pedometer vs speedometer

pedometer

noun
  • A device, often electronic, that measures the number of steps taken, and thus estimates the distance walked. 

speedometer

noun
  • Such a device incorporating an odometer. 

  • An instrument located within the dashboard of a vehicle that measures and indicates the current speed of the vehicle. 

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