McLeod gauge
（重定向自McLeod gage）
A McLeod gauge is a scientific instrument used to measure very low pressures, down to 10 Torr. It was invented in 1874 by Herbert McLeod (1841–1923). McLeod gauges were once commonly found attached to equipment that operates under vacuum, such as a lyophilizer. Today, however, these gauges have largely been replaced by electronic vacuum gauges.