comparator vs dial gauge

comparator

noun
  • Any device for comparing a physical property of two objects, or an object with a standard. 

  • An application or program that compares prices, rates, tariffs of flights, smartphones, cars, etc. 

  • anything that serves comparison 

  • An electronic device that compares two voltages, currents or streams of data. 

dial gauge

noun
  • Any device for comparing a physical property of two objects, or an object with a standard. 

How often have the words comparator and dial gauge occurred in a corpus of books? (source: Google Ngram Viewer )