The plans and measurements are evidences of the existence of mental capacities which were far in advance of those of the present Indian races, who are remarkable for their extreme indifference to all ideas of regularity of form, and who have not, and never could have had, the slightest acquaintance with the rules of geometry. The Licking river, after passing these inclosures, finally enters the Muskinghum, and the Muskinghum falls into the Ohio. The confluence takes place near the town of Marietta, where there are groups of earthworks which, in many respects, resemble those at Newark, and some of the areas were equal. The positions for the inclosures were evidently chosen upon similar principles. They were upon a comparatively elevated plateau, and had direct communication with the river. In the early part of the present century some discoveries were made, which were considered to be of the utmost importance. It was thought that they had a direct bearing upon the question of the civilisation and antiquity of the Mound Builders, and a letter, written by Dr. Hildreth, has been acknowledged to be a very important contribution to the evidence upon these subjects.[18] The letter ran as follows:- “Marietta, July 19th, 1819. “In removing the earth which composed an ancient mound in one of the streets of Marietta, on the margin of the plain, near the fortifications, several curious articles were discovered the latter part of June last. They appear to have been buried with the body of the person to whose memory this mound was erected. [Illustration: INCLOSURES AT MARIETTA. 1837.]