(765 ILCS 230/1) (from Ch. 1, par. 3501)
    Sec. 1. That any person employed under and by virtue of an act of congress of the United States, approved the tenth day of February, one thousand eight hundred and seven, and of the supplements thereto, for the survey of the coasts of the United States, or under the direction of congress, to form a geodetic connection between the Atlantic and Pacific coasts, and to furnish triangulation points for state surveys, may enter upon lands within this state for the purpose of exploring, triangulating, leveling, surveying, and of doing any other act which may be necessary to carry out the object of said laws, and may erect any works, stations, buildings, and appendages requisite for that purpose, doing no unnecessary injury thereby.
(Source: Laws 1881, p. 154.)