In the fourth line the first 10 columns need no further explanation. The (11th) column is the sum of the (10th) column, and the (11th) column in the third line. It represents the total number of persons tributary to manhole 3.4 on lateral No. 8. Column (13) in the fourth line is the sum of column (13) in the third line and the (12th) column in the fourth line, and the (15th) column in the fourth line is the product of the 2 preceding columns in the fourth line. Note that in no case is the figure in column (15) the sum of any previous figures in column (15). With this introduction the student should be able to check the remaining figures in the table, and should compute the quantity of sewage entering manhole No. 142 from the west, making reasonable assumptions for the tributary quantities from beyond the limits of the map. TABLE 19 COMPUTATIONS FOR QUANTITY OF SEWAGE FOR A SEPARATE SEWERAGE SYSTEM ──────────┬──────────┬──────────┬───────┬───────┬──────┬───────┬───── On Street │ From │To Street │ From │ To │Length│Mark of│Area, │ Street │ │Manhole│Manhole│ Feet │ Added │Acres │ │ │ │ │ │ Areas │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ ──────────┼──────────┼──────────┼───────┼───────┼──────┼───────┼───── Nebraska │Map margin│Alley S. │ 3.5│ 3.4│ 338│ │ St. │ │ Grant │ │ │ │ │ │ │ St. │ │ │ │ │ Alley S. │Railroad │E. of │ 8.3│ 8.2│ 328│ 8.2│ 2.7 of Grant│ │ Missouri│ │ │ │ │ St. │ │ St. │ │ │ │ │ Alley S. │E. of │E. of │ 8.2│ 8.1│ 355│ 8.1│ 3.41 of Grant│ Missouri│ Kansas │ │ │ │ │ St. │ St. │ St. │ │ │ │ │ Alley S. │E. of │Nebraska │ 8.1│ 3.4│ 340│3.4_{8}│ 2.68 of Grant│ Kansas │ St. │ │ │ │ │ St. │ St. │ │ │ │ │ │ Nebraska │Alley S. │Alley S. │ 3.4│ 3.3│ 380│ │ St. │ of Grant│ of │ │ │ │ │ │ St. │ Meridian│ │ │ │ │ │ │ │ │ │ │ 7.1│ Alley S. │Railroad │Nebraska │ 7.2│ 3.3│ 800│3.3_{7}│ 7.14 of │ │ St. │ │ │ │ │ Meridian│ │ │ │ │ │ │ Nebraska │Alley S. │Alley S. │ 3.3│ 3.2│ 304│ │ St. │ of │ of Smith│ │ │ │ │ │ Meridian│ Av. │ │ │ │ │ │ │ │ │ │ │ 6.1│ Alley S.