When the ordinance under which said improvement is ordered to be made shall not provide that such improvement shall be made wholly by special assessment upon property benefited, the whole amount of such damage and costs, or such part thereof as shall not be assessed upon property benefited shall be paid from the general fund of such city or town, and if sufficient funds therefor are not already provided, such city or town shall levy and collect a sufficient sum therefor as part of the general taxes of such city or town, or may contract indebtedness by the issuance of bonds or warrants therefor as in other cases of internal improvements.