The report of Mr. STUART, Secretary of the Department of the Interior, presents a variety of interesting information concerning the various subjects which come under his supervision. The expenses of the department for the year have been $5,403,372; those for the next year are estimated at $7,132,043. The report enters at some length into an explanation of the various items of this increase. The whole number of persons on the pension rolls of the United States is 19,758; the whole number who have drawn pensions during the first two quarters of the present year is 13,079. The whole amount expended for pensions during the year is estimated at $1,400,000. The number of land warrants issued for Revolutionary service is 12,588; and for the war of 1812, 28,978. The number of claims presented for service in the Mexican war is 81,373, and for scrip in lieu of land, 3332, making a total of 84,705. The number of claimants under the general Bounty Land Law of the last session of Congress is estimated at 250,000. The sales of Public Lands during the first three quarters of 1850 have amounted to 869,082 acres; the amount sold in 1849 was 1,329,902. The amount located by Mexican bounty land warrants during three quarters of the present year was 1,520,120, against 3,405,520, during the whole of last year. The aggregate amount disposed of in three quarters of 1850 was 2,815,366--in 1849 it was 5,184,410. The revenue derived from the sale of public lands has averaged about a million and a quarter of dollars per annum, for the last fifty years, above all expenses. The extension of our Land System over our possessions on the Pacific is strongly urged; and a commission is suggested to adjudicate on all questions of disputed titles to land in California. Mr. STUART recommends the sale of the mineral lands, in fee simple to the highest bidder at public auction--in lots small enough to afford persons in moderate circumstances the opportunity of being bidders. The annexation of Texas and our treaty with Mexico, have added about 124,000 Indians to our population; many of them are fierce in their disposition and predatory in their habits. Further legislation for the protection of our people from them has become necessary. The Secretary urges the necessity of a highway to the Pacific; whether a railway, a plank road, or a turnpike would be most expedient, he says, can only be determined after a careful survey of the country and its resources shall have been made. He suggests the propriety of authorizing an immediate survey. The establishment of an Agricultural Bureau is urged, and statements are made of the steps taken in securing the census returns.