(a) By serving, as in the case of a summons, such of those named in the writ, or added thereto, as may be found in the county in which the writ issued; and,

(b) Where the sheriff has information that those named in the writ, or added thereto, or any of them, may be found in any other county of this Commonwealth, the said person shall be served, as in the case of a summons, by the sheriff of the county in which the said defendants or any of them may reside, he being deputized for that purpose by the sheriff of the county in which the writ issues; and,

(c) In case any of those named in the writ, or added thereto, cannot be found by the sheriff, or their residences within this Commonwealth are unknown to him, or in case they reside without the Commonwealth, the said writ may be served by advertising a copy thereof, or a brief notice of the contents of the same, once a week for three successive weeks, in one newspaper of general circulation in the county, and in the legal periodical, if any, designated by the court for that purpose: Provided, however, That any defendant may accept service of said writ, in person or by counsel, with the same effect as if duly served therewith by the sheriff.

Where the said writ, or the brief notice of the contents thereof, have been advertised as aforesaid, the same shall have the same effect as if the writ had been personally served; and all those named therein, or added thereto, as to whom publication has been made, shall file their affidavit of defense, as required by the said writ, within fifteen days after the date of the last weekly advertisement of the said writ; and all those named therein or added thereto, who have been served as in case of a summons, shall file their affidavit of defense, as required by said writ, within fifteen days after such service. Service of any such writ may be made at any time within three months from the date on which it was issued, but it shall be served and returned at the earliest date possible, and the plaintiff may require its return at any time, whether or not it be actually served.