The Collaborative International Dictionary of English v.0.48:

Espial \Es*pi"al\, n. [OE. & Norm. F. espiaille. See Espy.]
   1. The act of espying; notice; discovery.
      [1913 Webster]

            Screened from espial by the jutting cape. --Byron.
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   2. One who espies; a spy; a scout. [Obs.] "Their espials . .
      . brought word." --Holland.
      [1913 Webster]

WordNet (r) 3.0 (2006):

espial
    n 1: the act of detecting something; catching sight of something
         [syn: detection, catching, espial, spying,
         spotting]