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,
How Many More Times Wolf's "How Many More Years" (1951), as well as other songs by blues musicians he admired at the time of recording. In 1970, "How Many More Times" was dropped from Led Zeppelin's typical setlist, although they continued to perform it on occasion until the early stages of their 1975 North American tour, when it was re-introduced in full as a result of Jimmy Page's injured finger, which temporarily prevented him from playing the more challenging "Dazed and Confused". In a contemporary review for "Led Zeppelin" on release, John Mendelsohn of "Rolling Stone" called "How Many More Times" as the album's