1. The obligation of opening the railways to the traffic of all nations (Art. 16, § 1), and the inviolability at all times of the lines thus opened to the trade of all nations (Art. 25, § 1). 2. The obligation to refrain from any excessive railway rates, that is to say, “not calculated on the cost of construction, maintenance and management, and on the profits due to the promoters.” The Berlin Act states but these general principles, its object being to give the basis of calculation rather than a detailed solution of the problem, since it does not draw up a schedule of rates with respect to the nature of goods or the scale of the charges. 3. The obligation to observe, in fixing a tariff within these broad limits, “equality of treatment for the strangers and the subjects of the respective territories.” [Illustration: Coffee Plantation at Yalicombe (Oriental Province).] Thus, equality is sure to be observed as regards the tariff, both in the case of subjects and foreigners, and especially so in business which may be called the sphere of private activity, _i. e._, commerce. Thus also the power of the State to allow exclusive access to the railways, to impose extra or unfair charges, is minimised. The Berlin Act goes so far, but does not pass these limits. Beyond this, it does not affect the sovereign prerogatives of the State as regards its territory. According to the usual right of the Powers in all that regards railways, the State can order the establishment of the same, can have them constructed, run them itself, and fix their tariff. It can also, if deemed preferable, authorise a concessionaire to collect the charges on the contemplated line, on condition that he shall undertake the construction and maintain the established tariff. The Berlin Act respects these fundamental rights. It offers no opposition against whatever arrangements the State makes with its concessionaire as regards a schedule of rates with respect to the nature of goods or the scale of the charges. It does not intrude upon the internal organisation of the rates, except so far as it circumscribes them within the following limitations: 1, all are free to use the railways; 2, no distinction can be based on the nationality of individuals; 3, and no excessive rates are to be imposed. Circumstances may render changes in the tariff advisable, and the State may modify the rates periodically.[24] It may also exercise the right of ordering its concessionaire to make certain modifications and reductions.