The board of county commissioners of any county having a population of less than ten thousand (10,000) and having a total assessed tangible valuation of more than twenty million dollars ($20,000,000) is hereby authorized to make an annual tax levy of not to exceed one and one-half (1 1/2) mills upon all the taxable tangible property of the county to create a fund for the purpose of rebuilding, remodeling, re-equipping and refurnishing of a courthouse, or making additions thereto, or for one or more of such purposes and to pay a portion of the principal and interest on bonds issued under the authority of Kan. Stat. Ann. § 12-1774, and amendments thereto, by cities located in the county. Said levy may be made annually for a period of not to exceed two years.