Two kinds of wire rope are manufactured; the larger sizes, as also the most pliable, are composed of 133 wires, and are generally used for hoisting or running rope. Those of 49 wires are stiller, and are better adapted for standing rope, guys, and rigging.

For safe working load, allow 1/5 to 1/7 of ultimate strength, according to speed and vibration When substituting Wire Rope for hemp rope, it is good economy to allow for the former the same rate per foot run which experience has approved of for the latter.

Wire Rope is as pliable as new hemp rope of the same strength ; the former will therefore run over the same sized sheaves and pulleys which are used for the latter. But the greater the diameter of the sheaves, pulleys, or drums, the longer Wire Rope will last. In the construction of machinery for Wire Rope it will be found good economy to make the drums and sheaves as large as possible. The size of drum is as follows: The same figure which expresses the circumference in inches in the second column of the table is also the minimum diameter of drum in feet; doubling that figure will give the maximum. The diameter of drum should be no lees than the minimum, nor is it necessary to exceed the maximum. As an example, take a No. 4 rope, circumference 5 inches; therefore the minimum diameter of drum is 5 feet, and the maximum 10 feet. Or a No. 10¼ rope, circumference 2 inches; therefore minimum diameter is 2 feet; and maximum 4 feet. A smaller diameter of drum may answer, but the short bending will result in a much more rapid wear. In most cases the Rope will wear twice as long on a maximum diameter as on a minimum.

Experience has also demonstrated that the wear increases with the speed. It is better to increase the load than the speed.

Wire Rope is manufactured either with a wire or hemp centre. The latter is more pliable than the former, and will wear better where there is short bending.

Wire Rope must not be coiled or uncoiled like hemp rope. When mounted on a reel the latter should be turned on a spindle to pay off the rope. When forwarded in a coil without reel, roll it over the ground like a wheel, and run off the rope in that way. All untwisting must be avoided.

To preserve Wire Rope apply raw linseed oil with a piece of sheepskin, wool inside; or mix the oil with equal parts of Spanish brown and lampblack.

To preserve Wire Rope under water or under ground, take mineral or vegetable tar, add 1 bushel of fresh slacked lime to 1 barrel of tar, (which will neutralize the acid,) and boil it well, then saturate the rope with the boiling tar.

The grooves of cast-iron pulleys and sheaves should be filled with well-seasoned blocks of hard wood, set on end, to be renewed when worn out. This end wood will save the rope and increase adhesion. The small pulleys or rollers which support the ropes on inclined planes should be constructed on the same plan. When large sheaves run with a very great velocity, the grooves must be lined either with leather set on end. with cork, or with India rubber. This is done in the case of all sheaves used in the transmis-tion of power between distant points by means of ropes, which frequently run at the rate of 4000 feet per minute. Rope ¾ inch diameter will transmit 100 horse power to a great distance.