Before the Civil War, large quantities were given to the states for the construction of canals and railroads. Large tracts of the public lands have also been granted to private corporations as subsidies for the building of transcontinental railways. Finally, by an act of 1902, the proceeds from the sale of all public lands in seventeen Western states are set aside for constructing irrigation works in those states. By the _preëmption act_ of 1841, it was provided that 160 acres of land should be given to any family living thereon for a period of six months and paying $200 therefor. This act was repealed in 1891, but millions of acres were disposed of during the fifty years it was in force. By the _homestead act_ of 1863, still in force, any head of a family may acquire 160 acres by living on it for three years (it was five years before 1912), cultivating a certain part of it, and paying a small fee. _The Public Lands now Remaining_ aggregate about 665,000,000 acres, including those in Alaska. Of these lands a large part have been set aside for Indian reservations, national parks, military reservations, and national forests,[92] and is therefore not open to purchase or entry under the homestead act. Arid lands are sold in tracts not exceeding 640 acres at $1.25 per acre; mineral lands are sold at from $2.50 to $5 per acre; timber and stone lands at a minimum of $2.50 per acre; town site lands at a minimum of $10 per acre; and agricultural lands at $1.25 per acre. [92] There are now 153 national forests, embracing 175,940,000 acres. _Land Offices_ are established in all the states where there is any considerable amount of public land left. At each office there is a register and a receiver who examines applications for entries and issues certificates upon which patents or deeds are finally granted. =Indian Affairs.=--Another important branch of the government service falling within the department of the interior is the management of Indian affairs. For a long time each tribe was treated to some extent as though it were an independent community, and was dealt with somewhat as foreign nations are dealt with. In 1871, however, it was enacted that henceforth no Indian tribe should be acknowledged or treated as an independent nation or power with which the United States may contract by treaty--an act which marks the beginning of the end of Indian tribal authority. The policy of extending the jurisdiction of the government over the Indians was begun by an act of 1885 which gave the United States courts jurisdiction over seven leading crimes when committed by Indians on their reservations. Previous to that time, crimes committed by Indians against Indians within a reservation were left to be dealt with by the tribal authorities themselves.