The Fatal Accident at New Hartley Colliery: view from the railway, taken shortly after the catastrophe, 1862. The Hartley Colliery disaster was a coal mining accident in Northumberland, England, that occurred on 16 January 1862 and resulted in the deaths of 204 men and children. The beam of the pits pumping engine broke and fell down the shaft, trapping the men below. The disaster prompted a change in British law that required all collieries to have at least two independent means of escape. From "Illustrated London News", 1862.