§ 307. Liens. Every fine imposed by judgment under section three
hundred four upon an owner shall be a lien upon the premises in relation
to which the fine is imposed from the time of the filing of a certified
copy of said judgment in the office of the clerk of the county in which
such premises are situated, subject only to taxes, assessments and water
rates and to such mortgage and mechanics' liens as may exist thereon
prior to such filing; and it shall be the duty of the department upon
the entry of said judgment to file such certified copy forthwith, and
such copy shall be forthwith indexed by such clerk in the index of
mechanics' liens.