To this group of works an interest attaches similar to that of the group of works mentioned in Louisiana. We are not certain but that we catch a glimpse of it while it was yet an inhabited Indian town. This is contained in the brief accounts we have of the wanderings of the unfortunate De Soto and his command. One of the chroniclers of this expedition La Vega, describes one of the towns where the weary Spaniards rested, and which we are sure was somewhere in Northern Georgia, in such terms, mentioning the graded way leading to the top, that Prof. Thomas, who has spent some time in this investigation, thinks his description can apply only to the mound under consideration.40 Whether this conclusion will be allowed to stand, remains to be seen. But, if true, then the darkness which rests upon this aboriginal structure lifts for a moment and we see around it a populous Indian town, able to send five hundred warriors to battle. The Spaniards marched on to sufferings and death, and darkness again closed around the Etowah Mound. When the Europeans next beheld it around it was the silent wilderness; the warriors had departed; the trees of the forest overspread it. We have now described the principal mound structures, and shown the different classes into which they are divided. But a large class of mounds are found scattered all through the Mound Builders’ territory that were probably used as signal mounds. Burial mounds were also often used for this purpose.41 This was because their location was always very favorable for signal purposes. Signaling by fire is a very ancient custom. The Indians on our western plains convey intelligence by this means at the present day. Some tribes use such materials as will cause different shades of smoke, using dried grass for the lightest, pine leaves for the darkest, and a mixture for intermediate purposes. They also vary the signal by letting the smoke rise in an unbroken column, or cover the fire with a blanket, so as to cause puffs of smoke. The evidence gathered from the position of the mounds, and traces of fire on their summit, is that the Mound Builders had a very extensive system of signal mounds. Hill Mounds.