▁this ▁field ▁for ▁his ▁pl ating ▁research ▁regarding ▁the ▁New ▁York ▁Post master ' s ▁Pro vis ional , ▁the ▁nation ' s ▁first ▁prov is ional ▁stamp ▁to ▁be ▁issued ▁by ▁a ▁local ▁post ▁office ▁in ▁response ▁to ▁the ▁con gression al ▁postal ▁reform ▁act ▁in ▁ 1 8 4 5 . ▁He ▁took ▁a ▁particular ▁interest ▁in ▁the ▁" 5 c ▁New ▁York s ", ▁and ▁was ▁the ▁first ▁person ▁in ▁the ▁field ▁to ▁as certain ▁that ▁the ▁st amps ▁were ▁printed ▁using ▁a ▁plate ▁of ▁forty ▁positions ; ▁by ▁borrow ing ▁deal ers ' ▁stock s ▁of ▁the ▁stamp ▁and ▁the ▁collections ▁of ▁Henry ▁Need ham , ▁Congress man ▁Ernest ▁A ck erman , ▁and ▁Alfred ▁H . ▁C asp ary , ▁and ▁en larg ing ▁photograph s ▁of ▁all ▁the ▁horizontal ▁and ▁vertical ▁pairs , ▁he ▁was ▁ultimately ▁able ▁to ▁find ▁enough ▁over la pping ▁pairs ▁to ▁prove ▁that ▁there ▁had ▁been ▁ 4 0 ▁st amps ▁to ▁a ▁sheet . ▁Prior ▁to ▁his ▁work ▁on ▁the ▁subject , ▁collect ors ▁first ▁thought ▁the ▁plate ▁had ▁ 1 0 0 ▁subjects , ▁and ▁then ▁exper ts ▁had ▁decided ▁there ▁must ▁have ▁been ▁ 5 0 ▁st amps ▁to ▁a ▁sheet ; ▁Hat field ' s ▁efforts ▁proved ▁that ▁the ▁sheets ▁had ▁actually ▁consisted ▁of ▁eight ▁horizontal ▁rows ▁of ▁five . ▁Hat field ▁wrote ▁The ▁New ▁York ▁Post master ' s ▁St amp , ▁which ▁was ▁published ▁in ▁ 1 9 2 1 ▁by ▁the ▁Scott ▁St amp ▁and ▁Co