Hartley Colliery disaster

The Hartley Colliery disaster (also known as the Hartley Pit disaster or Hester Pit disaster) was a coal mining accident in Northumberland, England that occurred on Thursday 16 January 1862 and resulted in the deaths of 204 men. The beam of the pit's pumping engine broke and fell down the shaft, trapping the men below. The disaster prompted a change in UK law that henceforth required all collieries to have at least two independent means of escape.