§7. The navigation laws also provide for the safety of passengers and the crews of vessels, limiting the number of passengers on passenger vessels, and prescribing the quantity of water and certain kinds of provisions which merchant vessels are required to have for each person on board. They also declare what persons may be employed on board, and how funds shall be provided for sick and disabled seamen. §8. Under the power to regulate commerce, congress has also passed laws relating to quarantines. The word _quarantine_, from the Latin _quarantina_, signifies the space of forty days. Originally vessels suspected of having contagious sickness on board, or of being infected with malignant, contagious disease, were forbidden, for forty days, to have intercourse with the place or port at which they arrived. The period for which ships are now detained is not defined, but is fixed by the proper officers at their discretion, according to circumstances. Quarantines are required by the health laws of the states; and by the laws of congress, vessels are to be subject to the health laws of the state at whose ports they arrive. §9. In connection with the power to regulate foreign commerce, power is given to regulate "commerce among the several states," or _internal_ commerce. We have noticed the difficulties which attended the different commercial regulations of the states, and the necessity of a uniform system, which could be had only by giving congress alone the power to regulate commerce. (Chap. XXXI., §7.) Without the power to regulate _internal_ commerce, congress could not give effect to the power to regulate foreign commerce. One state might impose unjust and oppressive duties upon goods imported or exported through it by another state. But in the hands of congress, the power to regulate internal as well as foreign commerce, secures to all the states the benefits of a free and uninterrupted trade. §10. In granting to congress the power to regulate commerce "with the Indian tribes," it was intended to lessen the dangers of war. Murders and war had been provoked by the improper conduct of some of the states. It was believed, that, by a uniform policy, difficulties would be more likely to be prevented; and that if they should occur, they would be more likely to be amicably settled by the general government than by a state, which, being an interested party, would be more liable to misjudge the matter in dispute, and more rigid in demanding satisfaction for injuries, as well as more severe in redressing them. Chapter XXXIV. Powers of Congress in relation to Naturalization; Bankruptcy; Coining Money; Weights and Measures; Punishment of Counterfeiting.