As will be explained later, the length of sub-surface tiling necessary to receive a given quantity of sewage effluent should vary, within certain limits, with the character and porosity of the soil, thus requiring larger quantities of effluent to be delivered from the siphon or dosing chamber in the case of the more compact soils. Also the size of this chamber should be determined with reference to the number of sections into which the sub-surface tiling system is divided. TABLE II FOR USE IN THE CONSTRUCTION OF SUB-SURFACE IRRIGATION SYSTEMS IN SANDY OR VERY POROUS SOILS Dimensions given are for inside measurement. ══════╤═══════╤═══════╤═══════╤═══════╤═══════╤════════╤════════╤════════ Number│ Total │No. of │ Mean │ Mean │ Depth │Diameter│ Dis- │Distance of │Length │ Sect- │ Width │Length │ of │ of │charging│ from Per- │ of │ions in│ of │ of │Siphon │ Siphon │Depth or│Roof to sons │3–inch │ Sub- │Siphon │Siphon │Chamber│ (Inch- │Maximum │ Top of Served│ Sub- │surface│Chamber│Chamber│ from │ es). │Depth of│ Wall by │surface│System.│(Feet).│(Feet).│Roof of│ │Effluent│between Sewer.│Tiling.│ │ │ │ Tank │ │ above │Settling │ │ │ │ │(Feet).│ │ Lower │Tank and │ │ │ │ │ │ │Edge of │ Siphon │ │ │ │ │ │ │ Siphon │Chamber │ │ │ │ │ │ │ Bell │ (Inch- │ │ │ │ │ │ │ (Inch- │ es). │ │ │ │ │ │ │ es). │ ──────┼───────┼───────┼───────┼───────┼───────┼────────┼────────┼──────── 4│ 140│ 2│2´ │2´ │ 2´ 4˝│ 3˝│ 13˝│ 12˝ 8│ 280│ 2│2´ 6˝ │2´ 6˝ │ 2´ 4˝│ 3˝│ 13˝│ 12˝ 12│ 420│ 2│2´ 6˝ │4´ │ 2´ 4˝│ 3˝│ 13˝│ 12˝ 15│ 525│ 2│3´ 6˝ │4´ │ 2´ 4˝│ 3˝│ 13˝│ 12˝ 25│ 875│ 2│3´ │4´ │ 3´ 2˝│ 5˝│ 23˝│ 12˝ 35│ 1225│ 2│3´ 8˝ │4´ 6˝ │ 3´ 2˝│ 5˝│ 23˝│ 12˝ 50│ 1750│ 2│4´ │6´ │ 3´ 2˝│ 5˝│ 23˝│ 12˝ 75│ 2625│ 2│3´ │6´ │ 3´ 2˝│ 5˝│ 23˝│ 16˝ 100│ 3500│ 2│4´ │7´ │ 3´ 2˝│ 5˝│ 23˝│ 16˝ 125│ 4375│ 3│5´ 6˝ │8´ │ 3´ 2˝│ 5˝│ 23˝│ 16˝ 150│ 5250│ 3│7´ │8´ │ 3´ 2˝│ 5˝│ 23˝│ 16˝ 175│ 6125│ 3│7´ 6˝ │8´ │ 3´ 9˝│ 6˝│ 30˝│ 16˝ 200│ 7000│ 3│8´ │8´ │ 3´ 9˝│ 6˝│ 30˝│ 18˝ ──────┴───────┴───────┴───────┴───────┴───────┴────────┴────────┴──────── TABLE III