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The Collaborative International Dictionary
Stadia hairs

Stadia hairs \Sta"di*a hairs\ or Stadia wires \Sta"di*a wires\ (st[=a]"d[i^]*[.a] h[^a]rz). (Surv.) In a theodolite, etc., horizontal cross wires or hairs equidistant from the central horizontal cross wire.