The proper assessors shall make the assessment and valuations of all subjects of taxation within their respective districts as provided by existing law, and in so doing shall view all taxable property in their district. The assessors shall make a personal house-to-house canvass of their district in order that such lists of persons may be accurate and correct in so far as it is possible to so make them. A list of all persons shall not be required to be made yearly but triennially in the year immediately preceding the regular triennial assessment. Any assessor who shall fail to make such assessments and valuations and lists in the manner herein provided or who shall knowingly and wilfully make any false assessment, shall be guilty of a misdemeanor, and, upon conviction thereof, shall be sentenced to pay a fine not exceeding one thousand dollars ($1,000), and in default of the payment of such fine and costs, to undergo an imprisonment not exceeding six (6) months.