Compass has a half-life of only about 12 years, so a compass that contains 120 mCi of tritium when new will contain only 60 when it is 12 years old, 30 when it is 24 years old, and so on. Consequently, the illumination of the display will fade. Mariners' compasses can have two or more magnets permanently attached to a compass card, which moves freely on a pivot. A "lubber line", which can be a marking on the compass bowl or a small fixed needle, indicates the ship's heading on the compass card. Traditionally the card is divided into thirty-two points
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