The Collaborative International Dictionary of English v.0.48:

Locator \Lo"ca*tor\, n.
   One who locates, or is entitled to locate, land or a mining
   claim. [U.S.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

locator
    n 1: a person who fixes the boundaries of land claims [syn:
         locator, locater]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

LOCATOR, civil law. He who leases or lets a thing to hire to another. His
duties are, 1st. To deliver to the hirer the thing hired, that he may use
it. 2d. To guaranty to the hirer the free enjoyment of it. 3d. To keep the
thing hired in good order in such manner that the hirer may enjoy it. 4th.
To warrant that the thing hired has not such defects as to destroy its use.
Poth. Du. Contr. de Louage, n. 53.