Mr. Chief Justice Taft,
after stating the case as above, delivered the opinion of the Court.
Two questions are to be decided in this case. The first is under what appraisement the preferential right conferred on the relator by the second section of the Act of 1918 to purchase the surface previously reserved to it by the Secretary of the Interior, was to be exercised. Should it have been under that of the Act of 1912, or under that ordered by the Secretary after the Act of 1918? The second question is whether the construction necessary to determine the first question is vested by the statute in the legal discretion of the Secretary which it is not within the power of the Supreme Court of the District by mandamus to control.
First. We have no doubt that the appraisement referred to in the second section of the Act of 1918 under which the preferential right was to be exercised was that provided for in the Act of 1912. It will be observed that the Act of 1912 provided for the sale of the surface lands covering the coal and asphalt deposits of the Choctaws and Chickasaws, and elaborate provisions were made for the appraisement of them. A board of appraisers was to be appointed by the President of the United States, regulations were to be made by the Secretary for the appraisement, and minute requirements were set forth in the first section as to the different classes of such surface lands. More than that, six months' time was allowed for it and $50,000 was appropriated out of the treasury of the nations to complete the appraisement and sale. By the second section it was attempted to protect the lessees of the minerals in retaining enough surface land to enjoy their leases by giving them short time options to purchase certain percentages of the whole surface and if they did not purchase, by an agreed reservation without purchase of what the Secretary might deem necessary. The object of this legislation was the ap-praisement, offering, sale and disposition of the surface of the mineral land.' The Act of 1918 was enacted not to sell the surface. That had been all disposed of except these agreed reservations by the Secretary specifically provided for in the Act of 1912. The later act was to sell outright the coal and asphalt deposits, much of which had been leased until 1929, subject to such leases. That was its chief purpose. Everything else was incidental. As part of this chief purpose, it provided elaborately for an appraisement of the mineral deposits, just as the Act of 1912 had provided for the appraisement of the surface land. There is nothing in the Act of 1918 as to the appraisal of the reserved surface land except in the two words italicized in the following paragraph, taken from § 4:
"Any lessee shall have the preferential right, provided the same is exercised within ninety days after the approval of the completion of the appraisement of the minerals as herein provided, to purchase at the appraised value any or all of the surface of the lands lying within such lease held by him and heretofore reserved by order of the Secretary of the Interior."
This paragraph is in the middle of § 4, a section devoted to saving the rights of the lessees of the coal and asphalt deposits from impairment by the sale of such deposits contemplated by the act. It was entirely natural, as such reservation of the surface had been made to preserve the mining opportunities of the lessees under the Act of 1912, that now that it was hoped that the lessees would buy the leased deposits outright under the act, as we may judge from the provision giving them preferential rights to do so contained in the same section, provision should also be made to secure them permanent ownership of that which the Secretary had deemed necessary for their mining under the leases. These privileges extended to the lessees show clearly that this act is in pari materia with all the previous legislation concerning these mineral lands, both as to surface and deposits, and especially with the Act of 1912 as to the surface. This is confirmed by the proviso in § 4 that " nothing herein contained shall be construed as limiting or curtailing the rights of any lessee or owner of mineral deposits from acquiring additional surface lands for mining operations as provided by the Act of Congress of February 19, 1912."
There is nothing in the Act of 1918. expressly or impliedly authorizing the Secretary to order a reappraise ment of the surface land. There is no appropriation for the purpose.
If by the words quoted from § 4 of the act it was intended to authorize a new appraisement of the surface reservations, the language would not have been " the " appraisement but " an " appraisement. The use of the definite article means an appraisement specifically provided for. Such an appraisement of the minerals was provided for in the Act of 1918 and this is mentioned in the same sentence in which " the appraisement " of the surface land is referred to. Construing the Acts of 1912 and 1918 together, the appraisement can only refer to that so elaborately provided for in 1912.
Second. We think that the preferential right of relator conferred by § 4 of the Act of 1918 was not to be left to the legal discretion of the Secretary in the construction of that act. There are no words to qualify that which the lessee has as a right granted by the statute, or to vest in the Secretary the final discretion to determine or define that right.
Section 7 of the Act of 1918 provides that when the full purchase price for any property sold hereunder is paid, the chief executives of the two tribes shall execute and deliver, with the approval of the Secretary of the Interior, to each purchaser an appropriate patent conveying to the purchaser the property so sold. This is language of command, and brings the case within Lane v. Hoglund, 244 U. S. 174, and the many cases cited there, and in which this Court quotes from its opinion in Roberts v. United States, 176 U. S. 221, 231, as follows:
" Every statute to some extent requires construction by the public officer whose duties may be defined therein. Such officer must read the law, and he must therefore, in a certain sense, construe it, in order to form a judgment from its language what duty he is directed by the statute to perform. But that does not necessarily and in all cases make the duty of the officer anything other than a purely ministerial one. If the law direct him to perform an act in regard to which no discretion is committed to him, and which, upon the facts existing, he is bound to perform, then that act is ministerial, although depending upon a statute which requires, in some degree, a construction of its language by the officer." See also Work v. United States ex rel. Mosier, 261 U. S. 352.
The decree of the Court of Appeals of the District of Columbia is
Affirmed.