All assessments on lands authorized to be made for the costs and expenses of the drainage of wet or overflowed lands by a commissioner or commissioners appointed by any court, or justice or judge thereof, under any general or special law enacted prior to April second, one thousand eight hundred and sixty-eight, shall be made with reference to the benefits resulting from such drainage and shall in no case be greater than the benefits. Any such general or special law authorizing such assessments shall be considered and construed in all courts as authorizing assessments to be made as herein above provided.