The City of Dunbar is hereby authorized to issue and sell bonds of said City for the purpose of buying and building electric light plants, water works, gas lines and fields and other public utilities, and for buying and building Municipal buildings, jails, and fire stations; and such bonds shall be sold for not less than par, and be payable within a period not to exceed thirty-four years, and shall bear interest, not to exceed six per centum per annum; and in the issuance and sale of said bonds the City shall be governed by all the restrictions of the Constitution of this State and the statutes of this State, with respect to the issuance and sale of other bonds, provided, that said City shall not, by the sale or issue of bonds for the purposes above mentioned,  cause the aggregate of its indebtedness, of every kind whatever, to exceed five per centum of the value of the taxable property therein, but may for the above purpose issue bonds to the maximum limit of said five per cent; nor shall said City make such issue and sale of bonds without, at the same time, providing for the collection of a direct annual tax sufficient to pay annually the interest on the same, and to create a sinking fund to pay the principal within the time for which said bonds shall be issued.