Rangers ──────┬──────┬─────────┬──────┬────────────────────┬──────┬───────────┬─────── │ Area │ │ │ │ │ │ │ of │Intensity│ │ │ │ │ │Panel │ of │ │ │ │ │Maximum │Below │Pressure,│ │ │ │ Maximum │Stress │ this │ Pounds │Total │ │ │ Bending │Pounds │Depth,│ per │ Load │ │ │ Moment in │ per │Square│ Square │ in │Load Transmitted to │Size, │ Thousand │Square Depth │ Feet │ Inch │Pounds│the Ranger from the │Inches│Inch-Pounds│ Inch ──────┼──────┼─────────┼──────┼──────┬──────┬──────┼──────┼───────────┼─────── │ │ │ │Panel │Panel │ Both │ │ │ │ │ │ │Below │Above │Panels│ │ │ ──────┼──────┼─────────┼──────┼──────┼──────┼──────┼──────┼───────────┼─────── 26′ 9″│ 24│ 508.5│12,200│ 6000│ 6890│12,890│8 × 10│ 155│ 1160 23′ 0″│ 30│ 448│13,440│ 6545│ 6240│12,785│8 × 10│ 153│ 1150 19′ 0″│ 32│ 378│12,100│ 5860│ 2000│ 7,860│8 × 10│ 94.3│ 708 17′ 6″│ 12│ 328.5│ 3,942│ 1942│ 5190│ 7,132│8 × 10│ 85.6│ 636 13′ 0″│ 36│ 274.5│ 9,880│ 4690│ 4080│ 8,770│8 × 10│ 105│ 790 8′ 0″│ 40│ 189│ 7,560│ 3480│ 1060│ 4,540│6 × 8│ 54.4│ 850 6′ 0″│ 16│ 126│ 2,020│ 960│ 1727│ 2,687│6 × 8│ 32.2│ 503 0′ 0″│ 48│ 54│ 2,590│ 863│ 0│ 863│6 × 8│ 10.4│ 161 ──────┴──────┴─────────┴──────┴──────┴──────┴──────┴──────┴───────────┴─────── in which _S_ = permissible crushing across the grain in a column whose length is greater than 15 diameters; _S__{1} = unit working compressive strength of wood; _l_ = length of the column; _d_ = smallest dimension of the column; _l_ and _d_ are in the same units. The lower intermediate cross brace supports a length of 8 feet of the lower ranger on which the load has been found to be 12,890 pounds. The load on the end cross brace for the same ranger is one-half of this or 6,445 pounds. The length of each brace is 4 feet 4 inches. From Table 59, _S__{1} is 1,000 pounds per square inch. From the column formula, _S_ is 784 pounds per square inch. A 4 × 8 inch cross brace is the smallest that is feasible. This is stressed only 12,890 pounds or 403 pounds per square inch, which is well within the permissible limits. The results of the other computations for cross braces are shown in Table 60.