Just a bit of a puzzle. Chapter 14 of Following the Equator has Sam and party railroading from Sydney to Melbourne. The border of New South Wales and Victoria has an abrupt change in railway gauge requiring the passengers to disembark from one train and board the next. This was done in the early morning chill. Twain's narrative has it with a narrow gauge to the frontier and a wide gauge to Melbourne. The illustration and chapter abstract has it the other way around.