caliper vs gradate

caliper

verb
  • To use calipers to measure the size of. 

noun
  • The part of a disc brake that holds the brake pads. 

gradate

verb
  • To bring to a certain strength or grade of concentration. 

  • To change imperceptibly from one gradation of tone etc. to another. 

  • To arrange in order of grades. 

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