavÂius wrote an astronÂoÂmy text called AstroÂlabiÂum. It turns out, howÂevÂer, that the hisÂtoÂry of the decÂiÂmal point stretchÂes back anothÂer 150 years–to the work of the VenetÂian merÂchant GioÂvanÂni BianÂchiÂni. In his text TabÂuÂlae priÂmi mobilis, writÂten durÂing the 1440s, BianÂchiÂni used the decÂiÂmal point to calÂcuÂlate the coorÂdiÂnates of planÂets. In so doing, he inventÂed a sysÂtem of decÂiÂmal fracÂtions, which, in turn, made the calÂcuÂlaÂtions underÂpinÂning modÂern sciÂence more effiÂcient and less comÂplex, notes SciÂenÂtifÂic AmerÂiÂcan.
Glen Van BrumÂmeÂlen, a hisÂtoÂriÂan of mathÂeÂmatÂics, recentÂly recountÂed to NPR how he disÂcovÂered BianÂchini’s innoÂvaÂtion:
I was workÂing on the manÂuÂscript of this astronomer, GioÂvanÂni BianÂchiÂni. I saw the dots inside of a table — in a numerÂiÂcal table. And when he explained his calÂcuÂlaÂtions, it became clear that what he was doing was exactÂly the same thing as we do with the decÂiÂmal point. And I’m afraid I got rather excitÂed at that point. I grabbed my comÂputÂer, ran up and down the dorm hallÂway lookÂing for colÂleagues who still hadÂn’t gone to bed, sayÂing, this perÂsonÂ’s workÂing with the decÂiÂmal point in the 1440s. I think they probÂaÂbly thought I was crazy.
In a new artiÂcle appearÂing in the jourÂnal HisÂtoÂria MathÂeÂmatÂiÂca, Van BrumÂmeÂlen explains the hisÂtorÂiÂcal sigÂnifÂiÂcance of the decÂiÂmal point, and what this disÂcovÂery means for the hisÂtorÂiÂcal develÂopÂment of mathÂeÂmatÂics. You can read it online.
RelatÂed ConÂtent
TrigonomÂeÂtry DisÂcovÂered on a 3700-Year-Old Ancient BabyÂlonÂian Tablet
How the Ancient Greeks Shaped ModÂern MathÂeÂmatÂics: A Short, AniÂmatÂed IntroÂducÂtion
Love this kind of disÂcovÂery! Kudos to GVB.