All houses and buildings now built or to be built on any part of the park grounds, by or for boat or skating clubs, or zoological or other purposes, shall be taken to have rights subordinate to the public purposes intended to be subserved by acquiring and laying out the park, and shall be subject to the regulations of said park commissioners under licenses, which shall be approved by the commission and signed by the president and secretary, and will subject them to their supervision and to removal or surrender to the city whensoever the said commissioners may require.
53 P.S. § 16479