The Wonder Book Of Knowledge Part 20

The old-time rag-paper had disappeared for newspaper work, being superseded by wood-pulp paper, the cheapness of which added to the desire to produce presses of greater speed and efficiency. It was also desirable that papers should be delivered folded for the carrier, and this led to the invention of folding machines, one of the earliest of which, produced in 1875, folded 15,000 per hour.

We have in the foregoing pages told the main story of the evolution of the printing press from the crude machine used by Gutenberg in 1450 to the rapid cylinder press of four centuries later. There is little more to be said. Later changes were largely in the matter of increase of activity, by duplication and superduplication of presses until s.e.xtuple and octuple presses were produced, and by adding to the rapidity and perfection of their operation, and the extraordinary ingenuity and quickness with which the printed sheets were folded and made ready for the convenience of the reader. Sir Rowland Hill's dream of a press which would print both sides of the paper at one operation in due time became a realized fact, while vast improvements in the matter of inking the forms, and even the addition of colored ink by which printing in color could be done, were among the new devices.

[Ill.u.s.tration: WAs.h.i.+NGTON HAND PRESS, 1827]

What we have further to say is a question of progress in rapidity of action rather than of invention. The 20,000 papers printed per hour, above stated, has since been seen pa.s.sed to a degree that seems fairly miraculous. The quadruple press of 1887 turned out eight-page papers at a running speed of 18,000 per hour, these being cut, pasted and folded ready for the carrier or the mails. Four years later came the s.e.xtuple press (the single press six times duplicated) with an output of 72,000 eight-page papers per hour, and in a few years more the octuple press, its output 96,000 eight-page papers per hour. Larger papers were of course smaller, but its capacity for a twenty-page paper was 24,000 per hour.

[Ill.u.s.tration: ISAAC ADAMS' BED AND PLATEN PRESS, 1830]

[Ill.u.s.tration: SINGLE LARGE CYLINDER PRESS, 1832-1900]

[Ill.u.s.tration: SINGLE SMALL CYLINDER PRESS, 1835-1900]

[Ill.u.s.tration: DOUBLE CYLINDER PRESS, 1835-1900

These presses were built up to 1900 and this picture shows the latest design brought out about 1882.]

[Ill.u.s.tration: DOUBLE OCTUPLE NEWSPAPER WEB PERFECTING PRESS, 1903]

[Ill.u.s.tration: ELECTRIC-HEATED PNEUMATIC MATRIX-DRYING MACHINE, 1911]

As may well be conjectured, the twentieth century has had its share in this career of progress, the perfected press of 1916 being credited with the astounding output of 216,000 eight-page papers in an hour, all folded, cut and counted in lots. Where part of the pages are printed in three colors this press has still a running speed of 72,000 per hour.

This machine is composed of 27,100 separate pieces, it being 47 feet long, 8 feet wide and 13 feet high, while such a mighty complication of whirling wheels and oscillating parts nowhere else exists.

A word more and we are done. To feed such giant presses the old hand method of setting and distributing type has grown much too slow. The linotype machine has added greatly to the rapidity of this centuries-old process. To this has been added the later monotype, of similar rapidity, while type distributing has become in large measure obsolete, the types, once used, going to the melting pot instead of to the fingers of the distributors.

What do We Mean by the "Flying Dutchman"?

The Flying Dutchman is a phantom s.h.i.+p said to be seen in stormy weather off the Cape of Good Hope, and thought to forbode ill luck. One form of the legend has it that the s.h.i.+p is doomed never to enter a port on account of a horrible murder committed on board; another, that the captain, a Dutchman, swore a profane oath that he would weather the Cape though he should beat there till the last day. He was taken at his word, and there he still beats, but never succeeds in rounding the point. He sometimes hails vessels and requests them to take letters home from him.

The legend is supposed to have originated in the sight of some s.h.i.+p reflected from the clouds. It has been made the ground-work of one or two novels and an opera by Wagner.

Why does a Duck's Back Shed Water?

Nature has provided the duck with a protection against water just as she has so wisely protected all animals against such elements as they have to live in.

The feathers on a duck are very heavy and close together, and at the bottom of each feather is a little oil gland that supplies a certain amount of oil to each feather. This oil sheds the water from the back of a duck as soon as it strikes the feathers.

Canvasback ducks are considered the finest of the water-fowls for the table. The canvasback duck is so called from the appearance of the feathers on the back. They arrive in the United States from the north about the middle of October, sometimes a.s.sembling in immense numbers.

The waters of Chesapeake Bay are a favorite locality for them. Here the wild celery, their favorite food, is abundant, and they escape the unpleasant fishy flavor of the fish-eating ducks.

Why doesn't the Sky ever Fall Down?

The sky never falls down because there is nothing to fall. What we see and call the sky is the reflection of the sun's rays on the belt of air that surrounds the earth. That beautiful blue dome that we sometimes hear spoken of as the roof of the earth is just the reflected light of the sun on the air.

The atmosphere of the earth consists of a ma.s.s of gas extending to a height which has been variously estimated at from forty-five to several hundred miles, possibly five hundred, and bearing on every part of the earth's surface with a pressure of about fifteen pounds per square inch.

How are Sand-Dunes Formed?

Sand-dunes are composed of drift sand thrown up by the waves of the sea, and blown, when dry, to some distance inland, until it is stopped by large stones, tree roots or other obstacles. It gradually acc.u.mulates around these, until the heaps become very large, often forming dunes or sand-hills.

What do We Mean by an "Eclipse"?

Any good dictionary will tell us that an eclipse is an interception or obscuration of the light of the sun, moon or other heavenly body by the intervention of another and non-luminous heavenly body. Stars and planets may suffer eclipse, but the princ.i.p.al eclipses are those of the sun and the moon.

An eclipse of the moon is an obscuration of the light of the moon occasioned by the interposition of the earth between the sun and the moon; consequently all eclipses of the moon happen at full moon; for it is only when the moon is on that side of the earth which is turned away from the sun, and directly opposite, that it can come within the earth's shadow. Further, the moon must at that time be in the same plane as the earth's shadow; that is, the plane of the ecliptic in which the latter always moves. But as the moon's...o...b..t makes an angle of more than five degrees with the plane of the ecliptic, it frequently happens that though the moon is in opposition it does not come within the shadow of the earth.

[Ill.u.s.tration: DIAGRAMS ILl.u.s.tRATING THE THEORY OF ECLIPSES.]

The theory of lunar eclipses will be understood from Fig. 1, where _S_ represents the sun, _E_ the earth, and _M_ the moon. If the sun were a point of light there would be a sharply outlined shadow or umbra only, but since the luminous surface is so large, there is always a region in which the light of the sun is only partially cut off by the earth, which region is known as the penumbra (_P P_). Hence during a lunar eclipse the moon first enters the penumbra, then is totally eclipsed by the umbra, then emerges through the penumbra again.

An eclipse of the sun is an occultation of the whole or part of the face of the sun occasioned by an interposition of the moon between the earth and the sun; thus all eclipses of the sun happen at the time of new moon.

Fig. 2 is a diagram showing the principle of a solar eclipse. The dark or central part of the moon's shadow, where the sun's rays are wholly intercepted, is here the umbra, and the light part, where only a part of them are intercepted, is the penumbra; and it is evident that if a spectator be situated on that part of the earth where the umbra falls there will be a total eclipse of the sun at that place; in the penumbra there will be a partial eclipse, and beyond the penumbra there will be no eclipse.

As the earth is not always at the same distance from the moon, and as the moon is a comparatively small body, if an eclipse should happen when the earth is so far from the moon that the moon's shadow falls short of the earth, a spectator situated on the earth in a direct line between the centers of the sun and moon would see a ring of light around the dark body of the moon; such an eclipse is called annular, as shown in Fig. 3; when this happens there can be no total eclipse anywhere, because the moon's umbra does not reach the earth.

An eclipse can never be annular longer than twelve minutes twenty-four seconds, nor total longer than seven minutes fifty-eight seconds; nor can the entire duration of an eclipse of the sun ever exceed two hours.

An eclipse of the sun begins on the western side of his disc and ends on the eastern; and an eclipse of the moon begins on the eastern side of her disc and ends on the western.

The average number of eclipses in a year is four, two of the sun and two of the moon; and as the sun and moon are as long below the horizon of any particular place as they are above it, the average number of visible eclipses in a year is two, one of the sun and one of the moon.

What are Dreams?

The dictionary tells us that a dream is a train of vagrant ideas which present themselves to the mind while we are asleep.

We know that the princ.i.p.al feature, when we are dreaming, is the absence of our control over the current of thought, so that the princ.i.p.al of suggestion has an unlimited sway. There is usually a complete want of coherency in the images that appear in dreams, but when we are dreaming this does not seem to cause any surprise.

Occasionally, however, intellectual efforts are made during sleep which would be difficult to surpa.s.s when awake.

It is said that Condillac often brought to a conclusion in his dreams, reasonings on which he had been employed during the day; and that Franklin believed that he had been often instructed in his dreams concerning the issue of events which at that time occupied his mind.

Coleridge composed from two to three hundred lines during a dream; the beautiful fragment of "Kubla Khan," which was all he had committed to paper when he awoke, remaining as a specimen of that dream poem.

The best thought points to the fact that dreams depend on natural causes. They generally take their rise and character from internal bodily impressions or from something in the preceding state of body or mind. They are, therefore, retrospective and resultant, instead of being prospective or prophetic. The latter opinion has, however, prevailed in all ages and among all nations, and hence the common practice of divination or prophesying by dreams, that is, interpreting them as indications of coming events.

What Makes Our Teeth Chatter?

When one is cold there is apt to be a spasm of s.h.i.+vering over which the brain does not seem to have any control. The spasm causes the muscles of the jaw to contract very quickly and as soon as they are contracted, they let the jaw fall again of its own weight. This occurring many times in rapid succession is what causes the teeth to chatter.