To illustrate this system, we would state that the city of Newark, Ohio, was the site of a very extensive settlement of the Mound Builders. This settlement was in a valley, but on all the surrounding hills were located signal mounds. And it is further stated that lines of signal mounds can be traced from here as a center to other and more distant points. The large mound at Mt. Vernon, twenty miles to the north, was part of this system. As the settlements of the Mound Builders were mostly in river valleys, we would expect to find all along on the bluffs fronting these valleys traces of signal mounds. In the Scioto Valley, from Columbus to Chillicothe, a distance of about forty miles, twenty mounds “may be selected, so placed in respect to each other that it is believed, if the country was cleared of forests, signals of fire might be transmitted in a few minutes along the whole line.” Some think the chain is much more extensive than this, and that the whole Scioto Valley, from Delaware County to Portsmouth, was so provided with mounds that signals could be sent in a very few minutes the whole distance.42 Miamisburg Mound. The valley of the Miami River was equally well provided with signal mounds. This great mound, at Miamisburg, Ohio, rising to the height of sixty-eight feet, was one of the chain by which signals were transmitted along the valley. Not only was each river valley thus provided, but there is evidence that communication was established between different river systems, so we can easily see how quickly the invasion of their country by an enemy from any quarter would become known in widely scattered sections. Immediately across the river from Chillicothe, Ohio, on a hill nearly six hundred feet high, was located a signal mound. A fire built upon it would be visible twenty miles up the valley, and an equal distance down. It would be also visible far down the valley of Paint Creek. Some think that such a system of lofty observatories extended across the whole State of Ohio, of Indiana, and Illinois, the Grave Creek mound, on the east, the great mound at Cahokia, on the west, and the works in Ohio filling up the line. We do not believe, however, it is safe to draw such conclusions. It is doubtful whether there was any very close connection between the tribes in these several sections.