§  2.  Classification of transportation corporations. A transportation  corporation shall be either, 1. A gas corporation, an electric corporation or a  gas  and  electric  corporation. 2. A telegraph corporation, a telephone corporation or a telegraph and  telephone corporation. 3. A water-works corporation. 5. A ferry corporation. 6. A pipe line corporation. 7. A freight terminal corporation. 8. A district steam corporation. 9. Sewage-works corporation.