CORDAGE.
Ropes are distinguished as to size by their circumference in inches. Their length is given in fathoms.
Hemp rope when new stretches freely, and deteriorates very much after a few months' wear. It is about one third stronger than manilla rope.
To ascertain the strain in pounds a rope will bear without breaking, square the circumference and multiply the result by the tabular unit in the following table:
| Kind. | Circumference. | White. | Tarred. | ||
| 3-strand. | 4-strand. | 3-strand. | 4-strand. | ||
| Hemp | 2.5 to 6 in. | 1140 | 1330 | 850 | 1000 |
| 6 " 8 " | 1090 | 1360 | 825 | 940 | |
| Manilla | 2.5 to 6 in. | 810 | 950 | .... | .... |
| 6 " 12 " | 760 | 835 | .... | .... | |
For ropes in daily use reduce the tabular unit one third to meet reduction in strength by wear and exposure.
A safe general rule for all ropes is, one fourth the square of the circumference gives the breaking weight in short tons.