baths vs hot spring

baths

noun
  • A building containing a public swimming pool or shower facilities; originally a place having individual cubicles where people without bathrooms could have a bath. 

hot spring

noun
  • A natural spring producing water whose temperature is greater than about 20°C (68°F). 

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