The doctrine laid down generally in the third and fourth articles, and exemplified specially in the fifth, amounts to this: "The vessels of the most favored nations coming from foreign ports are exempted from the duty of 100 sols; therefore you are exempted from it by the third and fourth articles. The vessels of the most favored nations coming coastwise pay that duty; therefore you are to pay it by the third and fourth articles. We shall not think it unfriendly in you to lay a like duty on coasters, because it will be no more than we have done ourselves. You are free also to lay that or any other duty on vessels coming from foreign ports, provided they apply to all other nations, even the most favored. We are free to do the same under the same restriction. Our exempting you from a duty which the most favored nations do not pay does not exempt you from one which they do pay." In this view, it is evident that the fifth article neither enlarges nor abridges the stipulations of the third and fourth. The effect of the treaty would have been precisely the same had it been omitted altogether; consequently it may be truly said that the reservation by the United States in this article is completely useless. And it may be added with equal truth that the equivalent reservation by France is completely useless, as well as her previous abandonment of the same duty, and, in short, the whole article. Each party, then, remains free to raise or lower its tonnage, provided the change operates on all nations, even the most favored. Without undertaking to affirm, we may obviously conjecture that this article has been inserted on the part of the United States from an overcaution to guard, _nommément, by name_, against a particular aggrievance, which they thought they could never be too well secured against; and that has happened which generally happens--doubts have been produced by the too great number of words used to prevent doubt. II. The Court of France, however, understands this article as intended to introduce something to which the preceding articles had not reached, and not merely as an application of them to a particular case. Their opinion seems to be founded on the general rule in the construction of instruments, to leave no words merely useless for which any rational meaning can be found. They say that the reservation by the United States of a right to lay a duty equivalent to that of the 100 sols, reserved by France, would have been completely useless if they were left free by the preceding articles to lay a tonnage to any extent whatever; consequently, that the reservation of a part proves a relinquishment of the residue.