ATRA'TO, a river of Colombia, more important from its position than from its magnitude. It has already been mentioned under the head of AMERICA in connection with the scheme of opening a communication by water between the Atlantic and the Pacific.
The main stream falls into the gulf of Darien by 9 mouthsthe quantity of water, from the almost daily rains, being large in proportion to the area drained, which does not, at the utmost, exceed 300 m. by 75. Of the 9 mouths, the third in rank, the Boca. Coquito, appears to offer the most available facilities for iniProving the navigation. About 220 tn. above this entrance, opposite to Quibdo, the A. is 850 ft. wide and 8 ft. deep at the shallowest parts, while the entire fall to the sea averages less than 3 in. to a mile. Unfortunately, however, the A. itself cannot advantageously be followed thus far, because, as one advances to the s., the intervening ridge to the w. and its streams towards the Pacific, beco'me less and less practicable.
A comparatively convenient route was surveyed through the munificence of Mr. F. M. Kelley, a private citizen of New York. Ascending the Boca Coquito as before, this route leaves the main stream at a distance of 63 m. from the sea, following the Truando, one of, its western affluents, for 36 m. more without impediment or interrup tion. From this point on the Truando to the Pacific there would still remain 32 miles.
The heaviest work would be a tunnel of 3-+ m. in length. According to the plan, the canal would be without a lock. The examination made by the United States govern ment in 1871, resulted in the opinion that the route wnich promised the least difficulty lay between the middle branch of the A. and the Jurador, flowing into the Pacific, which would require 48 m. of canal. Thus would the A. realize the destiny which Humboldt chalked out for it 70 years ago.