(after stating the facts). 1. The libel exhibits this theory of recovery: Defendant, though an instrumentality of the state, could not lawfully alter the course of the river without the consent of the Secretary of War. In obtaining that consent defendant made a promise, which inured to the benefit of libelants, that it would pay' all damages occasioned by the change. The change created a current which naturally would (and in libelants’ case actually did) require more time and more expense in moving barges than formerly. Therefore defendant must pay. The permit does not contain a promise by defendant to pay damages caused by the change. The third condition, which is relied on, obliges defendant to “assume all responsibility for damages” by reason of the introduction of a current in the river. This was an indemnifying contract, purely between the parties, and not an undertaking by defendant to pay to outsiders damages for which otherwise they would have no cause of action. Defendant’s obligation was to pay or fight all claims for damages on account of the current and save the federal government harmless. No elaboration, we believe, can make this conclusion more apparent than does a mere reading of the permit.
2. In argument at the bar libelants urged that defendant should be held liable on account of the rate of the current on October 4, 1900. Some of many reasons for denying the contention are these:
(1) It is outside of the scope of the libél. No averment respecting rate of current was made. Liability was predicated on the introduction of a current (any current) that would render navigation more difficult and expensive than it was previously.
(2) The grant of permission was not conditioned .upon defendant’s keeping within a stated maximum. The second condition indicates the secretary’s intention to observe the effect of defendant’s canal operations, and thereafter, if he should deem it necessary in behalf of the public interests committed to his care, to regulate the rate and volume of the current.
(3) In the grant of permission no reference to rate is found. The only reference is in the second clause of. the preamble to the grant. But a preamble cannot be resorted to- except to help solve an am*856biguity in the body of the grant or enactment. The grant here is unambiguous.
(4) But, if the-preamble be taken up, the reference to rate is found to be in a recital of defendant’s purpose in asking an earlier grant of permission to correct and regulate the cross-section of the river. ' Observe that defendant asked leave to do a certain thing to accomplish a certain result. Certainly defendant thereby neither bourfd itself to do the work, nor guarantied the resulting rate, nor covenanted to remove the abutments and piers of bridges which it had no right to touch.
' (5) Defendant’s evidence, by engineer’s measurements, showed* an average velocity of- a mile and an eighth an hour, and that on October 4, 1900, no unusual current prevailed. Libelants’ witnesses observed the effect of the current upon the movement of the barge, and estimated the velocity at three miles an hour between bridge's and four miles in the draws. Even at the places where defendant was at liberty to correct and regulate the cross-' section, it was not undertaking to secure a limit of a mile and a quarter an hour when 600 or 700 square feet of the cross-section' tvas taken up by the barge Algeria.
3. Libelants have taken the further position here that the part of section 10 (Act March 3, 1899, c. 425, 30 Stat. 1151 [U. S. Comp. St. 1901, p. 3541]), which purports to authorize the Secretary of War to issue permits is unconstitutional as being a delegation of legislative power; that by reason of appropriations made from 1892 on, and by reason of the inhibitory portion of section 10, the federal government had taken exclusive control of the river, and defendant had no power to modify the volume and current; and that the defendant must therefore be made to respond.
(1) This theory of liability is not merely outside of, it is repugnant to, the scope of the libel. Libelants came into court asserting the legality of the permit, and a legal right in themselves to recover on the strength of defendant’s assumption of responsibility in the third condition. Even if we perceived any merit in the present contention, we should not be warranted in giving libelants a decree on a matter concerning which there is no issue of fact or of law in the pleadings, thus rewarding them for disavowing their libel.
(2) The federal government’s expenditure of money for the improvement of the river did not evidence an intent on its part to exclude the state from all dominion and control over this waterway which lies wholly within the state. Willamette Iron Bridge Co. v. Hatch, 125 U. S. 13, 8 Sup. Ct. 811, 31 L. Ed. 629; Cummings v. Chicago, 188 U. S. 410, 23 Sup. Ct. 472, 47 L. Ed. 525.
(3) A decision of the question whether legislative poAver was delegated to the secretary (see Field v. Clark, 143 U. S. 649, 12 Sup. Ct. 495, 36 L. Ed. 294; Buttfield v. Stranahan, 192 U. S. 470, 24 Sup. Ct. 349, 48 L. Ed. 525) is unnecessary, for the reason that libelants are in error in assuming that section 10, thus emasculated, would remain ' in force. Congress, acting under the commerce clause, said to Illinois, which would otherwise be sovereign, “You *857are not to change the course of the river unless you first obtain the secretary’s approval of your plan.” The sentence in its entirety—the subjunctive clause as well as the indicative—expressed the will of Congress. The expressed intention was, not to exclude Illinois utterly from exercising her police powers over the river for the welfare of her citizens (and that suggests a nice and delicate question), but to permit the,continuation of the exercise upon condition. Now, if the conditional clause is to be deleted, it is not for the courts to construct a new congressional policy out of the fragment. Compare Montgomery v. Portland, 190 U. S. 105, 23 Sup. Ct. 735, 47 L. Ed. 965.
(4) If section 10 stands, libelants’ attack fails, because defendant obtained the permit and complied with its conditions. If section 10 falls, what is the result? If a matter affecting commerce is of national scope and susceptible of uniform regulation, the failure of Congress to speak to the subject is deemed equivalent to a declaration that the states shall let the matter alone; but if the matter is local, and concerns the public policy of a state, though it may incidentally affect interstate and foreign commerce, congressional inaction is a recognition that the subject is fitter for local regulation, and is an invitation that the state continue in the unimpeded exercise of its police powers, on the understanding, however, that Congress may thereafter intervene to the extent, at least, of destroying and forbidding whatever unnecessarily embarrasses commerce. Covington Bridge Co. v. Kentucky, 154 U. S. 204, 14 Sup. Ct. 1087, 38 L. Ed. 962; Lake Shore, etc., Ry. Co. v. Ohio, 173 U. S. 285, 19 Sup. Ct. 465, 43 L. Ed. 702, and cases therein cited. The bridging, dredging, purification of a navigable water-way wholly within a state are matters of the latter class. Escanaba Transp. Co. v. Chicago, 107 U. S. 678, 2 Sup. Ct. 185, 27 L. Ed. 442; Lake Shore, etc., Ry. Co. v. Ohio, 165 U. S. 365, 17 Sup. Ct. 357, 41 L. Ed. 747. With the commerce clause in abeyance, Illinois, as to every being in the world except future Congresses, was absolute sovereign in the premises. The absolute sovereign may change the grade of highways or may vacate them, may. alter the courses and currents of rivers or may dam or fill them up, and neither alien nor subject traveler and navigator may complain. No one can claim a vested right to have the United States interfere with Illinois, nor can a cause of action arise from want of interference.
The decree is affirmed.