53 Pa. Stat. § 16510
If in laying out and adjusting the grades of the boundary avenues of Fairmount park the configuration of the ground shall make it advantageous to vary from the boundaries as now authorized by law, said park commissioners are hereby authorized and empowered to negotiate and agree with any owner or owners of ground bounding upon the park, and so required for the proper location and adjustment of said boundary avenues, as to the price and conveyance thereof, and to that end may take and receive additional ground or make exchanges or releases as the case may require: Provided, That the area of the said park shall not be increased thereby; in case of inability from any cause to fix the price of any land, or to adjust the terms of any exchange of ground required for the purpose aforesaid, the same shall be determined by a jury, appointed for the purpose, in the manner provided in the act to which this is a supplement.
53 P.S. § 16510