knout vs nagaika

knout

noun
  • A leather scourge (multi-tail whip), in the severe version known as 'great knout' with metal weights on each tongue, notoriously used in imperial Russia. 

verb
  • To flog or beat with a knout. 

nagaika

noun
  • A short, thick braided whip with a round cross-section, used by the Cossacks. 

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