lever vs slough shark

lever

noun
  • A levee. 

  • A bar, as a capstan bar, applied to a rotatory piece to turn it. 

  • An arm on a rock shaft, to give motion to the shaft or to obtain motion from it. 

  • A rigid piece which is capable of turning about one point, or axis (the fulcrum), and in which are two or more other points where forces are applied; — used for transmitting and modifying force and motion. 

  • A small such piece to trigger or control a mechanical device (like a button). 

  • Specifically, a bar of metal, wood or other rigid substance, used to exert a pressure, or sustain a weight, at one point of its length, by receiving a force or power at a second, and turning at a third on a fixed point called a fulcrum. It is usually named as the first of the six mechanical powers, and is of three kinds, according as either the fulcrum F, the weight W, or the power P, respectively, is situated between the other two, as in the figures. 

verb
  • To use, operate or move (something) like a lever (physically). 

  • To move with a lever. 

  • To increase the share of debt in the capitalization of a business. 

  • To use (something) like a lever (in an abstract sense). 

slough shark

noun
  • northern pike 

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