▁port ra its ▁by ▁Kn eller , ▁which ▁suggests ▁he ▁may ▁have ▁been ▁a ▁pup il ▁of ▁that ▁artist . ▁He ▁died ▁at ▁Oxford ▁in ▁ 1 7 2 0 . ▁ ▁The ▁Philip ▁M ould ▁gallery ▁in ▁London ▁states : ▁" To o ▁little ▁is ▁known ▁of ▁By ng ' s ▁work ▁as ▁studio ▁assistant ▁to ▁Sir ▁God f rey ▁Kn eller ▁in ▁his ▁last ▁years , ▁and ▁too ▁much ▁ind ifferent ▁work ▁is ▁attributed ▁to ▁him ▁on ▁the ▁basis ▁purely ▁of ▁convenience ". ▁ ▁External ▁links ▁ ▁References ▁ ▁Category : 1 7 2 0 ▁death s ▁Category : 1 6 6 6 ▁birth s <0x0A> </s> ▁The ▁Vector ▁Map ▁( V MAP ), ▁also ▁called ▁Vector ▁Sm art ▁Map , ▁is ▁a ▁vector - based ▁collection ▁of ▁ge ographic ▁information ▁system ▁( G IS ) ▁data ▁about ▁Earth ▁at ▁various ▁levels ▁of ▁detail . ▁Level ▁ 0 ▁( low ▁resolution ) ▁coverage ▁is ▁global ▁and ▁entirely ▁in ▁the ▁public ▁domain . ▁Level ▁ 1 ▁( global ▁coverage ▁at ▁medium ▁resolution ) ▁is ▁only ▁partly ▁in ▁the ▁public ▁domain . ▁ ▁Description ▁Co ordinate ▁reference ▁system : ▁Geographic ▁coordinates ▁stored ▁in ▁decimal ▁degrees ▁with ▁southern ▁and ▁western ▁hem is pher es ▁using ▁negative ▁values ▁for ▁latitude ▁and ▁longitude , ▁respectively . ▁Hor izontal ▁Dat um : ▁World ▁Ge od etic ▁System ▁ 1 9 8 4 ▁( W GS ▁ 8 4 ). ▁Vert ical ▁Dat um : ▁Mean ▁Sea ▁Level . ▁ ▁Th ematic ▁data ▁layers ▁Fe atures ▁and ▁data