If three fifths of those voting at said election have voted for the proposed taxation, the county commission shall levy said special tax and cause the tax assessor to assess the same on the taxable property in said county, which shall not exceed $.10 on each $100.00 of taxable property in said county; but the rate of such special tax shall not increase the rate of taxation, state and county combined, in any one year to more than $1.25 on each $100.00 of taxable property in said county, but all special county taxes for public buildings, roads, bridges and the payment of debts existing at the ratification of the Constitution of 1875 shall not be included in the aforesaid $1.25 on the $100.00 of taxable property.