Except for liability for the negligence of the Port Authority and its employees, the Port Authority will not be responsible for the injury or loss of any cargo being loaded or unloaded at the public wharves or while on wharves or in the warehouses awaiting shipment or delivery, and will not be responsible for any delay for same nor for injury to or loss of cargo on its wharves or in its sheds by fire, leakage, or discharge of water from fire protection sprinkler system, collapse of building, shed platform or wharves, subsidence of floors or foundations, breakage of pipes. nor for loss or injury caused by rats, mice, moths, weevils or other animals or insects, frost or the elements, nor shall it be liable for any delay, loss or damage arising from damage to combinations of strikes, railroad derailments, delays to equipment breakdowns, tumult, insurrection, or acts of God; nor from any contingencies. Steamship companies arranging to use the wharves may be required to furnish watchman service at times when they have freight on the wharves.