Henequen is now grown on large plantations, the plant being about five years old before the long, sword-like leaves are ready to cut. It continues to yield a supply for ten or twenty years, this lasting until the flower stalk, or “pole,” appears, after which the plant soon dies. As Manila fiber is at times adulterated with Sisal, so has the latter its adulterant in a plant called Istle, which grows in Mexico and has hitherto been chiefly used in brush making. [Illustration: NEW ZEALAND HEMP OR FLAX] [Illustration: CRUDE HAND METHOD OF CLEANING MANILA FIBER ON PLANTATION] These are the chief plants used in rope making. To them we may add coir, obtained from the brush of the cocoanut, which has been long used in India, and has come into use in Europe in recent years. It is fairly strong and has the advantage of being considerably lighter than hemp or Manila. And, unlike these, it does not need to be tarred for preservation, as it is not injured by the salt water. Two other rope-making fibers of importance are the Sunn hemp of India and cotton, ropes of the latter being largely used for certain purposes, such as driving parts of textile machinery. Wire Ropes. We have not completed the story of rope making. There is the wire rope to consider, a kind of cordage now largely used in many industries, in which it has superseded hemp ropes and chains. These seem to have originated in Germany about 1821. In the bridge at Geneva, built in 1822, ropes of untwisted wire, bound together, were used, and some fifteen years later “stranded” wire ropes were employed in the Harz mines. These at first were made of high-class wire, but only steel is now used in their manufacture. A strand of wire rope generally consists of from six to nine wires and sometimes as many as eighteen, but much larger ropes are made by twisting these strands together. They are generally galvanized to prevent them from rusting. [Illustration: STACKING BALES OF MANILA FIBER WITH PORTABLE COMPRESSED AIR ENGINE] [Illustration: HANK OF MANILA FIBER TWELVE FEET LONG] The applications of wire ropes are very numerous, an important one being for winding and hauling purposes in mines. For aerial ropeways they are extensively employed, and are of high value in bridge building, the suspension bridge being sustained by them. The strength of the steel wire used for ropes varies from seventy to over one hundred tons per square inch of sectional area, the weight of a hemp rope being about three times that of a wire rope of equal strength. Pine Tar for Ropes.