This settled the interest question and the next one to arise was the question as to the payment of five per cent, of the net earnings towards the extinguishment of the Government indebtedness, as provided for in the act of 1862, viz., "And after said road is completed, until said bonds and interest are paid, at least five per centum of the net earnings shall be annually applied to the payment thereof." By act of Congress, June 22nd, 1874, the Secretary of the Treasury was directed to require this payment, failing which, to bring suit. The Supreme Court decided this in 1878 that the Company must pay this five per cent and defined net earnings as what was left out of the gross earnings after deducting all the expense of organization, operation, or for betterments paid out of earnings. In 1878 the so called "Thurman Act" became law, by which a sinking fund was established looking to the extinguishing of the Company's indebtedness to the Government. This sinking fund was to be made up of one half the amount accruing on Government Transportation, the five per cent of net earnings, plus enough more of the earnings to make up in all twenty-five per cent of the total net earnings, but not to exceed eighty-five thousand dollars per annum,--this sinking fund to be invested by the Secretary of the Treasury in Government Bonds. Up to 1879 the policy of the Company was to transfer all through freight at its eastern termini, none of its equipment being allowed to leave its own rails. Soon after the absorption of the Kansas Pacific Railroad and through it the Denver Pacific Railroad, the Union Pacific entered upon a policy of extension by the absorption of other roads and building of branch lines. Under this arrangement the Texas lines--Fort Worth, Texas, to Denver, Colo., eight hundred and one miles--were completed and added to the system. This line was built under the name of the Denver, Texas and Gulf (formerly Denver and New Orleans), the Fort Worth and Denver City and the Denver City and Fort Worth Railroads. In 1880 the Railroad from Atchison west--originally the line that was to have connected with the Union Pacific Railroad at the hundredth Meridian, known as the Central Branch Union Pacific--became part of the system by purchase and was leased to the Missouri Pacific Railway Company who have since that time operated it. Another line added to the system was the narrow (three foot) gauge line from Denver to Leadville and Gunnison. This line was commenced in 1873 under a Charter from the Colorado Legislature, reaching Buena Vista, February 22nd, 1880 and Gunnison, the summer of 1881. It was absorbed by the Union Pacific on January 1st, 1881.