| Circumference. | Wire Ropes Hawser-laid. | Round-link Crane-chain, Length of Link not Exceeding Five Diameters of the Iron. | ||||
| Iron. Safe Working Strain. | Steel. Safe Working Strain. | Weight per Fathom. | Diameter of Iron of Link. | Safe Working Strain. | Weight per Fathom. | |
| Inches. | Cwts. | Cwts. | Lbs. | Inches. | Cwts. | Lbs. |
| ¾ | -- | -- | -- | 3/16 | 8 | 2.1 |
| 1 | 10 | -- | 0.94 | ¼ | 15 | 4.88 |
| 1¼ | 13½ | -- | 1.5 | 5/16 | 22 | 7.26 |
| 1½ | 21½ | 62½ | 2.5 | ⅜ | 32 | 10.57 |
| 2 | 40 | 112 | 3.5 | 7/16 | 45 | 13.0 |
| 2¼ | 50 | -- | 4.5 | ½ | 65 | 16.0 |
| 2½ | 60 | 195 | 5.75 | 9/16 | 75 | 21.0 |
| 2¾ | 77 | -- | 6.5 | ⅝ | 92 | 25.0 |
| 3 | 92 | 245 | 7.5 | 11/16 | 112 | 29.0 |
| 3¼ | 109 | -- | 8.5 | ¾ | 135 | 36.0 |
| 3½ | 125 | 275 | 10.75 | 13/16 | 157 | 43.0 |
| 4 | 157½ | 450 | 13.25 | ⅞ | 182 | 46.5 |
| 4½ | 210 | 545 | 17.75 | 15/16 | 210 | 58.0 |
| 5 | 248 | 669 | 21.5 | 1 | 240 | 63.5 |
BLOCKS, TACKLE, ETC.
Blocks are of two kinds, made and mortised. A made block consists of four parts: shell, sheave, strap, and bush. A mortised block is made of a single block of wood, mortised out to receive a sheave.
Blocks are single, double, or treble, according to the number of sheaves.
A Tackle is a purchase formed by reeving a rope through two or more blocks for the purpose of hoisting.
A Whip is a purchase made by a rope rove through one single block.
A Gun-tackle Purchase is a rope rove through two single blocks, and made fast to the strap of the upper block. The parts of all tackles between the fasts and sheave are called the standing parts. The parts between the sheaves are the running parts, and the part which is taken hold of in hoisting is called the fall.
A Whip upon Whip is where the block of one whip is made fast to the fall of another.
A Luff-tackle Purchase is a single and a double block, the end of the rope being fast to the upper part of the single block, and the fall coming from the double block. A luff-tackle upon the fall of another luff-tackle is called luff upon luff.