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,
Weight training be performed while sitting or lying on an exercise ball. There are a number of weight machines that are commonly found in neighborhood gyms. The Smith machine is a barbell that is constrained to vertical movement. The cable machine consists of two weight stacks separated by 2.5 metres, with cables running through adjustable pulleys (that can be fixed at any height so as to select different amounts of weight) to various types of handles. There are also exercise-specific weight machines such as the leg press. A multigym includes a variety of exercise-specific mechanisms in one apparatus. One limitation of many