"Oh, I want to go back to the Rio Grande! The Rio! That's where I long to be!" The words, sung in a soft and musical tenor, died away and changed to a plaintive whistle, leaving the scene more lonely than ever. For a few moments nothing was to be seen except the endless expanse of wilderness, and nothing was to be heard save the mournful warble of the singer. Then a horse and rider were suddenly framed where the sparse timber opened out upon...