Any such city shall have the power to contract for materials, supplies, or work, to be supplied to, or performed for, said city, subject to the provisions of section five of this article,¹ during one or more years, and the city council may by ordinance authorize such contract without the necessity of making an appropriation therefor beyond the current year. Such contracts shall be enforceable notwithstanding the provisions of section ten, article seventeen hereof.² When the term of any such contract exceeds four years, there shall be inserted in the contract a clause reserving to the city the right to terminate the same at its option at any time after the expiration of four years without liability to the contractor for damages for the loss of profits which would have been realized had the contract not been terminated. If the term of any such contract exceeds one year, a reasonable time, not exceeding six months, shall be allowed the contractor thereunder to secure the necessary equipment to perform such contract and to begin the performance thereof.