Coins of the pound sterling also became known as a "pound". (240 actual pennies, however, weighed only 5400 troy grains, known as tower pound, a unit used only by mints. The tower pound was abolished in the 16th century.) The silver penny remained the primary unit of coinage for about 500 years. The purity of 92.5% silver (i.e., sterling silver) was instituted by Henry II in 1158 with the "Tealby Penny" — a hammered coin. Over the years, the penny was gradually debased until by the 16th century it contained about a third the silver content of a proper troy 24 grain pennyweight. By 1915,
Pennyweight the alternative drams and grains measurement has been used since a new set of scales was purchased by the Egton Bridge Old Gooseberry Society in 1937. As of 2018, the world record for the heaviest gooseberry of 41 dwt 11 gr was held by Kelvin Archer of Cheshire. The most common abbreviation for pennyweight is "dwt"; "d", for the Roman "denarius", was the abbreviation for "penny" before Decimalization of the British monetary system. Alternate abbreviations are "pwt" and "PW". Although the abbreviations are the same, the pennyweight bears no relation to the weight of the American penny nail. That name