Buchanan says that "A useful contrivance, in an engraving in the original, has been here adopted for the ease of the animal in descending; instead of causing it to run behind the waggon, a carriage is made, in which the horse stands at his ease all the time the waggons are descending, and starts perfectly fresh to his task of drawing them back. This plan was first practised in North America on the Mauchunk Railway. The reference is to the Mauch Chunk Switchback Railway.