The mayor and clerk of the city is authorized to carry out the terms of any contracts heretofore or hereafter entered into by the city council for the purchase, leasing, acquiring, installation, operation, maintenance, supervision, regulation, and use of the parking meters provided for in this chapter, whether for a trial period or otherwise. The payment for the parking meters and their installation is to be provided for solely from the receipts, funds, and revenues obtained from the operation of the parking meters, without in any manner obligating the city to pay for the same from any other source.