A taximeter is a mechanical or electronic device installed in taxicabs which calculates passenger fares based on a combination of distance travelled and waiting time. The taximeter was invented by German Wilhelm Bruhn in 1891, and the Daimler Victoria --the world's first meter-equipped (and gasoline-powered) taxicab--was built by Gottfried Daimler in 1897. Taximeters work much like an odometer, by measuring wheel revolutions; they usually also have a timer, however, to calculate additional fare when a taxi is sitting still but carrying a passenger, or, at the request of the passenger, waiting for him or her. Taximeters were originally mechanical and mounted outside the cab, above the driver's side front wheel. Meters were soon relocated inside the taxi, and in the 1980s, electronic meters were introduced, doing away with the once-familiar tick-tick-ticking sound of the meter's timing mechanism.