digital watch vs sundial

digital watch

noun
  • A watch, usually electronic, that displays time in the form of numbers, rather than by a dial and hands. 

sundial

noun
  • A device measuring the time of day by the position of a shadow cast by a pole or plate (gnomon) upon an engraved series of marks. 

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