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,
Great Recoinage of 1816 shillings weighing 87.2727 grains (or 5.655 grams), half-crowns of 218.1818 grains (14.138 grams) and crowns of 436.3636 grains (28.276 grams). Over the many reigns until decimalisation other denominations came and went, such as the threepence, sixpence, florin, and double florin, always weighing exactly one troy pound per 66 shillings (irrespective of fineness, which was reduced to 50% in 1920, and to 0% in 1947). This made 5 sterling silver shillings (which is 1 crown), about the weight of .9091 troy ounce of sterling silver. Great Recoinage of 1816 The Great Recoinage of 1816 was an attempt by the British Government