Watt within the then-existing system of practical units as "the power conveyed by a current of an Ampère through the difference of potential of a Volt." In October 1908, at the International Conference on Electric Units and Standards in London, so-called "international" definitions were established for practical electrical units. Siemens' definition was adopted as the "international" watt. (Also used: 1 ampere x 1 ohm.) The watt was defined as equal to 10 units of power in the "practical system" of units. The "international units" were dominant from 1909 until 1948. After the 9th General Conference on Weights and Measures in 1948,
Introduction to the metric system The result is that there are a variety of different named units available to measure the same quantity (for example 10 millimetres = 1 centimetre, 100 centimetres = 1 metre, 1000 metres = 1 kilometre). Each unit and each prefix has a standard symbol (not abbreviation) associated with it. In 1861, during discussions about standardising electrical units of measure, Charles Bright and Latimer Clark proposed that these units be named, not in relation to what they are used for, or common objects, but after eminent scientists; with the electrical units of resistance, potential difference and capacitance being named the ohm,