The situation and the question can be easily presented to the mind by considering the significant lines as lines of a right-angled triangle; the vein descending on its dip being the hypothenuse, the tunnel the base line, and the boundary between the two claims the side line of the triangle. The St. Louis company, being the owner of the vein, may pursue and appropriate that vein on its course downward, although it extends outside the vertical side lines of its claim and beneath the surface of the Nine Hour lode claim. Such is the plain language of § 2322, Rev. Stat. (U.S.C.omp. Stat. 1901, p. 1425) which grants to locators 'the exclusive right of possession and enjoyment of all the surface included within the lines of their locations, and of all veins, lodes, and ledges throughout their entire depth, the top or apex of which lies inside of such surface lines extended downward vertically, although such veins, lodes, or ledges may so far depart from a perpendicular in their course downward as to extend outside the vertical side lines of such surface locations.'

In other words, it has a right to the hypothenuse of the triangle. May it also occupy and use the base line? Is it, in pursuing and appropriating this vein, confined to work in or upon the vein, or is it at liberty to enter upon and appropriate other portions of the Nine Hour ground in order that it may more conveniently reach and work the vein which it owns? Its contention is that the mining patent conveys title to only the surface of the ground and the veins which go with the claim, and that the balance of the underground territory is open to anyone seeking to explore for mineral, or at least may be taken possession of by one other than the owner of the claim for the purpose of conveniently working a vein which belongs to him. The question may be stated in another form: Does the patent for a lode claim take the subsurface as well as the surface, and is there any other right to disturb the subsurface than that given to the owner of a vein apexing without its surface, but descending on its dip into the subsurface, to pursue and develop that vein?

St. Louis Mining & Milling Company of Montana v. Montana Mining Company/Opinion of the Court

We are of opinion that the patent conveys the subsurface as well as the surface, and that, so far as this case discloses, the only limitation on the exclusive title thus conveyed is the right given to pursue a vein which on its dip enters the subsurface. By § 2319, Rev. Stat. (U.S.C.omp. Stat. 1901, p. 1424) 'all valuable mineral deposits in lands belonging to the United States' are 'open to exploration and purchase, and the lands in which they are found to occupation and purchase.' By § 2325 (U.S.C.omp. Stat. 1901, p. 1429) 'a patent for any land claimed and located for valuable deposits may be obtained in the following manner: Any person . . . having claimed and located a piece of land for such purposes . . . shall thereupon be entitled to a patent for the land.' In a subsequent part of the same section it is provided that the applicant shall pay $5 per acre. Appellants rely upon the clause heretofore quoted from § 2322 as a limitation upon the full extent of the grant indicated by these provisions. But this limitation operates only indirectly and by virtue of the grant to another locator to pursue a vein apexing within his surface boundaries on its dip downward through some side line into the ground embraced within the patent. It withdraws from the grant made by the patent only such veins as others own and have a right to pursue. As said by Lindley (1 Lindley, Mines, 2d ed. § 71):

St. Louis Mining & Milling Company of Montana v. Montana Mining Company/Opinion of the Court

'In other words, under the old law he located the lode. Under the new, he must locate a piece of land containing the top, or apex, of the lode. While the vein is still the principal thing, in that it is for the sake of the vein that the location is made, the location must be of a piece of land including the top, or apex of the vein.'

St. Louis Mining & Milling Company of Montana v. Montana Mining Company/Opinion of the Court

'Prima facie, such a patent confers the right to everything found within vertical planes drawn through the surface boundaries; but these boundaries may be invaded by an outside lode locator holding the apex of a vein under a regular valid location, in the pursuit of his vein on its downward course underneath the patented surface.'

See also Calhoun Gold Min. Co. v. Ajax Gold Min. Co. 182 U.S. 499, 508, 45 L. ed. 1200, 1206, 21 Sup. Ct. Rep. 885. The decisions of the courts in the mining regions are referred to in the opinion of the court of appeals in this case, from which we quote: