Kammala wannan jumla: Likitan Burtaniya John Snow ya yi amfani da zane-zane mai kama da Voronoi a 1854 don nuna yadda yawancin mutanen da suka mutu a cikin
Cutar cutar kwalara ta Broad Street ta rayu kusa da famfon Broad Street da ke dauke da cutar fiye da kowane famfon ruwa.