castell, v. — Green’s Dictionary of Slang

castell v.

[? SE castle, from the battlements of which one can get a long-range view]

(UK Und.) to look, to see.

1610

Rowlands Martin Mark-all 41: To tower or Castell to see. [Ibid.] 43: O ben mort Castle out & Towre, / Where all the Roome coues slopne that we may tip the lowre.