It shall be the duty of the Assessor to ascertain the tithables and property within said City subject to taxation, and make return thereof to the Council, at such time as may be prescribed, substantially in manner and form as in the case of assessments by county assessors; and to this end he shall have access to the most recent books and records of the County of Mason upon payment of reasonable fees and charges, to be arranged and provided for by the Council. The latest accessible assessment for State and County purposes, including value, shall be used and adopted by him; but as to property not included in such assessment, he shall ascertain the same, fix the value thereof, and include the same in his assessment; but the Council may correct any error on his part in this regard, upon the application of any person aggrieved. In the discharge of his duties he shall have the same powers as are conferred by law upon county assessors. He shall receive a salary to be fixed by the Council of not less than two hundred dollars nor more than three hundred dollars per annum, which shall not be increased or diminished for the term for which he shall be elected.