River Surveys and Profiles Made During 1903 (Classic Reprint) - Softcover

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Excerpt from River Surveys and Profiles Made During 1903

The elevations were based upon reliable heights derived from primary or precise levels of the United States Geological Survey. On this datum, with few exceptions, lines of flying levels were car ried up the bank of each stream and bench marks were established at intervals of about 1 'mile, usually on nails on tree roots. The elevations of the surface of the water at the head and foot of each shoal, rapid, or fall were noted These levels, with few exceptions, have been tied at both ends. In the case of Broad River primary levels were used instead of flying levels, and regulation bronze tab lets left at intervals of 6 miles.

The horizontal control of the survey was by plane table oriented by compass, while the distance was always obtained by means of stadia measurements. To further insure the accuracy of the work, the stadia rod was so divided that one division on it equaled one division of the scale used 1n plotting.

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