(3). They were acquainted with some of our most famous mountain passes, showing that they were not ignorant of the law of least resistance; and, to a marked degree, their works are found beside, and in general alignment with, our modern roads—which to a great degree followed the ancient routes of the Indians which so invariably obeyed this law.
(4). The comparative study of the mound-building Indians’ works proves that the migrations of that race did not follow even the larger streams by which they labored most extensively.