blotter vs writing pad

blotter

noun
  • A piece of blotting paper in a pad as a piece of desk furniture. 

  • A register of the related events made in the form of the list of times and brief descriptions. 

  • A daily register of arrests and other events in a police station. 

  • A portion of blotter acid. 

writing pad

noun
  • A collection of blank pages of writing paper, bound together, often with a cardboard cover 

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