The Wonder Book Of Knowledge Part 15

2. Starting fire.

3. Racking back coals.

4. Tar coming from kiln.

5. Dipping and barreling.

6. Working around kiln.

7. After hard day and night.

8. Tar makers at home.

9. Burning completed.]

Manila and Sisal Fibers.

Manila hemp, as it is called, is a product of our Philippine dependency, being obtained from a species of the banana plant which grows abundantly in those islands. Its fiber is very long, ranging from six to ten feet, and is noted for its smoothness and pliability, a feature which makes it ideal for rope making. Gloss and brilliancy are also characteristics of good quality Manila.

[Ill.u.s.tration: AMERICAN HEMP STACKED IN FIELDS]

Manila hemp is obtained from the leaf stalks of the Philippine plant known as the Abaca, the leaf stems of which are compressed together, and const.i.tute the trunk of the plant. It is obtained by sc.r.a.ping the pulp from the long fibers, drying these when thoroughly cleaned, and baling them for market.

The high price of the Manila product, however, has brought a cheaper fiber, of American growth, into the market; this being that known as Sisal, extracted from henequen, a cactus-like plant of Yucatan. As a subst.i.tute for or rival of Manila hemp it has come into common use. Its cheapness recommends it despite the fact that it is not of equal strength, and also that its fibers are shorter, being from two to four feet in length. Sisal also lacks the flexibility of Manila, being much more stiff and harsh. The development of the self-binding reaper on our western grain-fields has opened a gold mine for Sisal cordage. Of the annual import of this fiber to the United States, 300,000,000 pounds in quant.i.ty, a large proportion finds its way to the wheat fields of the West. It is also used in all other wheat-yielding countries.

[Ill.u.s.tration: PHILIPPINE HEMP CART]

[Ill.u.s.tration: LOADING FIBER FROM SISAL FIBER PLANT ONTO PLANTATION CAR]

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. .h.i.therto been chiefly used in brush making.

[Ill.u.s.tration: NEW ZEALAND HEMP OR FLAX]

[Ill.u.s.tration: 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-cla.s.s 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.

[Ill.u.s.tration: STACKING BALES OF MANILA FIBER WITH PORTABLE COMPRESSED AIR ENGINE]

[Ill.u.s.tration: 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.

Who does not know of the tarred rigging that once meant so much to the rope maker? Its very odor seems to cling to the pages of seafaring books. When steam power took the place of wind power in ships the use of tarred rigging naturally declined, yet tarred goods still form an important branch of the rope business. Pine tar is the kind best suited for cordage, the yellow, longleaf, or Georgia pine holding the first rank in the United States for tar making. This tree is found along the coast region from North Carolina to Texas.

In tar-kiln burning only dead wood is used, the green tree yielding less tar and of lower quality. It is a slow process, as a brisk fire would consume the wood without yielding tar. As the tar comes from the kiln it is caught in a hole dug before the outlet and is dipped up and poured into barrels, the average yield being one barrel of tar to the cord of wood. As above said, it is indispensable to protect cordage exposed to the effects of moisture, except in the case of coir ropes. Oiling is also an important process in the manufacture of ropes from hard fibers, as Manila, Sisal and New Zealand. This softens them and makes them more workable, and it also acts as a preservative.

[Ill.u.s.tration: INSPECTING MANILA FIBER AT DOCK]

[Ill.u.s.tration: SHIPPING PLATFORM OF A LARGE FACTORY]

Why does Rope Cling Together?

This is probably due to a degree of roughness in the surface of fibers, often imperceptible to the eye, yet preventing them when in close contact from slipping easily upon each other. This is greatly increased by twisting the fibers together, and is added to by the toughness of the fibers themselves, the whole giving to rope a great resisting power. In the case of wire rope it is the firmness with which the metal holds together that gives it its great resisting strength. It is also not unlikely that the pressure of gravitation takes part in rope making, by holding the fibers in close contact, even if we do not know how this force operates.

What is Rope Used for?

This is a question that has already been answered in great part. Its uses, in fact, are innumerable. It serves to hold things together, and also to hold them apart; to lift things into the air and to hold them down to the ground; to pull things forward and pull things back--but not to push things forward. For the latter something less flexible than rope is needed. Animals are tied or tethered by it and led by it, and man, himself, is one of its victims. This is especially the case in the dismal way in which man's career upon earth has so often been ended by lifting him from the ground by the aid of a rope loop around his neck.

It is of some comfort to know that this brutal use of the rope is being replaced by more humane methods of ending the lives of condemned criminals.

How did the Expression "A-1" Originate?

We have all become so accustomed to hearing the term "A-1" used to designate a thing as perfect that it does not occur to many of us to wonder how it originally came to be used in that connection. Its first use was as a symbol in the code by which vessels were graded in the register of shipping kept by Lloyd's, the originators of marine insurance. "A-1" was the best rating given to the highest cla.s.s vessels, "A" standing for perfect condition of the hull of the ship and "1"

meaning that the rigging and whole equipment was complete and in good order.

How has Man Helped Nature Give Us Apples?

The original of all the varieties of the cultivated apple is the wild crab, which is a small and extremely sour fruit, and is native of most of the countries of Europe. We use the crab-apple for preserving even now, although man's ingenuity has succeeded in inducing nature to give us many better tasting kinds.

The amazingly large number of different varieties which we have today have all been brought into existence through the discovery of the process of "grafting." There are a half a dozen or more different methods of grafting. The method most commonly practiced in working with apple trees is called "bud-grafting," and consists of transferring a plate of bark, with one or more buds attached, from one tree to another.

The wood of apple trees is hard, close-grained and often richly colored, and is suitable for turning or cabinet work. Apple-growers cla.s.sify apples into three different kinds, each consisting of a great many separate varieties. The three general divisions are--table apples, which are characterized by a firm, juicy pulp, a sweetish acid flavor, regular form and beautiful coloring; cooking apples, which possess the quality of forming by the aid of heat into a pulpy ma.s.s of equal consistency, and also by their large size and keeping properties; and cider apples, which have a considerable astringency and a richness of juice.

[Ill.u.s.tration: IN THE LAND OF THE APPLE

The Rogue River Valley, Oregon, in one section of which this photograph was taken, is known all over America for its wonderful apples. One apple-raiser in this district gathered two hundred bushels of apples per acre from his six-year-old trees.]

What Kind of a Crab Climbs Trees?

Besides the water-crabs that we are most of us used to seeing and eating, there are several different kinds of land-crabs. Probably the most interesting of them all is the great Robber-crab, which is found on certain islands of the Pacific. He is a creature of immense strength and climbs palm trees in order to pick, and break open, the cocoanuts. He lives in a den which he digs for himself in the ground.

Darwin gives an interesting description of these extraordinary animals: "I have before alluded to a crab which lives on cocoanuts; it is very common on all parts of the dry land, and grows to a monstrous size. The front pair of legs terminate in very strong and heavy pincers, and the last pair are fitted with others weaker and much narrower. It would at first be thought quite impossible for a crab to open a strong cocoanut covered with husk, but Mr. Liesk a.s.sures me that he has repeatedly seen this effected. The crab begins by tearing the husk, fiber by fiber, and always from that end under which the three eye-holes are situated. When this is completed, the crab commences hammering with its heavy claws on one of the eye-holes till an opening is made. Then turning round its body, it extracts the white alb.u.minous substance with its posterior and narrow pair of pincers.

"Every night it is said to pay a visit to the sea, no doubt for the purpose of moistening its gills. The young are likewise hatched, and live for some time, on the coast. These crabs inhabit deep burrows, which they hollow out beneath the roots of trees, and there they acc.u.mulate surprising quant.i.ties of the picked fibers of the cocoanut husk, on which they rest as a bed. To show the wonderful strength of the front pair of pincers, I may mention that Captain Moresby confined one in a strong tin box, the lid being secured with wire; but the crab turned down the edges and escaped. In turning down the edges, it actually punched many small holes through the tin!"

How are Files Made?

A good tool-kit holds a number of files of various shapes. Some are flat, others half-round, three-sided, square and round. They are generally thickest in the middle, while their teeth are of various degrees of fineness and of different forms.