“ Appellant, along with other railroads, has for years engaged in the 'roller lumber traffic' by performing intentionally delayed service in the transportation of lumber from the West Coast to market. Six roads so engaged have filed tariffs covering such services at the same rate as their fast freight, and the Interstate Commerce Commission now has such tariffs under investigation and consideration. Appellant, however, has refused to file a tariff covering such service but continues to handle roller lumber traffic on the same tariff as its fast freight. ”