The historical record is scanty but it seems that the Steam Horse operated successfully for an unknown period. So much so, that another, larger, one seems to have been built for the Newbottle Colliery, in County Durham. This locomotive cost £540 and may have had two cylinders. During 1814 and 1815 it hauled loads up a 1 in 36 gradient at 3 miles per hour (4.8 km/h), but the colliery owners were not happy with it. On 31 July 1815, during a demonstration, the new wrought iron boiler exploded, killing thirteen spectators and injuring several others, and the idea was not pursued. This incident was the first recorded railway disaster.