First of all, the duration of the franchise should be limited. Formerly, it was not uncommon to grant franchises for fifty or one hundred years, and indeed sometimes for an indefinite period. The objection to this practice is that with the growth of the city, the increased value of the franchise resulting from such growth goes entirely to the company, while the city is deprived of the opportunity of making a better bargain with the company. A franchise ought, however, to be for a period sufficiently long to enable the company to derive a reasonable return on its investment. Obviously, no company could afford to establish an electric light plant or gas plant if its franchise were limited to a period as short as five years. The better opinion now is that twenty or twenty-five years is a reasonable period, and the constitution or statutes of a number of states forbid the granting of franchises for a longer period. Frequently the franchise contains provisions in regard to the rates to be charged and the quality of service to be performed. In many states there are state commissions which have power to supervise the operations of all public service corporations and in some cases even to fix the rates which they shall be allowed to charge. As long as such rates are reasonable, that is, high enough to allow the corporation a reasonable return on its investment, the courts will not interfere. It is now the practice to require public service companies to pay a reasonable compensation for the franchises which they receive. This is usually a certain percentage of the gross receipts, or sometimes, in the case of street railway companies, a certain sum for each car operated. When the compensation is a certain percentage of the receipts, provision ought to be made for examination of the books of the company in order to prevent the public from being defrauded of its share of the earnings. =Municipal Ownership.=--Sometimes, instead of relying upon private corporations to supply the people with water, gas, and electric light, the city itself undertakes to do this. Very many cities own their waterworks,[8] while some own their electric light plants, and a few own their gas plants. In Europe, municipal ownership and operation of such public utilities is very common, and even the telephone and street railway services are often supplied by the city. [8] The Census Bureau reported in 1916 that 155 of the 204 cities having populations in excess of 30,000 owned their water supply systems.