be at the head of vs operate

be at the head of

operate

verb
  • To deal in stocks or any commodity with a view to speculative profits. 

  • To perform some manual act upon a human body in a methodical manner, and usually with instruments, with a view to restore soundness or health, as in amputation, lithotomy, etc. 

  • To act or produce effect on the mind; to exert moral power or influence. 

  • To perform a work or labour; to exert power or strength, physical or mechanical; to act. 

  • To produce, as an effect; to cause. 

  • To produce an appropriate physical effect; to issue in the result designed by nature; especially (medicine) to take appropriate effect on the human system. 

  • To put into, or to continue in, operation or activity; to work. 

How often have the words be at the head of and operate occurred in a corpus of books? (source: Google Ngram Viewer )