53 Pa. Stat. § 16951
The chief engineer and surveyor of the city of Philadelphia, under an ordinance and appropriation by the councils thereof, shall cause to be made books of plans of the said city, divided into sections, so far as the streets of the said city are or shall be laid out, which shall show the situation and dimensions of each property therein, with the city numbers thereof, and who are the owners, with such succession of blank columns as will permit the names of future owners to be entered therein, with the dates of transfer, and with index for recording such names alphabetically. And the person or persons who shall be employed to perform such duty shall have access to all plans of survey in the offices of any surveyor of the said city, to all books in the recorder of deeds' office, and all records of the courts, and in the register's office, and may take copies or extracts thereof without any charge therefor.
53 P.S. § 16951