Section 16. If Such Owner or Some Person on His Behalf Shall Within

two weeks from the mailing of such notice notify in writing the Commonwealth or the city that such owner wishes for an appraisal of such parcel, the Commonwealth or the city shall cause such parcel to be appraised by three competent and disinterested persons, one of whom shall be appointed by the Commonwealth or the city, one by said owner, and one by the superior court for the county: Provided, however, that the Commonwealth or the city and said owner may in writing appoint a sole appraiser. Said appraiser or appraisers shall forthwith after his or their appointment view the property and determine the fair value of such parcel, and shall make written report to the Commonwealth or the city of the same. The reasonable fees and expenses of the appraiser or appraisers shall be paid by the Commonwealth or the city. The Commonwealth or the city shall forthwith by writing mailed to such owner offer such parcel to such owner at the value as determined by the report of a majority of such appraisers, or by that of the sole appraiser in case of the appointment of one appraiser.