Duncan and Sons Cryptic Zipper Block EAPG Circa 1880's

Love this pair of Early American Pattern Glass by George Duncan and Sons Pittsburgh. The pattern was made during the late 1880's. I obtained the first one at an estate sale and the lady indicated that she thought it was depression era. I obtained the second one at an auction and the auctioneer actually identified it right and said he believed it to be this, but still got it for $10.00. Both are in excellent condition. This pattern is also known as Iowa and Nova Scotia Ribbon and Star. Excellent but difficult to collect EAPG pattern.