Coal burns with much less sparks than wood, which is why early steam trains had different kind of smoke stacks. In the west, wood was very readily available, and so was used as the primary source of fuel, which generated more sparks, and needed a spark catcher on the top of the smokestack. In the east, to opposite was true, and coal was a more efficient source of fuel. It is very clearly seen in this photograph of the completing of the transcontinental railway, linking the east and the west: [/TRAINFAN]