Section 15
SEC. 15. All work of repair, construction, or equipment of roads or buildings involving a greater cost than five hundred dollars in money of the United States shall he let to the lowest responsible bidder, after ten days' public notice of the letting by advertisement in a paper of general circulation in the province, or, if there is no such paper, by a notice posted for ten days at the main entrance to the supervisor's office in the capital of the province. If the provincial board shall regard the contract to he let and the work to be done of sufficient magnitude, it may authorize the supervisor, in addition to giving the public notices above required, to advertise for bids in a newspaper published in the city of Manila. The supervisor is authorized to reject any or all bids, and if the bids are too high, he may recommend to the board that he be allowed to purchase the material and hire the labor and himself supervise the work and the board may then authorize such a course.