The Collaborative International Dictionary of English v.0.48:

Napierian \Na*pie"ri*an\, Naperian \Na*pe"ri*an\,, a.
   Of, pertaining to, or discovered by, Napier, or Naper.
   [1913 Webster]

   Naperian logarithms. See under Logarithms.
      [1913 Webster] Napier's bones