Rubuta ci gaba ga wannan sakin layi - likitan Burtaniya John Snow yayi amfani da zane-zane mai kama da Voronoi a cikin 1854 don nuna yadda yawancin mutanen da suka mutu a cikin annobar cutar kwalara ta Broad Street
ya zauna kusa da bututun ruwan Broad Street da ke dauke da cutar fiye da duk wani bututun ruwa.