There are some interesting corners to this subject. Mr Dickinson who carried out the research told me that when the L&Y railway was constructed by George Stephenson up the Calder Valley, they initially used stone sleepers. The Low Moor Company certainly used them. At later they switched to wooden sleepers. I have just walked the Honister Mine Incline in the Lake District. There are some excellent examples of wooden sleepers with the spikes intact. The impression is that the use of wood would lead to cheap efficient tramway construction. But when the Hartshead incline was constructed around the 1900's they reverted to stone sleepers. :confused: