Descriptions and elevations of precise level bench marks, etc.-Continued. TABULATION OF PRECISE LEVEL RESULTS, BLAIR, NEBR., TO DE WITT, MO., 1893. In the table of results column 1 gives the bench mark, T. B. M., signifying temporary bench mark, and P. B. M, signifying precise level bench mark. Column 2 gives the bench mark from which that in column 1 was determined. Column 3 gives the length of stretch in meters. Column 4 gives the distance in kilometers from initial bench mark. Column 5 gives the direction in which the line was leveled. Dir. is for the direct line. Rev. is for the reverse line. Column 6 gives successive differences of elevation in millimeters between bench marks and the means of such determinations. Column 7 gives the residuals found by substracting each determination from the mean. Column 8 gives the discrepancy between the direct line and the mean, and is the algebraic sum of the residuals. Column 9 gives the discrepancy between the reverse line and the mean, and is the algebraic sum of the residuals. Column 10 gives the probable error, r, of the mean in column 5. Column 11 gives the probable error, R, of the mean elevation of each bench mark as computed from the beginning of the section. Column 12 gives the total rod correction as computed from initial bench mark (not used). Column 13 gives the elevation in meters of all bench marks referred to St. Louis directrix. Column 14 gives the elevation in feet of all bench marks referred to St. Louis directrix. Column 15 gives the elevation in feet of all old bench marks connected with referred to St. Louis directrix. Column 16 gives the discrepancy in feet of old bench marks. Column 17 gives the initial of observers; T. is for Assistant Engineer O. H. B. Turner. Bench marks marked with an asterisk (*) are not in the main line. |