a possible
reference to a disastrous flood which occurred in Johnstown,
Pennsylvania, USA. In May of 1889, after heavy rains, a dam on the Conemaugh River gave way and
released a
wall of water about 75 feet high (23 m) and 1/2 mile wide (.81 km) on Johnstown. By the
time the water
hit the town it was traveling at approximately 50 miles (80.5 km) an hour, causing