64. An illustration of the constitutional use of the power of the State over commerce is afforded by the tax, in Texas, on telegraph messages sent from one place to another exclusively within the State, by private parties, and not by the agents of the government of the United States. The Texas law imposing this tax is not in conflict with the power of Congress to regulate commerce,[166] and therefore was not repugnant to the Constitution of the United States. The line of demarcation as to exercise of the police power by a State is drawn “by the undoubted right of the States of the Union to control their purely internal affairs, in doing which they exercise powers not surrendered to the general government.”[167] Many State laws regulating its administration of internal affairs are applications of its police power. The police power of the State is of right, and is founded on “the sacred law of self-defense.”[168] But this sacred law applies strictly to the domain of the State—to its own jurisdiction. “It cannot invade the domain of the national government.”[169] A State inspection law is a familiar example of the exercise of its police power, but such a law, working obstruction of interstate commerce, or any limitation of it, though such effect be only incidental, is repugnant to the Constitution.[170] Such repugnancy is effected by a State law levying a tax on tonnage, and is void.[171] But a charge for mooring or landing at a wharf, is not a tax on tonnage, but a charge for services rendered;[172] neither is the tax a tonnage tax when the State imposes a tax on vessels (even if regularly engaged in interstate commerce), the property of persons residing within the jurisdiction of the State, the vessels themselves being part of the mass of property within the State, being moored for long periods at the wharf for repairs and being under the protection of the State. The taxing power is a distinct and separate power from the power to regulate commerce. The right of taxation in a State remains over every subject where it existed before the adoption of the Constitution with the exception only of prohibitions expressed or implied in the Constitution. The sovereign jurisdiction of the State is not limited; within that jurisdiction it is free to tax. But the powers to tax and to prohibit taxation are given in the Constitution by separate clauses, and these powers are separate and distinct from the power to regulate commerce. From this it follows that the enrolment of a ship or vessel in interstate commerce does not exempt its owner from taxation for his interest in it as property, upon a valuation by State law, as in the case of other personal property.[173]