The Collaborative International Dictionary of English v.0.48:

Stadimeter \Sta*dim"e*ter\ (st[.a]*d[i^]m"[-e]*t[~e]r), n.
   [Stadium + -meter.]
   A horizontal graduated bar mounted on a staff, used as a
   stadium, or telemeter, for measuring distances.
   [1913 Webster] Stadia hairs